The effect of haloperidol on epinephrine-stimulated adenylate cyclase in humans

Administration of epinephrine in man has been shown previously to lead to a rise in plasma cyclic AMP levels by activation of the β-adrenergic-stimulated adenylate cyclase. Therapeutic doses of lithium in humans block the epinephrine-induced rise in plasma cyclic AMP levels, suggesting that lithium inhibits β-adrenergic adenylate cyclase. In contrast, ten subjects receiving haloperidol, a drug also effective in the treatment of mania, show a mean rise in plasma cyclic AMP levels after epinephrine administration and the magnitude of the response is the same as for non-drug treated individuals. These findings are discussed in relation to the possible pharmacological mechanisms of action of lithium and haloperidol in the control of mania.