Receptors, Neurotransmitters and Drug Responses

ABNORMALITIES in sensitivity to endogenous hormones and neurotransmitters as well as to exogenous drugs pervade clinical medicine. Idiosyncratic responses to medication are well known, but their causes are rarely ascertained. Although chronic decreases in sensitivity to drugs accompany classic forms of drug addiction, underlying mechanisms are unknown. Acute tolerance, also known as tachyphylaxis or desensitization, is fundamental to synaptic transmission and has many clinical manifestations, such as the decreased responsiveness of an asthmatic person to epinephrine after multiple administrations. Supersensitivity to endogenous or exogenous agents also has clinical relevance. Examples include the apparent supersensitivity to circulating catecholamines in hyperthyroidism and.