Biomaterials for Controlled Drug Delivery Applications

Abstract

A drug delivery system (DDS) is by definition a platform that can transfer a therapeutic agent to the disease site in order to elicit and improve the desired therapeutic response. Currently, the traditional DDSs include tablets, syrups, capsules, creams, ointments, etc. The efficiency of the aforementioned systems is limited by their bioavailability level and their stability at the administration stage, which determines their ability to control the drug’s dosage level and frequency. Researchers and clinicians aimed to overcome the current limitations by exploiting novel biomaterials for controlled drug delivery applications. The new biomaterials exhibit improved bioavailability and the ability to control drug release kinetics in terms of steady and long-term drug release within the therapeutic window, with minimum side effects.

This chapter overviews the concept of DDSs, from understanding its basics up to describing the role of biomaterials in different drug delivery applications. Initially, the chapter starts by introducing the fundamentals of drug delivery systems including classification of drugs based on drug delivery systems, why there is a need of controlled drug delivery, different routes of drug administration, pharmacokinetics of drug delivery systems, and different release kinetics of drugs. These discussions provide a brief understanding for a particular type of drug and disease model which type of biomaterials should be designed. Whereas in the second part of the review, we have focused on the design considerations for controlled drug delivery systems, role of biomaterials for controlled drug delivery applications, and different biomaterials for drug delivery applications.

Graphical Abstract

Questions

• 1. How the physicochemical properties of a drug can affect its functionality?

  • Drug functionality depends mainly on its solubility that can be adjusted by using appropriate counterpart excipients.

  • Drug functionality depends mainly on its permeability, which also dictates the drug administration form.

  • The drug’s solubility and permeability affect the drug’s functionality, and therefore, should be considered in the way of drug administration as well as the DDS designing.

  • The drug’s physicochemical properties don’t affect the drug’s functionality.

  Explanation: both drug solubility and permeability do affect the drug functionality. For effective drug functionality, it should be first dissolved followed by its absorption in the blood. For different drugs classifications, different solutions are used to overcome lower drug solubility/permeability.

• 2. What is the need for a DDS utilization?

  • Modulating the pharmacokinetics behavior of a drug

  • Targeted delivery of a drug

  • Stabilizing the drug

  • All of the above

  Explanation: DDS can alter the drug release rate, where it can maintain the drug level in between the minimum effective and minimum toxic levels. Moreover, DDS can enable long-term drug release, as well as enabling its delivery to a certain organ/tissue, for targeted treatment. For less stable drugs, a suitable DDS can stabilize it to ensure its effective effect.

• 3. What are the principle considerations in DDS election?

  • DDS pharmacokinetics and administration route

  • The medical application

  • Drug’s classification and release kinetics

  • All of the above

  Explanation: DDS election and designing depends first on the medical problem that should be addressed, as well as the relevant drug classification, which supposed to be adjusted by the DDS pharmacokinetics and administration.

• 4. What are the main material properties that dictate their utilization in a DDS?

  • Biocompatibility, biodegradability, and non-immunogenicity

  • Biocompatibility, toughness, and non-immunogenicity

  • Biocompatibility, biodegradability, and flexibility

  • Biodegradability, toughness, and non-immunogenicity

  Explanation: the main material properties that dictate their utilization in a DDS are biocompatibility, biodegradability, and non-immunogenicity. These material properties can insure their enhanced functionality with minimal toxicity to the body, as well as minimal immunological response. The material biodegradability is also important to insure their elimination in a safe way. For specific applications, the material’s mechanical properties do also matter.

• 5. Nano-formulation of DDS are preferred because of their:

  • Low surface-to-area ratio

  • Efficient navigation within the tissue

  • Mechanical properties

  • None of the above

  Explanation: Nano-formulation of DDS are preferred because of their higher drug loading per unit volume due to a large surface to area ratio. Together with enhanced bioavailability, efficient navigation in the remote sites of tissue, flexibility in formulations, and improved intracellular trafficking of drugs.

• 6. Drug release from crystals is controlled by?

  • Crystal size

  • Crystal purity

  • Crystal Morphology

  • All of the above

  Explanation: Drug release from crystals can be manipulated by all of the above parameters, where they can help to achieve a slower or faster drug release to fit a specific application.

• 7. Drug release from crystals versus amorphous formulation is expected to be?

  • Faster

  • Similar

  • Slower

  • Either similar or faster

  Explanation: Drug release from crystals is always slower than amorphous as the crystalline structure represents the most stable form compared to the randomly organized amorphous form.

• 8. Drug crystals of hydrophobic drugs versus drug crystals of hydrophilic drugs are expected to exhibit?

  • Faster release

  • Similar release

  • Slower release

  • Either similar or faster release

  Explanation: Although both are crystals and should exhibit a slower release profile from the amorphous version but since the drug is released from hydrophobic-based crystals the release is anticipated to significantly exhibit a slower release from the hydrophilic-based crystals.

• 9. Conventional drug delivery system versus controlled drug delivery system?

  • Increases the chances to range between low-effective dose to toxic dose

  • Can be used for long-term release

  • Favored for all of the applications

  • None of the above

  Explanation: Conventional drug delivery system allows drug concentration in the plasma following the administration to range from very low effective dose to high concentration (might be toxic both in the short or long term).

• 10. Which of the following is best describing classification of Type 4 in drugs based on biopharmaceutics?

  • High solubility & High permeability

  • Low solubility & Low permeability

  • High solubility & Low permeability

  • Low solubility & High permeability

  Explanation: Drugs-based biopharmaceutics that classified Type 4 are identified with both low solubility and low permeability.