Effects of prazosin and clonidine on sympathetic and baroreflex function in patients with essential hypertension. J Clin Pharmacol 1983;23(8-9):348-54
Date
08/01/1983Pubmed ID
6630584DOI
10.1002/j.1552-4604.1983.tb02747.xScopus ID
2-s2.0-0020551150 (requires institutional sign-in at Scopus site) 12 CitationsAbstract
Prazosin, a peripherally active alpha-adrenoceptor antagonist, and clonidine, a centrally active alpha-adrenoceptor agonist, both reduce blood pressure but with different alterations in sympathetic nervous system activity. We studied the effects of monotherapy with either prazosin or clonidine in 10 and 30 patients, respectively, with essential hypertension. Prazosin reduced blood pressure without affecting heart rate or circulating plasma catecholamines. Sensitivity to injected phenylephrine was markedly reduced by prazosin, and sensitivity to isoproterenol was increased, whereas baroreflex sensitivity was not significantly altered. Blood pressure response to prazosin was correlated with basal plasma norepinephrine concentration (r = 0.64, P less than 0.04). In contrast, clonidine reduced heart rates and plasma concentrations of both norepinephrine and epinephrine, increased the sensitivity to phenylephrine, and increased baroreflex sensitivity. Blood pressure response to clonidine was correlated with reduction in plasma norepinephrine concentration (r = 0.51, P less than 0.004). Thus, blood pressure reduction resulting from monotherapy with either prazosin or clonidine occurs through different antisympathetic effects, suggesting that combined therapy might be useful in those unresponsive to either drug alone.
Author List
Guthrie GP Jr, Kotchen TAMESH terms used to index this publication - Major topics in bold
AdultBlood Pressure
Clonidine
Depression, Chemical
Female
Heart Rate
Humans
Hypertension
Male
Middle Aged
Norepinephrine
Prazosin
Pressoreceptors
Pulse
Quinazolines
