Midodrine

Midodrine hydrochloride tablets are indicated for the treatment of symptomatic orthostatic hypotension (OH). Because midodrine hydrochloride tablets can cause marked elevation of supine blood pressure (BP>200 mmHg systolic), it should be used in patients whose lives are considerably impaired despite standard clinical care, including non-pharmacologic treatment (such as support stockings), fluid expansion, and lifestyle alterations. The indication is based on midodrine’s effect on increases in 1-minute standing systolic blood pressure, a surrogate marker considered likely to correspond to a clinical benefit. …

• The recommended dose of midodrine hydrochloride tablet is 10 mg, 3 times daily
• Dosing should take place during the daytime hours when the patient needs to be upright, pursuing the activities of daily living
• A suggested dosing schedule of approximately 4-hour intervals is as follows: shortly before, or upon arising in the morning, midday and late afternoon (not later than 6 P.M.)
• Doses may be given in 3-hour intervals, if required, to control symptoms, but not more frequently
• Single doses as high as 20 mg have been given to patients, but severe and persistent systolic supine hypertension occurs at a high rate (about 45%) at this dose
• In order to reduce the potential for supine hypertension during sleep, midodrine hydrochloride tablets should not be given after the evening meal or less than 4 hours before bedtime
• Total daily doses greater than 30 mg have been tolerated by some patients, but their safety and usefulness have not been studied systematically or established
• Because of the risk of supine hypertension, midodrine hydrochloride tablets should be continued only in patients who appear to attain symptomatic improvement during initial treatment
• The supine and standing blood pressure should be monitored regularly, and the administration of midodrine hydrochloride tablets should be stopped if supine blood pressure increases excessively. …

• Safety and effectiveness
• In pediatric patients have not been established

• Patients should be told that certain agents in over-the-counter products, such as cold remedies and diet aids, can elevate blood pressure, and therefore, should be used cautiously with midodrine, as they may enhance or potentiate the pressor effects of midodrine (see Drug Interactions )
• Patients should also be made aware of the possibility of supine hypertension
• They should be told to avoid taking their dose if they are to be supine for any length of time, i.e., they should take their last daily dose of midodrine 3 to 4 hours before bedtime to minimize nighttime supine hypertension

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

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. …

Supine Hypertension: The most potentially serious adverse reaction associated with midodrine 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 . 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 in such patients is not recommended. …

The most frequent adverse reactions seen in controlled trials were supine and sitting hypertension; paresthesia and pruritus, mainly of the scalp; goosebumps; chills; urinary urge; urinary retention and urinary frequency. The frequency of these events in a 3-week placebo-controlled trial is shown in the following table: Adverse Events Placebo n=88 Midodrine n=82 Event # of reports % of patients # of reports % of patients Total # of reports 22 77 Paresthesia 1 4 4.5 15 18.3 Piloerection 0 0 11 13.4 Dysuria 2 0 0 11 13.4 Pruritis 3 2 2.3 10 12.2 Supine hypertension 4 0 0 6 7.3 Chills 0 0 4 4.9 Pain 5 0 0 4 4.9 Rash 1 1.1 2 2.4 1 Includes hyperesthesia and scalp paresthesia 2 Includes dysuria ( …

Pregnancy Midodrine increased the rate of embryo resorption, reduced fetal body weight in rats and rabbits, and decreased fetal survival in rabbits when given in doses 13 (rat) and 7 (rabbit) times the maximum human dose based on body surface area (mg/m 2 ). There are no adequate and well-controlled studies in pregnant women. Midodrine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. …

Symptoms of overdose could include hypertension, piloerection (goosebumps), a sensation of coldness and urinary retention. There are 2 reported cases of overdosage with midodrine, both in young males. One patient ingested midodrine drops, 250 mg, experienced systolic blood pressure greater than 200 mmHg, was treated with an IV injection of 20 mg of phentolamine, and was discharged the same night without any complaints. …

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