Most antipsychotics have both a-adrenergic and cholin-ergic antagonist activities, and blocking actions at hista-mine and serotonin receptors also contribute to the au-tonomic effects of some agents. Postural hypotension and depression of medullary cardiovascular centers resulting from (^-adrenoceptor blockade is particularly troublesome in elderly or debilitated patients. (2-Agonists, such as epinephrine, are contraindicated, as they may worsen the hypotension. The anticholinergic effects can be very bothersome but usually subside as tolerance to these effects occurs. Typically, autonomic signs can be controlled by adjustment of dose.
All antipsychotics except clozapine and perhaps olanzapine produce hyperprolactinemia by removing the inhibitory actions of dopamine on prolactin secretion. This results in amenorrhea, galactorrhea, and infertility in women and in loss of libido and impotence in men. Inhibition of the release of follicle-stimulating and luteinizing hormones may also play a role. In addition, weight gain is common, and food intake must be monitored.
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