May 29, 2008 -- The erectile dysfunction drug Levitra is getting a label change noting rare reports of transient global amnesia in men taking the drug.
Transient global amnesia, or TGA, is a brief bout of amnesia, not lasting longer than a day, without causing other problems.
Levitra's label change isn't a warning or a precaution, and it doesn't mean that the drug causes memory problems. The reported cases of transient global amnesia in men taking Levitra may have been spurred by something else, even by sex.
"Sex can trigger TGA," says Harvard neurology professor Louis R. Caplan, MD. He likens TGA to a tape recorder that's not working.
"People otherwise can walk and talk and read and do high-level things, but they're not recording the information, as if their tape recorder is off," Caplan explains.
Transient global amnesia "scares people" but it doesn't affect function, long-term memory, or other aspects of health, Caplan says. "It isn't a reason not to take the drug."
Still, men who experience transient global amnesia should see a doctor to rule out illness or injury, says Caplan, who is also an attending physician in the Comprehensive Center for Stroke and Cerebrovascular Diseases at Beth Israel Deaconess Medical Center in Boston.
Not a "Warning" or "Precaution"
Transient global amnesia will join a list of other rare, reported adverse events -- including vision problems and sudden hearing loss, which are noted for all ED drugs -- in the "Post-Marketing" section of Levitra's label.
Levitra's label got the transient global amnesia note "because of a limited number of post-marketing reports of men who experienced TGA" around the time they took Levitra, the FDA tells WebMD in an email.
But those reports don't prove that Levitra was to blame.
Bayer Pharmaceuticals and the FDA have agreed on the wording of Levitra's label change, Bayer Pharmaceuticals spokesman Mark C. Burnett tells WebMD by email. Bayer "constantly monitors product safety reports and works closely together with worldwide regulatory authorities, including the FDA, to ensure that appropriate product information is shared with physicians and with their patients," Burnett says.
Transient Global Amnesia and ED Drugs
Caplan, a transient global amnesia expert, has seen many TGA patients, but only one man who had TGA after taking an ED drug.
The patient, a 51-year-old man with a history of hypertension and migraines, had played golf in the morning. After returning home with his girlfriend, he took Viagra.
"After 30 minutes, as he was about to engage in sexual intercourse, the patient reported that he 'felt weird'... [and] could not remember that he had played golf that morning," Caplan and colleagues wrote in Neurology's Sept. 10, 2002, issue.
The man was hospitalized for a day. His memory gradually improved during that time, though he hadn't regained his lost memories when he was discharged from the hospital.
Few other cases of transient global amnesia in men taking ED drugs have been published in medical journals. Those cases include a German man who experienced TGA after he apparently took Cialis, his doctors wrote in the International Journal of Impotence Research's July/August 2005 issue.
None of the case reports confirm that ED drugs prompted transient global amnesia.
Cialis, Viagra: No Label Changes
The three erectile dysfunction drugs -- Cialis, Levitra, and Viagra -- belong to a class of drugs called phosphodiesterase type 5 (PDE-5) inhibitors. None has been shown to cause transient global amnesia.
Only Levitra is changing its label to note reports of transient global amnesia. The FDA tells WebMD it can't comment on whether the makers of Cialis and Viagra have been asked to make similar label changes.
Pfizer makes Viagra. "We can't really speculate whether the Viagra label will be updated, but we certainly do believe that the current label accurately reflects the safety and efficacy of Viagra," Pfizer spokeswoman Jennifer Jacob tells WebMD in an email.
Eli Lilly & Co. makes Cialis. "Lilly typically doesn't discuss potential label changes or regulatory action," Stephanie Kenney-Andrzejewski, senior vice president for communications firm MS&L Global Health, tells WebMD on behalf of Lilly in an email. Kenney adds that "Cialis continues to be a generally well-tolerated and effective treatment for ED," with a safety profile backed by clinical research in more than 16,000 patients and more than 11.5 million men worldwide who have been prescribed Cialis.