Bioavailibiliteetin

Bioavailibiliteetin, often shortened to bioavailability, refers to the fraction of an administered dose of an unchanged drug that reaches the systemic circulation. In simpler terms, it's the extent and rate at which a drug or nutrient is absorbed into the bloodstream and becomes available to exert its intended effect. When a substance is taken orally, it must pass through the digestive system, where it can be metabolized or eliminated before reaching the bloodstream. Intravenous administration, on the other hand, bypasses these barriers, resulting in 100% bioavailability.

Factors influencing bioavailability include the route of administration, the chemical properties of the substance, the formulation of the drug (e.g., tablets, capsules, liquids), and individual patient characteristics like gastrointestinal motility, pH, and the presence of food. For orally administered drugs, the first-pass effect, where the drug is metabolized by the liver before it can reach systemic circulation, significantly reduces bioavailability. Understanding bioavailability is crucial in pharmacology for determining appropriate dosages, designing drug delivery systems, and ensuring therapeutic efficacy.