Factors Affecting Drug Bioavailability
Start with the big picture
The lesson organizes bioavailability factors across several connected areas. Physicochemical properties include solubility, dissolution rate, particle size, solid-state form, salt selection, and chemical stability. Formulation choices—such as excipients and immediate-, sustained-, or enteric-release designs—can alter drug release and absorption. Gastrointestinal conditions also matter: pH, gastric emptying, intestinal transit, food, and regional blood flow can change dissolution, contact time, or uptake. Finally, transporters and intestinal or hepatic metabolism may affect the drug reaching systemic circulation. For example, low aqueous solubility or slow dissolution can limit absorption, while micronization can increase surface area and accelerate dissolution. These interacting factors provide a framework for understanding variation in bioavailability.
What you'll learn
- Identify physicochemical properties that can influence drug absorption and bioavailability.
- Explain how particle size and formulation choices may affect dissolution or drug release.
- Describe how gastrointestinal pH, emptying, transit, and food can modify absorption.
- Recognize the potential roles of transporters and first-pass metabolism in oral bioavailability.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
