# PT-141 Dosage in the Research Literature > PT-141 dosage data from 43 clinical trials: subcutaneous 1.75 mg labeled dose, Phase 2 intranasal dose-escalation, half-life ~2.5 hours, onset 30-60 minutes. Cited from primary sources. ## PT-141 Dosage in the Research Literature PT-141 dosage has been studied across a broad range in the bremelanotide clinical development program — from 0.3 mg intranasal Phase 1 safety studies through 20 mg intranasal in women with sexual arousal disorder, and from 0.75 mg to 1.75 mg subcutaneous in the Phase 2b and Phase 3 registration trials. The FDA-approved dose is 1.75 mg subcutaneous per event. All dosing described here reflects what was administered to study subjects in published research; this is not a clinical recommendation. **Key parameters:** - Approved dose: 1.75 mg SC - Tmax: 0.5–1.0 hours - Half-life: ~2.5 hours - Maximum frequency: 8 doses/month ## Approved Dosing Regimen (Phase 3 Clinical Data) The FDA-labeled dose of bremelanotide is 1.75 mg administered subcutaneously at least 45 minutes before anticipated sexual activity. Maximum one dose per 24-hour period. Maximum eight doses per month. Discontinuation is recommended after 8 weeks without benefit [6]. This dosing regimen was established through the Phase 2b dose-ranging study (0.75, 1.25, 1.75 mg SC), in which 1.75 mg was the dose that achieved statistically significant improvement across all 7 pre-specified endpoints versus placebo (p≤0.03) in premenopausal women with HSDD [13]. The lower doses showed numerically smaller improvements that did not meet p-value thresholds across all endpoints, establishing 1.75 mg as the minimum effective dose for the registration program. The drug is contraindicated in subjects with uncontrolled hypertension or known cardiovascular disease [8]. ## Phase 2 Intranasal Dose History Phase 1 and Phase 2 studies tested intranasal delivery as the primary route. Dose-escalation in healthy males and men with mild-to-moderate ED identified doses above 7 mg intranasal as the threshold for statistically significant erectile response versus placebo, with onset approximately 30 minutes post-administration [1]. No maximum tolerated dose was reached in the tested intranasal range. A 20 mg single intranasal dose in premenopausal women with sexual arousal disorder produced significantly increased subjective desire and arousal satisfaction versus placebo [3]. The intranasal formulation was ultimately discontinued due to bioavailability variance. Subcutaneous administration provided 100% bioavailability and consistent exposure at the 1.75 mg dose [7]. ## PT-141 Half-Life and Duration of Effect Plasma half-life of bremelanotide in human pharmacokinetic studies is approximately 2.5 hours (range 1.9–2.7 hours across studies) [7]. In early intranasal Phase 1 studies, half-life values of 1.85–2.09 hours were reported [1]. Peak plasma concentration (Tmax) occurs approximately 0.5–1.0 hours post subcutaneous injection. After 1.75 mg SC, peak plasma concentration is approximately 72.8 ng/mL. Clearance is 6.5 ± 1.0 L/h. Protein binding is 21%. Excretion is primarily renal (64.8%) with fecal clearance at 22.8% [7]. Duration of pharmacodynamic effects in clinical trial subjects has been characterized as approximately 6–12 hours based on event-diary assessments. Blood pressure effects (transient systolic increase) resolved within 12 hours [8]. ## How Long Does PT-141 Last? Clinical trial data indicates effects lasting approximately 6–12 hours in human subjects, with onset typically 30–60 minutes after subcutaneous administration [7, 8]. Duration varies by dose and individual response in study subjects. ## PT-141 Onset: How Long Does It Take to Work? In Phase 3 trials, subjects reported onset of effect approximately 30–60 minutes after subcutaneous injection, consistent with the pharmacokinetic Tmax of 0.5–1.0 hours [7]. The approved product instructs administration at least 45 minutes before anticipated sexual activity — reflecting the median onset from clinical data. ## Frequency of Administration in PT-141 Study Protocols The approved bremelanotide dosing regimen specifies no more than one dose per 24 hours and a maximum of 8 doses per month [6]. Hyperpigmentation — an MC1R-mediated adverse event — was observed in over one-third of subjects receiving consecutive daily doses for 16 days in research protocols, but was rare at the label-compliant dosing frequency [9]. The safety database of 3,500 subjects across 43 studies, including a 52-week open-label extension, provides the basis for confidence in the label-compliant frequency [14]. ## Routes of Administration Studied for PT-141 Three routes were studied across the bremelanotide development program: intravenous (Phase 1 safety only), intranasal (Phase 1–2 dose-finding), and subcutaneous (Phase 2b and Phase 3 registration, and the approved product). Subcutaneous administration — delivered via an auto-injector into the abdomen, thigh, or upper arm — provided 100% bioavailability and was the route that generated the Phase 3 efficacy data supporting approval [7]. ## References [1] Diamond LE, et al. Double-blind evaluation of intranasal PT-141. Int J Impotence Research. 2004. https://pubmed.ncbi.nlm.nih.gov/14963471/ [3] Diamond LE, et al. Effect on subjective sexual response in women with sexual arousal disorder. Journal of Sexual Medicine. 2006. https://pubmed.ncbi.nlm.nih.gov/16839319/ [6] Mayer D, Lynch SE. Bremelanotide: New Drug Approved for HSDD. Annals of Pharmacotherapy. 2020. https://pubmed.ncbi.nlm.nih.gov/31893927/ [7] Edinoff AN, et al. Bremelanotide for Treatment of Female HSDD. Neurology International. 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC8788464/ [8] White WB, et al. Ambulatory blood pressure monitoring for bremelanotide. Journal of Hypertension. 2017. https://pubmed.ncbi.nlm.nih.gov/27977473/ [9] Clayton AH, et al. Safety Profile of Bremelanotide. Journal of Women's Health. 2022. https://pubmed.ncbi.nlm.nih.gov/35147466/ [13] Althof S, et al. Responder Analyses from Phase 2b dose-ranging study. Journal of Sexual Medicine. 2019. https://pubmed.ncbi.nlm.nih.gov/31277966/ [14] Simon JA, et al. Long-Term Safety and Efficacy of Bremelanotide. Obstetrics and Gynecology. 2019. https://pubmed.ncbi.nlm.nih.gov/31599847/ --- Coin-operated reading room for the bremelanotide literature — every trial catalogued, no clinical service rendered.