What is the effect of an IV bolus administration?

• A. Gradual onset
• B. Slow distribution
• C. Rapid onset; medication enters directly into the bloodstream
• D. Delayed effect

Answer: (C)

Direct entry into the bloodstream via an IV bolus causes rapid onset of action because the drug bypasses the absorption step and goes straight into systemic circulation. This means plasma levels rise quickly to therapeutic concentrations, so tissues and target receptors are exposed almost immediately, producing an immediate effect. The speed of onset reflects the bypass of absorption, with the remaining timing depending on distribution, metabolism, and the drug’s pharmacodynamics rather than any absorption delay.