Midodrine: a selective alpha-adrenergic agonist for orthostatic hypotension and dialysis hypotension.

Midodrine is an oral agent which acts as a selective peripherally-acting alpha-receptor agonist. Midodrine is a prodrug that is almost completely absorbed after oral administration and converted into its active drug de-glymidodrine in the systematic circulation, with a bioavailability of 93%. It has been used successfully in the treatment of neurogenic orthostatic hypotension and more recently, in the treatment of dialysis hypotension. It acts through vasoconstriction of the arterioles and the venous capacitance vessels, thereby increasing peripheral vascular resistance and augmenting venous return, respectively. It is a unique agent in the armamentarium against orthostatic hypotension since it has minimal cardiac and CNS effects. This article will review the literature on midodrine for conditions of autonomic dysfunction, with focus on recent studies on its use in haemodialysis patients.