We are entering a new era in the management of obesity and leading that charge are new medications from a class of drug called Glucagon-like peptide-1 (GLP-1) receptor agonists, also known as GLP-1 analogs. These drugs lead people to average losses of between 10-25% of their body weights, and newer versions still in clinical trials suggest greater losses to come. To get a better understanding of how these drugs work and if one might be right for you, keep on reading.
Understanding Ozempic and Mounjaro
Comparing Ozempic and Mounjaro in Weight Loss Efficacy
Side Effects and Safety Profile
Administration and Lifestyle Considerations
Cost and Accessibility
Conclusion: The Future of Weight Management with Ozempic and Mounjaro
FAQ: Frequently Asked Questions
Ozempic 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 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, however in the US it has also received approval for the treatment of obesity.
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, the primary determinant of which medication to choose tends to be cost. Given both drugs lead to meaningful weight loss, coverage and cost are perhaps more important considerations. At dosages up to 1mg weekly of semaglutide, its monthly cost tends to be slightly lower than comparable dosages of Tirzepatide. This changes those in dosages higher than 1mg of semaglutide because currently in Canada we do not have access to the higher dose pens of semaglutide (marketed as Wegovy) and so to have a higher dosage requires the purchase of multiple pens which in turn increases the cost (eg. 2mg weekly would require the purchase of two 1mg pens). Tirzepatide in Canada is priced by vial whereby regardless of dosage, each vial carries the same cost and so even higher dosages carry the same monthly cost.
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 is yet to be a head to head Ozempic vs Mounjaro 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 Mounjaro leads to lesser amounts of nausea than 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.
There are no major differences between Ozempic and Mounjaro 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 is sold already preloaded in a syringe.
Both medications support rather than replace behavioural changes meaning that to get the best outcomes from the medications in terms of weight will be with people who coincident with their prescription, 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.
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.
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.
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.
• Yes, absolutely, though in Canada Mounjaro hasn’t been formally approved for weight management, while Ozempic, which is the drug semaglutide branded and marketed for the treatment of type 2 diabetes, is approved for use in weight management in Canada, the approval is for that same drug semaglutide branded and marketed as Wegovy which for some will mean they do not have insurance coverage unless they are being prescribed ozempic for the treatment of type 2 diabetes.
•There really aren’t appreciable differences at this point and we don’t have a head to head randomized controlled trial comparing the two.
•Patients tend to know whether these drugs have strong effects on their hunger, cravings, and fullness within 6 to 8 weeks of use and sometimes within the first week.
•None that are common enough to expect, though non-significant gastrointestinal side effects are common but they usually dissipate with ongoing use.
•Certainly you’ll need to discuss suitability with your prescriber, but if you’re deemed suitable, the decision is wholly up to you. Given there are no real risks, especially with a short course of medication, a trial of medication just for you to have a frame of reference to help in the determination of whether it’s worthwhile for you may be valuable.
•Coverage really varies. While there are some insurance companies who will cover both for any purposes deemed appropriate by a person’s physicians, there are other who won’t. You’ll need to check with your provider and it may be worth checking in with them periodically as coverage can change
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