What is bio-availability?

Bioavailability, in the context of pharmaceuticals, refers to the proportion of a drug or substance that enters the systemic circulation and becomes available to produce an effect after administration. It essentially measures the rate and extent to which the active ingredient of a drug is absorbed and reaches the target site in the body.

When a drug is administered, its bioavailability can be affected by various factors such as its chemical form, formulation, route of administration, and interactions with other substances in the body. For example:

1. Oral bioavailability: When a drug is taken orally, it must first pass through the gastrointestinal tract, where it may encounter factors like pH levels, enzymes, and transporters that can affect its absorption. Only the portion of the drug that is absorbed into the bloodstream contributes to its bioavailability.
2. Intravenous bioavailability: Drugs administered intravenously bypass the gastrointestinal tract and are delivered directly into the bloodstream, resulting in 100% bioavailability since the entire dose reaches systemic circulation immediately.
3. Formulation and delivery systems: Different formulations and delivery systems can influence the bioavailability of a drug. For example, nano-emulsions or other advanced delivery systems can improve the solubility and absorption of poorly soluble drugs, thereby enhancing their bioavailability.

Bioavailability is an important consideration in pharmaceutical development because it directly impacts the effectiveness and dosage requirements of a drug. Pharmaceutical companies often conduct bioavailability studies to evaluate how different formulations and administration routes affect the absorption and distribution of a drug in the body.