Individuals who may have been exposed to HIV can decrease their chances of infection with post-exposure prophylaxis (PEP), an emergency course of combined antiretroviral drugs believed to combat HIV infection that is being more readily prescribed by doctors in hospitals and clinics across the province.
The treatment, available in Canada since 1996, was for years administered only to workers in high-risk environments where exposure to HIV via needle-stick injuries or cuts was a concern. Healthcare providers, police, firefighters and sanitation workers were the main recipients of the treatment. More recently however PEP has been prescribed to those facing possible HIV-exposure in nonoccupational settings including condom breaks, barebacking, intravenous drug use, sexual assault and to prevent transmission of the virus from mother to child during pregnancy.
Steven (who didn’t want his last name used for this story) took PEP four years ago after his condom broke during a bathhouse encounter. He says he knew nothing about the treatment until a staff member at the bathhouse told him about it.
“I admit I was pretty frightened,” he says. “I wound up going to the emergency at St Mike’s at 3am… and was given a prescription for a one-month supply of a drug called Combivir, which I had to take twice a day.”
PEP medications like Combivir are composed of two antiviral drugs, lamivudine (3TC) and zidovudine (AZT). In some cases an inhibitor like indinavir is added to make them more potent. To be effective the treatment must be initiated right away — preferably within the first two to 24 hours — and no later than 72 hours after possible exposure, and taken every day for a period of 28 days.
Unless the patient is on social assistance or has private healthcare insurance they may be left to pay anywhere from the $600 to $1,200 for PEP. Victims of sexual assault may have the drugs provided to them at no cost by the province.
“The pills were very expensive, nearly $700,” says Steven. “I didn’t have enough money to pay for them all at once so the pharmacy agreed to give me the drugs on a week-by-week basis, so I could pay for them in four installments.”
US studies on administering PEP following workplace exposure peg the success rate at about 80 percent or better. But when it comes to nonoccupational exposure, studies in either Canada or the US are virtually nonexistent, leading some doctors to question its effectiveness.
“It’s hard to gauge a success rate because what do you compare it to?” asks Sean Hosein, the science and medicine editor with the Canadian AIDS Treatment Information Exchange. “The mechanics of these things haven’t been well studied in people because it’s not ethically possible. If you were going to do a trial, how could you not give PEP to everybody? It’s unethical not to give it to them.”
Although it is now believed to be administered on a larger scale across the province than in past years, no accurate account exists of how many Ontarians have used PEP.
“Unfortunately we don’t do surveillance of HIV post-exposure prophylaxis in nonoccupational settings,” says Jacinthe Perras, a media relations officer with the Public Health Agency of Canada.
“There really aren’t any stats available,” says Rita Shahin, the associate medical officer of health for Toronto Public Health. “It would be very hard to obtain that data from individual physicians and hospitals and there is no systematic provincial program available for collecting and reporting the data.”
Shahin says logistics currently prevent the gathering and documenting of information on the dispensing of PEP in Ontario.
“But it’s probably not too difficult to get PEP in Toronto, compared with other smaller towns in Ontario,” she says.
PEP has the potential for a myriad of side effects including headaches, nausea, diarrhea, skin rashes, dizziness, muscle and joint pain, sleeplessness, irregular heartbeat and seizures.
“I would say that 10 years ago, or even five years ago that more people might have stopped therapy because of the side effects,” says Hosein. “Now the drugs are more tolerable, so more people may be finishing their treatment.”
“Fortunately for me… all I wound up with were a few headaches, a couple of days of nausea and a bit of fatigue,” says Steven. “I got off lucky I guess.”
Because of the high price of the drugs and the difficult side effects associated with them it’s estimated that roughly 50 percent of participants do not complete the full regimen, which has led to concern that the treatment itself could result in drug-resistant strains of HIV.
“Theoretically it may,” says Shahin, “but one thing to remember is that even if somebody has been exposed the chance of them becoming infected with HIV is very, very low. It’s less than one percent. So it’s a theoretical risk but it’s unlikely to happen.”