FDA warns methylphenidate drugs associated with priapism


In very rare cases, methylphenidate medications have been associated with priapism in both boys and men taking the drugs for attention-deficit/hyperactivity disorder, the Food and Drug Administration has reported.

Records of the FDA Adverse Event Reporting System, combined with data from the extant literature, identified 15 cases of priapism associated with the drug’s use. The cases occurred from 1997-2012; most (12) occurred in patients younger than 18 years. The patients’ mean age was 12, although ages ranged from 8-33 years.

In response to the findings, the FDA has updated the methylphenidate drug labels and patient information leaflets to include information about the condition. Patients who take methylphenidate and develop erections lasting longer than 4 hours should seek immediate medical treatment to prevent long-term problems with the penis.

Priapism occurred after withdrawal of methylphenidate in four patients, but also under other conditions, such as restarting the drug, or when there was a longer than typical time between doses, FDA noted in a safety announcement. Two patients required surgical intervention – one with a shunt and the other with needle aspiration of the corpus cavernosum.

In some patients, priapism resolved after the drug was restarted, the announcement said, adding: "It is possible that priapism may be more likely to occur with the use of immediate-release methylphenidate, which has a shorter half-life."

Amphetamine products also are used to treat ADHD, and the FDA has received reports of priapism in four patients taking one of those drugs. However, whether the amphetamine products caused the priapism is uncertain, the agency said, because all of these patients had been taking other medications that also could have caused the problem.

The risk of priapism might prompt some physicians to consider switching patients to atomoxetine (Strattera), FDA said. But that drug also has been associated with priapism in children, teens, and adults, the report said – and it appears to be more common than among patients taking methylphenidate medications. "However, because of limitations in available information, we do not know how often priapism occurs in patients taking either type of product. Use caution when switching patients from methylphenidate to atomoxetine."

The number of reported cases represents a tiny fraction of patients treated with methylphenidate. According to the FDA, 20 million prescriptions were written and 4 million patients received a dispensed prescription in 2012 alone. Most of those scrips (61%) were written for males.

The following methylphenidate drugs are marketed in the United States:

• Concerta (methylphenidate hydrochloride)

• Daytrana (methylphenidate)

• Focalin, Focalin XR (dexmethylphenidate hydrochloride)

• Metadate CD, Metadate ER (methylphenidate hydrochloride)

• Methylin, Methylin ER (methylphenidate hydrochloride)

• Quillivant XR (methylphenidate hydrochloride)

• Ritalin, Ritalin LA, Ritalin SR (methylphenidate hydrochloride

Although the condition appears to be exceedingly uncommon, the FDA recommended discussing the possibility with both patients and parents. "Younger males, especially those who have not yet reached puberty, may not recognize the problem or may be embarrassed to tell anyone if it occurs," the agency noted. "All male patients and their caregivers should be taught the signs and symptoms of priapism and the importance of seeking immediate medical treatment if it occurs."

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