MEDizzy - A 14-year-old girl suffering from seasonal rhinitis started

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Pharmacodynamics

A 14-year-old girl suffering from seasonal rhinitis started therapy with loratadine, a drug that binds to H1 histamine receptors. Which of the following terms describes a characteristic of loratadine binding to the H1 receptor?

ExplanationD Affinity is the tendency of a drug to bind to a receptor. According to the occupation theory, binding to a receptor is driven by the law of mass action; that is, the number of bound receptors increases when the number of available drug molecules increases. Suppose that 100 receptors are exposed to 1000 molecules of drug A or to 1000 molecules of drug B. Also suppose that, in this instance, 40 molecules of drug A are found to be bound to the receptors, but only 10 molecules of drug B are bound to the receptors. It can be concluded that receptor Affinity of drug A is greater than that of drug B. A Intrinsic activity (often intrinsic efficacy is used as a synonym ) refers to the ability of a drug (once bound to a receptor) to initiate changes that lead to a biologic response. B Potency refers to the dose of a drug required to produce a given effect. The lower the dose required to produce the effect, the higher the potency. C Maximal efficacy refers to the maximum effect produced by the drug.