Deadly cocktails

If you want to understand how prescription drugs can interact in the body, sometimes in a deadly way, think of a tractor-trailer jack-knifing on a four-lane highway. The resulting traffic jam plugs up the roadway. Nothing gets through. The backed up traffic builds, and sometimes, there are more pile-ups as cars slam into the stopped vehicles.

When there’s a traffic jam like this in the body, it’s because too many drugs are using the same pathway to clear out of the body. The chances for bad drug interaction increase with each prescription you take.

– If you take two prescriptions, there’s a six per cent chance of some adverse interaction.

– If you take five medications, there’s a 50 per cent chance for some kind of interaction.

– If you take eight medications, it’s 100 per cent sure you’ll have a negative interaction.

Who’s at risk?

But how likely is it that the average person would take five to eight medications? The likelihood is increasing as the population ages and baby boomers head into their 50s. That’s the time of life when illness and medication use traditionally increase.

The traffic jam analogy helps people understand drug interaction, but the processing of drugs within the body is quite complex. It’s done by enzymes, found in the intestinal wall, the gut and liver. These particular enzymes are called cytochromes. And they process and clear the chemicals out of the body by becoming pathways. Certain cytochromes can be pathways for a variety of chemicals. And the sources for these chemicals can be prescription drugs, over the counter drugs, herbs, even food.

Cytochromes pathways can have different speeds, just like roadways. If a cytochrome slows down too much, say becomes a 30-mile school zone and there are a lot of chemicals to clear, that’s when you can get a problem. When that happens, traffic backs up, you get a rise in the levels of certain chemicals. And if the chemical level gets too high, it can be toxic or interfere with critical body functions.

It’s important that patients and the medical profession, including pharmacists, become more aware about the problem of drug interaction.

High-tech help

The Capital Health Authority in Edmonton uses computer link-ups with all the city’s pharmacies to keep a record of the drugs used by individual patients. Hospital emergency departments can call up the list of drugs and get a complete history on the patient.

Manitoba and British Columbia are other jurisdictions using a similar approach. In Ontario, pharmacies are connected for people in the seniors’ drug program or on social assistance. But the data is used for billing the government, not for avoidance of potential drug interactions.

Patients need to realize that taking generic and brand names of the same drug is doubling the amount of the drug in their system. And that can create a problem with the efficacy of any medication and increase the chances of bad interaction with other drugs.