Ozempic's cousin drug liraglutide is about to get cheaper. But what does it look like?

Fourteen years ago, semaglutide's older cousin (Ozempic and Wegovy) came onto the market. The drug liraglutide is sold under the brand names Victoza and Saxenda.

The patents for Victoza and Saxenda have now expired. Therefore, other pharmaceutical companies are working on developing “generic” versions. This is likely to be a fraction of the current cost, which is around A$400 per month.

How does liraglutide compare to semaglutide?

How do these medications work?

Liraglutide was not originally developed as a weight loss agent. Like semaglutide (Ozempic), it was originally used to treat type 2 diabetes.

The class of drugs liraglutide and semaglutide are called GLP-1 mimetics, meaning they mimic the natural hormone GLP-1. This hormone is released from your small intestine in response to food intake and works in various ways to improve the way your body handles glucose (sugar).

How do they stop hunger?

Liraglutide works in several regions of the unconscious part of your brain, particularly the hypothalamus, which controls metabolism, and parts of the brain stem that are responsible for communicating your body's nutritional status to the hypothalamus.

Its effect here appears to reduce hunger in two different ways. First, it helps you feel full sooner, making smaller meals more filling. Second, it changes your “motivation salience” toward food, meaning the amount of food you seek out is reduced.

The original formulation of liraglutide for the treatment of type 2 diabetes was marketed under the name Victoza. Its ability to cause weight loss became apparent soon after its launch.

Shortly thereafter, a stronger formulation called Saxenda was released, intended for weight loss in people with obesity.

How much weight can you lose with liraglutide?

People react differently and lose different amounts of weight. But here we note the average weight loss that users can expect. Some will lose more (sometimes much more), others will lose less, and a small portion will not respond.

The first GLP-1 mimicking drug was exenatide (Bayetta). It remains available to treat type 2 diabetes, but there are currently no generics available. Although exenatide does provide some weight loss, this is quite small and is typically around 3-5% of body weight.

Those taking liraglutide to treat obesity resort to the stronger drug (Saxenda), which typically results in about 10% weight loss.

Semaglutide with the stronger formulation called Wegovy typically results in 15% weight loss.

The newest GLP-1 mimicking drug on the market, tirzepatide (Mounjaro for type 2 diabetes and Zepbound for weight loss), results in weight loss of about 25% of body weight.

What happens if you stop taking it?

Despite the effectiveness of these medications in weight loss, they do not appear to change people's weight set points.

When people stop taking it, in many cases they return to their original weight.

How high is the dose and how often do you have to take it?

Liraglutide (Victoza) is for type 2 diabetes Exactly the same drug as Saxenda for weight loss, but Saxenda is in a higher dose.

Although the target for each formulation is the same (the GLP-1 receptor), for glucose control in type 2 diabetes, liraglutide must reach (mainly) the pancreas.

But to achieve weight loss, it must reach parts of the brain. This means that the blood-brain barrier has to be overcome – and not all of them make it, so more has to be taken.

All current formulations of GLP-1-like drugs are injectables. This will not change when liraglutide generics come onto the market.

However, they differ in how often they need to be injected. Liraglutide is a once-daily injection, while semaglutide and tirzepatide are administered once weekly. (That makes semaglutide and tirzepatide much more attractive, but we won't see semaglutide as a generic until 2033.)

What are the side effects?

Since all of these medications have the same target in the body, they usually have the same side effects.

The most common gastrointestinal symptoms include nausea, vomiting, flatulence, constipation and diarrhea. These occur in part because these medications slow the movement of food out of the stomach, but are generally controlled by slowly increasing the dose.

Current clinical data suggests that slowing gastric emptying may be problematic for some people and may increase the risk of food entering the lungs during surgery. Therefore, it is important that you tell your doctor if you are taking any of these medicines.

Because they are injectables, they can also cause reactions at the injection site.

There have been some reports of thyroid disease and pancreatitis (inflammation of the pancreas) during clinical trials. However, it is not clear whether these are due to GLP-1 mimicking drugs.

In animals, drugs that mimic GLP-1 have been found to negatively affect the growth of the embryo. There are currently no data from controlled clinical trials regarding their use during pregnancy. However, based on animal studies, these medicines should not be used during pregnancy.

Who can use them?

The GLP-1 mimicking weight loss medications (Wegovy, Saxenda, Zepbound/Mounjaro) are approved for use in people with obesity and should only be used in conjunction with diet and exercise.

These medications must be prescribed by a doctor and are not covered by the Pharmaceutical Benefits Scheme for obesity, which is one of the reasons they are expensive. But over time, generic versions of liraglutide will likely become more affordable.