Drug Flaws

It's a sunny Sunday morning as you reach for the grapefruit juice. But before you gulp, ask yourself: are you taking any drugs that could turn this nutritious beverage into a life-threatening danger?

Or are you taking erythromycin, an antibiotic linked to increased risk of heart attack when combined with certain high blood pressure and infection drugs?

Potential drug-food and drug-drug interactions represent two giant knowledge gaps in Canada's drug regulatory system. For years, critics have spoken out about the "closed door" approach to drug safety information, the close relationship between Health Canada and pharmaceutical giants, and the relative lack of follow-up once a drug hits the market.

Even though fewer than nine percent of new drugs represent significant improvements over existing ones, the Federal Government promised an additional $190 million between 2003 and 2008 to speed up regulatory drug processes.

Joel Lexchin, associate professor at York University, noted recently in the Canadian Medical Association Journal: "From the point of view of return on investment, industry's preoccupation with timeliness makes perfect sense; whether that preoccupation is warranted from a public health point of view is another question."

Health Canada assesses pre-market drug research provided by the manufacturer, but doesn't conduct independent studies. New drugs are not required to be tested for how they interact with other drugs and food; usually, contraindications are noted only once a drug is in public use.

Take the case of the seemingly innocuous grapefruit. We now know grapefruit, sour oranges, tangelos and their juices don't mix well with some drugs for angina, anxiety, cancer, depression, high blood pressure, high cholesterol, and irregular heart rhythm. One glass of grapefruit juice can cause increased blood drug levels for three days or more.

Unknown drug-drug interactions are another major concern, especially among multiple-medicating seniors. Ten percent of Canadians aged 65 to 74 take five or more medications daily.

Recently, researchers discovered erythromycin, a commonly prescribed antibiotic, doubles one's risk of sudden death from cardiac causes, and increases risk of cardiac arrest when combined with blood pressure medications verapamil and diltiazem. In September 2004, the New England Journal of Medicine reported that combining erythromycin with vaginal yeast infection drug fluconazole, or antifungal drugs itraconazole or ketoconazole, increases risk of heart attack.

In 2003, Health Canada received 9,209 reports of suspected adverse drug reactions, up 7.5 percent from 2002. Of the 2.5 million Canadians admitted to hospital each year, approximately 7.5 percent suffer "adverse events," with reactions to drugs the second most common cause, after surgery. In May 2004, The Canadian Adverse Events Study reported 9,250 to 24,000 Canadian hospital patients die every year due to medical errors.

With the average Canadian spending $500 annually on pharmaceuticals, it's time to be asking tough questions. Consumers need more than a spoonful of sugar to make the medicine go down. To report an adverse drug reaction, call 1-866-234-2345 or email cadrmp@hc-sc.gc.ca.