Uncommon adverse side effects
Evaluation of Treatments for Muscle Cramps
SOURCE: Neurology Now: March/April 2010, Vol. 6, Issue 2, p.10
Wesolowski, Kierstin
A new American Academy of Neurology (AAN) guideline that evaluates treatments for muscle cramps advises against the use of the drug quinine, an anti-malarial drug that has both analgesic and anti-inflammatory properties. Although the guideline authors acknowledge quinine’s effectiveness, they say its use should be avoided because of uncommon but adverse side effects. The guideline is published in the Feb. 23, 2010 issue of Neurology.
Only when the patient experiences disabling muscle cramps, has exhausted all other medication options, and has been made aware of the possible serious side effects, can quinine treatment be considered, says lead guideline author Hans D. Katzberg, M.D., of Stanford University. Patients on quinine drugs should receive “frequent history and physical examinations, as well as routine blood work,” Dr. Katzberg adds.
The guideline authors advise against the use of quinine because of the potential for toxicity, which can result in headache, dizziness, and hearing loss (cinchonism). Other more serious side effects may include a tendency to spontaneous bleeding (bleeding diathesis), and abnormalities—usually blood clots—that occur within the small blood vessels of the body.
Muscle cramps are temporary involuntary contractions of a muscle or a group of muscles that are sudden, forceful, and often painful and can last from a few seconds to minutes. A variety of neuropathic conditions, such as amyotrophic lateral sclerosis (ALS), peripheral neuropathies, and cramp-fasciculation syndrome (the uncontrollable twitching of muscles beneath the skin) are associated with muscle cramps.
The guideline authors evaluated treatments specifically for muscle cramps that have no known cause and those that occur as the result of neurological conditions, such as neuropathy or ALS. The authors reviewed 563 potential articles and identified 24 that satisfied their inclusion criteria of prospective trials (studies where participants are enrolled in clinical trials and investigators subsequently follow up with them) that evaluated the efficacy of a specific treatment for muscle cramps as a primary or secondary outcome. (The “primary outcome” of a study is the one the investigators are most interested in measuring; a secondary outcome is one that is of lesser interest to the investigators, but still of interest.)
Naftidrofuryl oxalate, diltiazem, and vitamin B complex can be considered possible treatments for muscle cramps, according to the AAN guideline. Natfitdrofuryl oxalate is a drug that may enhance utilization of oxygen and glucose in peripheral vascular disease; however, it is not available in the U.S. Diltiazem, a calcium channel blocker, slows the electrical current in the heart, which slows heart rate and normalizes heart rhythm. Vitamin B complex is a compound that contains many groups of vitamins the body requires in small amounts to remain healthy. However, further research is needed on the safety and effectiveness of all of these therapies.
“Any future studies should also include an assessment of the impact of cramps on the quality of life and non-pharmacological interventions in the treatment of muscle cramps,” Dr. Katzberg says. Dr. Katzberg advises that anyone who experiences persistent or disabling muscle cramps be evaluated by a health care professional to determine whether an underlying neurological or other medical condition could be causing the cramps.
Copyright © 2010, AAN Enterprises, Inc.
Here is the full transcript of the FDA alert:
July 8, 2010 – Physicians should not prescribe the malaria drug quinine
(Qualaquin) for nocturnal leg cramps – an off-label use – because it may
result in serious and life-threatening hematologic adverse effects, the US
Food and Drug Administration (FDA) announced today.
Quinine, marketed by AR Scientific, is approved only for uncomplicated
malaria caused by the parasite Plasmodium falciparum, according to the
agency.
The FDA issued a similar warning in 2006, but the agency noted today that the majority of quinine used in the United States is still for the
prevention or treatment of leg cramps.
Quinine therapy may result in thrombocytopenia, which can cause serious
bleeding, or hemolytic-uremic syndrome/thrombotic thrombocytopenic purpura, which may lead to permanent kidney damage. The FDA said that it received 38 reports of serious adverse events associated with quinine between April 2005 and October 1, 2008, in the United States through its Adverse Event Reporting System. Only 1 patient was taking quinine to treat malaria. Two patients died.
Under a risk management plan approved by the agency, the drug’s manufacturer will issue a letter to prescribers warning of the risk for hematologic reactions to the drug. In addition, patients must be given a medication guide explaining what quinine is and is not approved for, and its potential adverse effects.
More information on the FDA quinine warning is available on the agency’s Website www.fda.gov <http://www.fda.gov>