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Generic and Brand-Name Prescription Drugs: What’s the Difference?

woman examining medicationEven though generic drugs are dispensed to fill two-thirds of all prescriptions in Canada, many people still do not understand the difference between brand-name and generic drugs.

Generic drugs are low-cost versions of brand-name drugs that are produced by several manufacturers once the patents expire on the brand-name versions.

In Canada, brand-name drugs have patent terms of 20 years and they often list several patents on the same medicine. After that, other manufacturers can apply to Health Canada to produce generic versions. 

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When Health Canada approval is given, government – and employer – sponsored drug benefit plans and patients can benefit from the availability of a lower-priced generic equivalent of the original, brand-name drug.

The most important thing to know about generic prescription medicines in Canada is that there are no differences in terms of quality, purity, effectiveness, and safety between generic drugs and higher-priced brand-name drugs.

When a generic drug is approved by Health Canada that means the medicine is as safe and as effective as the original brand-name drug and that it will work the same way.

Health Canada reviews and approves all drugs, brand-name and generic, before they can be sold in Canada.

Further, Health Canada requires that both brand-name and generic drug companies follow the same rules for the manufacturing process and for ensuring the quality of their ingredients.

Health Canada mandates that generic drugs have the same active ingredient (the chemical that makes the drug work) in the same amount and that they work the same way in the body as the brand-name drug.

Health Canada even regulates the non-medicinal ingredients, such as fillers and preservatives, for both brand-name and generic drugs and they are subject to the same approval process.

Bioequivalence and bioavailability: What are they?

Some people who are paid by brand-name drug companies attempt to confuse prescribers and patients about generic prescription medicines by making inaccurate or misleading statements about “bioequivalence” and what it means.

In doing so, they fail to note that brand-name drug companies also rely on bioequivalence measures for regulatory approval of their process.

To understand bioequivalence, we must first understand variability within products and people.

For example, it is impossible for all capsules or tablets in a single prescription – brand or generic – to be absolutely identical and to contain the exact amount on the label.

It is impossible for all batches from the same manufacturer – brand or generic – to be identical.

Therefore, brand-name and generic drugs meet Canada’s regulatory requirements when their content variability is within an approved range, most commonly 10 percent of the label claim.

Variability also applies to humans, who are the volunteers in the trials and studies used for approving brand-name and generic prescription drugs.

When testing a drug in humans to determine its safety and effectiveness, variability must be part of the analysis because even though the drug is the same, not every person’s response will be the same. This “acceptable range of variability” exists when testing a brand-name drug as well as when testing a generic drug.

Bioavailability is assessed by measuring the amount of the active ingredient in the blood over time and the maximum concentration in the blood stream.

In typical bioequivalence studies, individuals are separated into two groups and the study includes two periods. In the first stage, Group 1 is given a generic drug and Group 2 is given the brand-name version of the drug. The extent of drug absorption based on the blood concentration of the drug over time, the maximum observed concentration of the drug and the time it takes to reach that maximum concentration are measured to assess the bioavailability of the drug in both groups of peoples.

At the second stage of the bioequivalence study, the group that had received the generic drug in stage one is given the brand-name drug, and the group that was given the brand-name drug is given the generic drug. The bioavailability of the drug in the two groups is assessed in the same way as stage one.

The bioavailability of the brand-name drug is then compared to that of the generic drug in each individual. When these comparisons demonstrate a relatively similar extent of absorption and a similar maximum drug concentration, bioequivalence is achieved and the generic drug is proven to be as safe and effective as the brand-name version.

It is extremely important to note that in a group being tested for bioavailability each individual person will have a different level of absorption so the blood levels of the active ingredient will also be different across the group. This could depend for example, on differences in the size of the two people or what and how much they have eaten at any particular point in time.

A common misunderstanding is that everyone absorbs the same amount of a brand-name drug and it is always absorbed at 100% from day to day. This is not true. The blood concentration of a brand-name drug will demonstrate a scientifically acceptable variability across a wide group of people and even more crucially, from day to day within the same individuals.

In the end, each person’s absorption of the active ingredient and the maximum concentration achieved are unique; no one absorbs at the same rate as another person, and no single person will absorb the exact same amount of the active ingredient at various times after taking the drug administration, therefore health authorities in Canada and around the world rely on an “acceptable range of variability.”

The standards for bioequivalence in Canada are built upon internationally recognized standards and the criteria are the highest in the world. Health Canada scientists ensure that the standards for bioequivalence are adhered to and kept up to date as they work closely with an expert panel of scientists, physicians, and pharmacists from across Canada.

As noted above, while bioequivalence is most commonly discussed in relation to generic drugs, bioequivalence studies must also be performed on the brand-name version of a drug when it’s being tested, marketed or re-launched.

For example, bioequivalence studies are performed for brand-name drugs between the early and the late clinical trials because the later trial’s formulation must prove to be bioequivalent to the early stage formulation if the formulation has been modified.

The formulation used to manufacture and market a new brand-name drug at large commercial batch sizes must prove to be bioequivalent to the formulation of the clinical trial drug, a very small test batch size.

In summary, the brand industry relies on these same recognized bioequivalence standards for every market approval of each brand product.

The key difference between generic and brand-name drugs is price. Generic drugs are dispensed to fill 66% of prescriptions in Canada, but account for only 24% of the $22-billion dollars Canadians spend annually on prescription drugs.

Jim Keon is President of the Canadian Generic Pharmaceutical Association

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