Indoramin is a postsynaptic selective alpha 1-adrenoceptor antagonist used in the treatment of
hypertension. In contrast to some other alpha-blockers, animal studies suggest that its blood pressure lowering effect results from relaxation of peripheral arterioles as a consequence of blockade of postsynaptic alpha 1-adrenoceptors. Furthermore, unlike some other alpha-blockers, this lowering of blood pressure is rarely associated with reflex
tachycardia or
postural hypotension. Therapeutic trials have shown
indoramin to be effective in lowering blood pressure in all grades of
hypertension: mild and moderate
hypertension when used alone, but generally in combination with a
thiazide diuretic, and in moderate to moderately severe
hypertension when used in combination with a beta-blocker and
diuretic. In a few small comparative studies, no significant difference was found in the blood pressure lowering effects between
indoramin and
methyldopa,
propranolol and
prazosin. Side effects were similar for
indoramin,
propranolol and
methyldopa; however in the 1 comparative study with
prazosin,
prazosin produced a lower incidence of sedation. Indeed, the most common side effect with
indoramin therapy has been sedation of a mild to moderate and/or transient nature, reported in about 19% of cases. Other side effects which have sometimes led to a withdrawal of
indoramin treatment have been dry mouth,
dizziness, and in males, failure of ejaculation; however, side effects may be reduced by starting
therapy with smaller doses and titrating more gradually.