Tirzepatide

Tirzepatide is a dual GIP/GLP-1 receptor agonist, while semaglutide only targets GLP-1 receptors. The addition of GIP receptor agonism enhances fat metabolism in adipose tissue and may improve insulin sensitivity through complementary pathways. In head-to-head trials (SURPASS-2), tirzepatide at all doses showed superior HbA1c reduction and comparable or superior weight loss compared to semaglutide 1 mg. The SURMOUNT trials showed up to 22.5% weight loss, exceeding semaglutide's typical 15-17%.

Tirzepatide starts at 2.5 mg once weekly for 4 weeks, then increases to 5 mg weekly. Further titration occurs in 2.5 mg increments every 4 weeks through 7.5 mg, 10 mg, 12.5 mg, and up to the maximum dose of 15 mg weekly. The maintenance dose is typically 5-15 mg based on individual response and tolerability. Most clinical trial benefits were observed at the 10 mg and 15 mg dose levels.

Tirzepatide shares similar gastrointestinal side effects with GLP-1 agonists, including nausea, diarrhea, vomiting, and constipation. However, some evidence suggests the GI side effect profile may be slightly better tolerated due to the biased, lower-potency agonism at the GLP-1 receptor. Nausea rates in SURMOUNT trials were approximately 24-33% depending on dose, compared to ~44% for semaglutide 2.4 mg. Side effects are most common during dose escalation periods.

Yes, tirzepatide is FDA-approved for both indications under different brand names: Mounjaro for type 2 diabetes and Zepbound for chronic weight management in adults with obesity (BMI ≥30) or overweight (BMI ≥27) with at least one weight-related comorbidity. The dosing and titration schedules are the same for both indications. It is not currently approved for weight management in patients without obesity/overweight criteria.