The price of the so-called 'wonder drug' Ozempic is set to fall as rivals begin to copy it, according to Professor Luke O’Neill.
Ozempic is traditionally used to treat diabetes; however, it has recently become a popular form of treatment for people with obesity – with numerous celebrities endorsing its use for weight loss.
The Irish Medical Council has warned doctors not to prescribe the drug for weight loss - and there are concerns the trend could lead to further shortage among diabetes patients.
"They're great for diabetics, type 2 diabetes in particular really well," he said.
"They work very well for severe obesity, which is a really serious condition.
"You will lose weight on these drugs; you also feel a bit nauseous and that stops you eating.
"Anybody really will lose weight if you're on these drugs; the question then becomes the ethics of this.
"Clearly obesity is a massive health problem - there's a risk of cancer, heart disease - so it makes sense then to use the drugs to help people lose weight to stop those other consequences."
'Even more potent'
Prof O'Neill said more and more companies are replicating the drug.
"All drug companies are making their [own] version and trying to compete," he said.
"
"They're all predicting now Eli Lilly might become the main supplier.
"There's a prediction now that many companies will start to make versions of this.
"That'll bring the price down."
'A way to treat heart failure'
"The people said they felt stronger, their fatigue went, they weren't quite as breathless," he said.
"So, there's clearly a protective effect on the heart.
"That's causing a massive excitement because heart failure's very common and very hard to treat.
"Here we have a way to treat heart failure."
'Helps your metabolism'
"It's based on a natural hormone called GLP1, and in your body after a meal you make GLP1.
"It makes your cells release insulin, to take up the glucose, and also regulates food intake.
"Food passing through your gut is slowed by GLP1 - you feel full.
"It's a natural hormone that helps your metabolism."
Prof O'Neill said the Danish drug maker of Ozempic, Novo Nordisk, is now valued at US$428 billion (€399bn) - which is worth more than the Danish economy, currently valued at US$406 billion (€375bn).