Glossary of Pharmacology 

Dose-Response Relationships

In in vivo assays, the biological response to a drug is dependent on its concentration at the receptor site. This is determined by both the dose of drug and the drug’s pharmacokinetic profile, such as rate of absorption, distribution, metabolism, and elimination. A dose-response curve establishes the relationship between the drug dose (X-axis) and its biological response (Y-axis), such as enzyme inhibition, blood pressure rise, smooth muscle contraction, or behavioural response. A dose-response curve allows us to estimate maximal response and the dose needed to produce 50% of  maximal response (EC50 or ED50). 

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