AssayIndex
Melanocortin-receptor peptides

PT-141 (Bremelanotide)

bremelanotide · Vyleesi · PT141 · C50H68N14O10 · monoisotopic 1024.5242 Da. The index holds 152 assay reports on this compound across 31 batches from 19 suppliers.

152 reports31 batchesmedian 99.38 %index spec 98.5 %
Section 1

Analytical fingerprint

Hand-authored chemistry. These properties describe the substance and do not change when a record is added.

Bremelanotide differs from melanotan II by one dalton: it has a C-terminal free acid where MT-II has an amide. That is the single most consequential 1 Da difference in the index. The two compounds are 0.32 min apart on RG-2 and indistinguishable on a unit-resolution instrument, and the index has 23 confirmed cases of material sold as one and identified as the other. High-resolution MS is mandatory on all PT-141 submissions here; a PT-141 report from a unit-resolution instrument is recorded as identity-unconfirmed regardless of how good the purity number is.

Molecular formula
C50H68N14O10
Monoisotopic mass
1024.5242Da
Average mass
1025.16Da
Residues
7
Nominal retention (RG-2, 30 min)
9.52min
Retention window
0.25min
Counter-ion as usually shipped
acetate
Typical label claims
10 mg
Analytical difficulty (index scale)
0.90 — straightforward
Purity is a defined quantity
YES
Section 2

Representative chromatogram

Drawn from this page's own medians. Not a scan, not an illustration, and not any single report.

028195638845711276 PT-141 (Bremelanotide)9.52 min · 99.38 % 9.18 same trace · ×200 vertical expansion, baseline-corrected · main peak off-scale reporting threshold 0.05 % area 05101520253035 Retention time (min) Response (mAU)
Figure 1. A representative PT-141 (Bremelanotide) trace on the index reference method RG-2, constructed from this page's own numbers: the main peak carries the index median purity of 99.38 % area at the nominal retention time of 9.52 min, and each impurity peak carries the median area the index has observed for that named species at its characteristic retention offset. It is not a scan of any single report — every individual record's own chromatogram is on its own page. The lower panel is the same trace at a stated vertical expansion, baseline-corrected, so the impurities are visible; the main peak runs off-scale there by design. Baseline noise is seeded from the compound slug.
Section 3

What the index has observed

Arithmetic over the 152 records the index holds. Aggregates on this page are computed over the records the index holds, which are not a random sample of the material on the market. Lots that get tested are lots someone chose to test. Read every figure here as a description of this dataset rather than as an estimate of a population.

Median purity 99.38% n=152
Interquartile range 0.97pp n=152
Minimum 97.73% n=152
Maximum 99.93% n=152
Pass rate vs spec 82.9% n=152
Median recovery vs claim 98.0% n=84
Median water 4.72% n=152
Median |mass error| 2.5ppm n=125
012243692.093.094.095.096.097.098.099.0100.092.00–92.25 %: n=092.25–92.50 %: n=092.50–92.75 %: n=092.75–93.00 %: n=093.00–93.25 %: n=093.25–93.50 %: n=093.50–93.75 %: n=093.75–94.00 %: n=094.00–94.25 %: n=094.25–94.50 %: n=094.50–94.75 %: n=094.75–95.00 %: n=095.00–95.25 %: n=095.25–95.50 %: n=095.50–95.75 %: n=095.75–96.00 %: n=096.00–96.25 %: n=096.25–96.50 %: n=096.50–96.75 %: n=096.75–97.00 %: n=097.00–97.25 %: n=097.25–97.50 %: n=097.50–97.75 %: n=197.75–98.00 %: n=398.00–98.25 %: n=598.25–98.50 %: n=1798.50–98.75 %: n=998.75–99.00 %: n=1199.00–99.25 %: n=1799.25–99.50 %: n=2399.50–99.75 %: n=2599.75–100.00 %: n=41median 99.38 Purity (% area) Reports
Figure 2. Purity distribution across all 152 PT-141 (Bremelanotide) records. Dashed line is this compound's median (99.38 %); the solid vertical is the index acceptance specification for the melanocortin-receptor peptides class (98.5 %). Domain is fixed at 92–100 % on every purity histogram on this site so that compounds can be compared by eye — a wide distribution here is a hard compound, a narrow one is an easy one, and neither is a statement about the suppliers.
Section 4

By supplier

Suppliers with fewer than two purity records on this compound are omitted from the figure rather than drawn as a line. The full table, including the thin cells, is on the by-supplier page.

97.698.098.498.899.399.7100.1WXTWXT: Q1 98.41, median 98.69, Q3 99.03, n=27n=27MKMMKM: Q1 99.10, median 99.42, Q3 99.80, n=22outlier 98.03n=22FGPFGP: Q1 99.41, median 99.64, Q3 99.83, n=16outlier 98.77n=16JEEPJEEP: Q1 98.31, median 98.44, Q3 98.72, n=12n=12TFCTFC: Q1 99.78, median 99.93, Q3 99.93, n=11n=11AMBAMB: Q1 99.74, median 99.83, Q3 99.93, n=10outlier 99.45n=10GSPGSP: Q1 99.37, median 99.64, Q3 99.70, n=9n=9ASYASY: Q1 99.48, median 99.57, Q3 99.66, n=9outlier 99.09n=9SWBSWB: Q1 99.11, median 99.23, Q3 99.54, n=6n=6QYBQYB: Q1 99.58, median 99.72, Q3 99.77, n=5outlier 99.16n=5QSCQSC: Q1 99.44, median 99.55, Q3 99.86, n=5n=5CPCCPC: Q1 97.75, median 97.77, Q3 97.84, n=4outlier 98.03n=4SSASSA: Q1 98.49, median 98.65, Q3 98.82, n=4n=4GL BiochemGL Biochem: Q1 98.69, median 98.78, Q3 98.91, n=3n=3HYBHYB: Q1 99.19, median 99.27, Q3 99.44, n=3n=3HomopeptideHomopeptide: Q1 99.93, median 99.93, Q3 99.93, n=2n=2SGNSGN: Q1 98.35, median 98.66, Q3 98.96, n=2n=2 Purity (% area)
Figure 3. PT-141 (Bremelanotide) purity by supplier, ordered by coverage. The vertical line is the index acceptance specification. Boxes that overlap are suppliers this dataset cannot separate, and most of them overlap.

Full per-supplier table with n= caveats →

Section 5

Characteristic impurities and degradants

The left three columns are authored chemistry — what this molecule characteristically carries and where it elutes. The right three are what the index has actually reported.

Named speciesΔRT (min, RG-2)Δ mass (Da)Seen inMedian % areaMax % area
linear precursor (+18 Da)-0.70+18.01195%0.101.06
oxidised Trp (+16 Da)-0.34+15.99591%0.140.99
melanotan II (C-terminal amide, −1 Da)+0.32-0.98491%0.141.32
des-acetyl (−42 Da)-0.46-42.01184%0.111.37

Degradation pathways

  • Trp oxidation
  • lactam hydrolysis

Full impurity profile, with what each named species implies about the synthesis →

Section 6

Clinical context

Included because it is routinely misapplied. Trial data describes a licensed medicinal product manufactured under a marketing authorisation, and it does not transfer to research-grade material of unknown provenance.

Bremelanotide was approved in the United States in 2019 for hypoactive sexual desire disorder in premenopausal women.

Section 7

Quarterly coverage

QuarterReportsMedian purityRange
2024-Q11499.8399.39–99.93
2024-Q2699.2398.91–99.93
2024-Q32399.4898.03–99.93
2024-Q41n<3—
2025-Q11998.5597.87–99.85
2025-Q22n<398.40–99.93
2025-Q31898.9997.73–99.75
2025-Q42299.3798.77–99.93
2026-Q11n<3—
2026-Q24199.5998.01–99.93
2026-Q3599.7299.16–99.93

Quarter-by-quarter detail →

Section 8

Most recent records

The 25 most recent PT-141 (Bremelanotide) records of 152.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-041471QYBQYB-2607-L4875Janoshik2026-Q399.723.75101.7Buyer-sourced0PASS
AX-2026-041473QYBQYB-2607-L4875PeptideMeter2026-Q399.583.7494.4Buyer-sourced0PASS
AX-2026-041472QYBQYB-2607-L4875PeptideMeter2026-Q399.933.94—Buyer-sourced0PASS
AX-2026-041474QYBQYB-2607-L4875VendorInvestigate2026-Q399.163.7895.6Buyer-sourced0PASS
AX-2026-041470QYBQYB-2607-L4875Janoshik2026-Q399.774.10—Buyer-sourced0PASS
AX-2026-042139JEEPJEEP-2601-K8195VendorInvestigate2026-Q298.324.2999.4Buyer-sourced1FAIL
AX-2026-041964AMBAMB-2601-M5602Janoshik2026-Q299.933.20—Buyer-sourced0PASS
AX-2026-041664FGPFGP-2602-Y8741Janoshik2026-Q299.904.48106.5Buyer-sourced0PASS
AX-2026-042132JEEPJEEP-2601-K8195Medutest2026-Q298.654.3096.6Buyer-sourced1MARGINAL
AX-2026-041670FGPFGP-2602-Y8741Janoshik2026-Q299.704.27106.9Buyer-sourced0PASS
AX-2026-042135JEEPJEEP-2601-K8195Janoshik2026-Q298.444.64—Buyer-sourced1FAIL
AX-2026-042133JEEPJEEP-2601-K8195Medutest2026-Q298.954.23—Buyer-sourced1MARGINAL
AX-2026-041960AMBAMB-2601-M5602Janoshik2026-Q299.453.63100.1Buyer-sourced0PASS
AX-2026-042140JEEPJEEP-2601-K8195Janoshik2026-Q298.283.89—Buyer-sourced1FAIL
AX-2026-041969AMBAMB-2601-M5602Medutest2026-Q299.793.0789.8Laboratory-retained1MARGINAL
AX-2026-041968AMBAMB-2601-M5602Janoshik2026-Q299.673.68—Buyer-sourced0PASS
AX-2026-041665FGPFGP-2602-Y8741Nordanalyt2026-Q299.513.8991.3Buyer-sourced0PASS
AX-2026-042136JEEPJEEP-2601-K8195Kestrel2026-Q299.323.93105.8Buyer-sourced1MARGINAL
AX-2026-041962AMBAMB-2601-M5602VendorInvestigate2026-Q299.933.36—Buyer-sourced0PASS
AX-2026-041852GSPGSP-2512-N3921Nordanalyt2026-Q299.625.4490.6Buyer-sourced0PASS
AX-2026-042142JEEPJEEP-2601-K8195Medutest2026-Q298.014.02—Buyer-sourced1FAIL
AX-2026-041855GSPGSP-2512-N3921Janoshik2026-Q299.295.5489.8Buyer-sourced1MARGINAL
AX-2026-041669FGPFGP-2602-Y8741Janoshik2026-Q299.394.82—Buyer-sourced0PASS
AX-2026-041850GSPGSP-2512-N3921PeptideMeter2026-Q299.865.3491.6Buyer-sourced0PASS
AX-2026-041853GSPGSP-2512-N3921Janoshik2026-Q299.705.4393.7Supplier-supplied0PASS