What term describes extent and rate medication reaches systemic circulation?

• A. Dosage Ranges
• B. Toxicity
• C. Bioavailability
• D. Adverse Reactions

Answer: (C)

Bioavailability is the extent and rate at which a drug reaches the systemic circulation after administration. It reflects how much of the dose actually gets into the blood and how quickly that happens, which in turn influences onset, intensity, and duration of effect. intravenous administration yields essentially complete bioavailability because the drug enters the bloodstream directly, while other routes (like oral) often have lower, more variable bioavailability due to incomplete absorption and first-pass metabolism in the liver. This concept is distinct from dosage ranges (how much to give), toxicity (harmful effects at high levels), or adverse reactions (unwanted effects), which is why bioavailability best answers the question.