MIDODRINE Drug Interactions: What You Need to Know

Drug Interactions When administered concomitantly with midodrine, cardiac glycosides may enhance or precipitate bradycardia, A.V. block or arrhythmia. The risk of hypertension increases with concomitant administration of drugs that increase blood pressure (phenylephrine, pseudoephedrine, ephedrine, dihydroergotamine, thyroid hormones, or droxidopa). Avoid concomitant use of drugs that increase blood pressure. If concomitant use cannot be avoided, monitor blood pressure closely. Avoid use of MAO inhibitors or linezolid with midodrine. Midodrine has been used in patients concomitantly treated with salt-retaining steroid therapy (i.e., fludrocortisone acetate), with or without salt supplementation. The potential for supine hypertension should be carefully monitored in these patients and may be minimized by either reducing the dose of fludrocortisone acetate or decreasing the salt intake prior to initiation of treatment with midodrine. Alpha-adrenergic blocking agents, such as prazosin, terazosin, and doxazosin, can antagonize the effects of midodrine. Potential for Drug Interaction It appears possible, although there is no supporting experimental evidence, that the high renal clearance of desyglymidodrine (a base) is due to active tubular secretion by the base-secreting system also responsible for the secretionof such drugs as metformin, cimetidine, ranitidine, procainamide, triamterene, flecainide, and quinidine. Thus there may be a potential for drug-drug interactions with these drugs.

CONTRAINDICATIONS Midodrine hydrochloride tablets are contraindicated in patients with severe organic heart disease, acute renal disease, urinary retention, pheochromocytoma or thyrotoxicosis. Midodrine hydrochloride tablets should not be used in patients with persistent and excessive supine hypertension.

WARNING: Because midodrine hydrochloride can cause marked elevation of supine blood pressure, it should be used in patients whose lives are considerably impaired despite standard clinical care. The indication for use of midodrine hydrochloride in the treatment of symptomatic orthostatic hypotension is based primarily on a change in a surrogate marker of effectiveness, an increase in systolic blood pressure measured one minute after standing, a surrogate marker considered likely to correspond to a clinical benefit. At present, however, clinical benefits of midodrine hydrochloride, principally improved ability to carry out activities of daily living, have not been verified.

Warnings

Supine Hypertension: The most potentially serious adverse reaction associated with midodrine hydrochloride therapy is marked elevation of supine arterial blood pressure (supine hypertension). Systolic pressure of about 200 mmHg were seen overall in about 13.4% of patients given 10 mg of midodrine hydrochloride. Systolic elevations of this degree were most likely to be observed in patients with relatively elevated pre-treatment systolic blood pressures (mean 170 mmHg). There is no experience in patients with initial supine systolic pressure above 180 mmHg, as those patients were excluded from the clinical trials. Use of midodrine hydrochloride in such patients is not recommended. Sitting blood pressures were also elevated by midodrine hydrochloride therapy. It is essential to monitor supine and sitting blood pressures in patients maintained on midodrine hydrochloride. Uncontrolled hypertension increases the risk of cardiovascular events, particularly stroke.