Comparison
Metformin vs PT-141
Side-by-side of Metformin and PT-141. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
Metformin
Metformin for longevity: biguanide mechanism of action, TAME trial status, anti-aging dosage, weight loss data, life extension evidence in non-diabetics.
PT-141
PT-141 peptide (bremelanotide, Vyleesi): MC4R agonist for libido and erectile dysfunction. 1.75 mg subcutaneous, 30 to 60 min onset, 2 to 4 h half-life.
Effects at a glance
Metformin
- •Reduces HbA1c by ~1.0 to 1.5 percentage points in type 2 diabetes; first-line agent in major guidelines
- •DPP trial: 31% reduction in T2DM incidence in adults with prediabetes over 2.8 years
- •Suppresses hepatic gluconeogenesis via AMPK activation and complex I inhibition
- •Long-term use depletes B12; annual monitoring recommended after year 2
- •Lifespan extension in non-diabetic humans is not established; TAME trial pending
- •MASTERS trial reported blunted resistance-training hypertrophy in older adults
PT-141
- •Cyclic 7-amino-acid synthetic peptide and melanocortin receptor agonist (MC4R-preferring)
- •FDA approved in 2019 as Vyleesi for hypoactive sexual desire disorder in pre-menopausal women
- •Acts centrally on hypothalamic sexual-desire circuits rather than peripherally on vasculature
- •On-demand dosing: subcutaneous 1.75 mg approximately 45 minutes before sexual activity
- •Common adverse effects: nausea (~40%), flushing, headache, injection-site reactions, hyperpigmentation
- •Off-label male ED use is documented but not FDA approved; mechanism is distinct from PDE5 inhibitors
Side-by-side
| Attribute | Metformin | PT-141 |
|---|---|---|
| Category | pharmaceutical | peptide |
| Also known as | Glucophage, Fortamet, Glumetza, dimethylbiguanide | Bremelanotide, Vyleesi |
| Half-life (hr) ↗ | 6 | 2.7 |
| Typical dose (mg) ↗ | 1500 | 1.75 |
| Dosing frequency | 1 to 3 times daily with meals; XR once daily | as needed (max once per 24 hours, max 8 per month) |
| Routes | oral | subcutaneous |
| Onset (hr) | 1 | 0.75 |
| Peak (hr) | 2.5 | 1.5 |
| Molecular weight | 129.16 | 1025.18 |
| Molecular formula | C4H11N5 | C50H68N14O10 |
| Mechanism | Suppresses hepatic gluconeogenesis primarily via AMPK activation and complex I inhibition; modestly improves peripheral insulin sensitivity and shifts gut microbiome composition. | Synthetic agonist of melanocortin receptors with preference for MC4R, expressed in hypothalamic and limbic circuits regulating sexual motivation. Engages central pathways distinct from peripheral PDE5-mediated vasodilation. |
| Legal status | Prescription only (FDA approved for type 2 diabetes 1994) | Prescription only as Vyleesi; FDA-approved 2019 for HSDD in pre-menopausal women. Compounded versions sold off-label for male sexual function are research-use-only grey market. |
| WADA status | allowed | allowed |
| DEA / Rx | Rx only (not a controlled substance) | Rx only (not a controlled substance) for the FDA-approved Vyleesi formulation |
| Pregnancy | Category B; used in gestational diabetes and PCOS per current guidance | Not recommended; contraindicated during pregnancy per Vyleesi label |
| CAS | 657-24-9 | 189691-06-3 |
| PubChem CID | 4091 | 9941379 |
| Wikidata | Q19484 | Q422059 |
Safety profile
Metformin
Common side effects
- nausea
- diarrhea
- abdominal discomfort
- metallic taste
- decreased appetite
- B12 depletion (long-term)
Contraindications
- eGFR below 30 mL/min/1.73m2
- acute or chronic metabolic acidosis
- severe hepatic impairment
- acute heart failure
- iodinated contrast within 48 hours
Interactions
- iodinated contrast media: renal injury risk; hold 48 hours peri-imaging(major)
- alcohol (heavy use): elevated lactic acidosis risk(major)
- cimetidine: raises metformin plasma levels via OCT2 inhibition(moderate)
- insulin and sulfonylureas: additive hypoglycemia risk in combination(moderate)
- dolutegravir: raises metformin exposure via OCT2(moderate)
PT-141
Common side effects
- nausea (~40%)
- flushing
- headache
- injection-site reactions
- hyperpigmentation (focal, gums, face, breasts)
- transient blood pressure increase (~6 mmHg systolic)
Contraindications
- uncontrolled hypertension
- established cardiovascular disease
- pregnancy
- naltrexone co-administration (reduces opioid efficacy due to MC receptor crosstalk)
Interactions
- naltrexone (oral): bremelanotide reduces oral naltrexone exposure significantly; avoid co-administration(major)
- antihypertensives: transient BP rise after bremelanotide can offset BP control(moderate)
- PDE5 inhibitors (sildenafil, tadalafil): no documented adverse interaction; mechanisms are non-overlapping(minor)
Which Should You Take?
Metformin comes out ahead for most readers on the criteria we weight: 2 catalogued goals, prescription-only, oral dosing, with a Tier-A outcome catalogued. PT-141 is the right call when one of the conditionals below applies.
- → If your priority is metabolic health and glucose control, pick Metformin.
- → If your priority is healthspan extension, pick Metformin.
- → If your priority is sexual function, pick PT-141.
- → If your priority is libido, pick PT-141.
Edge case: If you cannot self-administer injections, Metformin is the only oral option in this pair.
Default choice: Metformin. Wider use case, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for PT-141 only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between Metformin and PT-141?
Metformin and PT-141 differ in category (pharmaceutical vs peptide), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Metformin or PT-141?
Metformin half-life is 6 hours; PT-141 half-life is 2.7 hours.
Can you stack Metformin with PT-141?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
Go deeper