Magnesium hydroxide and Midodrine Hydrochloride

• Generic Name: magnesium hydroxide
• Dosage Forms: n.a.
• Other Brand Names: Ex-Lax Milk of Magnesia, Milk of Magnesia, Pedia-Lax Chewable, Phillips Milk of Magnesia, Concentrated Phillips Milk of Magnesia, Dulcolax Milk of Magnesia

Magnesium is a naturally occurring mineral. Magnesium hydroxide reduces stomach acid, and increases water in the intestines which may induce bowel movements.

Magnesium hydroxide is used as a laxative to relieve occasional constipation.

Magnesium hydroxide is also used as an antacid to relieve indigestion, sour stomach, and heartburn.

Magnesium hydroxide may also be used for purposes not listed in this medication guide.

• Generic Name: midodrine
• Dosage Forms: n.a.
• Other Brand Names: Proamatine, Orvaten

Treatment of symptomatic orthostatic hypotension (designated an orphan drug by FDA for this use). Indication is based on effect on increases in 1-minute standing systolic BP, a surrogate marker; clinical benefits (principally improved ability to perform life activities) not established. Continue the drug only in patients who report substantial symptomatic improvement.

Use recommended only in patients whose lives are considerably impaired despite standard clinical care; use only after nondrug therapies (e.g., support hose, increased sodium intake, life-style modifications) and fluid expansion have failed. May be more effective than comparative drugs (e.g., ephedrine) in managing postural symptoms.

In August 2010, FDA proposed to withdraw approval of midodrine because required postapproval studies verifying the clinical benefit of the drug had not been done. FDA stated that neither the original manufacturer (Shire) nor any generic manufacturer had demonstrated clinical benefit (e.g., performance of life activities); data submitted had not verified expected clinical benefit. In September 2010, FDA clarified that its proposal was part of the regulatory process and that midodrine could remain on the market as that process moves forward. Subsequently, FDA and Shire reached an agreement that Shire would conduct 2 additional clinical studies to verify the clinical benefit of midodrine in patients with symptomatic orthostatic hypotension. In February 2012, FDA announced that the proposal to withdraw approval of midodrine will be deferred until these studies have been conducted; meanwhile, the drug remains approved and available on the US market. In September 2014, FDA extended the deadline to March 31, 2015 for final submission of study results and analyses for FDA review.