Introduction

Type 2 diabetes mellitus is a persistent or long-term medical condition that impacts the body's ability to produce or utilise insulin, a hormone crucial for the body's utilisation of glucose for energy [1]. The global incidence of type 2 diabetes mellitus is on the rise, affecting approximately 422 million adults, according to the latest update report from the World Health Organization website. This increase is mainly due to the rising rates of obesity and physical inactivity.

Gliptins are medications to lower blood glucose levels by inhibiting the dipeptidyl peptidase-4 (DPP4) enzyme. This inhibition leads to a reduction in both postprandial and fasting plasma glucose levels. Gliptins increase the half-life time of the circulating active form of glucagon-like peptide-1 protein (GLP-1). Glucagon-like peptide-1 protein (GLP-1) decreases glucose levels through four mechanisms (releasing insulin, inhibiting glucagon, decreasing gastric emptying, and promoting satiety). These mechanisms occur by binding GLP-1 to its receptors on the surface of B-cells of the pancreas [1]. This binding causes the activation of adenylyl cyclase, which converts ATP into cyclic AMP, leading to insulin release and decreased glucose levels associated with food intake [2, 3]. GLP-1 is degraded by the enzyme dipeptidyl peptidase-4, so inhibiting this enzyme increases GLP-1 levels and induces insulin action. [2, 3]

The molecular composition of Saxagliptin HCl (SXG) is characterised by. the chemical composition (1S, 3S, 5S)-2-[(2S)-2-Amino-2-(3-hydroxytricyclo [3.3.1.13,7] dec-1-yl) acetyl]-azabicyclo [3.1.0] hexane-3-carbonitrile, formerly identified as BMS-477118, as depicted in Figure 1S [4, 5].

SXG, as a reversible and discerning inhibitor of dipeptidyl peptidase 4, has demonstrated substantial enhancements in glycemic control when used alone or in combination with thiazolidinediones, sulphonylurea, and metformin without significantly changing the weight of the body and with a low risk of hypoglycemia [4]. The primary challenge associated with this drug is its metabolism, as it undergoes breakdown by liver enzymes, metabolised explicitly on the active site of cytochrome p450 3A4. This metabolic process leads to forming a major active mono-hydroxylated metabolite known as 5-hydroxy SXG, which is only half as potent as SXG itself [6]. In addition, the drug exhibits a UV absorption wavelength of approximately 212 nm, making the application of traditional methods for determining drug concentration with a UV–VIS spectrometer represent another challenge.

The oral drug administration route is highly favoured due to its precision, ease of application, adaptability, and widespread patient acceptance. In the context of this route, numerous innovative techniques have been developed, particularly tailored to pediatric use. This polymeric film technique delivers drugs through the oral cavity [7].

Orally disintegrating film (ODF), upon being placed on the tongue and hydrated by saliva, undergoes immediate disintegration, followed by dissolution and then release of the active agent from this form in a fraction of time. Passing any possible degradation in the gastrointestinal tract and minimising the first-pass effect [8].

The pharmaceutical industry has employed diverse analytical techniques and encompassing methods. Although these methods exhibit high sensitivity and selectivity, some are costly, technically intricate, and require extended analysis times due to extensive sample preparation. Ion-selective electrodes (ISEs) have become increasingly prominent in pharmaceutical analysis, benefiting from several advantages [9]. These advantages encompass portability, low energy consumption, limited sample pretreatment, rapidity, non-destructiveness, adaptability to small sample volumes, and suitability for online monitoring. Capitalising on these benefits, endeavours are being made to devise a rapid analytical method requiring minimal sample pretreatment. The objective is to monitor the concentration of critical components during pharmaceutical manufacturing processes. [10].

Given these considerations, the objective of this study was to formulate SXG as a rapidly dissolving oral film to facilitate the direct absorption of the drug into the systemic circulation, thereby bypassing potential degradation in the gastrointestinal tract [11], Which occurs due to poor membrane permeability, low oral bioavailability, short elimination half-life, and gastrointestinal side effects. These limitations can impact patient compliance and treatment efficacy [11] and minimise the first-pass effect. Different formulation factors (polymer type, polymer concentration, and plasticiser concentration) were studied by the implementation of optimal response surface model (RSM) via Design-Expert® software version 11 to study their effects on the crucial film parameters (disintegration time and folding endurance) to obtain the optimised formula. The selected formulas were subjected to further evaluation, which included physical characterisation and in vivo assessment. In addition, a novel analytical technique of solid ion selective electrodes was developed and applied, which offers real-time drug concentration monitoring for the release study and represents a critical parameter for ODFs.

Experiment Section

Materials and Reagents

Saxagliptin hydrochloride (SXG) was gifted by Mash première company (Badr City, Egypt). Polyvinyl alcohol (PVA), potassium bromide (KBr) pellets, hydroxypropyl methylcellulose (HPMC), gelatin, and glycerol were purchased from Sigma-Aldrich (USA). Aniline, 2-nitrophenyl octyl ether (NPOE), sodium dodecyl sulfate (SDS), calyx [8] arene, sodium phosphomolybdate hydrate (PMH), Potassium tetrakis 4-chlorophenyl borate (KTPCB) and tetraphenylborate were purchased from Aldrich (Steinheim, Germany). Tetrahydrofuran (THF) and xylene were obtained from BDH (Poole, England). Ammonium persulfate (APS) was obtained from E. Merck (Darmstadt, Germany). Methanol HPLC grade (Fischer Scientific, UK). Potassium dihydrogen phosphate and disodium hydrogen phosphate (El-Nasr Pharmaceutical Company, Egypt). A dialysis membrane with a 12,000 molecular weight cut-off was obtained from Sigma (St. Louis, USA). All other solvents and chemicals were of analytical grade, and bi-distilled water was consistently employed throughout the work. The pharmaceutical dosage form used in this study was commercially available Saxaptin film-coated tablets. (Saxagliptin hydrochloride 5 mg/ tablet) was obtained from the local market.

Compatibility Testing, Experimental Design, and Preparation of SXG-ODFs

Fourier Transform Infrared Spectroscopy (FT-IR) Study

FTIR (Shimadzu, Japan) was employed to analyse pure SXG, the physical mixture of SXG with excipients; after obtaining satisfactory compatibility results, it was also further used for the optimised ODF as the additional recommended step. About 3 mg of the sample and 300 mg of KBr were ground and mixed, then placed in the sample container and exposed to FTIR scanning between 4500 and 400 cm−1 [12].

Differential Scanning Calorimetry (DSC) Testing

DSC analysis (Shimadzu, Japan). was used to assess compatibility with other components. SXG and excipients were heated to the same temperature to study the interactions based on heat exchange. A small quantity of ODF was cut and placed into an alumina pan and then examined at one atmospheric nitrogen flow rate (mL/min) [13].

Experimental Design and Preparation Method of SXG-ODFS

Optimal RSM design was used to aid in achieving the optimised formula using DESIGN-EXPERT® software (Version 11.1.2.0; Stat-Ease Inc., Minneapolis, MN, USA) The impact of the formulation factors: X1 (polymer conc, in 2 levels), X2 (plasticiser conc., in 2 levels), and X3 (polymer type, where three different polymers were used) on the responses of Y1 (disintegration time) and Y2 (Folding number) The design summary is described in Table 1S.

An ANOVA was utilised to determine each factor's impact and interactions on the dependent variables, with significance attributed to p-values below 0.05. Film preparation using various film-forming polymers, namely, hydroxypropyl methylcellulose E15 (HPMC E15), polyvinyl alcohol (PVA), and gelatin, was performed using the solvent casting technique. [14]. Each polymer was precisely weighed, and a precalculated amount of the drug was added to obtain a dose of 2.5 mg/film strip (2 × 3 cm). The polymer was dispersed in 10 mL of distilled water, and the mixture was left to soak overnight until a uniform viscous solution was obtained. Theplasticiser and precalculated amount of SXG were added, and the previously prepared polymeric solution was introduced to a preheated water bath until a clear, viscous solution, free from any entrapped air, was achieved. A 10 mL volume of this solution was applied to the casting surface (petri dish (9.5 cm) in diameter) covered with a funnel to avoid sudden solvent evaporation and reduce the blistering film surface. A sharp razor blade cut the obtained film for each polymer type into (2 × 3 cm) films subjected to drying in an oven set at 40°C until a constant weight was achieved. Subsequently, the films were delicately peeled off, securely sealed in containers, and stored at 30°C. The prepared films were kept in desiccators to ensure ongoing drying, each individually wrapped in aluminium foil [15] and packed in self-sealing covers until further evaluation.

Characterization and Optimisation of the Prepared SXG-ODFS

In-vitro Disintegration Time

The slide frame and ball (SFaB) method has shown that fulfilling demands required that the disintegration test for the ODFS involved fixing it on a test surface. Before the measurement started, distilled water (900 µL) was carefully placed in the middle of the formed film surface using a micropipette. A stainless-steel ball (diameter = 10 mm, mass = 4 g), simulating the mechanical stress of the tongue, was then positioned on the first water drop. The film was disintegrated when a ball passed through the film and dropped on the bottom of the forming system [16, 17]. The measurements were done in triplicate.

Folding Endurance

A piece of each film measuring 2 × 3 cm was repeatedly folded at a specific angle until a fracture occurred. This experiment was conducted thrice, and the mean folding endurance was calculated [18].

Formula Optimisation (desirability)

The Design-Expert program software was used to apply the desirability function, as the optimised formula was selected to fulfil the required constraints presented in Table 1S (minimum disintegration time and maximum folding number). The formula with the highest desirability, indicative of optimisation, was selected for further evaluation.

Characterization of the Optimised SGX-ODFs

Visual Inspection

The optimised SXG-ODFs were visually evaluated for surface, colour, homogeneity, and transparency [19].

Surface pH Determination

A glass pH electrode (JENWAY, UK) was applied to measure pH through a strip selected from each optimised SXG-ODF formula. After placing the film on a petri dish and lightly moistening it with a millilitre of distilled water, it was let to stand for thirty seconds. The pH was recorded after putting the electrode in touch with the film's surface and watching it for a minute. [18, 20].

Drug Content

The optimised SXG-ODFs formula (2 × 3 cm) was transferred into a 100-mL volumetric flask, and phosphate buffer at pH 6.8 was used to adjust the volume to the mark. After stirring the mixture using a magnetic stirrer to dissolve the films, the insoluble excipient was separated and filtered through a syringe filter with a pore size of 0.22um. SXG content was determined using HPLC and ISEs. The estimations were carried out in triplicate. The results were evaluated following Japanese pharmacopoeia and United States pharmacopoeia (USP27), which required/stated that the contents should range from 85 to 115% [21, 22].

HPLC measurements were performed according to the Zinjad et al. [23] procedure with a slight modification: The samples were subjected to analysis employing Shimadzu’s HPLC system model LC-20AT attached to a dual-wavelength detector (SPD-20AD Model), an automatic sampler, a quaternary pump, and a degasser was used for HPLC measurements. The 150 cm Phenomenex ® C18 column (Length: 150 mm, Internal Diameter: 4.6 mm, Particle Size: 2.6 μm) was procured from GL Science® (Tokyo, Japan). Data acquisition and manipulation were performed using the LC solution software V.1.2 (Shimadzu, Japan). Methanol and water (65:35 v/v) were eluted isostatically at a flow rate of 1.5 mL/min to form the mobile phase. Using a UV detector, the eluent was detected at 212 nm. The preconstructed calibration curve was used to calculate the actual concentrations.

The working solution for HPLC was done. A precise amount of 0.01 g of SXG powder was meticulously transferred to a 10-ml volumetric flask, and the volume was adjusted with water to obtain a 1000 µg/ml standard solution. A suitable dilution was performed to get 100 µg/ ml as a working solution [24, 25]. For potentiometric measurements: A precisely measured 0.088 g of SXG powder was carefully transferred into a 25-ml volumetric flask, and the volume was adjusted with phosphate buffer (pH 6.8) to obtain a stock solution with a concentration of 1 × 10–2 mol L−1. The remaining serial dilutions from 1 × 10–8 to 1 × 10–3 mol L−1 were the desired concentrations achieved by iteratively transferring 2.5 mL from the higher concentration to the lower concentration, followed by adding phosphate buffer to adjust the volumes to the appropriate level. Giving a calibration curve (R2 value over 0.95) used for concentration estimation for drug content and formula release.

Tensile Strength

Tensile strength is the maximum tensile force applied to a thin film before rupture or breakage. The film's tensile strength is crucial for films to withstand mechanical motions while packaging, storing, and shipping. The tensile strength was determined using a tensile tester (Qualitest, model EMS301, USA) with two clamps: a movable lower clamp and a permanent upper clamp positioned 10 mm apart and holding the film sample in place. The computation does not account for the moment the film samples broke at the clamping point rather than in between the clamps. Triplicate results for each film were considered [22]. Tensile strength (MPa) is calculated as breaking force (n) / sample's cross-sectional area (mm2) × 100 [26].

Scanning Electron Microscopy

The topography and structure of the sectioned surface of the optimized SXG-ODFs were examined using a 20 kV acceleration voltage on a Hitachi SEM SU 3500 (Japan). To avoid accumulating an electrostatic charge and enhance the conductivity of non-conductive or poorly conductive materials, the samples underwent sputter-coating with a thin layer of gold, facilitating better conduction of electrical signals during imaging with SEM. [22, 27].

Application of the Release Study

In-vitro release studies of SXG-ODFs were conducted using a USP type II dissolution apparatus (Distek, 2500, USA). To prevent film floating and ensure accurate dissolution testing, the films were sandwiched between glass and mesh structures within the dissolution vessels. 200 mL phosphate buffer (pH = 6.8) for SXG -ODFs loaded with dose (2.5 mg of SXG) and 400 ml of the same dissolution medium for commercially available tablet loaded with double SXG oral disintegration film dose (5 mg of SXG), the medium was equilibrated to 37 ± 5 ºC with maintained stirring speed at 50 rpm. The test continued until a steady state was achieved. Then, the amount of SXG released at each predetermined time was tracked offline using HPLC and the Potentiometric method online.

Off-line Tracking of SXG Release using the HPLC

A sample of 2 mL was withdrawn at predetermined intervals (every minute in the first five minutes, followed by 7,10, and 15 min and replaced immediately with an equal volume of fresh dissolution medium to maintain the volume constant. The collected samples were subjected to analysis using HPLC. All determinations were carried out in triplicates, and the cumulative percentages of the released SXG from SXG-ODFs and the commercial tablet were represented.

On-line Tracking of SXG Release using Potentiometric Method

Potentiometric measurements were conducted using a JENWAY Potentiometer digital analyzer (Model 3505, Essex, UK). The instrument was connected to the Calomel double junction Hg/HgCl2 reference electrode (Beckman, USA). CH Instruments in the USA bought a single disc graphitic carbon SE101 screen-printed ion selective electrode (SP-ISE) with 50 × 13 mm (H x W) dimensions. The experimental setup included connecting a Calomel double junction Hg/HgCl2 reference electrode and a screen-printed working electrode to the device. For each measurement, the electrodes were immersed into the dissolution apparatus containing the under-investigation samples (SXG-ODFs and the commercial tablet) with continuous recording of the potential readings. The glass pH electrode was used for pH measurements.

The potentiometric method was developed by the following:

PANI Nanoparticles Preparation & Characterization

PANI (Polyaniline) nanoparticles were synthesized according to the procedure outlined by Moulton et al. [28]. In a nutshell, the chemical polymerization of nanoparticles took place in a water bath at 20 ºC. Equimolar amounts (1.3 mol L−1) of aniline and SDS (Sodium Dodecyl Sulfate) were combined in 100 ml of distilled water within a rounded stoppered flask, and the mixture was allowed to blend for 1 h. The process involved mechanically stirring the aniline and SDS equimolar mixture in 100 ml of distilled water. Subsequently, 100 ml of 1.3 mol L−1 APS (Ammonium Persulfate) was added to the milky solution of aniline/SDS. The polymerization continued for 2.5 h, resulting in the formation of a dark green dispersion of PANI.

Dialysis was performed on the polymerized dispersion for 48 h using a dialysis membrane with a molecular weight cutoff of 12,000 against deionized water. Following dialysis, the dispersion underwent centrifugation at 10,000 rpm for 10 min, followed by four consecutive washes with water to eliminate residual SDS. PANI nanoparticles were then mixed with xylene (10% m/m) and kept out of the light in a closed chamber glass bottle.

The Process of Fabrication of the Sensor and its Optimization

The SXG selective membrane was created by adding 0.015 g of calyx [8] arene as an ionophore and 0.01 g of PMH as an ion exchanger to a glass petri dish. Subsequently, 0.4 mL of 2-NPOE was added as a plasticizer. After thorough mixing with 8 ml of tetrahydrofuran (THF), approximately 0.19 g of PVC (polyvinyl chloride) was incorporated into the petri dish to achieve a homogeneous membrane cocktail. Using a micropipette, ten microliters from the prepared cocktail were carefully dispensed and cast onto the SP-ISE disc to form the membrane-selective SP-ISE sensor. The membrane was allowed to dry at room temperature for five hours or until complete evaporation of tetrahydrofuran (THF), resulting in the SP-ISE having a dry and solid membrane. The drop-casting procedures must be adequately carried out using a calibrated micropipette over a horizontal carbon disc to guarantee that the cocktail is distributed uniformly throughout the carbon disc. Ultimately, the constructed sensor was conditioned by submerging it in solutions containing 1 × 10–2 mol L−1 SXG for a whole night. Sensor optimization studies were conducted to find the ideal experimental conditions for quantitative measurements of SXG using SP-ISE following the IUBAC guidelines [9, 29].

The Influence of pH on the Electrode Response

Phosphate buffer was utilized at various pH levels to investigate the effects of pH. The pH range of 2.0 to 12.0 and the potential of two SXG concentrations, 1 × 10–3 – 1 × 10–4 mol L − 1, were measured using the fabricated sensor [30].

Evaluation of the Time Required to Get a Steady Response

Exploration of dynamic response time was driven by the necessity to capture rapid and accurate data within a brief timeframe. The duration necessary to attain a stable measurement was recorded using a stopwatch, whereby the concentration of SXG was increased tenfold. The duration required for stabilizing the sensors in achieving a ± 1 mV equilibrium potential was plotted for every concentration.

Construction of the Calibration Response

The calomel reference electrode and the conditioned sensor were submerged into 25 mL beakers produced in a pH 6.8 phosphate buffer solution, each containing SXG in Concentrations spanning 1 × 10–8 to 1 × 10–2 mol L−1. After allowing it to settle, the emf was measured while being continuously stirred. In between measurements, clean water served as the washing solution. Subsequently, the electromotive force (emf) was plotted against the logarithm of SXG concentration. Then, using the linear range of the curve, regression equations were calculated and applied to determine the unknown SXG concentration.

Potentiometric Aqueous Layer Test

The potentiometric aqueous layer test was employed to investigate the potential formation of an aqueous layer. Beneath the sensor membrane and its potential impact on measurement stability when shifting from an SXG solution (0.1 mmol L − 1) to a highly concentrated interfering ion solution, such as Vildagliptin (10 mmol L − 1), and then reverting to the SXG solution.

The foundation of the test lies in detecting potential drifts in the measurements. If an aqueous layer forms below the membrane, the trans-membrane ion fluxes will also alter the ionic composition of the layer, resulting in typical potential drifts.

Evaluation of the Membrane Selectivity

The sensors' selectivity toward SXG was evaluated by measuring the potential response when exposed to various substances, including PVA, Gelatin, HPMC, and glycerin, were present. The method of separate solutions was employed to determine the selectivity coefficient of the sensors and assess the extent of reference caused by an external substance on the selectivity of the sensors towards SXG [31]. The subsequent mathematical expression was utilized.

$${\text{log}}\left({{\text{k}}}_{{\text{SXG}},\mathrm{ Interferent}}^{{\text{pot}}}\right)= \frac{{{\text{E}}}_{2}-{{\text{E}}}_{1}}{{\text{S}}}+ \left(1-\frac{{\text{A}}}{{\text{B}}}\right)\mathrm{log\;aA}$$

The selectivity coefficient is represented by log (, while the slope of Pb2+ SP-ISE is denoted by "S". The symbol "E1" represents the electrochemical potential that has been quantified in a solution containing 1 × 10–3 mol L−1 of SXG ions. The symbol "E2" represents the potential determined in a solution containing 1 × 10–3 mol L−1 interferent ions. The charge of lead ions is denoted by the symbol "A". The interfering ions carry a charge denoted by the symbol "B". The variable "a" represents the activity of Pb2+ ions.

In-Vivo Oral Glucose Tolerance Test

The oral glucose tolerance test (OGTT) method was carried out by relevant guidelines and regulations according to the Declaration of Helsinki 1975, as revised in 2008. The ethics committee approved the technique and the study on October 6 University (O6U-REC) under the approval number FWA00017585.OGTT serves as a fundamental and primary diagnostic tool for evaluating changes in glucose tolerance within the physiological context of murine models. In this study, normal male mice Wistar albino mice (30–50 g) were purchased from the National Institute of Ophthalmology, Giza, Egypt. By focusing exclusively on male rats to reduce potential variability associated with sex-specific differences, ensuring a more homogeneous study population. Mice were kept in plastic cages at the O6U animal house for at least two weeks before starting the experiment to acclimatise the conditions: room temperature (25 ± 3 ◦C), 60–70% humidity, and maintained at 12 h light–dark cycles. Mice received water and standard mice pellets (bought from El-Nasr Chemical Co., Cairo, Egypt). Following an overnight fast of 12 h, OGTT was used as a methodological benchmark [32]. This standardised approach provides a comprehensive evaluation of the animals' glucose tolerance.

The experimental design comprised four distinct groups with seven subjects per group: a control group and three test groups. The latter received either Saxaptin® oral tablets or the optimised SGX-ODFs at a uniform 10 mg/kg drug dose, per established protocols [33]. Subsequently, a glucose challenge was administered intraperitoneally (2 g/kg) after a 30-min interval, facilitated by a commercially available 25%W/V glucose solution [34].

Blood glucose levels were meticulously monitored at various time intervals following glucose loading to elucidate the impact of the drug on glycaemic response dynamics in the murine subjects [35]. Glucose measurements were conducted using a glucometer (Accuchek Active II; Roche, Germany) with blood samples extracted from the tail vein and analysed utilising glucose-specific test strips [36]. This approach ensures precision in assessing glucose levels, providing a robust dataset for subsequent analyses.

Result and Discussion

Compatibility Testing, Experimental Design, and Preparation of SXG-ODFs

Fourier Transform Infrared Spectroscopy Study

FTIR can provide fingerprints for molecules [37, 38]. FTIR spectrums of SXG and the drug in combination with excipients depicted in Fig. 1 show that SXG does not interact chemically or physically with the polymeric structure. Major SXG absorption peaks are seen at N–H stretching (3450.12 cm−1), C-H stretching (2912.61 cm-1), O–H stretching (3301 cm−1), C-N stretching (1614.47 cm−1), and C-stretching (1255.70 cm-1), which are consistent with the literature peaks verifying that the drug sample's purity remained unchanged.

Fig. 1
figure 1

FT-IR spectra comparison of a formulation containing SXG, b physical mixture of SXG with gelatin, HPMC, and PVA, respectively, and c pure SXG

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Differential Scanning Calorimeter Testing

Differential scanning calorimeter (DSC) Fig. 2 depicts the DSC thermogram testing SXG pure drug, testing excipients, SXG-excipient mixtures, and prepared SXG-ODF. It is clear from DSC thermograms that SXG produced a pronounced exothermic peak at 223.9℃, which was preserved in the mix without notable measured shift, demonstrating physical compatibility between the SXG and the tested excipients utilized in the film preparation.

Fig. 2
figure 2

DSC thermograms of PVA, HPMC, Gelatin, Pure SXG, physical mixture of SXG with gelatin, HPMC, and PVA, and the optimised SXG-ODFs prepared using HPMC and PVA

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Characterization, Statical Analysis, and Optimization of the Prepared SXG-ODFs

The applied optimal RSM design suggested 13 formula compositions of SXG-ODFs, successfully prepared and characterized for disintegration time and folding endurance, as recorded in Table 2S. The selection of the optimal mathematical model involved the creation of factor effect plots and response surface plots, considering various statistical parameters like R2, predicted R2, and adjusted R2.

The statistical analysis of the results revealed that the two responses fit the sequential sum of squares for the two-factor interaction (2FI) model. Table 3S encapsulates the outcomes of the statistical analysis. The p-values calculated were significant (< 0.0001) for both disintegration time DT and folding FDN, along with F-values of 43.52 and 34.01, underscoring the considerable impact of these two responses. Model validation, gauged by the actual model R2 (with values close to one) and the marginal difference between predicted R2 and adjusted R2 for each response (less than 0.2).,. Moreover, the model exhibited adequate precision, as reflected in the signal-to-noise ratio, with values greater than 4 (15.6252 for DT and 14.4070 for FDN). This signifies an acceptable signal-to-noise ratio, underscoring the model's efficacy in navigating the d02esign space. Polynomial equations were derived to estimate the impact of the tested factors on each response.

By comparing factor coefficients, the coded equation becomes a valuable tool for assessing the relative influence of factors. Holding all other factors constant, the coefficient estimates the predicted change in response for each unit alteration in factor value. Indeed, in the context of the coded equation, positive values indicate an increased effect on the measured dependent variable. In contrast, negative values signify a decreased effect when the corresponding factor changes. Therefore, by comparing the coefficient values, one can discern the relative impact of each component, with a higher coefficient indicating comparatively, higher coefficients indicate a more pronounced effect on the response. Figure 3 depicts the influence of two factors at a consistent value of the third factor for each response. Further insights into the collective impact of all factors (A, B, and C) on responses (Y1, Y2) were further elucidated through three-dimensional (3D) plots, as shown in Fig. 4.

Fig. 3
figure 3

Factor Effect Plots Demonstrating the Influence of Polymer Concentration, Plasticizer Concentration, and Polymer Type on the Measured Responses: Disintegration Time a and b and Folding endurance d and e, Along with Their Interaction Plot c and f. Gelatin, HPMC, and PVA are Represented by Red, Green, and Blue, respectively."

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Fig. 4
figure 4

Three-dimensional response surface plots for the effect of SXG-ODFs factors (polymer concentration-plasticizer concentration) with different polymer types (Gelatin-PVA and HPMC) on the measured responses, the disintegration time a, respectively folding number d, e, and f. The highest values are of orange shades, while the lowest values are of blue shades

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Given its direct influence on ODF's performance, DT is critical in assessing SXG-ODF. A shorter DT is advantageous, as it enhances drug solubility, release, and dissolution, subsequently improving drug bioavailability and efficacy. The obtained SXG-ODF's DT values ranged from 17 to 890 s, as shown in Table 2S. The following equation studied the factor's effects:

$$\mathrm{DT}=(-1053.666667\;\mathrm{Gelatine}-249.73333\;\mathrm A)(-258.5000\;\mathrm{HPMC}\;+55.80000\;\mathrm A)$$
$$(-107.50000\;\mathrm{PVA}\;+28.2000\;\mathrm A)$$

As seen in Fig. 4, the polymer type (C) effect could be arranged in the following order: PVA, HPMC, and gelatine for decreasing DT. Polymer concentration (A) demonstrated a favourable impact on DT in the cases of PVA and HPMC. According to the ANOVA analysis report, A, C, and AC are significant model terms (p < 0.05). Interaction between (A, C) on DT shows that higher polymer concentration increased the DT for all polymer types. The impact of the polymer type observed with the highest DT for gelatine could be based on the fact that gelatine swells and softens in buffer and gradually absorbs 5 to 10 times its water weight. At the same time, HPMC & PVA disintegrates directly in the buffer [39].

The results shown in Table 2S demonstrated that SXG-ODF disintegration time increased with increasing polymer concentration. Additionally, Polyvinyl alcohol (PVA) films plasticized with glycerin demonstrated remarkably short disintegration times (17 s) and heightened hydrophilicity. This enhanced hydrophilicity can be rationalized by increased humidity absorption, causing a reduction in internal hydrogen bonds among polymer chains and an augmentation of internal space within the polymer's molecular structure. The plasticizing effect of glycerin promotes PVA films' flexibility and water uptake capacity, contributing to their rapid disintegration. HPMC E15 oral films exhibit high water absorption, forming a porous structure upon saliva contact. This porosity enables rapid water and saliva penetration, fostering quick film disintegration. The porous structure also facilitates capillary action, expediting hydration and saliva infiltration. In its swollen state, HPMC E15 disrupts intermolecular bonds, weakening the film's structure for accelerated disintegration. The gel layer formed by HPMC E15, characterized by low viscosity, contributes significantly to quick dispersion and dissolution, further enhancing the overall fast disintegration of the oral film.

In contrast, gelatin films exhibited prolonged disintegration times, extending to 890 s. The delayed disintegration can be attributed to gelatin's inherent properties, including its proteinaceous nature. As a protein-based material, gelatin forms a more cohesive and denser matrix. This characteristic results in slower water penetration and disintegration than PVA and HPMC films. Additionally, the protein structure of gelatin may change in the presence of moisture, leading to a more intricate network and delayed dissolution.

FDN is a crucial parameter for assessing the strength of the formed SXG-ODFs. A higher FDN value indicates more excellent elasticity and strength of ODFs, ensuring their stability. FDN values of the prepared SXG-ODFs ranged from 130–400 count folding at the same ODF site; the polynomial equation was:

$$\mathrm{Folding}\;\mathrm{number}=(+95.75\;\mathrm{Gelatin}+182.125\;\mathrm{HPMC}+267.125\;\mathrm{PVA})+9.55\;\mathrm B$$

In this instance, terms B and C are deemed significant model terms; C exhibited the highest effect, As shown in Fig. 3, illustrates that FDN was significantly increased by increasing plasticiser concentration, and the most suitable polymer type, as shown in the interaction chart was PVA followed by HPMC finally Gelatine.

Based on the tabulated results, PVA films exhibited remarkable folding endurance, surpassing 200 folds without rupture, indicative of exceptional flexibility. This resilience is attributed to the establishment of robust hydrogen bonds between the PVA polymer and the plasticizer, enhancing the film's ability to endure deformation. The significant folding endurance underscores the film's flexibility, a characteristic crucial for practical applications.

Conversely, HPMC-generated films displayed limited flexibility and durability, supported by folding numbers below 200. The observed fragility can be attributed to weak intermolecular links between HPMC polymer chains, which cannot maintain structural integrity during folding. This contrasts with the robust hydrogen bonding in PVA films, highlighting the impact of polymer-plasticizer interactions on film flexibility. Gelatin films exhibited diminished flexibility, evidenced by fewer than 200 folds, and this flexibility further declined with reduced plasticizer concentration. The data aligns with the understanding that protein-based gelatin forms a less flexible and cohesive matrix. Decreased flexibility with lower plasticizer concentration emphasises plasticiser content's critical role in influencing gelatin films' mechanical properties [40].

Formula Optimization (desirability)

The Design Expert® software version 11 was an effective way to choose the optimized formula to minimise disintegration time and maximise the folding number. The software suggested two formulas with high desirability values (F10 & F11 prepared by PVA & HPMC); they showed the fastest DT (17 &18 ± 1.5, respectively) and the highest FDN (345 & 300 folds, respectively) with overall desirability of 0.919 and 0.738 respectively.

Characterization of the Optimized SGX-ODFs

Visual Inspection

Visual inspection of the optimized SXG-ODFs revealed uniformly smooth, clear, colorless, flexible, non-sticky, and elegant appearances.

Surface pH Determination

The surface pH of the optimized SXG-ODFs was found to be between (6.2 and 7.1 for F10 and F11, respectively); this is suitable with the salivary pH (pH = 6.8), indicating that the films are appropriate and won't irritate or inflame the mucosa of the oral cavity, making them acceptable by the patients [41, 42].

Drug Content

The results exhibited uniformity of SXG within the optimized SXG-ODFs and good solubilization of the drug in the formulation. These results were 93.89% & 97.12% for F10 &F11 formula, respectively.

Tensile Strength

The optimized SXG-ODFs possess high to moderate tensile strength. F10 film exhibited superior tensile strength, possibly due to the strong hydrogen bonds between the plasticizer and the hydrophilic polymer (PVA). The polymer gains flexibility from this contact, making it more ruptured and resilient. Furthermore, the published results [26] imply that, concerning plasticizer concentration, an increase in PVA content is correlated with an increase in the films' tensile strength. These words are proven by the following values of tensile strength: 4.53 Mpa & 2.15 Mpa for F10 and F11, respectively.

Scanning Electron Microscopy

Figure 5 shows the cross-sectional view of optimized SXG-ODFs F10 & F11 micrographs, which were found to be homogeneous and compact surface structures without transverse striations or scratches, indicating that the SXG is uniformly distributed without accumulation of SXG crystals on the surface [3].

Fig. 5
figure 5

Scanning electron micrograph of the selected a optimised SXG-ODFs F11 and b optimised SXG-ODFs F10 showing homogeneous and compact surface structure without transverse striations or scratches (Magnification X 1500- X 6000 respectively)

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Application of the Release Study

The optimized SXG-ODFs (F10 & F11) and the commercially available Saxaptin® oral tablet were assessed for drug release. Two determination methods were applied as follows.

Off-line Tracking of SXG Release using the HPLC

Chromatographic techniques, particularly RP-HPLC, are widely utilised for quantitatively assessing drug release profiles in pharmaceutical formulations. In this study, RP-HPLC was employed to monitor the release of SXG from conventional Saxaptin® tablets and the optimised SXG-ODFs. The established chromatographic conditions facilitated a high-resolution separation of SXG, with a retention time of 3.98 min. The RP-HPLC method was chosen for its accuracy and sensitivity in quantifying drug release rates. However, the conventional off-line quantitative analysis using HPLC necessitated extensive time and chemical consumption due to frequent sampling and preparatory steps. This approach resulted in intermittent time gaps between measurements, as depicted in Fig. 6. Despite these challenges, the HPLC release testing demonstrated satisfactory results, with SXG release percentages of 88.9%, 94.96%, and 95.09% observed after 15 min for Saxaptin® tablets and the optimised SXG-ODFs F10 & F11, respectively. These findings align with the dissolution criteria outlined in the United States Pharmacopeia (USP), indicating the suitability of both formulations for pharmaceutical use.

Fig. 6
figure 6

RP-HPLC in-vitro Release profiles of SXG from the optimised HPMC, PVA-SXG ODFs, and Saxaptin®film-coated tablets in phosphate buffer saline (pH 6.8) at 37 ± 0.2 ºC. (Results are reported as mean ± SD, n = 3)

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The percentages of SXG released after 2 min (Q2min) from the tested formula were recorded to compare the release profiles. At Q2min, 38.6%, 79.04%, and 70.64% were released from Saxaptin® tablets, F10, and F11, respectively. Based on the statistical analysis using Tukey's multiple comparisons test, obtained from GraphPad Prism Statistical Analysis software, significant differences (p < 0.0001) were observed between the mean values of the tested formula.

Considering SXG-ODFs, F10 showed a higher percentage released at Q2min than F11; this could be attributed to the PVA-based oral film formula demonstrating superior drug release compared to HPMC counterparts, result of PVA’s excellent film-forming properties, its hydrophilic nature promotes rapid hydration and disintegration of the film upon contact with saliva, accelerating drug release., and enhanced mechanical strength, ensuring consistent drug distribution and optimal therapeutic outcomes.

On-line Tracking of SXG Release using Potentiometric Method

As the drug release from ODFs is a crucial parameter, we use this method to track the SXG concentration released from the tested samples online. The process was successfully employed and validated.

The Performance Characteristics of the Fabricated Sensors

The developed SXG-sensitive membrane demonstrated perm-selectivity and ion exchange selective properties tailored explicitly for SXG. Numerous research studies have underscored that the selectivity and precision of ion-selective membranes are contingent on the composition of the PVC membrane, incorporating elements such as plasticizer, ionophore, PVC, and ion exchanger. The constituents of the membrane cocktail were deliberately chosen to impart a high degree of selectivity for SXG ions, aiming to yield rapid, sensitive, and precise outcomes.

Polyvinyl chloride (PVC) was chosen based on its demonstrated capability to effectively bind all the constituent elements of the membrane. Moreover, it serves the purpose of augmenting the dielectric constant, thereby facilitating the attainment of elevated ionic concentration inside the membrane [43]. Plasticizer: Several plasticisers, including DOP, 2-NPOE, and DBS, were evaluated to identify the most effective plasticizer for liquefying the PVC membrane components, achieving homogeneous stabilization, modifying the ion exchanger distribution constant, and maintaining all these characteristics throughout the measurement process. It has been determined that DBS is the most effective plasticizer compared to DOP and 2-NPOE in terms of providing optimal sensitivity and selectivity for SXG analysis [44]. Ionophores, such as Calixarene and ß-CD, function as molecular receptors for various substances. The ionophores can identify guest molecules, such as SXG, using their capacity to generate specific inclusion complexes and establish complementary hydrogen or ionic bonds with the target analytes.

The current study investigated two ionophores, calyx [8] arene and ß-CD. The superior performance of incorporating calyx [8] arene in the membrane cocktail, compared to ß-CD, can be attributed to its larger cavity that facilitates SXG incorporation, ease of solvation during membrane mixing, and longer stability. Several cationic ion exchangers have been examined to select the optimum. These substances are integrated into the membrane matrix to create mobile ionic sites that facilitate interfacial ion exchange and reduce ionic resistance [45]. The SXG ion exhibits monovalent cationic characteristics, thus necessitating the SXG ion-selective membrane to exhibit cationic exchange behavior. Lipophilic cationic exchangers, such as PMH, can facilitate this process.

The prepared sensor was subjected to a conditioning process lasting several hours in 1 × 10–2 mol L−1 SXG, which served to substitute the exchangeable potassium ions (Na+) of PMH. Various cationic exchangers were evaluated, namely PMH, TPB, and KTPCB. The initial TPB and KTPCB trials demonstrate regression slope values of -61.3 and correlation coefficients 0.9997. However, it also demonstrates reduced sensitivity, a lack of reproducible response, and a limited operational lifespan. In contrast, the PMH membrane exhibits a consistent Nernstian slope, prompt response, and a reduced detection threshold.

In summary, the selectively fabricated polyvinyl chloride (PVC) membrane exhibited high hydrophobicity and impermeability toward SXG. The plasticization process involves hydrophobic DBS and is necessary to achieve the desired softening effect. Adding cationic exchanger salts, such as PMH, and complexing ligands, such as calyx [8] arene, reduced the resistance to ions' permeability. Ultimately, the membrane transforms into a perm-selective membrane that hinders all ions except SXG ions.

PANI Chemical Polymerization and Characterization

The chemical polymerization technique reported by Han et al. for the synthesis of Polyaniline (PANI) using Sodium Dodecyl Sulfate (SDS) as a supporting agent,

Utilizing a 1:1 monomer to oxidant ratio."). [46, 47] At 20 ºC, aniline underwent polymerization utilising SDS as the stabilizer and dopant and APS as the initiator-oxidant. Following a reaction duration of 2.5 h, a dark green emeraldine PANI SDS emerged, suggesting the formation of the conductive emeraldine salt form of PAN. To get a high level of doping in the PANI SDS dispersion, a dopant (SDS) ratio of 1 was also required. SEM of PANI nanoparticles was determined. The nanoparticle size of PANI was examined by SEM, as shown in Fig. 7.

Fig. 7
figure 7

Scanning electron micrograph of polyaniline nanoparticles (Magnification X 10000, and13000 respectively)

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Effect of pH on Membrane Response

The influence of fluctuating pH values on electrode response was investigated using SXG solutions of 1 × 10–4 and 1 × 10–3 M. As shown in Fig. 2S. The suggested sensor exhibited a consistent response throughout the pH range. (3.5 – 7.5). Therefore, this pH range is the manufactured sensors' operational pH range. There was a detected EMF response deviation outside this range, which might result from competition between the hydrogen ions on the membrane active sites and the SXG ions.

The Dynamic Response Time of the Fabricated Sensor

The dynamic response time, or the amount of time required to achieve stable EMF values (± 1 mV), is the primary metric typically utilized to assess the efficacy of membrane sensors. Interestingly, reaction speed is a reliable metric for accurate drug release monitoring. After examining the practical response time for the sensor under study throughout its whole linearity range, it was determined that 6 s was an appropriate time to provide a stable response (± 1 mV). As seen in Fig. 8, the time traces of the sensor demonstrated the electrode's superior performance, demonstrating its capacity to instantly gather the necessary real-time data that aligns with the concept of tracking drug release from the dosage form in real-time.

Fig. 8
figure 8

Time traces showing the electrode reversibility

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The Method Calibration and Validation Data

Figure 3S depicts the concentrations of SXG's linear range spanning from 1 × 10-6 to 1 × 10-2 M, featuring a favorable slope of -61.4 mV/decade, Nernstian. The envisioned sensor's detection limit is 1.9 × 10-7 M. The validation of potentiometric performance adhered to IUPAC rules. Accuracy verification was conducted using blind SXG concentration measurements (1 × 10-5, 1 × 10-4, and 1 × 10-3 M) for both sensors. Employing the procedure on the same day, with the same circumstances and concentrations, yielded precise and consistent results.

Additionally, the same concentrations were measured on different days to ensure intermediate precision, and the unknown concentrations were computed using the calibration regression equations. As outlined in Table 4S, the results reveal determined RSD values greater than two and mean recovery percentages between 97 and 101%. These findings indicate excellent accuracy and precision in the calculated results. The results demonstrated that the potentiometric technique performed well in detecting unknown SXG concentrations with high accuracy and precision.

The Sensor's Selectivity Towards SXG

The sensors' selectivity for SXG was investigated in the presence of several substances and the expected tablet excipients (glucose, lactose, talc, HPMC, and PVA). Furthermore, the appropriateness of the electrode was evaluated when specific organic cations, like Ca2+ and Mg2+, were present. That could be present in water. Selectivity coefficients were calculated, and the results indicated a high degree of applicability for the electrode, showcasing selectivity towards SXG.

Tracking SXG Release using the Potentiometric Method

The sensor was created to track SXG's release from its tablet dosage form and optimal formula. Since release monitoring involves extended periods of immersing the electrodes in an acidic solution at 37 ºC, the solid contact screen-printed ion-selective electrode (SC-SP-ISE) without an inner filling solution was chosen. This design eliminates the need for an inner-filling solution, addressing the anticipated issues associated with traditional ISEs. All solid contact SP-ISEs lack internal solutions and utilise an economical, highly conductive layer composed of polymers or nanostructures as a solid contact beneath the selective ISE membrane layer.

The conditioned SC-SP-ISE and the Calomel reference electrode were immersed in the release medium, and the EMF was continuously recorded. -The release testing was conducted individually for Saxaptin® tablets, and the optimized SXG-ODFs F10 & F11. Subsequently, the relevant regression equation was applied to compute the percentage of SXG release. The construction of the release profile is illustrated in Fig. 9. A complete release of SXG was 88.21, 98.10, and 95.81% for Saxaptin® tablets, the optimized SXG-ODFs F10 and F11, respectively, for 15 min. According to USP's acceptance dissolution criteria, the results match. SC-SPISE and traditional HPLC function similarly when monitoring SXG release from pharmaceutical preparations.

Fig. 9
figure 9

Polyaniline nanoparticles-based solid-contact ion-selective electrode in-vitro Release profiles of SXG from the optimised HPMC, PVA-SXG ODF formulas and Saxaptin® film-coated tablets (Saxagliptin hydrochloride 5 mg per tablet) obtained from a local market in phosphate buffer saline (pH 6.8) at 37 ± 0.2 ºC

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The percentages of SXG released after 2 min (Q2min) from the tested formula were recorded to compare the release profiles. At Q2min, 35.2%, 96.5%, and 78.15% were released from Saxaptin® tablets, F10, and F11, respectively. Based on the statistical analysis using Tukey's multiple comparisons test, obtained from GraphPad Prism Statistical Analysis software, significant differences (p < 0.0001) were observed between the mean values of the tested formula, and like the HPLC data, F10 recorded the highest release %.

These findings underscore the dynamic nature of drug release and ion concentration profiles, with significant differences observed among the tested formulations at Q2min points. The consistent statistical significance (adjusted p-values < 0.0001) across all comparisons further validates the observed differences. The ion-selective electrode analysis demonstrates its reliability in evaluating the pharmaceutical quality and performance of SXG drug formulations.

Comparison between Offline and Online Release Profiles of SXG Tested Formula

This analysis aims to compare the effectiveness of HPLC and ISE in assessing the release profiles of the investigated formulations, providing insights into their applicability for pharmaceutical analysis. This comparison is achieved by examining the percentage of SXG released at Q2min for each formula using both HPLC and ISE, as it allows for early-stage assessment of the fast-release formula; the first few minutes after administration are critical for drug absorption in the body.

ISE can provide online monitoring of the release as the electrode just dipped into the dissolution media, and it starts to give readings once the release begins so that several readings can be obtained within two minutes [9, 48]. On the contrary, HPLC is an offline technique that requires multiple sampling at certain time intervals, so only two readings can be obtained during the two minutes. The reason for time intervals is the sampling process, as one ml from the dissolution media must be withdrawn and replaced by buffer solution followed by HPLC measurements.

As determined by HPLC, the percentages of SXG released at Q2min from Saxaptin® tablets, F10 and F11, were 38.6%, 79.1%, and 70.6%, respectively. Conversely, the corresponding values obtained via ISE were 35.2%, 96.5%, and 78.2%, respectively. Statistical analysis revealed significant differences between the results obtained from HPLC and ISE for the tested formulas (p < 0.05 for Saxaptin® tablets and p < 0.0001 for F10 and F11).

Despite the notable disparities between the percentages of SXG released determined by each analytical method, the final release percentages obtained at the end of the study using both methods met the requisite criteria outlined in the United States Pharmacopeia (USP). This suggests the suitability of both HPLC and ISE for determining SXG release.

Traditional off-line methods, such as HPLC, necessitated laborious processes involving frequent sampling for monitoring SXG release. In contrast, the adoption of online monitoring via ISE proved advantageous, particularly given that SXG is a lipophilic cationic compound that aligns well with the selective membrane of the ion-selective electrode.

In addition to its sensitivity and selectivity, well-known characteristics of HPLC, ISE offers the advantage of rapid and direct measurements of specific ions or molecules in solution. However, discrepancies between these methods may arise due to inherent differences in principles and sensitivity.

Oral Glucose Tolerance Test OGTT

SXG treatment in mice yielded notable improvements in glucose tolerance within 60 min, as evidenced by a significant decrease in blood glucose levels from 198.7 mg/dL as baseline blood glucose level to 152.0 mg/dL,134.0 mg/dL,107.7 mg/dL,114.0 mg/dL for control, market tablet, F10 & F11 treated groups respectively as shown Fig. 10. This effect is intricately linked to the expected reduction in DPP4 activity in the bloodstream. The downregulation of DPP4 mediated the elevation of endogenous GLP-1 levels, subsequently leading to an increase in insulin secretion. This physiological cascade underscores the therapeutic efficacy of Saxagliptin in enhancing glucose metabolism.

Fig. 10
figure 10

Oral glucose tolerance test (OGTT) for the optimised SXG-ODFs formulae prepared using PVA (F10), HPMC (F11), and Saxaptin® film-coated tablets (Saxagliptin hydrochloride 5 mg per tablet) obtained from a local market

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The comparison of blood glucose levels between the tested formulas revealed notable differences across different time points. At 30 min post-administration, all formulas (Saxaptin® tablets, F10, and F11) showed a significant decrease compared with the control group (p < 0.05). This suggests an initial rapid response to the formulations in reducing blood glucose levels. However, as time progressed, variations in efficacy between formulations became apparent. Specifically, the F10 formula consistently demonstrated the most significant reduction in blood glucose levels compared to both Saxaptin® tablet and F11 formulations across all time points (p < 0.05).

On the other hand, while the Tablet and F11 formulations also showed significant reductions compared to the control group, their efficacy diminished later (e.g., 240 min). This indicates potential differences in the formulations' sustained effects or pharmacokinetic profiles over time. Overall, these findings highlight the formulation-specific differences in glucose-lowering effects and underscore the importance of considering formulation attributes in designing optimal formulations for glucose regulation., indicating that the optimized SGX-ODFs exhibited a swifter response to glucose challenges in comparison to the conventional oral tablet, as shown in the literature [49]. This accelerated response can be attributed to the rapid release of SXG from the ODFs in the oral cavity and avoiding the first pass effect, which results in a higher availability of the drug in the bloodstream. The optimized SGX-ODFs, with their enhanced formulation, facilitate a more efficient and prompt absorption of SGX, resulting in a faster and more pronounced improvement in glucose handling.

The dual impact of SGX on DPP4 activity and subsequent GLP-1-mediated insulin secretion, coupled with the superior performance of SGX-ODFs in terms of rapid drug availability, collectively underscores the potential clinical benefits of Saxagliptin in managing glucose homeostasis.

Conclusion

This research represents a significant step forward in pharmaceutical formulation, optimisation, and analytical techniques. By exploring the development of SXG-ODFs using the response surface model (RSM) design, we have identified vital formulation parameters, such as polymer concentration, polymer type, and plasticiser concentration, crucial for achieving desired characteristics and enhancing patient adherence. Using Design Expert® software has provided valuable insights into formula optimisation, as suggested by two optimised formulas, F10 & F11. The comprehensive evaluation of the optimised SXG-ODFs, including visual inspection, surface pH determination, uniform drug content, mechanical strength assessments, and scanning electron microscopy, reinforced their pharmaceutical suitability and quality. Comparisons with commercial oral tablets further emphasised the superiority of SXG-ODFs in drug release studies. The introduction of the solid-contact screen-printed ion-selective electrode (SC-SP-ISE) for real-time monitoring, alongside traditional HPLC methods, showcases a novel analytical approach with promising selectivity and precision.

Furthermore, the statistical analysis of data obtained shows a significant difference between the two methods, with more selective and in-time monitoring being superior for ISEs over HPLC. The physiological impact of SXG-ODFs is evidenced by enhanced glucose tolerance observed in treated mice, underscoring their potential clinical significance as a patient-friendly dosage form. Statistical analysis revealed a significant difference between the commercial tablet and the optimised SXG-ODFs with superior F10 prepared using PVA over F11 prepared using HPMC. Future research directions could involve in-depth in vivo studies and clinical trials, exploring alternative polymers, innovative analytical techniques, sustainable materials, combination therapies, and patient-centric approaches. Consideration of regulatory requirements will be essential for translation to clinical applications and alignment with evolving pharmaceutical trends. Overall, this study paves the way for advancing drug delivery systems and improving patient outcomes.