Where does the tirzepatide (Mounjaro) prescribing information indicate that an enteric‑coated oral contraceptive was used in the drug‑interaction study?

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Last updated: February 19, 2026 • View editorial policy

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Tirzepatide Drug Interaction Study: Oral Contraceptive Formulation

Location of Enteric-Coated Contraceptive Information

The tirzepatide prescribing information does not explicitly state that an enteric-coated oral contraceptive was used in the drug-interaction study. The available evidence describes the contraceptive formulation used in the pharmacokinetic study but does not specify enteric coating. 1

What the Prescribing Information Actually States

Contraceptive Formulation Details

  • The tirzepatide drug-interaction study evaluated a combined oral contraceptive containing ethinyl estradiol and norgestimate, which are the active hormonal components tested for pharmacokinetic interactions. 1

  • The study demonstrated statistically significant reductions in area under the plasma drug concentration-time curve (AUC), maximum concentration (Cmax), and time to maximum plasma concentration (Tmax) when tirzepatide was co-administered with the oral contraceptive, indicating meaningful pharmacokinetic interference. 1

Mechanism of Interaction

  • Tirzepatide causes substantially greater gastric emptying delay compared to typical GLP-1 receptor agonists due to its dual GIP/GLP-1 receptor mechanism, which is the primary driver of the oral contraceptive interaction. 1

  • The gastric emptying delay is most pronounced after the first dose of tirzepatide, with subsequent tachyphylaxis developing over time, though the interaction remains clinically relevant throughout treatment. 1

Clinical Implications

Prescribing Guidance

  • Women using oral contraceptives should switch to non-oral contraceptive methods or add barrier contraception for 4 weeks after tirzepatide initiation and after each dose escalation, as recommended in the tirzepatide prescribing information to account for the absorption interference. 2

  • This precaution is unique to tirzepatide among incretin-based therapies, as GLP-1 receptor agonists alone (semaglutide, liraglutide, dulaglutide) have not demonstrated clinically significant interactions with oral contraceptives in formal studies. 1

Contrast with GLP-1 Receptor Agonists

  • Five separate clinical trials of GLP-1 receptor agonists (without GIP co-agonism) showed no statistically or clinically significant impact on oral contraceptive pharmacokinetics, distinguishing them from tirzepatide's interaction profile. 1

  • The rapid dose escalation protocol and greater gastric emptying delay with tirzepatide enhanced the impact on oral medication absorption, creating a unique interaction not observed with standard GLP-1 monotherapy. 1

Common Pitfall to Avoid

Do not assume the contraceptive formulation was enteric-coated based on the interaction data alone—the prescribing information describes the hormonal components (ethinyl estradiol/norgestimate) but does not specify pharmaceutical coating technology. The interaction is driven by tirzepatide's gastric effects rather than by any special contraceptive formulation. 1

References

2
Guideline

Converting from Ozempic (Semaglutide) to Zepbound (Tirzepatide)

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

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