Generic versus brand-name medicines: what’s the difference?

Swapping to a generic medication may save you money. But what do you need to know about generic medicines and do they work as well as the branded version?

Helen Foster
November 2018

When you’re offered the choice between a ‘brand-name’ or ‘generic-brand’ medications at the chemist, how do you know if you’re making the right choice? At first it may seem that the choice is entirely up to you, and your wallet.

A generic medicine is a drug containing the same active ingredient as its brand-name equivalent.

“When companies develop a new medication they have a period of exclusivity – normally around 10 years – where only they can produce that drug,” explains Aine Heaney, pharmacist and spokesperson at NPS Medicinewise. “When that exclusive period ends other companies can copy the drug and bring out their own version.”

A generic medicine must work in exactly the same way as its brand-name equivalent in terms of how fast it gets into the system and how much of it enters the system. This is known as bioequivalence.

In Australia, the law on this is very strict. A company must pass a number of bioavailability tests to prove the drug has the same bioequivalence as the branded drug.

The key differences with generic drugs

The other, inactive ingredients of the drug can differ though, such as binders, fillers, colours and preservatives. These might change the way the drug behaves in some people.

For example, if the filler used in the generic drugs contains lactose or gluten, someone with an intolerance to these substances may find they get side effects from the generic drug that they don’t get from the brand-name drug.

“The patient information leaflet in the pack lists every ingredient in the drug so you can compare this and see if there’s a difference in what the drug contains that might account for any new side effects,” says Heaney.

Our mind can also play a role in how well a generic drug might work. “Because the drugs are cheaper people often think they must be lower quality which can trigger a nocebo effect where they think the drugs don’t work as well,” explains Heaney. “But the drugs are only cheaper as they didn’t have to do the same testing and development as the original company, which cuts their price.”

Is this option available for all drugs?

Not every drug can have a generic equivalent. A drug still under patent is only available in branded form and there’s also one class of drugs where generics are simply not recommended.

“These are drugs with what’s known as a narrow therapeutic index – that means the dose window at which the drug works is very small – too little won’t give effects and too much can be toxic. For this reason, it’s hard to create bioequivalence.”

Some common drugs that fall into this group include the blood thinner warfarin, the heart drug digoxin and some anti-seizure drugs, according to Pharmacy Practice journal and Epilepsy Australia.

If you’d like to consider swapping to a generic version of your medication, talk to your GP or pharmacist about what’s available.