Key Takeaways
Understanding Wegovy, Ozempic, Mounjaro, and Zepbound
Ozempic & Wegovy is a GLP-1 called semaglutide. It is a once-weekly injection that leads the body to produce and utilize insulin more efficiently, but more importantly, in weight management, binds to a receptor in the appetite control centre of our brains which leads people to experience decreased hunger, decreased cravings, and enhanced fullness. In Canada semaglutide is approved for use both in the treatment of type 2 diabetes and in the treatment of obesity.
Mounjaro & Zepbound is a combination of a GLP-1 analog with a glucose-dependent insulinotropic polypeptide (GIP) together known as Tirzepatide and it too is a once-weekly injection. It has the same mechanism of action as semaglutide and perhaps as a consequence of its GIP component, it tends to be slightly more effective on average for weight loss. In Canada Tirzepatide is currently only approved for use in the treatment of type 2 diabetes under the Mounjaro name, however in the US it has also received approval for the treatment of obesity under the name Zepbound.
Comparing Ozempic & Wegovy to Mounjaro & Zepbound in Weight Loss Efficacy
Both Ozempic and Mounjaro (also marketed as Wegovy and Zepbound), lead people to very significant weight losses. Both drugs are dose dependent drugs meaning that higher dosages lead to greater effects. Outcome data from clinical trials see Mounjaro leading to a slightly larger average weight loss than Ozempic. Our real-world experiences with both see the same, but again, the difference is minor. We also tend to hear that Tirzepatide is slightly better tolerated as far as gastrointestinal side effects go.
At least here in Canada, currently the primary determinant of which medication to choose tends to be cost and coverage. Though costs vary by pharmacy and possibly by province, Wegovy tends to less expensive at lower doses than Mounjaro as the latter has recently implemented dose dependent pricing whereby higher dosages are more expensive. Coverage wise, Wegovy is formally approved for use in weight management in Canada whereby Zepbound has yet to receive that formalized approval. As a consequence Wegovy is more likely to be covered by insurers for weight management whereas Mounjaro often is only covered for those who also have type 2 diabetes.
Side Effects and Safety Profile
GLP1 medications are extremely well tolerated for most so long as they are started at low dosages and those dosages are advanced slowly and never if a person is still experiencing side effects. The most common side effects by far for these medications are gastrointestinal - constipation, diarrhea, heartburn, and/or nausea. The great news is that for most these side effects dissipate with ongoing use.
Though there has yet to be a head to head Weogvy vs Zepbound randomized trial that would answer which drug truly leads to greater weight loss or which drug has more common side effects, experientially it would seem that Zepbound & Mounjaro leads to lesser amounts of nausea than Wegovy & Ozempic.
Risk wise, beyond side effects, it would appear that in an extremely small number of patients (cases studies among hundreds of millions of prescriptions), intestinal slowing or stoppage can occur. Benefit wise, it seems not a week goes by that another benefit isn’t found among them and beyond the benefits expected from weight loss (decreased risk of weight responsive medical conditions including type 2 diabetes, hypertension, various cancers, and more) there is a significant risk reduction for heart attacks, strokes, kidney failure, fatty liver disease, and potentially dementia.
Administration and Lifestyle Considerations
There are no major differences between Ozempic, Wegovy, Mounjaro, and Zepbound regarding administration. The only difference is that Mounjaro is currently sold in Canada in single use vials which in turn need to be drawn up in a syringe to be self-administered whereby Ozempic & Wegovy are sold already preloaded in a syringe.
All four medications support rather than replace behavioural changes. What this means is that to get the best outcomes from the medications in terms of weight , people taking the medication are also working to change their lifestyles in manners that will help them with weight loss.
Think of these medications as amplifiers. Just as with a stereo system, if you have a great amplifier with a strong signal you’ll have great sound coming out of your speakers. But even with a great amplifier, if the signal is weak or choppy, the sound will be poor. What these drugs amplify are the body’s own fullness queues and so diets organized to maximize fullness will see these drugs work more effectively.
Cost and Accessibility
Beyond the dollars and cents of these medications is availability. Unfortunately both medications have faced supply chain challenges which in turn have at times seen patients having to switch between these medications. The good news is that switching between them is generally seamless and something that a physician comfortable with their prescription can manage easily.
How supply will fare as more people begin to use these medications remains to be seen.
Making the Choice: Ozempic, Wegovy, Mounjaro, or Zepbound for Weight Management
For most, the choice will come down to first, cost and coverage, and second side effects. Given there doesn’t appear to be a dramatic difference in average efficacy, whichever of these medications is covered for you should likely be your first choice.
Secondary factors would be side effects, whereby if one of these medications led you to sustained side effects you could certainly try the other, and availability which of course is unpredictable.
Conclusion: The Future of Weight Management with Ozempic and Mounjaro
The rise of GLP1s in weight management heralds the dawn of a new era - where finally we have safe and effective medications that lead to sustained meaningful weight loss. Looking ahead, these drugs appear to be getting better and better with one recent drug in study reporting an astonishing average weight loss of 24% at 48 weeks (and with the curve suggesting further loss may come beyond).
The hope of course is that one day not only will we have safe medications that regularly lead to weight losses comparable to those seen with bariatric surgery and there’s little doubt any longer that we’ll get there.
