# Kisspeptin Dosage in Research: Routes, Half-Life and the Tachyphylaxis Problem > Kisspeptin dosage as studied — the IV, subcutaneous and nasal-spray protocols by population, the half-life difference between the isoforms, and why continuous dosing desensitizes the axis. Research-context only — every figure reported as a studied dose in a named population by a named route, never as a recommendation. ## The short version This page describes kisspeptin dosage the way the studies describe it — as research protocols, not advice. No number here is a recommendation, and there is no human-use instruction anywhere on this site. Two facts shape everything. First, the two main forms clear at very different speeds: kisspeptin-10 lasts only about four minutes in the blood, while kisspeptin-54 lasts around half an hour, so the longer form sustains its effect. Second — and this is the heart of it — giving kisspeptin *continuously* or at *high doses* makes the effect fade within days, because the receptor desensitizes (tachyphylaxis). That is why researchers care so much about *how* it is delivered: a brief, well-spaced pulse behaves very differently from a steady drip. The doses below are written only as 'studied at X in this group by this route.' ## Kisspeptin dosage — the studied protocols Across the human record, kisspeptin dosage has been explored by four routes — intravenous bolus, continuous IV infusion, subcutaneous injection and, most recently, intranasal spray. Reported as studied doses only: - **Kisspeptin-54, IV infusion, healthy men:** `4 pmol/kg/min over 90 min` — the early HPG-axis study [8]. - **Kisspeptin-10, IV, healthy men:** `0.3–1.0 µg/kg` bolus; continuous infusion `1.5 µg/kg/h` [3]. - **Kisspeptin-54, IV infusion, hypothalamic amenorrhea:** `0.01–1.00 nmol/kg/h` [4]. - **Kisspeptin-54, SC bolus, IVF oocyte-maturation trigger:** `3.2–12.8 nmol/kg`, with the highest live-birth rate at `9.6 nmol/kg` [5]. - **Kisspeptin-54, intranasal, healthy men and women and amenorrhea:** `12.8 nmol/kg` primary dose [6]. Every one of these is a supervised research protocol in a defined population, not a self-administered dose. ## Kisspeptin half life — the short flare and the long burn The kisspeptin half life splits the two isoforms cleanly. Kisspeptin-10 has a functional plasma half-life of roughly `4 minutes` in humans — plasma peptidases clear the short fragment quickly, so its signal is a brief, sharp flare [3]. Kisspeptin-54 lasts far longer: its measured human half-life is `27.6 ± 1.1 minutes` [8]. The larger fifty-four-residue peptide resists endopeptidase cleavage better, which is why it reaches higher peak levels and sustains LH release longer at equimolar doses — a difference that mechanistic work has attributed directly to that greater enzymatic resistance [11]. The short half-life of kisspeptin-10 is not only a limitation: it may help *preserve* receptor sensitivity under well-spaced or pulsatile protocols, because the signal is not held on long enough to tire the receptor. ## Why continuous dosing defeats itself: tachyphylaxis The defining feature of kisspeptin dosing is that more is not better. Chronic twice-daily subcutaneous kisspeptin-54 in women with hypothalamic amenorrhea caused marked tachyphylaxis: the acute LH increment of about `24 IU/L` on day 1 fell to roughly `2.5 IU/L` by the fourteenth injection day [10]. High-dose continuous IV infusion (`1.0 nmol/kg/h`) likewise showed desensitization during the infusion [4]. The lesson is consistent across routes: sustained or frequent KISS1R activation downregulates the receptor, so the bolus-versus-continuous distinction is central, and pushing dose or duration tends to blunt the response rather than sustain it [10]. The investigational compound TAK-683, a metastin (kisspeptin) analogue, made the point in the opposite direction by design: in double-blind studies in healthy men, continuous dosing suppressed testosterone below castrate levels in most subjects — a demonstration that *continuous* kisspeptin-receptor agonism desensitizes the axis rather than driving it [12]. ## Kisspeptin nasal spray — the non-invasive route The kisspeptin nasal spray is the newest delivery story. In the 2025 study, intranasal kisspeptin-54 at a `12.8 nmol/kg` primary dose rapidly stimulated LH release across healthy men, healthy women and women with hypothalamic amenorrhea, with no adverse events reported, and the nasal-spray formulation was stable up to 60 days at 4 °C [6]. It is the first clinical demonstration that kisspeptin can work without a needle — a meaningful step for a peptide whose research has otherwise leaned on IV and subcutaneous routes. It remains an investigational protocol, not a product, and no human-use dose is recommended here. --- A noir reading of the Kisspeptin record — one upstream signal traced from KISS1 to GnRH and logged where the trials confirm it, the brief KP-10 flare set apart from the longer KP-54 burn, the fading-with-overuse and not-approved, not-a-supplement truths held in the light; no clinic behind the pulse, and nothing here dosed, dispensed, or sold.