GHRP-2

Origin and structure

GHRP-2 (growth hormone-releasing peptide 2), also called pralmorelin, is a synthetic chain of six amino acids: D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2. Three of them are D-amino acids, the mirror-image form of the building blocks of human proteins, and one of these, 2-naphthylalanine, does not occur in nature; the FDA notes that this unnatural amino acid makes the peptide harder to characterise. The Japanese medicine contains it as the dihydrochloride salt, C45H55N9O6·2HCl, with a molecular weight of 890.9.

It descends from GHRP-6, one of the small growth-hormone-releasing peptides designed in Cyril Bowers's laboratory at Tulane University in New Orleans before anyone knew which receptor they act on. GHRP-2 is a more potent analogue of GHRP-6; only after that receptor and its natural hormone, ghrelin, had been discovered did it become clear that these peptides mimic ghrelin.

The Japanese company Kaken Pharmaceutical developed it under the code KP-102. Japan approved it on 22 October 2004 as GHRP Kaken 100, a diagnostic medicine that has been on the market since February 2005. A nasal spray to treat short children was also tested, without success (see below).

How it works

GHRP-2 binds the growth hormone secretagogue receptor, the receptor for the stomach hormone ghrelin, in the hypothalamus and the pituitary. According to the Japanese label it acts mainly through the hypothalamus, and growth hormone in the blood peaks 15 to 60 minutes after an intravenous dose. It works differently from GHRH, the body's own growth-hormone-releasing hormone, and the two together release more growth hormone than either does alone.

It is not fully selective. In six young adults, intravenous GHRP-2 raised prolactin, ACTH and cortisol as well as growth hormone, with an ACTH and cortisol response similar to that after an injection of CRH. It also stimulates appetite: in a double-blind study of 19 lean and obese adults, a 270-minute infusion increased how much they ate at a buffet by 10.2% at a low dose and 33.5% at a high dose, compared with placebo.

It is cleared quickly. In 18 healthy men the elimination half-life after an intravenous dose was about 0.4 to 0.7 hours, and only about 2% left the body unchanged in the urine; most is thought to be excreted through the bile. Daily injections lose part of their effect: in 9 healthy young men in Amsterdam who had one injection under the skin a day for five days, the peak growth hormone response fell from 83 to 51 µg/L and IGF-1 did not rise. In 17 older adults, a continuous infusion under the skin for 30 days did keep growth hormone secretion and IGF-1 raised.

Is GHRP-2 approved?

Only in Japan, and only as a diagnostic test. GHRP Kaken 100 is a prescription medicine for diagnosing growth hormone deficiency: one slow intravenous injection on an empty stomach after a rest lying down, with blood taken before and 15, 30, 45 and 60 minutes after. A peak growth hormone level of 15 µg/L or lower (9 µg/L when the assay is calibrated to recombinant growth hormone) indicates severe deficiency. It is not approved to treat anything; the current label was revised in July 2025.

In the EU there is no marketing authorisation for GHRP-2, and it is not a registered medicine in the Netherlands, so it may not be sold or advertised for use in people. Research-grade GHRP-2, the freeze-dried peptide sold for laboratory use, is not the Japanese medicine and carries no approved label.

The FDA has not approved it. On 29 September 2023 the agency placed GHRP-2 for injection and nasal use in category 2 of its interim policy for outsourcing facilities, the list of bulk substances that may present significant safety risks. It cited possible immune reactions caused by aggregation and peptide-related impurities, the unnatural amino acid, and reports of serious adverse events in people who had received GHRP-2: a higher insulin requirement, deaths of critically ill study participants, infection and pancreatitis, while noting that causality had not been established. The list, last updated on 22 April 2026, still has GHRP-2 in category 2; unlike BPC-157 and several other peptides, it has not moved to the withdrawn nominations.

In sport it is prohibited at all times. The WADA Prohibited List names GHRP-2 (pralmorelin) among the growth-hormone-releasing peptides in class S2.2.4, and the Dopingautoriteit's Dutch translation of the 2026 list does the same.

What the research shows

Most human studies of GHRP-2 measured hormones after a single dose or over a few days. Only a handful gave it as a treatment, and none of those measured muscle, body fat, recovery or ageing in adults. The diagnostic work is the strongest part of the record, the treatment work the weakest:

• Diagnostic validation (Chihara et al., 2007): 77 healthy volunteers and 58 patients with severe growth hormone deficiency (a peak below 3 µg/L on the insulin tolerance test) had the intravenous test. Peak growth hormone averaged 84.6 µg/L in the healthy group against 1.36 µg/L in the patients, results were reproducible on repeat testing, and a cut-off of 15 µg/L matched the usual 3 µg/L cut-off of the insulin tolerance test. Older age and obesity lowered the response slightly without changing the diagnosis.
• Nasal spray in short children (Tanaka et al., 2014): 126 prepubertal children with growth hormone deficiency were assigned double-blind to placebo or a low or high dose twice daily for 48 weeks. Height SD scores changed by +0.07 on placebo, +0.03 on the low dose and +0.02 on the high dose, and IGF-1 did not change. The authors concluded that short bursts of the body's own growth hormone do not promote growth.
• Critical illness (Van den Berghe et al., 2002, Leuven): 33 men in prolonged intensive care were randomised to five days of placebo, GHRP-2, GHRP-2 with TRH, or GHRP-2 with TRH and GnRH. GHRP-2 alone reactivated growth hormone pulses and normalised IGF-1, but only the combinations reduced protein breakdown. The trial measured hormones and metabolic markers, not recovery or survival.
• Healthy young men (Nijland et al., 1998, Amsterdam): 9 men had a daily injection under the skin for five days. The peak growth hormone response fell from 83 µg/L on day 1 to 51 µg/L on day 5, and IGF-1 did not rise.
• Older adults (Bowers et al., 2004): in 17 healthy older men and women, a continuous infusion under the skin for 30 days kept growth hormone secretion more than 1.8 times above saline on days 14 and 30 and raised IGF-1 to a stable plateau; safety screening tests stayed normal.
• Appetite (Laferrère et al., 2006): in a double-blind study of 19 lean and obese adults, a 270-minute infusion increased food intake at a buffet by 10.2% at a low dose and 33.5% at a high dose compared with placebo, with no difference between lean and obese participants.

Side effects and warnings

For the single diagnostic injection, the Japanese label lists a feeling of warmth in 16.0% of people, and rumbling bowels and a raised white-cell count in 5% or more. Sweating, thirst, hunger, drowsiness, nausea, stomach discomfort, bloating, low blood pressure, a runny nose and tiredness occur in 0.1 to 5%; dizziness, headache, flushing and a rise in the liver enzyme ALT are listed without a frequency. In the Japanese trials before approval, 86 of 227 people (37.9%) had a side effect; a later review of 503 patients tested in routine care recorded none. The test is contraindicated in pregnancy, and the label warns that similar drugs have caused pituitary apoplexy, sudden bleeding or loss of blood supply in a pituitary tumour with headache, vomiting and visual disturbance, in patients with pituitary adenomas.

Repeated use is less well described. Besides growth hormone, GHRP-2 raises cortisol, ACTH and prolactin, and it increases hunger. In the Leuven critical-illness trial, five days of GHRP-2, alone or with TRH, raised blood lactate and white-cell counts; the triple combination with GnRH did not. The FDA's 2023 listing cites reports of a higher insulin requirement, infection, pancreatitis and deaths among critically ill study participants, without established causality, and flags a risk of immune reactions from impurities in injectable and nasal products. The longest controlled study lasted 48 weeks, in children; there are no long-term safety data in adults.

GHRP-2, GHRP-6 and ipamorelin

All three act on the ghrelin receptor, but they are not interchangeable. GHRP-2 and hexarelin are more potent analogues of the older GHRP-6. In six young adults given each intravenously, GHRP-2 and hexarelin released similar, large amounts of growth hormone, more than GHRH did, together with prolactin, ACTH and cortisol.

Ipamorelin, a five-amino-acid peptide developed at Novo Nordisk, was designed to be more selective. In pigs, GHRP-2 and GHRP-6 raised ACTH and cortisol while ipamorelin did not, even at more than 200 times the dose needed to release growth hormone. In the same study GHRP-2 was the most potent of the three, but its maximum growth hormone response was the lowest. These comparisons come from short hormone studies, not from treatment trials.

Frequently asked questions

Is GHRP-2 legal in the Netherlands?

It is not a registered medicine in the Netherlands or anywhere else in the EU, so it may not be sold, advertised or supplied for use in people. Selling it as research material is a different status, which our guide on research-use-only products in the Netherlands explains. For athletes it is a prohibited substance at all times, however it was obtained.

Is GHRP-2 an approved medicine?

Only in Japan, and only for a test. Since February 2005 doctors in Japan have been able to prescribe GHRP Kaken 100, a single intravenous injection that shows whether the pituitary can still release growth hormone. It is not approved to treat anything, and neither the EMA nor the FDA has authorised it; the FDA has listed injectable and nasal GHRP-2 as a compounding safety risk since September 2023.

Is GHRP-2 banned in sport?

Yes, at all times, in and out of competition. The WADA Prohibited List names GHRP-2 (pralmorelin) in class S2.2.4 among the growth-hormone-releasing peptides, and the Dutch anti-doping rules apply the same list. See our guide on peptides and the doping list.

Does GHRP-2 build muscle or burn fat?

There is no human evidence for it. Those claims rest on the growth hormone pulse it causes; no trial in adults has measured muscle or body fat as an outcome. The pulse itself fades with daily injections: in nine healthy men the peak response fell by almost 40% over five days, and IGF-1, which carries much of growth hormone's effect on tissues, did not rise. Only a 30-day continuous infusion in older adults raised IGF-1.

What is the difference between GHRP-2, GHRP-6 and ipamorelin?

All three activate the ghrelin receptor and release growth hormone. GHRP-2 is a more potent analogue of the older GHRP-6, and in people it also raises prolactin, ACTH and cortisol. Ipamorelin was designed to be more selective: in pigs it released growth hormone without raising ACTH or cortisol, while GHRP-2 and GHRP-6 raised both. Of the three, only GHRP-2 is on an approved label, as Japan's diagnostic test.

Does GHRP-2 make you hungry?

In studies it did. In a double-blind study of 19 lean and obese adults, a 270-minute infusion made them eat 10.2% more at a buffet on the low dose and 33.5% more on the high dose than on placebo, and on the high dose they rated their appetite higher before the meal. Hunger is also listed as a reaction on the Japanese label.

Storage and handling

Store according to product-label instructions and batch handling notes. Lyophilized research peptides are commonly kept dry, protected from light, and handled with clean laboratory technique.

References

Checked against these sources on 28 October 2026.

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