Drugs called dopamine agonists, used to treat Parkinson’s disease, may trigger sudden uncontrollable somnolence in about one in five patients.
The side effect has been reported previously in people with Parkinson’s disease being treated with dopamine agonists, including Mirapex and Requip, “but controversy persists concerning their nature, severity, and frequency,” according to a report in the Archives of Neurology.
Dr. Jerry Avorn and colleagues from Harvard Medical School, in Boston, quantified the risk of sudden uncontrollable somnolence in 929 patients taking drugs for Parkinson’s disease.
The subjects were an average of 66.7 years old and predominantly white and male. They were interviewed about medication use, adverse events, and clinical status in the previous 6 months. The patients’ physicians completed record reviews on clinical histories and drug regimens.
Most (91 percent) used levodopa either alone or in combination with another medication. Overall, 39 percent used Mirapex (generic name, pramipexole) alone or in combination with another agent and 18 percent used Requip (ropinirole) alone or in combination with another agent.
Twenty-two percent of the respondents reported episodes of uncontrollable somnolence. Of the 206 subjects who reported at least one episode, 34 percent had a small number of events (one to four) and 37 percent reported many frequent events (26 or more). Twelve percent of patients reported daily episodes.
A total of 124 of the affected patients were classified as having severe episodes.
The team found that patients treated with a dopamine agonist — pramipexole, ropinirole or pergolide (Permax) --were nearly three times as likely to experience episodes of sudden uncontrollable somnolence compared with all other Parkinson’s drug users.
The newer dopamine agonists have been shown to reduce the occurrence of movement complications as compared with levodopa when used as an initial treatment “and may pose a significant advantage in this respect,” Avorn’s team writes.
“However,” they caution, “these findings indicate that their increased capacity to cause clinically important episodes of uncontrollable somnolence will also need to be considered in the assessment of therapy for any given patient.”
