GHRP-2 Calculator

What Is GHRP-2?

GHRP-2 (Growth Hormone Releasing Peptide-2, also known as pralmorelin or KP-102) is a synthetic hexapeptide composed of six amino acids. It belongs to the class of growth hormone secretagogues and acts as a ghrelin mimetic, prompting the body to release its own growth hormone (GH). Unlike the direct administration of recombinant growth hormone, GHRP-2 does not introduce GH from an external source. Instead, it stimulates the pituitary gland to amplify its own pulsatile GH bursts, which means the natural feedback mechanisms of the GH axis remain largely intact.

GHRP-2 was developed during the 1980s and 1990s as part of the search for small-molecule GH secretagogues, making it one of the longest-studied peptides in its class. In research literature, GHRP-2 is frequently positioned between GHRP-6 and ipamorelin. It is more potent than GHRP-6 in terms of raw GH release, yet it tends to produce less appetite stimulation. At the same time, it is considered less selective than ipamorelin, since it can influence prolactin and cortisol to a modest degree.

GHRP-2 is used and studied strictly for research purposes. It binds to the growth hormone secretagogue receptor (GHS-R1a) in the pituitary and hypothalamus — the same receptor targeted by the body's own hormone ghrelin. Because of its short half-life of roughly two hours, most research protocols administer GHRP-2 several times per day to generate repeated GH pulses.

Mechanisms of Action

GHRP-2 exerts its effects by activating the ghrelin receptor and modulating the downstream GH axis. The principal mechanisms can be summarized as follows:

• GHS-R1a receptor agonism: As a ghrelin mimetic, GHRP-2 binds to the growth hormone secretagogue receptor 1a. This binding triggers an intracellular signaling cascade that causes the somatotroph cells of the pituitary to release stored growth hormone.
• Amplification of pulsatile GH bursts: Rather than creating a continuously elevated GH level, GHRP-2 increases the amplitude of the body's natural GH pulses. This pulsatile character resembles physiological GH secretion far more closely than a continuous external supply.
• Suppression of somatostatin: GHRP-2 dampens the influence of somatostatin, the body's natural inhibitor of GH release. By releasing this inhibitory brake on the pituitary, the GH burst is amplified further.
• Synergy with GHRH: GHRP-2 works through a different receptor than growth hormone-releasing hormone (GHRH). When a GHRP and a GHRH analog are combined, their effects do not simply add together but reinforce one another, producing a disproportionately larger response.
• Appetite stimulation: Because GHRP-2 acts on the ghrelin receptor, it can trigger a sensation of hunger that sets in a few minutes after administration. This effect is usually noticeably weaker than with GHRP-6, but stronger than with ipamorelin.
• Effects on prolactin and cortisol: At higher doses, GHRP-2 can slightly raise the secretion of prolactin and cortisol. These ancillary-axis effects are dose-dependent and are one reason why many research protocols favor moderate doses.

Dosage Calculation

GHRP-2 does not typically require a slow titration ramp. Most protocols begin directly within the moderate dose range and split the daily amount across several individual injections to take advantage of the pulsatile nature of the GH axis.

Standard Dosing Parameters

• Conservative dose: 50 mcg (0.05 mg) per injection
• Standard dose: 100 mcg (0.10 mg) per injection
• Higher range: 150–250 mcg (0.15–0.25 mg) per injection
• Frequency: 2–3 times daily, ideally in the morning on an empty stomach, before training, and before sleep
• Typical syringe: 0.3 mL insulin syringe (29–31 gauge, 6–8 mm needle)

A commonly cited reference point is the so-called saturating dose of approximately 1 mcg per kilogram of body weight. In research, doses above this threshold add little additional GH release while increasing the risk of ancillary-axis effects such as elevated cortisol or prolactin. Most protocols therefore remain in the range of 100 mcg per injection.

Example Calculation: 5 mg Vial with 2 mL BAC Water

The most common vial size for GHRP-2 is 5 mg. Adding 2 mL of bacteriostatic water gives a concentration of 2.5 mg/mL (2,500 mcg/mL).

• 50 mcg dose: 50 ÷ 2500 = 0.02 mL (2 units on a U100 syringe)
• 100 mcg dose: 100 ÷ 2500 = 0.04 mL (4 units)
• 150 mcg dose: 150 ÷ 2500 = 0.06 mL (6 units)
• 250 mcg dose: 250 ÷ 2500 = 0.10 mL (10 units)

The volumes to draw for GHRP-2 are very small. If the volume to withdraw falls below 0.05 mL, a larger reconstitution volume can improve measurement accuracy. If the 5 mg vial is reconstituted with 5 mL of BAC water instead of 2 mL, the concentration becomes 1 mg/mL, and a 100 mcg dose then corresponds to 0.10 mL, or 10 units. At a typical daily amount of 300 mcg (3 × 100 mcg), a 5 mg vial lasts roughly 16 days on paper. Use the GHRP-2 calculator above to compute exact volumes for any vial size, reconstitution volume, and target dose.

Reconstitution

GHRP-2 is supplied as a lyophilized (freeze-dried) powder in sealed vials. It must be reconstituted with bacteriostatic water (BAC water) before use. Sterile water for injection should not be used for multi-dose vials — BAC water contains 0.9% benzyl alcohol, which inhibits microbial growth and meaningfully extends the usable window of the reconstituted solution.

Step-by-Step Reconstitution Protocol

1. Gather supplies: the GHRP-2 vial, a bacteriostatic water vial, alcohol swabs, a sterile draw needle (18–21 gauge), and the insulin syringe for the eventual injection.
2. Wipe the rubber septa of both vials with fresh alcohol swabs and allow them to air-dry for about 30 seconds. Do not touch or blow on the septa after cleaning.
3. Draw the desired volume of BAC water into the draw syringe (2 mL is standard for a 5 mg vial, or 5 mL for a more dilute solution that is easier to measure).
4. Insert the needle into the peptide vial at an angle, directing the tip toward the inner glass wall rather than straight onto the powder cake. A direct stream onto the lyophilized powder can shear peptide bonds and damage the molecule.
5. Slowly depress the plunger so that the BAC water runs down the inside glass wall and gradually wets the powder from below.
6. Gently roll or swirl the vial between your palms until the powder is fully dissolved. The solution should appear clear and colorless. Do not shake or vortex the vial.
7. Label the vial with the reconstitution date and concentration (for example, "GHRP-2 2.5 mg/mL, reconstituted [date]").

If the solution appears cloudy, discolored, or contains visible particulate matter, the vial should be discarded and not used.

Storage and Shelf Life

• Lyophilized powder (unreconstituted): Store at −20°C for long-term storage, where the powder remains stable for 24+ months. Short-term storage at 2–8°C in a refrigerator is acceptable for a few weeks. Protect from light and moisture and do not leave at room temperature for extended periods.
• Reconstituted solution: Store in the refrigerator at 2–8°C. The solution is stable for approximately 28–30 days. Keep the vial upright and away from light, and discard it after 30 days regardless of remaining volume.
• Do not freeze reconstituted peptide. Freeze-thaw cycles cause protein aggregation and a loss of biological activity. Once reconstituted, the vial must remain refrigerated throughout its entire use window.
• Transport: Use an insulated cooler with an ice pack for any travel lasting longer than 1–2 hours. Commercial insulated medication pouches maintain 2–8°C for roughly 24–48 hours. Avoid exposure to temperatures above 25°C.

Side Effects and Safety Profile

GHRP-2 has been studied for several decades and is regarded as comparatively well tolerated at research doses. Because it stimulates GH release through the body's own pituitary gland, physiological feedback mechanisms remain largely intact. Nevertheless, GHRP-2 is not an approved drug, and comprehensive long-term human data is lacking.

Commonly Reported Observations

• Transient hunger that sets in a few minutes after administration. This effect is attributable to ghrelin agonism and is generally milder than with GHRP-6.
• Mild redness, brief swelling, or a transient feeling of pressure at the injection site. Rotating injection sites minimizes localized irritation.
• A sensation of warmth, mild tingling, or flushing shortly after injection, often felt in the face or head. This usually subsides within a few minutes.
• Temporary water retention or a slight feeling of tightness in the hands, related to increased GH activity, which often normalizes after the first few days.
• Drowsiness or grogginess, particularly when administered before sleep.

Less Common or Theoretical Concerns

• Elevated cortisol and prolactin: Particularly at higher doses, GHRP-2 can slightly increase the secretion of cortisol and prolactin. Persistently elevated prolactin levels could theoretically affect mood, libido, and general well-being. Staying within moderate doses limits this risk.
• Effects on blood glucose and insulin sensitivity: Increased GH activity can temporarily reduce insulin sensitivity and slightly raise fasting blood glucose. Individuals with impaired glucose tolerance should take this into account.
• Receptor desensitization: Sustained high-dose use over long periods can theoretically reduce the sensitivity of the GHS-R1a receptors. For this reason, research protocols frequently favor cyclical approaches with breaks.

Contraindications

• Active cancer or history of malignancy (without medical supervision)
• Pregnancy and breastfeeding (insufficient safety data)
• Poorly controlled diabetes or significant disorders of glucose metabolism
• Known hypersensitivity to any component of the preparation

No serious adverse events have been attributed to GHRP-2 in the published literature at standard research doses. However, given the absence of large-scale long-term human trials, caution is warranted, and consultation with a qualified healthcare professional is strongly recommended.

Combinations and Stacks

GHRP-2 + CJC-1295 (no DAC) — The GHRH-plus-GHRP Synergy

The most potent and best-documented combination for GHRP-2 is pairing it with a GHRH analog, most prominently CJC-1295 without DAC (also known as Mod GRF 1-29). The two peptides act on the same somatotroph cell population in the pituitary, but through different receptors:

• GHRP-2 activates the ghrelin receptor while simultaneously dampening somatostatin, the inhibitory counterpart of GH release.
• CJC-1295 without DAC activates the GHRH receptor and increases the amount of growth hormone that can be released per pulse in the first place.
• When both are administered together, the GH response does not simply add up but turns out disproportionately larger than the sum of the individual effects. This synergy is the central reason combined GHRH-plus-GHRP protocols are so popular in research.

A typical research protocol combines 100 mcg of GHRP-2 with 100 mcg of CJC-1295 without DAC per injection, 2 to 3 times daily. Because CJC-1295 without DAC has a half-life similar to that of GHRP-2, both can be administered comfortably within the same time window.

GHRP-2 Compared to Ipamorelin and GHRP-6

All three peptides are ghrelin mimetics, but they differ in profile. Ipamorelin is considered the most selective GHRP, with the least effect on cortisol and prolactin, and is therefore often preferred when ancillary-axis effects should be minimized. GHRP-6 produces the strongest appetite stimulation and is used in research specifically when a hunger signal is desired. GHRP-2 occupies a middle position: a stronger GH release than GHRP-6 with a moderate appetite effect. Hexarelin is the most potent member of the class, but it is also the most prone to receptor desensitization.

Stacking Notes

GHRP-2 should ideally be administered on an empty stomach, as high blood glucose and fatty-acid levels can blunt the GH response. A gap of roughly 20 to 30 minutes between the injection and the next meal is common in many protocols. When several peptides are combined, each should be reconstituted separately. Administering them in separate syringes eliminates dosing errors, even though adjacent injection sites can be used.

Frequently Asked Questions

How does GHRP-2 differ from GHRP-6?

Both are ghrelin-mimetic secretagogues, but GHRP-2 is more potent in terms of raw GH release and triggers noticeably weaker appetite stimulation. GHRP-6 produces a pronounced sensation of hunger, which can be desirable in research but is also inconvenient when that effect is not wanted. For a comparable GH response, slightly lower doses of GHRP-2 are therefore typically used.

Why should GHRP-2 be administered on an empty stomach?

High blood levels of insulin and fatty acids dampen the pituitary's GH response. Administering on an empty stomach — roughly two hours after the last meal and at least 20 to 30 minutes before the next — allows the strongest GH burst in research. The carbohydrate and fat content of a meal shortly before the injection can in particular weaken the effect.

How many times per day is GHRP-2 administered?

Because of its short half-life of around two hours, most research protocols use 2 to 3 administrations per day. Common timings are in the morning on an empty stomach, before training, and before sleep, since the largest natural GH pulse already occurs during the early deep-sleep phase.

Does GHRP-2 cause an increase in cortisol and prolactin?

At moderate doses, GHRP-2 has only a small effect on cortisol and prolactin. As the dose rises, however, this ancillary-axis effect increases. For this reason, most research protocols stay around 100 mcg per injection and avoid significantly exceeding the saturating dose, since beyond it there is little additional GH gain but more side effects to expect.

Can GHRP-2 be combined with CJC-1295?

Yes — combining a GHRP with a GHRH analog such as CJC-1295 without DAC is the most frequently studied stack variant. Because the two act through different receptors, they amplify GH release synergistically. In typical protocols, both peptides are administered at the same time and within the same window, but reconstituted from separate vials.

How long should a GHRP-2 cycle last?

In research, cyclical protocols of roughly 8 to 12 weeks followed by breaks are common. Breaks are scheduled as a precaution to guard against possible desensitization of the GHS-R1a receptors, even though robust long-term human data is limited. The dose is generally held constant throughout a cycle.

Is GHRP-2 detectable in sports drug testing?

GHRP-2 is on the World Anti-Doping Agency (WADA) prohibited list and is banned as a growth hormone secretagogue both in and out of competition. Specialized analytical methods can detect GHRP-2 and its metabolites. Athletes subject to WADA-compliant testing should always verify the applicable anti-doping rules in advance.

Does GHRP-2 permanently affect the body's own GH production?

GHRP-2 does not suppress the GH axis in the classical sense, because it stimulates the pituitary rather than supplying hormones from outside. Natural GH production fundamentally remains intact. In theory, very long and high-dose use can reduce receptor sensitivity, which is why breaks between cycles are recommended. Unlike steroid-based interventions, no dedicated post-cycle therapy is required.

Medical Disclaimer: The information on this page is provided for educational and research purposes only. GHRP-2 is not an approved drug or medical treatment and is sold strictly for research use. Nothing on this page constitutes medical advice, diagnosis, or a recommendation to use any specific compound. Always consult a qualified healthcare professional before beginning any peptide protocol. The legal status of peptides varies by region, and compliance with local regulations is your responsibility. BergdorfBio assumes no liability for the use or misuse of the information presented here.