Interaction Between Mounjaro And Pristiq Details
In our latest question and answer, the pharmacist discusses a reported interaction between Mounjaro and Pristiq.
Hi, I have a question about a potential interaction between desvenlafaxine and low-dose tirzepatide. I didn't see it listed on the interaction page, but when I checked drugs.com, it mentioned a moderate interaction that could increase heart rate. Can you confirm if this is accurate? Thank you for your help.
May 15, 2024- While Mounjaro and Pristiq are flagged together by some checkers due to a shared side effect of elevated heart rate, most drug interaction databases do not report a significant interaction between them. The actual heart rate increases seen with these medications in clinical trials were small (2-4 beats per minute for Mounjaro and similar to placebo for Pristiq) and unlikely to be clinically significant for most patients. If you have a heart condition where elevated heart rate could be a concern, your doctor should evaluate whether these medications are appropriate for you.
Answer
Hello and thank you for contacting us!
I have reviewed the information on Drugs.com, and you are correct; they do indicate a potential interaction between tirzepatide (generic for Mounjaro, Zepbound) and desvenlafaxine (generic for Pristiq), noting an increased risk of heart rate elevation.
This interaction is based on both medications sharing a common side effect, which is an elevated heart rate. Some drug interaction checkers may not flag this type of interaction because it is not a direct effect of one drug on another, but rather a potential additive side effect.
It is important to point out that most other drug interaction databases I looked at (and I looked at 3 others) did not report an interaction between these two medications.
Is There a Significant Risk of Increased Heart Rate?
While the prescribing information for Mounjaro does mention a potential for increased heart rate, the actual increase observed in clinical trials was relatively small, typically 2 to 4 beats per minute compared to placebo-treated patients, who had an increase of about 1 beat per minute. The following is an excerpt from the prescribing information:
Heart Rate Increase
In the pool of placebo-controlled trials, treatment with MOUNJARO resulted in a mean increase in heart rate of 2 to 4 beats per minute compared to a mean increase of 1 beat per minute in placebo-treated patients.
It is unlikely that this small increase would be clinically significant for most individuals. However, for patients with a cardiovascular condition where an elevated heart rate could pose a risk, caution should be exercised.
The prescribing information for Pristiq also mentions 'tachycardia' (elevated heart rate), but the data provided suggests that the increase is similar to what is seen with a placebo. Below is an image from the prescribing information for Pristiq showing the incidence rate of tachycardia in clinical studies:
As you can see, the incidence of tachycardia is low and in line with what those taking placebo experienced.
Overall, while I understand why an interaction might be flagged between Pristiq and Mounjaro based on their respective prescribing information mentioning increased heart rate, the actual risk seems to be low and unlikely to be clinically significant for most patients. This is likely why most other drug interaction checkers, besides Drugs.com, do not report this interaction.
Final Thoughts
Drugs.com typically reports more potential interactions than other drug interaction checkers. This is due to its consideration of additive side effects and its cautious approach, as it is a public-facing platform. This doesn't mean the information it provides should be disregarded, but I wanted to highlight some potential reasons why this interaction is showing up there and not elsewhere.
Thank you for your question! Please feel free to reach out again if you have any further inquiries!
References & sources
Glossary — Terms in This Answer
- Tirzepatide
- An injectable medication used to treat type 2 diabetes and weight loss, sold under brand names Mounjaro and Zepbound.
- Desvenlafaxine
- An antidepressant medication sold under the brand name Pristiq that works by affecting serotonin and norepinephrine in the brain.
- Drug interaction
- A situation where two medications affect each other's effectiveness or increase the risk of side effects when taken together.
- Tachycardia
- An abnormally elevated heart rate, typically defined as more than 100 beats per minute at rest.
- Placebo-controlled trials
- Medical studies where some patients receive the actual medication while others receive an inactive substance to compare the true effects of the drug.
- Prescribing information
- Official documentation provided by drug manufacturers that includes approved uses, dosage, side effects, and warnings for a medication.
- Additive side effect
- A situation where two medications each cause the same side effect, and their combined use increases the likelihood or severity of that effect.
- Cardiovascular condition
- A medical disorder affecting the heart and blood vessels, such as heart disease or abnormal heart rhythms.
Dr. Brian Staiger, PharmD
Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified
Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...
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