Biodisponibility

Biodisponibility refers to the rate and extent to which an active ingredient or active moiety is absorbed from a drug product and becomes available at the site of action. It is a key parameter in pharmacology and pharmacokinetics, influencing the effectiveness and safety of medications. For orally administered drugs, biodisponibility is primarily determined by the amount of drug that reaches the systemic circulation unchanged after absorption from the gastrointestinal tract and undergoes first-pass metabolism in the liver.

Several factors can affect a drug's biodisponibility. These include the formulation of the drug, such as its physical form (e.g., tablet, capsule, liquid) and the presence of excipients. The route of administration is also crucial; intravenous administration typically results in 100% biodisponibility as the drug directly enters the bloodstream. Other factors include the drug's solubility, chemical stability, and its interaction with food. Patient-specific characteristics, like age, disease state, and the presence of other medications, can also influence how well a drug is absorbed and utilized.

Understanding biodisponibility is essential for determining appropriate drug dosages, designing effective drug delivery systems, and comparing different generic or brand-name medications. When two drug products are considered bioequivalent, it means they have comparable biodisponibility, suggesting they are likely to produce similar therapeutic effects. Deviations in biodisponibility can lead to sub-therapeutic levels or toxic concentrations of a drug.