Mounjaro and Rosuvastatin Interaction: What Patients and Clinicians Need to Know

Is there a documented interaction?

The Mounjaro label describes a mechanism rather than a rosuvastatin-specific interaction. Tirzepatide delays gastric emptying, the delay is largest after the first dose and diminishes over time, and the label says this has the potential to affect the absorption of oral medicines given at the same time [1]. It asks for caution with oral drugs and for monitoring of drugs that depend on threshold concentrations for efficacy or have a narrow therapeutic index, with warfarin as the named example [1].

Mounjaro is the tirzepatide product approved for type 2 diabetes in adults and children 10 years and older, and for reducing major cardiovascular events in adults with type 2 diabetes at high risk [1]. Rosuvastatin is a statin that inhibits HMG-CoA reductase, the rate-limiting enzyme in cholesterol synthesis, and is labeled to lower LDL-C and to reduce major cardiovascular events in adults at increased risk [2].

What the label's absorption data show

The Mounjaro label's oral-absorption numbers come from acetaminophen. After a first 5 mg dose of tirzepatide, acetaminophen peak concentration fell 55% and its peak occurred about 1 hour later [1]. By week 6, at 15 mg once weekly, there was no meaningful effect on acetaminophen peak concentration or time to peak, and total exposure (AUC) was unchanged [1].

How rosuvastatin is handled by the body

Rosuvastatin reaches peak plasma concentration 3 to 5 hours after a dose, has an absolute bioavailability of about 20%, is about 88% protein bound and has a half-life of about 19 hours [2]. It is not extensively metabolized: about 10% of a dose is recovered as metabolite, mainly N-desmethyl rosuvastatin formed principally by CYP2C9, and about 90% is excreted in feces [2]. The Crestor label says it can be taken once daily at any time of day, with or without food, and that the AUC is the same after morning and evening dosing [2]. The Mounjaro label says the injection can be given at any time of day, with or without meals [1]. The one timing instruction in the Crestor label concerns antacids: take rosuvastatin at least 2 hours before an aluminum or magnesium hydroxide antacid, which cut rosuvastatin AUC by about 50% when taken at the same time [2].

The Crestor label documents dose limits or avoidance for several interacting drugs. Cyclosporine raised rosuvastatin AUC about 7-fold and Cmax about 11-fold, and the label caps the dose at 5 mg daily with cyclosporine [2]. Gemfibrozil raised AUC 1.88-fold and Cmax 2.21-fold in a randomized crossover study of 20 healthy volunteers, and the label says to avoid the combination or, if unavoidable, start at 5 mg and not exceed 10 mg daily [2][3].

Muscle symptoms: what the Crestor label says

The Crestor label lists risk factors for myopathy and rhabdomyolysis: age 65 or older, uncontrolled hypothyroidism, renal impairment, certain other drugs and higher doses, with myopathy risk greater at 40 mg daily than at lower doses; Asian patients may be at higher risk [2]. It instructs patients to promptly report unexplained muscle pain, tenderness or weakness, particularly if accompanied by malaise or fever [2].

In placebo-controlled studies of up to 12 weeks, myalgia was reported by 2.8% of patients on Crestor versus 1.3% on placebo [2]. In METEOR, which used 40 mg for a mean of 1.7 years, myalgia was 12.7% versus 12.1% on placebo and increased CPK 2.6% versus 0.7% [2]. Tirzepatide is not on the Crestor label's list of myopathy risk factors, and myopathy is not among the Mounjaro label's warnings and precautions [1][2].

Kidney function and the rosuvastatin dose

The Crestor label says that with creatinine clearance under 30 mL/min/1.73 m2 and not on hemodialysis, rosuvastatin should be started at 5 mg once daily and not exceed 10 mg daily, with exposure about 3-fold higher [2]. The Mounjaro label warns about acute kidney injury from volume depletion, mostly in patients who have nausea, vomiting or diarrhea, and says to monitor renal function in patients reporting reactions that could lead to volume depletion, especially during dose initiation and escalation [1].