PT-141 (Bremelanotide) Dosage Calculator: Units per Dose
- Calculator
- About 3 min
- Standard reconstitution arithmetic (Boyer, Math for Nurses)
- Runs in your browser, nothing is sent
- Medical review: Medical review pending
What this calculator works out
Bremelanotide is approved as a fixed-dose autoinjector, but compounded PT-141 arrives as a powder in a vial that has to be mixed before it can be drawn up. Once water is added, the dose on the prescription has to be turned into a volume, and that volume into marks on a syringe. That conversion is where mistakes happen, and it is all this page does.
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Concentration after mixing
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Volume and syringe units
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Doses per vial
How this compares with a typical online quiz
| Feature | Typical free quiz | Regenerated.com |
|---|---|---|
| Names the arithmetic and its source | Rarely | Yes, the reconstitution method in Boyer's Math for Nurses |
| Takes the dose from your prescription only | Often pre-filled with a suggested dose | Yes; no default dose, no protocol |
| Separates concentration from dose | Sometimes | Yes, with a worked example |
| Flags draws under 5 units or over 100 units | No | Yes, with what to ask the pharmacy |
| States the FDA label and approval status | Rarely | Yes, Vyleesi 1.75 mg, women only, with the label's limits |
| Answers sent to a server | Often | Never; scored in your browser, counts-only events |
What the FDA label for bremelanotide says
Bremelanotide is approved in the United States under the brand name Vyleesi for premenopausal women with acquired, generalized hypoactive sexual desire disorder. The approved product is a single-use autoinjector that delivers 1.75 mg under the skin of the abdomen or thigh. The label states that it is used as needed, at least 45 minutes before anticipated sexual activity, with no more than one dose in 24 hours and no more than eight doses in a month. Those figures are printed here as information about the approved product and nothing else: the only dose this calculator takes is the one your clinician prescribed, and it will not fill one in for you.
The label lists nausea as the most common side effect, reported by about four in ten women in the phase 3 trials, with flushing, injection-site reactions and headache next. Bremelanotide also raises blood pressure for a few hours after a dose, by roughly 6 mmHg systolic and 3 mmHg diastolic on average, with a matching dip in heart rate. For that reason the label says it is not to be used by people with uncontrolled high blood pressure or known cardiovascular disease. Darkening of the skin on the face, gums or breasts (focal hyperpigmentation) occurred in about one percent of women in trials and was more frequent in those with darker skin and in those who used more than eight doses a month; it did not always fade after stopping.
Who it is approved for, and who it is not
The approval covers premenopausal women with hypoactive sexual desire disorder, diagnosed by a clinician after other causes such as a medical condition, a relationship problem, a medication effect or a psychiatric condition have been considered. Bremelanotide is not approved for postmenopausal women, for men, or for erectile dysfunction. Early trials of an intranasal form in men with mild to moderate erectile dysfunction, published in 2004, showed erections in a higher share of men than placebo, and the compound is now sometimes prescribed to men by clinics working on sexual health. Every such use is clinician-directed off-label prescribing of the approved product. A compounded form is a step further: a compounded drug is not FDA-approved, and section 503A permits compounding a product that is essentially a copy of a commercially available drug only where the prescriber determines and documents that the compounded product has a significant difference for an identified individual patient, a position the FDA restated on its page for compounders current as of April 1, 2026, which we checked on October 8, 2026. Whether a particular compounded vial meets that condition does not follow from the rule alone, so ask the prescriber and the pharmacy on what basis it was compounded. That is not a judgment about whether it works for you; it is a statement about who carries the decision.
The mechanism is also why the side effects look the way they do. Bremelanotide activates melanocortin receptors in the brain, the same family involved in sexual arousal, appetite and skin pigment, rather than acting on blood vessels the way sildenafil or tadalafil do. It can therefore be used alongside those medicines in some patients, but that combination, like the dose, is a prescribing decision. Bring your blood pressure readings and your full medication list to the clinician who writes the prescription.
Compounded vial versus autoinjector: why the arithmetic matters
The autoinjector has no arithmetic in it: one device, one fixed 1.75 mg dose, no mixing. Compounded bremelanotide is different. It is dispensed by a compounding pharmacy as a freeze-dried powder in a vial, commonly labeled in milligrams (10 mg is a frequent strength), and it is mixed at home with bacteriostatic water. The pharmacy or clinic states how much water to add. From that point the dose on the prescription, written in micrograms or milligrams, has to be drawn as a volume, and most people draw it with a U-100 insulin syringe marked in units rather than mL.
Two vials of the same strength mixed with different amounts of water give different units for the same dose. A 10 mg vial with 2 mL of water holds 5,000 mcg/mL, so a 1,000 mcg dose is 0.2 mL, which is 20 units. The same vial with 4 mL of water holds 2,500 mcg/mL, so the same 1,000 mcg dose is 0.4 mL, which is 40 units. Neither is right or wrong; what matters is that the water volume you actually added is the one you enter here, and that the units you draw match the result. Re-run the calculation for every new vial and every change in diluent.
Reading a U-100 insulin syringe
U-100 syringes are marked for insulin, where 100 units equal 1 mL. The marking is only a volume scale: 10 units is 0.1 mL of anything, regardless of what the solution contains. A 0.3 mL syringe holds 30 units and often has half-unit marks; a 0.5 mL syringe holds 50 units; a 1 mL syringe holds 100 units. The result page prints both mL and units so you can match them to the syringe you were dispensed.
Small draws are the usual source of error. Below about 5 units, a half-mark misread is a tenth of the dose or more. If your result lands there, the question for the pharmacy is whether they intended a larger diluent volume, which lowers the concentration and makes the same dose a larger, easier-to-read draw. A result above 100 units does not fit in one standard insulin syringe and almost always means an input was entered in the wrong unit, for example a dose typed in milligrams into the micrograms field.
Methodology and sources
The calculator uses the dimensional-analysis method for reconstituted medications described in Boyer's Math for Nurses, the standard pocket reference for dosage calculation, applied to a lyophilized peptide vial. Concentration in mcg/mL equals the vial strength in milligrams times 1,000, divided by the milliliters of bacteriostatic water added. The volume for one dose equals the prescribed micrograms divided by that concentration. Units on a U-100 syringe equal the volume in mL times 100, and doses per vial equal the vial's micrograms divided by the dose, rounded down. The method assumes the powder adds negligible volume to the diluent, which holds for the milligram quantities in a peptide vial.
Worked example, the same one the engine prints under the result: a 5 mg vial reconstituted with 2 mL of bacteriostatic water holds 5,000 mcg divided by 2 mL, which is 2,500 mcg/mL. A prescribed 250 mcg dose is 250 divided by 2,500, which is 0.1 mL, and 0.1 mL times 100 is 10 units on a U-100 syringe. The vial holds 5,000 divided by 250, which is 20 such doses. For a 10 mg vial with 2 mL of water and a 1,000 mcg dose the same steps give 5,000 mcg/mL, 0.2 mL and 20 units, with 10 doses in the vial.
The limits are the limits of the inputs. The arithmetic is exact, but it cannot know whether the vial strength on the label is accurate, whether the water you added is the water you entered, or whether the prescribed dose is appropriate for you. Compounded products are not FDA-approved and their strength is not verified by the FDA; ask the pharmacy for its certificate of analysis if you want that checked. The dose on the prescription is the clinician's responsibility and this page does not evaluate it. The bands under the result describe only how readable the draw is on a standard syringe.
Medical review: Medical review pending. Last updated .
References
- Boyer MJ. Math for Nurses: A Pocket Guide to Dosage Calculation and Drug Preparation. 9th ed. Philadelphia, PA: Wolters Kluwer; 2016.
- US Food and Drug Administration. Vyleesi (bremelanotide injection) prescribing information, NDA 210557. Approved June 2019. Drugs@FDA, https://www.accessdata.fda.gov/scripts/cder/daf/
- Kingsberg SA, Clayton AH, Portman D, et al. Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials. Obstet Gynecol. 2019;134(5):899-908. doi:10.1097/AOG.0000000000003500
- Diamond LE, Earle DC, Rosen RC, Willett MS, Molinoff PB. Double-blind, placebo-controlled evaluation of the safety, pharmacokinetic properties and pharmacodynamic effects of intranasal PT-141, a melanocortin receptor agonist, in healthy males and patients with mild to moderate erectile dysfunction. Int J Impot Res. 2004;16(1):51-59. doi:10.1038/sj.ijir.3901139
- US Food and Drug Administration. FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize, setting out the conditions for the section 503A and 503B exemptions including products that are essentially copies of commercially available drugs. Content current as of April 1, 2026; checked October 8, 2026. https://www.fda.gov/drugs/drug-alerts-and-statements/fda-clarifies-policies-compounders-national-glp-1-supply-begins-stabilize