A family of natural human hormones (made from the KISS1 gene) that sit at the very top of the reproductive system — the master "on switch" that tells the brain to release the hormones controlling puberty, the menstrual cycle, ovulation, and fertility. Discovered in 1996 as a cancer-spread suppressor and humorously named after Hershey's Kisses, it turned out in 2003 to be indispensable for human reproduction. Unlike most peptides in this atlas, kisspeptin has a real clinical-trial program: it has been tested in IVF, in women who have lost their periods, and — most strikingly — in men and women with low sexual desire. As of 2026 it is still an investigational drug, not approved for any indication, and kisspeptin-10 remains on the FDA's restrictive 503A Category 2 list.
Endogenous RFamide neuropeptide family (KP-54, KP-14, KP-13, KP-10) encoded by KISS1, signaling through the Gq/11-coupled receptor KISS1R (formerly GPR54). It is the most potent known endogenous stimulator of GnRH neurons — the obligatory upstream gatekeeper of the hypothalamic-pituitary-gonadal axis — with loss-of-function KISS1R mutations causing congenital hypogonadotropic hypogonadism and failure of puberty. KP-10 has an intact-peptide plasma half-life of ~27–30 min; KP-54 roughly 6× longer. The clinical pipeline spans IVF oocyte-maturation triggering (Phase II), functional hypothalamic amenorrhea, HSDD (positive proof-of-concept RCTs in both sexes), pubertal diagnostics, and a 2025 intranasal proof-of-concept. The dominant pharmacologic limitation is tachyphylaxis with continuous dosing.
Kisspeptin (KISS1 gene, chr 1q32; KP-54 CAS 388138-21-4, PubChem CID 71306396; KP-10 PubChem CID 25240297) is a pleiotropic neuroendocrine signal acting at KISS1R (chr 19p13.3, 398-aa Class-A GPCR, MW 42.6 kDa) via Gq/G11 → PLCβ → IP3/DAG → intracellular Ca²⁺, with secondary MAPK/ERK1/2 and p38 arms. The arcuate-nucleus KNDy neuron (co-expressing Kisspeptin, Neurokinin B, Dynorphin) constitutes the GnRH pulse generator; an AVPV population mediates the pre-ovulatory LH surge in rodents. KP-10 (H-YNWNSFGLRF-NH₂, C₆₃H₈₃N₁₇O₁₄, MW 1302.4) binds KISS1R with Ki 0.042–2.35 nM. Beyond reproduction: glucagon→hepatic-kisspeptin→β-cell suppression of insulin (metabolic axis), direct osteogenic KISS1R signaling, placental trophoblast regulation, and context-dependent metastasis suppression. Overall clinical evidence grade by indication ranges from B (IVF) to C (HSDD/FHA proof-of-concept) to P (metabolic/bone/oncology).
Kisspeptin occupies an unusual position in this atlas: it is a true endogenous human hormone with a genuine, multi-indication clinical-trial program — not a research-chemical curiosity. The numbers below capture both its established physiology (the master upstream regulator of reproduction) and the live development pipeline (IVF, amenorrhea, low sexual desire, intranasal delivery). Evidence is strongest for IVF triggering and proof-of-concept psychosexual studies; metabolic, bone, and oncology roles remain preclinical.
Kisspeptin works at the very top of the reproductive chain of command. Brain cells that make kisspeptin act directly on GnRH neurons — the cells that ultimately control the ovaries and testes through the pituitary gland. When kisspeptin binds its receptor (KISS1R), it makes GnRH neurons fire, releasing a pulse of GnRH that tells the pituitary to release LH and FSH, which in turn drive the gonads. A special cluster of cells called KNDy neurons acts like a pacemaker, generating the rhythmic pulses that keep the whole system running. Kisspeptin also lights up parts of the brain involved in attraction and desire, which is why it's being studied for low sexual desire.
Five mechanistically linked arms. First — direct GnRH activation: kisspeptin neurons synapse onto GnRH cell bodies and median-eminence terminals; a single bolus reliably triggers LH release across species, abolished by GnRH antagonists and absent in Kiss1r-knockouts (all actions are KISS1R-mediated). Second — the KNDy pulse generator: arcuate neurons co-expressing Kisspeptin/Neurokinin B/Dynorphin fire synchronously, with NKB initiating bursts and dynorphin terminating them — the biological GnRH pulse generator. Third — dual estrogen feedback (tonic negative via ARC; phasic positive via the pre-ovulatory surge). Fourth — sexual brain processing: kisspeptin deactivates inhibitory self-monitoring regions while activating arousal/reward centers. Fifth — extra-reproductive signaling (placental, metabolic, bone).
KISS1R is a 398-aa Class-A GPCR coupling primarily to Gq/G11 → PLCβ → IP3/DAG → intracellular Ca²⁺ mobilization, with secondary MAPK/ERK1/2, p38, and arachidonic-acid arms. Receptor desensitization on sustained agonism (β-arrestin recruitment, internalization) is the molecular basis of clinical tachyphylaxis — the central engineering problem for chronic therapy. Two anatomically distinct neuron populations: arcuate/infundibular KNDy cells (pulse generation, steroid-negative feedback, ERα-expressing, relaying leptin/ghrelin) and rodent AVPV cells (estrogen-positive-feedback LH surge). The glucagon→cAMP-PKA-CREB→hepatic-kisspeptin1→β-cell-KISS1R axis suppresses glucose-stimulated insulin secretion — a metabolic mechanism distinct from the neuroendocrine role. No human EC50 for therapeutic effect is established; dosing is empirical/weight-based.
Unlike most peptides in this atlas, kisspeptin has trial-derived dose ranges for several indications — yet none is an FDA-approved regimen, so every ladder below is a research/protocol-design construct, not validated prescribing. Kisspeptin is dosed by body weight (nmol/kg as a bolus, or nmol/kg/h for infusion) rather than as a fixed microgram amount — a critical difference from BPC-157/GHK-Cu that the calculator below handles directly. Each protocol is built to the same skeleton: starting dose, escalation cadence, dose ladder, maintenance target, cycle structure, reconstitution/weight-conversion math, monitoring overlay, and explicit evidence grade. The single most important pharmacologic constraint threaded through all of them is tachyphylaxis: continuous or twice-daily dosing desensitizes KISS1R, so most regimens are acute single-pulse (IVF trigger), pulsatile (amenorrhea), or short acute infusion (HSDD).
3.2 nmol/kg SC × 1 (single subcutaneous injection) administered ~36 h before oocyte retrieval, mirroring the trial midpoint. The trigger is a one-time event, not a daily regimen.1.6 → 3.2 → 6.4 → 12.8 nmol/kg SC single dose. Higher doses increase oocyte yield up to the studied ceiling; 12.8 nmol/kg is the highest trial dose with maintained safety.6.4 nmol/kg SC × 1 (KP-54) acutely produces mean maximal LH +24.0 IU/L and FSH +9.1 IU/L within 4 h in women with HA. Pulsatility restoration: low-dose IV infusion 0.01–1.0 nmol/kg/h (KP-54).0.01 → 0.03 → 0.10 → 0.30 → 1.0 nmol/kg/h (the studied LH-pulsatility range). Acute bolus: single 6.4 nmol/kg SC. Pulsatile bolus delivery every 1–4 h is the strategy to sustain response.1 nmol/kg/h IV infusion × 75 min (KP-54), the dose used in both the male and female HSDD trials. A single short infusion, not a chronic regimen.12.8 nmol/kg intranasal × 1 (KP-54 nasal spray). Earlier dose-finding examined 3.2–25.6 nmol/kg in healthy men, with dose-dependent LH rises from 3.2 nmol/kg upward.3.2 → 6.4 → 12.8 → 25.6 nmol/kg intranasal (the studied range); 12.8 nmol/kg is the validated proof-of-concept dose. Formulation/dose optimization for a clinical product is ongoing.Kisspeptin's decision logic differs fundamentally from steady-state peptides: the dominant rule is avoid continuous KISS1R occupancy to prevent tachyphylaxis. Escalation is largely cycle/protocol-level (IVF dose selection, infusion-rate titration to restored pulsatility) rather than open-ended daily escalation. Hard stops reflect the reproductive/endocrine context (pregnancy already achieved, hormone-sensitive conditions) and regulatory caution.
| Decision node | Rule template | Grade |
|---|---|---|
| Escalate (IVF) | Select trigger dose by protocol across 1.6→12.8 nmol/kg based on follicle number / OHSS risk; higher dose for higher target oocyte yield. Not titrated within a cycle. | B |
| Titrate (infusion) | For FHA pulsatility restoration, titrate infusion rate 0.01→1.0 nmol/kg/h to restored LH pulse frequency/amplitude, not to maximal LH. Stop escalating once physiologic pulsatility returns. | C |
| Switch to pulsatile (anti-tachyphylaxis) | If LH response declines on repeated/continuous dosing (the 89% day-14 attenuation pattern), switch to pulsatile delivery (every 1–4 h) or a longer-acting analog — do NOT increase frequency. | C |
| Hold | OHSS signs after IVF trigger; any hormone-sensitive condition flare; unexpected hypotension during infusion (kisspeptin has mild vasoactive properties). Hold and reassess. | C/D |
| Permanent stop (hard) | Pregnancy achieved (trigger goal met) or any pregnancy outside protocol; known hormone-sensitive malignancy without specialist oversight; patient preference after disclosure. Encode as non-editable hard-stops. | D |
Special populations — pediatric (pubertal diagnostics only, specialist-supervised), pregnancy (placental kisspeptin already thousands-fold elevated — exogenous dosing not a therapeutic target), renal/hepatic impairment (no stratified PK): default to specialist/IRB oversight.
Kisspeptin has a genuine, hormone-based response biomarker (LH/FSH) — unusual in this atlas — so the engine can drive decisions off measured endocrine responses rather than borrowed surrogates. Each bundle maps to its indication; the validated_endpoint reflects whether the readout was a trial endpoint.
| Indication | Primary readout | Interpretation | Trial-validated? |
|---|---|---|---|
| IVF trigger | Oocyte maturation rate; serial LH/E2; OHSS surveillance | ≥ maturation threshold = success; rising hematocrit/ovarian volume = OHSS flag. | Yes (Phase II) |
| FHA / IHH | LH pulse frequency & amplitude (deconvolution); FSH; E2 | Restored pulsatility = response; declining LH on repeat dosing = tachyphylaxis → switch to pulsatile. | Yes (mechanistic) |
| HSDD | Validated psychosexual scales; fMRI (research); penile tumescence (men) | Increased arousal/desire scores; +penile rigidity in men = response. | Yes (RCT PoC) |
| Diagnostic test | Magnitude of LH rise to bolus | Robust rise = intact GnRH network; blunted = congenital IHH. | Emerging |
| Safety (all) | Vitals (BP), tolerability, OHSS markers (IVF) | Kisspeptin AE rate <15% across trials; mostly transient injection-site/headache/nausea. | Yes |
Architecture note: store each readout with an indication tag and a trial_validated level (Phase II / PoC RCT / mechanistic / emerging). Unlike practice-pattern peptides, several kisspeptin readouts are trial-grounded.
For reference only. Not medical dosing advice. Kisspeptin is dosed by body weight (nmol/kg). This calculator converts a nmol/kg target into a µg dose for the selected isoform (KP-54 MW ≈ 5857; KP-10 MW ≈ 1302.4), then into a draw volume from a reconstituted vial. Verify identity (MS), purity (≥98% HPLC), sterility, endotoxin, and storage; use pharmaceutical-grade material under specialist/IRB oversight only.
Note: for infusion targets (nmol/kg/h) the µg figure is the hourly amount; multiply by infusion duration (e.g. ×1.25 for a 75-min HSDD infusion) for the total. Intranasal bioavailability differs from injection — the figure is the nominal weight-based amount, not route-adjusted systemic exposure.
Kisspeptin's combinations are clinical/mechanistic — co-administration with established reproductive agents within assisted-reproduction or endocrine protocols — rather than the wellness "stacks" common to repair peptides. The pairings below reflect how kisspeptin slots into the HPG axis alongside gonadotropins, GnRH-axis drugs, and NKB-pathway modulators. Most are study-stage or mechanistic concepts; none is an approved combination regimen. The governing principle is to respect the pulse-generator biology — avoid stacking agents in ways that drive continuous KISS1R occupancy.
| Component | Role | Evidence |
|---|---|---|
| FSH / hMG | Follicle recruitment / growth | Approved (A) |
| GnRH antagonist | Prevent premature LH surge | Approved (A) |
| KP-54 trigger | Physiologic LH surge for maturation | Phase II (B) |
| Component | Node | Interaction |
|---|---|---|
| Kisspeptin | Upstream of GnRH | Drives GnRH pulse |
| GnRH antagonist | Pituitary GnRH-R | Blocks kisspeptin's LH effect |
| GnRH agonist (continuous) | Pituitary GnRH-R | Desensitization (parallel risk) |
| Component | Role | Status |
|---|---|---|
| Kisspeptin/KISS1R | Overactive in PCOS | Biomarker (B/C) |
| NK3R antagonist | Dampen KNDy pulse drive | Investigational (C) |
| Compound | Design goal | Status |
|---|---|---|
| MVT-602 | Extend t½, optimize surge | Phase II active (B/C) |
| TAK-448/683 | Sustained activation → castration | Discontinued (prostate Ca) |
The non-negotiable constraint across every kisspeptin combination is preservation of pulse-generator biology. Any pairing that produces continuous, high-level KISS1R occupancy (or continuous downstream GnRH-R occupancy) risks desensitizing the very axis kisspeptin is meant to activate — converting a stimulatory agent into a suppressive one. This is not a peptide "stack" domain like the repair peptides; kisspeptin combinations belong to supervised reproductive-endocrine protocols. No over-the-counter wellness stacking is appropriate.
Kisspeptin has one of the better-characterized safety profiles in this atlas because it has been given to humans across >20 published trials. The adverse-event rate is below 15% at doses up to 6.4 nmol/kg/h IV, with mostly transient injection-site reactions, mild headache, and mild nausea; no serious adverse events have been reported in the peer-reviewed literature as of 2026. The favorable profile is partly mechanistic — kisspeptin simulates a normal physiologic process rather than introducing a novel pharmacology, and its short half-life limits accumulation. The principal caveats are the absence of long-term/chronic-dosing data, tachyphylaxis (a pharmacologic, not toxic, limitation), and the reproductive-hormone context that defines its contraindications.
Kisspeptin's trial safety record is reassuring, but the following are precautionary given the reproductive-hormone context and the absence of chronic-use data.
| Condition / factor | Risk level | Applies to | Rationale |
|---|---|---|---|
| Pregnancy | Avoid | All routes | Placental kisspeptin already thousands-fold elevated; no indication for exogenous dosing and no reproductive-safety data. |
| Hormone-sensitive malignancy (active) | Caution | Systemic | Context-dependent cancer biology; paradoxical pro-metastatic effects reported in some tumors (e.g. prostate). Specialist oversight required. |
| Continuous / twice-daily dosing intent | Avoid | All routes | Tachyphylaxis — continuous KISS1R occupancy desensitizes the axis (89% LH loss by day 14). Use pulsatile or single-dose designs. |
| Uncontrolled cardiovascular disease | Caution | IV infusion | Mild vasoactive/vasoconstrictive properties in preclinical work; monitor BP during infusion. |
| Known prior OHSS / very high follicle count | Monitor | IVF trigger | Although kisspeptin lowers OHSS risk vs hCG, high-risk cycles still warrant OHSS surveillance. |
| Pediatric use (outside diagnostics) | Avoid | All routes | Only specialist-supervised pubertal diagnostic use is described; no therapeutic pediatric regimen exists. |
| Severe renal or hepatic impairment | Caution | Systemic | No PK stratified by eGFR / Child-Pugh; conservative specialist/IRB oversight. |
| Unverified "research-chemical" product | Avoid | All routes | Sequence-error and endotoxin contamination risk; require HPLC ≥98%, sterility, endotoxin, and MS identity for any injectable use. |
LH, FSH, estradiol/testosterone, prolactin; for IVF — follicle count, AMH, OHSS-risk assessment; vitals/BP; pregnancy test where relevant; indication-specific endpoint baseline (psychosexual scales for HSDD).
Serial LH/FSH (e.g. every 10–15 min over the response window); BP during IV infusion; tolerability (injection-site, headache, nausea). For pulsatility protocols, track pulse frequency/amplitude.
Estradiol and LH post-trigger; oocyte maturation at retrieval; OHSS surveillance (symptoms, ovarian volume, hematocrit) through the luteal phase.
Compare LH response across doses; a declining response signals desensitization → switch to pulsatile delivery or a longer-acting analog rather than increasing frequency.
Repeat indication endpoint and safety review; document objective endocrine response and subjective outcomes for protocol-to-protocol comparison.
OHSS signs, pregnancy achieved (trigger goal met), significant hypotension during infusion, hormone-sensitive condition flare, or any new diagnosis changing the risk/benefit calculus.
Kisspeptin's evidence base stands apart from most peptides here: a systematic analysis counts ~29 interventional clinical trials, spanning IVF triggering (Phase II with downstream pregnancy data), functional hypothalamic amenorrhea, two positive HSDD proof-of-concept RCTs, pubertal diagnostics, and a 2025 intranasal proof-of-concept. The headline studies, the synthetic-analog program, and the active trials are summarized below.
The landmark Phase II trial (NCT01667406, Hammersmith Hospital, n=60 high-OHSS-risk women) demonstrated 95% oocyte maturation, highest yield (121%) at 12.8 nmol/kg, live-birth rate 45% per transfer, and — critically — no moderate/severe/critical OHSS at any dose. The strongest efficacy-and-safety result in the kisspeptin program and the basis for ongoing trigger development.
Two randomized, double-blind, placebo-controlled 2-way crossover trials published in JAMA Network Open. Men (n=32, JAMA Netw Open 2023;6(2):e2254313): kisspeptin increased penile tumescence up to 56% over placebo, enhanced sexual brain processing, improved "happiness about sex," no AEs. Women (n=32, JAMA Netw Open 2022, DOI 10.1001/jamanetworkopen.2022.36131): deactivated inhibitory self-monitoring regions, increased "feeling sexy" (P=0.03), no adverse effects — first clinical evidence for kisspeptin in psychosexual disorders in both sexes.
A 2025 study (King's College London / Imperial, eBioMedicine/Lancet group) showed intranasal KP-54 at 12.8 nmol/kg rapidly stimulates LH/FSH: healthy men +4.4±0.6 IU/L (P=0.002), healthy women +1.4±0.3 IU/L (P=0.004), HA patients +4.4±0.2 IU/L (P<0.001), with the nasal spray stable up to 60 days at 4 °C and no adverse events. Mechanism: olfactory-bulb GnRH neurons expressing KISS1R — a novel extra-hypothalamic pathway.
Continuous IV KP-54 infusion (0.01–1.0 nmol/kg/h) increased LH pulsatility in all women with hypothalamic amenorrhea, with peak responses at patient-specific rates — demonstrating a dose-dependent therapeutic window (J Clin Endocrinol Metab, DOI 10.1210/jc.2013-1569). Acute SC KP-54 (6.4 nmol/kg) produced mean maximal LH +24.0 IU/L. The companion finding — 89% LH attenuation by day 14 on twice-daily dosing — defined the tachyphylaxis problem.
A 9-residue analog with elimination half-life 1.3–2.2 h (vs ~27 min for KP-10), greater LH AUC (169.0 vs 38.5 IU·h/L) and longer GnRH-neuron firing (115 vs 55 min) than native KP-54. In Phase 2a, 3 µg induced ovulation in 100% of stimulated women within 5 days with a placebo-equivalent safety profile — the leading engineered solution to native kisspeptin's short half-life.
A Massachusetts General Hospital study investigating pulsatile subcutaneous kisspeptin over 2 weeks in IHH men and women, with primary endpoints including LH pulse-amplitude change and follicle maturation in women — directly testing whether pulsatile delivery overcomes tachyphylaxis and re-engages the GnRH network.
Kisspeptin's evidence is indication-stratified rather than uniform. IVF triggering is the strongest (Phase II RCT with maturation and live-birth data, plus advancing analogs) — grade B. HSDD and FHA/IHH rest on small but rigorous proof-of-concept RCTs and mechanistic human studies — grade C, promising but not yet confirmatory. Pubertal diagnostics and intranasal delivery are emerging (grade C, early). Metabolic, bone, oncology, and pregnancy-biomarker roles are preclinical or observational — grade P/C. No indication has reached Phase III or regulatory approval, which is why the dosing engine above is framed as a research/protocol-design layer rather than a clinical guideline — but the underlying human data are far more substantial than for most peptides in this atlas.
| Parameter | Kisspeptin (KP-54/10) | GnRH / GnRH agonist | hCG (IVF trigger) |
|---|---|---|---|
| Class | Endogenous RFamide neuropeptide; KISS1R agonist | Decapeptide hypothalamic releasing hormone | Glycoprotein gonadotropin (LH-mimetic) |
| Axis position | Upstream of GnRH (master switch) | Pituitary-level (drives LH/FSH) | Gonad-level (LH-receptor agonist) |
| Primary mechanism | KISS1R → Gq/11 → GnRH-neuron firing → physiologic LH surge | GnRH-R → LH/FSH; continuous use desensitizes | Direct LH-receptor activation; long-acting |
| IVF trigger OHSS risk | Low — self-limiting physiologic surge (zero severe OHSS in trial) | Agonist trigger lowers OHSS but luteal-phase deficit | Higher — sustained stimulation, OHSS risk |
| Half-life | KP-10 ~27–30 min; KP-54 ~6× longer; MVT-602 1.3–2.2 h | Native GnRH minutes; agonists longer | Long (~24–36 h) |
| Tachyphylaxis | Yes — continuous dosing desensitizes KISS1R | Yes — basis of agonist "downregulation" therapy | Not the operative concern (single trigger) |
| Approval status | Investigational (no approved indication) | Approved (multiple indications) | Approved (IVF trigger) |
| Distinctive use | HSDD, pubertal diagnostics, intranasal route | Pulsatile GnRH for IHH; downregulation | Standard IVF trigger (the comparator) |