Posted by ed_uk on December 9, 2004, at 11:32:33
Hi,
In hospital, the intravenous alpha blocker phentolamine (Rogitine) is used to treat MAOI-induced hypertensive crises. Nifedipine and chlorpromazine can be self-administered by patients at home. Presumably, chlorpromazine is effective because it is an alpha-1 antagonist. Unfortunately, using chlorpromazine carries all the risks of neuroleptics eg. dystonia, akathisia etc. Nifedipine is a calcium channel blocker which acts as a vasodilator. Use of a selective oral alpha blocker would seem to be an attractive option because the hypertensive crisis is thought to result from tyramine-induced liberation of norepinephrine causing vasoconstriction via alpha-1 receptors. An alpha blocker would seem to be a more specific treatment that nifedipine.
Has anyone ever used an oral alpha blocker to treat a hypertensive crisis? I can't find any reports of these drugs being used. Why not?
Alpha blockers available in the UK include... prazosin, doxazosin and terazosin. Prazosin would seem to be the most suitable due to the rapid onset and short duration of its effects. (Nifedipine, chlorpromazine, prazosin and terazosin all carry the risk of inducing hypotension).
Regards,
Ed.
poster:ed_uk
thread:426719
URL: http://www.dr-bob.org/babble/20041206/msgs/426719.html