Definition of Efficacy
The ability of a drug to produce a predictable effect in the body. Many factors influence a drug’s efficacy, from foods and other drugs to health conditions and a person’s metabolic characteristics.
An individual’s age, weight, gender, and level of activity also may affect the rate at which a drug enters, and how long it stays in, the blood circulation. It is a key factor in determining a drug’s potential effectiveness to treat a particular condition in a specific individual.
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