The functionality of enteric-coating polymers can be greatly affected by factors, such as:
- The nature of the drug substance (active pharmaceutical ingredient) in the dosage form; especially when it is ionic in nature.
- The quantity of coating applied; application of excessive coating can substantially delay drug release from the dosage form while insufficient coating can result in ineffective gastric resistance.
- The presence of imperfections in the coating (e.g., cracks, “pick marks,” etc.) can destroy the integrity of the coating.
- The dissolution pH and dissolution rate of the polymer used.
- The influence of the in-vitro test conditions used (such as pH and ionic strength of the test solution; as well as the agitation rate used in the test).
- The presence or absence of plasticizers.
- Gastrointestinal physiological factors including:
- The pH of the stomach and intestinal contents
- Gastric emptying
- Enzyme activity of the gastrointestinal tract.
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