Quick answer: there is no approved treatment GHRP 2 dosage. GHRP-2 (pralmorelin) is approved only in Japan, as a one-time diagnostic test: 100 mcg injected slowly into a vein in adults, or 2 mcg per kg in children aged 4 to 17.[1] Research studies mostly used single IV doses of 1 to 2 mcg per kg, or infusions of up to 1 mcg per kg per hour, under medical supervision.[4][11]
This guide lists each human dose studied, what those doses did, and why doses promoted online have no trial behind them. For background, see our GHRP-2 profile and the growth hormone peptides hub.
What GHRP-2 is and why dose timing matters
GHRP-2 is a synthetic six-amino-acid peptide that binds the growth hormone secretagogue (ghrelin) receptor and makes the pituitary gland release a burst of growth hormone.[14][1] Its effect is brief:
- Short half-life. After IV doses in 18 healthy men, Japan’s label reports an elimination half-life of about 0.42 to 0.69 hours.[1] A US study in 10 children found about 0.55 hours.[6]
- Fast peak. Growth hormone usually peaks 15 to 60 minutes after an IV dose.[1]
- Brief action. In children given injections under the skin, the effect of each dose was short, with little effect on growth hormone later in the night.[13]
That is why researchers used either repeated doses or continuous infusions when they wanted a longer effect.
The approved diagnostic dose in Japan
Japan approved pralmorelin dihydrochloride on October 22, 2004, and Kaken Pharmaceutical launched it as GHRP Kaken 100 in February 2005.[2][1] Its only approved use is diagnosing growth hormone deficiency.[1]
| Who | Dose | How it is given |
|---|---|---|
| Adults (18 and older) | 100 mcg, once | Slow IV injection after fasting |
| Children 4 to 17 | 2 mcg/kg, once (100 mcg if over 50 kg) | Slow IV injection after fasting |
Blood is drawn before the dose and at 15, 30, 45 and 60 minutes. A peak growth hormone level of 15 ng/mL or less (9 ng/mL with recombinant standards) points to severe deficiency.[1] In the validation study of 77 healthy adults and 58 adults with severe deficiency, the average peak after 100 mcg was 84.6 micrograms per liter in healthy people versus 1.36 in patients.[3]
The label has not been tested in children under 4, and it should not be used in pregnancy.[1]
GHRP-2 doses used in human research
| Study | Who | Dose and route |
|---|---|---|
| Turin comparison[4] | 6 healthy young adults | 1 and 2 mcg/kg IV, once each |
| Moscow volunteers[5] | 8 healthy men | 1 mcg/kg IV, once |
| US pharmacokinetic study[6] | 10 children with short stature | 1 mcg/kg IV over 1 minute |
| New York hunger studies[7][8] | 7 lean men; 19 lean and obese adults | 0.1 or 1 mcg/kg per hour under the skin, for 270 minutes |
| Amsterdam repeated dosing[9] | 9 healthy young men | 100 mcg under the skin, once daily for 5 days |
| Tulane older adults[10] | 17 older adults | 1 mcg/kg per hour, continuous infusion under the skin for 30 days |
| Belgian critical illness[11] | 26 critically ill adults | 1 mcg/kg IV bolus, then 1 mcg/kg per hour for 21 hours |
| Prolonged critical illness[12] | 33 critically ill men | 1 mcg/kg per hour infusion for 5 days, alone or with other hormones |
| Chilean children[13] | 6 children with growth hormone deficiency | 0.3, 1 and 3 mcg/kg per day under the skin, 2 months each |
| Nasal spray in children[14] | 15 children with short stature | 5 to 15 mcg/kg in the nose, two to three times daily |
| Oral dosing in children[15] | 10 children with growth hormone deficiency | 900 mcg/kg by mouth, twice daily for 12 months |
Doses given by mouth or nose were many times higher than injected doses, so the numbers in this table cannot be swapped between routes.
What those doses did
Single doses
In Turin, 1 mcg/kg of GHRP-2 produced a strong growth hormone response, higher than the natural releasing hormone GHRH, and 2 mcg/kg produced a higher one still.[4] In Moscow, the growth hormone released over 90 minutes after 1 mcg/kg GHRP-2 was about three times that after the same dose of GHRH.[5] GHRP-2 also raised prolactin, ACTH and cortisol in Turin.[4]
Hunger at two infusion rates
In 19 lean and obese adults, food intake at a buffet rose by about 10% at 0.1 mcg/kg per hour and by about 34% at 1 mcg/kg per hour, compared with placebo.[8] Higher doses meant more hunger as well as more growth hormone.
Repeated daily injections
In Amsterdam, 100 mcg under the skin each morning still released growth hormone, but the average peak fell from 83 micrograms per liter on day 1 to 59 on day 3 and 51 on day 5. IGF-1, the hormone that reflects growth hormone activity over time, did not rise.[9]
Continuous infusions
A 30-day infusion under the skin in older adults kept growth hormone release more than 1.8 times higher than saline on days 14 and 30, held IGF-1 at a raised plateau, and left safety screening tests normal.[10] In critically ill adults, a 21-hour infusion raised IGF-1 by 61% within 24 hours.[11]
Children
In six children with growth hormone deficiency, growth velocity was higher during treatment and no adverse effects or toxicity were observed, but IGF-1 did not increase and the authors said longer-acting forms would be needed.[13] With the nasal spray, average height velocity rose from 3.7 to 6.1 cm a year at 6 months.[14] GHRP-2 was never approved to treat growth.
Where online GHRP-2 doses come from
Doses such as “100 mcg three times a day” do not come from a controlled trial. The closest published source is a retrospective US clinic chart review: of 105 men on testosterone prescribed 100 mcg each of GHRP-2, GHRP-6 and sermorelin three times daily, 14 met its strict criteria. Their IGF-1 rose from about 160 to 239 ng/mL, but the review did not measure muscle, fat or long-term safety.[16]
FDA’s concerns include possible immune reactions to clumped peptide or impurities, and reports of increased insulin needs, deaths of critically ill study subjects, infection and pancreatitis in people given GHRP-2, though it says causality has not been established.[17] For more on those risks, see our GHRP-2 side effects guide.
Converting the study doses
Most research doses were weight-based, while Japan’s approved diagnostic test uses one flat 100 mcg dose given by a clinician. Neither is a dose for home use. Our peptide calculator can help you read units on a prescription, and a clinician sets any dose.
How GHRP-2 dosing compares with related peptides
Ipamorelin was studied in people only by IV, and its half-life is about 2 hours, longer than GHRP-2’s; see our ipamorelin dosage guide and GHRP-2 vs ipamorelin. For the older peptides in the same family, see GHRP-2 vs GHRP-6 vs hexarelin. Sermorelin and tesamorelin act on a different receptor, the GHRH receptor.
Questions to ask a clinician
- Which human study is this dose based on, and was it given the same way?
- What do you expect it to do, and how will we measure it?
- Will you check my blood sugar, IGF-1, prolactin or cortisol?
- Is there an FDA-approved treatment for my goal instead?
- Who makes the product, and how is it tested for purity and sterility?
This is general information, not medical advice. Talk to a licensed clinician before using any growth hormone-related product.
