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FDA Warns Against the Use of Quinine to Prevent Nocturnal Leg Cramps, Orders Unapproved Quinine Drugs Off the Market

Worst Pills, Best Pills Newsletter article February, 2007

The use of unapproved quinine-containing drugs to prevent nocturnal leg cramps poses serious safety concerns, including the risk of death, according to a December 11, 2006, warning from the Food and Drug Administration (FDA).  

Quinine is not approved by the FDA to treat nocturnal leg cramps – in fact, the drug is only approved by the FDA to treat malaria. However, drug companies illegally market quinine-containing products for off-label uses, such as treating leg cramps. Off-label use is...

The use of unapproved quinine-containing drugs to prevent nocturnal leg cramps poses serious safety concerns, including the risk of death, according to a December 11, 2006, warning from the Food and Drug Administration (FDA).  

Quinine is not approved by the FDA to treat nocturnal leg cramps – in fact, the drug is only approved by the FDA to treat malaria. However, drug companies illegally market quinine-containing products for off-label uses, such as treating leg cramps. Off-label use is the use of a drug for any indication other than those for which a drug is approved.

In response to companies’ promotion of quinine for off-label uses, the agency also ordered drug companies to stop marketing unapproved drug products containing quinine, citing serious safety concerns.

The full text of the FDA’s warning is available on the agency’s Web site at http://www.fda.gov/bbs/topics/NEWS/2006/NEW01521.html.

FDA Steps Up Safety Initiatives
Quinine has been used to treat malaria since the 19th century. Drugs in the United States were not required to be approved for use by any federal agency until 1938 for safety and the 1960s for effectiveness. As a result, many older drugs were grandfathered into general use. This was the case with quinine. The drug was sold over-the-counter for decades.

Since 1969, FDA has received 665 reports of adverse events with serious consequences associated with the use of quinine, including 93 deaths. Some of these serious adverse effects include heart rhythm disturbances, a decrease in blood platelets that can cause hemorrhage or clotting problems (thrombocytopenia), and severe hypersensitivity (allergic) reactions. There is also the potential for serious interactions between quinine and a long list of other drugs. Public Citizen’s Health Research Group petitioned the FDA to ban over-the counter sale of quinine for leg cramps in 1988 and to ban prescription use of quinine for leg cramps in 1994.

It is not clear exactly when the use of quinine as a treatment for nocturnal leg cramps began, but the practice continued for many years. The FDA’s August 1994 announcement that it would no longer allow quinine, either alone or in combination products, to be sold for nocturnal leg cramps in response to our petitions and to reports of health problems related to quinine use was intended to stop use of the product for this purpose. However the drug is still popularly known as a treatment for this indication, so this use has endured.  

The FDA’s most recent warning against the use of quinine for nocturnal leg cramps is part of an FDA initiative started last year to ensure that consumers and health care professionals are provided with established and emerging drug safety information. The goal is to provide the information patients and doctors need to make better decisions about the safe and effective use of drugs.

Since the FDA announced this initiative, the agency has issued warning letters to several companies that are manufacturing unapproved drugs and federal courts have entered permanent injunctions against two others. The FDA expects to further accelerate its enforcement efforts against marketed unapproved drugs in 2007.

Quinine should not be used by individuals who fall into any of the following categories: 

  • Have had previous allergic reactions to quinine, quinidine or mefloquine (LARIAM). 
  • Have had previous serious adverse effects to quinine, such as decreased platelets (components of blood necessary for clotting). 
  • Have low levels of an enzyme called Glucose-6-phosphate dehydrogenase (G-6-PD). 
  • Have the disease myasthenia gravis. 
  • Have optic neuritis, which is the inflammation of the nerve important for vision. 
  • Have certain heart rhythm problems or certain inherited abnormalities on your electrocardiogram (ECG, EKG). Your doctor will tell you whether your ECG/EKG has these abnormalities.

Quinine-Containing Product Warnings Not Widely Distributed
Mutual Pharmaceutical Co. Inc., produces QUALAQUIN, a quinine-containing drug approved by the FDA to treat certain types of malaria. QUALAQUIN carries a bolded warning (displayed in the box that accompanies this article) regarding serious adverse events associated with use of quinine, potentially serious interactions with other drugs and conditions under which quinine should not be used. QUALAQUIN is the only quinine-containing product approved for use by the FDA.

Unlike QUALAQUIN, many unapproved quinine drug products are marketed without labeling cautioning against use of the drug for treatment of leg cramps.

What You Can Do
You should not use quinine alone or in combination with other products to treat or prevent nocturnal leg cramps. 

WARNING: Use of Qualaquin for Treatment or Prevention of Nocturnal Leg Cramps

Qualaquin may cause unpredictable serious and life-threatening hypersensitivity reactions, QT prolongation, serious cardiac arrhythmias including torsades de pointes, and other serious adverse events requiring medical intervention and hospitalization. Fatalities have also been reported. The risk associated with the use of quinine sulfate in the absence of evidence of its effectiveness for treatment or prevention of nocturnal leg cramps, outweighs any potential benefit in treating and/or preventing this benign, self-limiting condition.