The painkiller oxycodone appears to be effective at treating the intense pain of shingles, but not all patients are able to handle the side effects, a new study finds.
Shingles can develop in people who have had chicken pox earlier in life. It's caused by reactivation of the virus that causes both illnesses, varicella zoster.
For most shingles patients, the first symptom is pain, quickly followed by a rash. The pain can be excruciating for some patients, since the illness causes damage to nerves as well as inflammatory pain in the skin. The illness typically lasts about three or four weeks.
Treatment usually involves antiviral treatment, as well as ibuprofen, acetaminophen, or codeine to control the pain. But few placebo-controlled studies have evaluated which pain control method works best for shingles patients.
This study, published in the April issue of the journal Pain, studied 87 shingles patients in Rochester, N.Y., and Houston, Tex. The patients were divided into three groups and received either oxycodone (sold as Oxycontin and other names), gabapentin, or placebo. All patients also received antiviral medication.
Patients taking oxycodone were more than twice as likely to experience a meaningful reduction in their pain - at least a 30 per cent decrease - compared to their counterparts taking a placebo.
Although the medication was effective, nearly one-third of the participants on oxycodone withdrew from the study, mainly because of problems with constipation.
Gabapentin did not appear useful to treat pain, which surprised the researchers. Dr. Robert Dworkin, the University of Rochester Medical Center pain expert who led the study, said it's possible that a higher dose would be necessary to adequately treat shingles pain. But since the medication can only be increased over the course of three weeks or more, that may be too long to have an effect on shingles, which can run its course in a few weeks.
The team chose to study oxycodone and gabapentin because both are often effective for treating patients in whom shingles persists for months or even years - a condition called postherpetic neuralgia.
About one in five patients with shingles who are treated with antiviral medications will develop postherpetic neuralgia. Older patients who don't receive quick antiviral treatment have a 40 to 50 per cent chance of developing postherpetic neuralgia.
Health Canada recently approved a vaccine that helps prevent shingles outbreaks in older people. Zostavax is made by Merck Frosst Canada and should be available through doctors and pharmacies later this year.
