This was an in vitro study carried out in a single research laboratory at Abbott, Hannover, Germany between July and September 2010. The objective was to identify the smallest diameter and longest stoma length of G-tube that would allow administration of the pancrelipase pellets using baby food as the vehicle. Following determination of the appropriate tubes, an additional objective was to determine the integrity of the pancrelipase pellets following G-tube administration. Here we tested pancrelipase 12 000-lipase unit CREON® capsules from a single manufacturing batch. The assessment of multiple batches was not necessary because all batches are identical, being produced using a manufacturing process that has been validated according to current regulatory requirements, with strict specifications that are always met regarding quality, composition, pellet size and gastric resistance.
G-Tube Feasibility Testing
Based on G-tubes predominantly used in clinical practice, feasibility testing was initially planned for the following: Kimberly-Clark MIC Bolus® sizes 14, 16, 18, 20 and 24 French (Fr) and Kimberly-Clark MIC-KEY® low-profile sizes 14, 16, 18, 20 and 24 Fr (stoma length 5.0 cm) [Kimberly-Clark Health Care, Dallas, TX, USA]. Fr denotes the outer tube diameter (1 Fr = 0.33 mm).
A high-viscosity vehicle is required for the administration of pancrelipase pellets by G-tube to ensure that they are suspended properly, thereby guaranteeing passage through the entire G-tube to reach the intended site of action without sedimentation, which may lead to clogging of the tube. Baby food was selected as the vehicle in this study as it meets this specification, is readily available and is commonly used (particularly applesauce) for administering PERT in infants and young children. Four types of baby food available in the US were used: applesauce and bananas manufactured by both Gerber Products Company (Florham Park, NJ, USA) and Beech-Nut Nutrition Corporation (Amsterdam, NY, USA). Prior to administration, pH testing was carried out to ensure that all four baby foods had a pH <4.5 to avoid potential disruption of the enteric coating, early release of enzymes and/or loss of enzyme activity.
CREON® pancrelipase capsules were opened and the pellets sprinkled onto approximately 15 mL of baby food per capsule. The mixture was stirred gently and, after 15 minutes, poured into a 35 mL syringe from which the plunger had been removed and the outlet blocked to prevent spillage. With the syringe tip already in the G-tube, the plunger was inserted and the mixture pushed slowly through the G-tube at a rate of approximately 15 mL every 10–15 seconds until all of the mixture had passed through the tube. Pellets pushed through the tube were collected on a sieve and the tube was flushed with 10–30 mL water to collect any remaining material. G-tubes were inspected visually to assess clogging or sticking to the tube. Recovered pellets were then flushed with 200 mL simulated gastric fluid and visually inspected for damage. Simulated gastric fluid was prepared according to US Pharmacopeia (USP) guidelines: dissolve 2.0 g of sodium chloride in 80 mL of 1 mol/L hydrochloric acid and make up to 1000 mL (volumetric flask).[19] This process was repeated three times for each G-tube and food type.
Integrity Testing of Pancrelipase Pellets
For each tube type, if there was no clogging, sticking or damage with all four foods, pellet integrity (gastric resistance and lipase activity) was assessed using an in vitro dissolution method modified from the current USP monograph for ‘Pancrelipase delayed-release capsules’[19] and the European Pharmacopoeia,[20] with a 2-hour gastric simulation step. The predetermined level of activity required to confirm pellet integrity was ≥80% of actual USP lipase activity per capsule after dissolution within 30 minutes at pH 6.0 (an approved in-house specification). Following the successful feasibility testing with the Kimberly-Clark G-tubes noted above, integrity testing was also carried out using tubes by a different manufacturer with a similar diameter: Bard® Tri-Funnel replacement tube size 18 Fr and the Bard® Button size 18 Fr with stoma length 3.4 cm (Bard Access Systems, Salt Lake City, UT, USA). For comparison, untreated pancrelipase pellets were also subjected to integrity testing. Pellets were removed from the capsule and tested directly using the same in vitro dissolution method.