TORONTO - Canadians should not be running to their doctors seeking to stock up on prescription antiviral drugs out of fear they may get swine flu, public health experts say.
Two antiviral medications - Tamiflu and Relenza - appear to be effective against the new H1N1 influenza strain that has hit Mexico and spread to other countries.
The drugs, which must be taken within 48 hours of the start of symptoms, work by reducing the severity and duration of illness in people who have contracted the virus. They can also be used as a prophylaxis to prevent the disease if taken before exposure.
But with only a smattering of cases in Canada so far, and all of them reportedly mild, infectious disease experts say the use of antivirals at this time just isn't warranted.
"We don't recommend that people stockpile on their own," said Dr. David McKeown, Toronto's medical officer of health.
"Right now we have a small number of cases of relatively mild severity," McKeown said. "And if someone has very mild illness, a physician might not choose to prescribe an antiviral medication because it's not necessary. The person will recover successfully without it."
Allison Stuart, acting assistant deputy minister of public health for Ontario, agreed that the nature of symptoms being experienced in the small number of cases diagnosed as swine flu doesn't warrant people seeking out Tamiflu or Relenza.
"Right now, the cases that are presenting in Ontario aren't coming through as being ill enough to require anything other than symptomatic - what your mom used to do when you were sick at home - kinds of interventions," she said.
While Nova Scotia is following a similar guideline for mild illness, Tamiflu is being recommended for treating certain patients in the wake of a cluster of cases at the King's-Edgehill School in Windsor.
Dr. Robert Strang, the province's chief public health officer, said doctors are being advised to prescribe the drug for anyone who contracts swine flu and becomes moderately ill - and has known risk factors such as being over 65 or having an underlying medical condition.
However, Strang said the province is "strongly urging family physicians to not prescribe Tamiflu for prophylaxis." An exception was made for King's-Edgehill students and staff, who were offered the antiviral as means of preventing spread of the virus.
There are solid reasons for holding back on antivirals, stressed Canada's chief public health officer, in particular because of the risk of producing a drug-resistant strain of this never-before-seen swine flu.
"Currently the public health agency recommends only limited use of antivirals," Dr. David Butler-Jones said Wednesday. "It's a choice, obviously, between a doctor and patient. But it generally shouldn't be used unless someone is very ill or is at high risk of complications of influenza."
"In fact, inappropriate use could increase the risk of resistance and the drug would not be effective if we needed it in the event of more severe illnesses."
The emergence of a resistant strain would present a nightmare scenario for Canada and other countries, which have been stockpiling millions of doses of the medications over the last five years in preparation for a possible influenza pandemic.
In Canada, the federal government has amassed a national antiviral stockpile of more than 55 million doses, enough to treat almost 5.6 million people. Tamiflu (oseltamivir), an oral medication made by Hoffman-La Roche, accounts for about 90 per cent of that reserve. The remainder is made up of GlaxoSmithKline's inhaled antiviral Relenza (zanamivir).
A national emergency stockpile, meant as a backup for the larger national stockpile, contains 14 million doses of the drugs, enough to treat about 1.4 million Canadians.
The two stockpiles combined, along with other stores of flu antivirals held by governments, are estimated to contain enough medication to treat about a quarter of the population during a pandemic, officials say.
McKeown said it's important to distinguish between the situation in Canada now - relatively few cases involving mild illness - and some of the more dire scenarios for which pandemic preparedness planning has been carried out, including one in which the case count reaches epidemic proportions across the country.
"If we had large numbers of cases of very severe influenza, then there would be significant demand for this medication to treat people," he said. "And the stockpile is intended to help address that demand so that a surge in cases will not lead to a lack of availability of antiviral medications."
"So if we have a severe pandemic with many, many seriously ill people and there is a shortage of antiviral medication to treat them with, the stockpile would then be made available. And it would be made available essentially through the health-care system."
However, it appears some people aren't waiting to see how the swine flu saga will play out before taking action.
Tammy Smitham, director of communications for Shoppers Drug Mart Corp., said customer demand for hand-sanitizing products and N95 respirator masks has jumped noticeably since cases of the new flu virus were first reported late last week.
Smitham said she could not say whether stores in the chain are ordering more antivirals or whether more customers are coming in seeking the prescription-only drugs.
"We're actually not commenting on - and we don't comment on - sales of specific prescription drugs," she said.
But Roche Canada spokeswoman Laura Pagnotta confirmed that over the last few days, the company has "certainly seen an increase in calls ... both for requests for information as well as inquiries about orders for Tamiflu."
Pagnotta said calls are coming in from a variety of customers, including retail pharmacists, drug wholesalers, governments, hospitals and individual corporations.
In a statement released Wednesday, the company said it is working with the federal and provincial governments as well as hospitals to address their potential need for Tamiflu supplies.
"While we understand there is increased public demand for the product, Roche supports government's position on the appropriate use of antivirals and we remain focused on prioritizing government and hospital needs."
Meanwhile, Dr. Margaret Chan, director general of the World Health Organization, said in Geneva she has contacted Hoffman-La Roche and Glaxo to determine their capacity for possibly ramping up production of their antivirals.
