DOSAGE AND ADMINISTRATION: Treatment with MIDODRINE (midodhne hydrochloride) should be started under close medical supervision in a controlled clinical setting such as in hospital, in clinic, or in the office. Hourly measurements of blood pressure (supine and sitting) should be made for 3 hours after the first dose and also the second dose of a three times daily dosage regimen. This procedure should be followed also when the dose is increased. During the period of close medical supervision, the patient or a person living with the patient should be trained to measure blood pressure. Supine and sitting blood pressures should be measured daily for at least one month after the initiation of treatment and twice per week afterwards. The administration of MIDODRINE should be stopped and the attending physician notified immediately. if the blood pressure in either position increases above 180/100 mm Hg. The usual starting dose of MIDODRINE is 2.5 mg three times daily. Single doses of 2.5, 5 and 10 mg have been successfully employed. Most patients are controlled at or below 30 mg per day given in three or four divided doses. MIDODRINE can be given up to six times per day but a total daily dose of 30 mg should not be exceeded. Some patients require a morning dose that is higher than that taken later in the day. In some instances MIDODRINE has been given on a three times per day schedule as follows: 1 to 2 hours before arising in the morning, mid-morning and mid-afternoon. In order to reduce the potential for supine hypertension. it may be recommended that midodrine doses not be given after the evening meal or less than 4 hours before bedtime.
DRUG INTERACTIONS DIGITALIS: Cardiac glycosides may enhance or precipitate bradycardia, A.V. block or arrhythmia when administered concomitantly with midodnne.
Sympathomimetic agents: The use of drugs that stimulate alpha-adrenoceptors (e.g.. phenylephrine, pseudoephedrine ephedrine, phenylpropanolamine or dihydroergotamine) may enhance or potentiate the pressor effects of midodrine. Therefore, midodnne should not be used concomitantly with vasoconstrictor sympathomimetic agents and the patient should be warned not to use over-the-counter preparafions containing these drugs.
Sympatholytic agents: Alpha-adrenoceptor antagonists such as phentolamine. prazosin. doxazosin and labetalol can inhibit the vasopressor effect of midodrine.
Corticosteroids: Patients on salt-retaining steroids (e.g., fludrocortisone), with or without salt supplementation, may experience an excessive pressure effect after midodrine therapy, especially in the supine posture. The possibility of hypertensive effects with midodrine can be minimized by either reducing the dose of fludrocortisone or decreasing the salt intake prior to initiation of treatment with midodrine.
Potential for Drug Interactions: It appears possible, although there is no supporting experimental evidence, that the high renal clearance of desglymidodrine (a base) is due to active tubular secretion by the base-secreting system also responsible for the secretion of such drugs as metformin, cimetidine, ranitidine, procainamide. triamterene. flecainide. and quinidine. Thus there may be a potential for drug-drug interactions with these drugs