Gastroretentive dosage forms

Area of Science:

• Pharmacokinetics and Drug Delivery
• Gastrointestinal Physiology
• Biomedical Engineering

Background:

• Gastric emptying, small intestine transit, and colonic transit are critical for oral drug delivery system performance.
• Prolonging gastric residence time (GRT) is a key strategy for improving the efficacy of certain drug delivery systems.
• Buoyant dosage forms offer a promising approach to achieve sustained GRT.

Purpose of the Study:

• To review and analyze methods for prolonging GRT, with a focus on floating (F) dosage forms.
• To evaluate the in vitro and in vivo performance of floating vs. non-floating (NF) drug delivery systems.
• To investigate the influence of dosage form size on GRT for both F and NF systems.

Main Methods:

• Review of physiological processes in gastric emptying and passage through the gastroduodenal junction.
• Analysis of various GRT-prolonging strategies, including floating forms, bioadhesives, and large-unit dosage forms.
• In vitro assessment using a specialized apparatus to measure buoyancy and in vivo scintigraphic studies in human volunteers comparing F and NF capsules.

Main Results:

• Floating dosage forms demonstrated significantly prolonged and more reproducible GRTs compared to non-floating forms in nonfasting humans.
• The GRT prolongation effect of floating forms was most pronounced for small units and diminished with increasing size.
• Intragastric buoyancy was identified as the primary factor determining the prolonged GRT of floating forms, independent of size.

Conclusions:

• Floating drug delivery systems effectively prolong gastric residence time by maintaining buoyancy above gastric contents.
• The enhanced GRT of floating forms is mainly governed by the end of digestion, offering predictable drug release.
• Buoyancy is a superior mechanism for achieving prolonged and reproducible GRT compared to size-dependent retention of non-floating forms.