- Semaglutide targets one receptor, tirzepatide two, and retatrutide three, but the receptor count is not a ranking of results and this comparison does not present one.
- All three enrolled substantial numbers of women, yet few of the underlying trials reported outcomes stratified by sex.
- Tirzepatide's label warns it may reduce the effectiveness of oral hormonal contraceptives, a female-specific fact that most peptide sources omit.
The incretin story is usually told as a countdown of receptors: one, then two, then three. Semaglutide acts at a single target, tirzepatide at two, and retatrutide at three. It is a tidy narrative, and it is often mistaken for a ranking, as though more receptors automatically means a better compound. This comparison deliberately does not make that move. What it compares is the pharmacology, the trial stage, and the one axis that peptide coverage almost always skips, which is how much of each compound's human evidence actually involved women.
Receptor targets: one, two, and three
Semaglutide is a long-acting GLP-1 receptor agonist. Through GLP-1 agonism it enhances glucose-dependent insulin secretion, slows gastric emptying, and reduces appetite via central signaling pathways. It has been studied across diabetes, obesity, and broader cardiometabolic research, and it is the most extensively characterized of the three.
Tirzepatide is a dual agonist of the GIP and GLP-1 receptors, engineered to engage both incretin pathways with one molecule. It has been studied for glycemic regulation and body-weight and energy-balance endpoints, and investigators characterizing dual-incretin pharmacology use it as the reference against single-receptor agonists. Retatrutide is an investigational triple agonist that engages the GIP, GLP-1, and glucagon receptors; the added glucagon arm pairs appetite- and glucose-related signaling with glucagon-driven energy-expenditure pathways. It is the newest design of the three and, importantly, the only one not approved.
Trial stage: two approved, one investigational
Stage is where the practical difference between these compounds is sharpest. Semaglutide is approved for type 2 diabetes and chronic weight management, and tirzepatide is approved for type 2 diabetes and weight management. Retatrutide is investigational, in Phase 2 development for obesity, with no established dose outside of trial protocols and no long-term safety record yet.
| Semaglutide | Tirzepatide | Retatrutide | |
|---|---|---|---|
| Receptor targets | GLP-1 (single) | GIP + GLP-1 (dual) | GIP + GLP-1 + glucagon (triple) |
| Trial stage | Approved (T2D, weight management) | Approved (T2D, weight management) | Investigational (Phase 2, obesity) |
| Women enrolled in trials | Substantial | Substantial (large trial populations) | Substantial (Phase 2 obesity trials) |
| Outcomes reported by sex | Many trials included women; few stratified outcomes by sex | Large female enrollment; not stratified by sex | Enrolled women well; few sex-stratified outcomes |
| Oral-contraceptive interaction | Oral formulation carries timing guidance relevant to oral contraceptive users | Label warns it may reduce effectiveness of oral hormonal contraceptives | Not characterized; plausible but unstudied for this compound |
| Pregnancy / lactation | Contraindicated in pregnancy; not established in lactation | Not recommended in pregnancy; lactation effects not established | No pregnancy or lactation safety data; investigational |
Female inclusion: enrolled, but rarely reported by sex
Here all three compounds share a pattern that is better than most of this catalog and still incomplete. Their trials enrolled women in substantial numbers, so the raw evidence base is not male-only the way it is for BPC-157 or TB-500. What is missing is the next step. In the indexed literature, many of these studies included women but few reported outcomes stratified by sex, so the question of whether the metabolic response differs between men and women is enrolled-but-unanswered rather than truly examined.
There is also a female-specific hormonal detail that separates tirzepatide from the others. Its label warns that tirzepatide may reduce the effectiveness of oral hormonal contraceptives, likely via delayed gastric emptying, and advises a non-oral method or a backup barrier method for four weeks after starting and after each dose increase. Semaglutide's oral formulation carries its own timing guidance relevant to oral contraceptive users. For retatrutide, an oral-contraceptive interaction has not been characterized; as a GLP-1-containing agent that delays gastric emptying, an effect on oral drug absorption is plausible but unstudied for this compound.
Dose figures for the approved compounds are set per their labels and titrated by a clinician; they are reported here for reference only, not as advice or a protocol. Retatrutide has no established dose outside trials. Nothing here recommends use. Pregnancy status is noted as contraindicated or unestablished for each compound and should be read that way.
The temptation with an incretin table is to draw an arrow from one receptor to three and call it progress. That is not what the evidence supports, and it is not the comparison worth making. The useful comparison is that two of these compounds are approved and one is not, that all three enrolled women without fully reporting their outcomes by sex, and that the most decision-relevant female fact, the tirzepatide contraceptive interaction, lives in a label warning rather than in the marketing. That is the lens this catalog keeps returning to. The full sex-disaggregated breakdowns, including cycle-phase, hormonal, and perimenopause rows for each, are on the semaglutide profile, the tirzepatide profile, and the retatrutide profile, where enrolled-but-unreported is recorded as its own honest state.