It is used as a cough suppressant, although it can sometimes be used, medicinally, as a pain reliever, and is also used as a recreational drug.Quinidine sulfate affects the way the heart beats, and is generally used in people with certain heart rhythm disorders. It is also used to treat malaria. Quinidine sulfate, as a metabolic inhibitor, "increases plasma levels of dextromethorphan by competitively inhibiting cytochrome P450 2D6, which catalyzes a major biotransformation pathway for dextromethorphan," enabling therapeutic dextromethorphan concentrations.Dextromethorphan/quinidine is a combination of these two generic drugs, and is the first FDA-approved drug for the treatment of PBA, approved on October 29, 2010.For this multicenter study, the "Objectives...[were] to evaluate the safety, tolerability, and efficacy of two different doses of AVP-923 [Dextromethorphan/quinidine combination]...when compared to placebo." The conditions and results of that study are as follows:

At one study site, a total of 326 participants received one of three dose options. "METHODS: In a 12-week randomized, double-blind trial, ALS and MS patients with clinically significant PBA" were given a twice-daily dose of one of the following:
placebo (N=109)
dextromethorphan hydrobromide 30 mg/quinidine sulfate 10 mg (N=110)
Nuedexta – dextromethorphan hydrobromide 20 mg/quinidine sulfate 10 mg (N=107)283 patients (86.8%) completed the study. The number of PBA episodes (laughing, crying or aggressive outbursts) were 47% and 49% lower (based on the trials outcome measures), respectively, for the drug-combination options than for the placebo. The "mean CNS-LS scores" decreased by 8.2 points for both drug-combination options, vs a decrease of 5.7 points for the placebo.
Esterified estrogens/methyltestosterone (EEs/MT), sold under brand names such as Covaryx, Eemt, Essian, Estratest, Menogen, and Syntest, is a hormonal preparation that combines esterified estrogens (EEs) with methyltestosterone (MT) in one tablet and is used in menopausal hormone therapy. Medical uses
EEs/MT is used to treat menopausal women who suffer from hot flashes, but do not get relief from estrogen-only therapy. Available forms
EEs/MT is sold in tablet form, with either 1.25 mg EEs/2.5 mg MT or 0.625 mg EEs/1.25 mg MT available. Pharmacology
The product is a combination of esterified estrogens, an estrogen, and low-dose methyltestosterone, an androgen/anabolic steroid, in a single tablet. History
EEs/MT was first marketed in the United States in 1965 by Reid-Provident Laboratories, which as 100% of Reid-Rowell, Inc. stock was acquired by the Belgian pharmaceutical company Solvay in 1986. There has been some controversy surrounding the drug in recent years as to its status with the U.S. Food and Drug Administration. Solvay sponsored a clinical trial of EEs/MT in the United States to determine whether the product is superior to treatment with esterified estrogens tablets. EEs/MT was supplied by Solvay. In March 2009 Solvay announced that, based on a variety of business factors, it would discontinue supplying Estratest and Estratest HS tablets, and would stop accepting orders for the product on March 31, 2009. See also
Conjugated estrogens/methyltestosterone
List of combined sex-hormonal preparations

References
External links
The products web site