GH Secretagogue
GHRP-6
The original GHRP; a hexapeptide studied for its potent appetite-stimulating qualities.
At a glance
- Category
- GH Secretagogue
- Example vial
- 5 mg
- Example diluent
- 2 mL BAC water
- Resulting concentration
- 2.50 mg/mL
Concentration
2.50 mg/mL
Draw (units)
0.00
Draw (mL)
0.000
Doses / vial
50000
- • Draw is very small — consider less diluent for better measurement accuracy.
GHRP-6 is a short-acting injectable peptide people use to trigger pulses of their own growth hormone, often when increased appetite is also a goal. Like GHRP-2, it mimics ghrelin at the GH-secretagogue receptor, but it produces a noticeably stronger hunger response. Studies confirm clear post-injection GH peaks alongside meaningful appetite stimulation. This page covers reconstitution math and per-injection logging cadence.
What GHRP-6 is
GHRP-6 (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) is the foundational molecule in the growth hormone releasing peptide class, first synthesized and studied in the 1980s. Its development established that small synthetic peptides could elicit significant growth hormone pulses via a mechanism distinct from GHRH. The defining characteristic of GHRP-6, which separates it from its successors like GHRP-2 and ipamorelin, is a powerful appetite-stimulating effect that mirrors the action of the endogenous hormone ghrelin. This orexigenic property makes it a unique subject of study, particularly in research contexts monitoring caloric intake, appetite signaling, or body weight in underweight subjects.
Compared to later-generation GHRPs, GHRP-6 demonstrates a less selective activity profile, causing more pronounced transient elevations in cortisol and prolactin. This specific asymmetry was the primary impetus for the development of more refined molecules with greater receptor selectivity. For personal tracking and data analysis, this profile suggests that a log should not only document dosing and GH-related markers but also systematically record hunger levels, sleep quality, and other physiological variables. The analyzable unit of data is therefore not the response to a single administration but the aggregate trend observed over a multi-week documentation period.
How GHRP-6 is studied
GHRP-6 functions as a synthetic agonist for the growth hormone secretagogue receptor, type 1a (GHS-R1a). This is the identical receptor targeted by the natural hormone ghrelin, which is involved in both GH regulation and hunger signaling. The molecule's binding action at this receptor in the hypothalamus and pituitary gland directly initiates the release of a growth hormone pulse from somatotroph cells. Its less-refined structure allows it to mimic ghrelin's broad physiological actions more closely than subsequent peptides, accounting for its robust effect on appetite alongside its somatotropic function. This dual activity is a hallmark of GHRP-6's documented mechanism of action, operating independently of the GHRH receptor pathway.
How people log GHRP-6
Published research examining GHRP-6 often documents administration schedules ranging from one to three times daily, a cadence planned to study its pulsatile effect on pituitary GH output. A critical variable to record in any log is the timing of each dose relative to food intake, as this can significantly influence the observable impact on appetite. For example, a protocol might standardize administration to a fasted state, such as 30-60 minutes before a meal or prior to a nighttime sleep period, to consistently observe its effects on hunger and sleep patterns. A U-100 insulin syringe is the standard instrument used to draw and administer the precise microgram-level volumes calculated from a reconstituted solution.
When constructing a long-term research plan, maintaining a consistent schedule is crucial for generating a clean dataset. The documented effects of GHRP-6 on cortisol and prolactin mean that a comprehensive log may also include fields for subjective stress levels, perceived water retention, or disturbances in sleep architecture. Documenting these secondary variables alongside primary metrics like hunger ratings allows for a more holistic observation of the molecule's physiological impact. The goal is to build a detailed record where correlational analyses can be performed over the entire study duration.
A practical scheduling note that comes up repeatedly in long-running GHRP-6 logs is the interaction between the peptide's strong appetite stimulus and the rest of the day's eating pattern. A pre-bed administration that produces a sharp hunger response within thirty to sixty minutes can derail a fasted overnight window, while a pre-meal administration may amplify caloric intake well beyond the planned baseline. Researchers who treat this as a variable rather than a nuisance typically also record the size and macronutrient composition of the meal that follows each dose, since the same hunger score after a high-protein meal and after a snack of refined carbohydrate are not equivalent data points. Building these fields into the log from the first day of a cycle avoids a common failure mode where a reader looks back at week four of an otherwise meticulous record and discovers that the single most distinctive variable for this molecule was never captured.
Reconstitution notes for GHRP-6
Reconstitution is the process of dissolving the lyophilized powder into a liquid solution for measurement. The dose volume calculation requires three inputs: the total peptide mass in the vial, the volume of diluent added, and the target dose in micrograms. As a specific numeric example, if one reconstitutes a 5 mg vial of GHRP-6 with 2 mL of bacteriostatic water, the final concentration is 2,500 mcg per mL. To administer a 100 mcg dose from this solution, one would calculate that 0.04 mL is required (100 mcg dose / 2,500 mcg/mL), which converts to 4 units on a U-100 insulin syringe.
The volume of diluent used is a key variable in protocol design, as it presents a tradeoff between measurement convenience and dosing precision. Using a lower diluent volume, such as 1 mL per vial, results in a highly concentrated solution where each unit on a syringe represents a large quantity of peptide, potentially making small dose adjustments difficult. In contrast, using a higher diluent volume, like 4 mL, yields a less concentrated solution; this requires drawing a larger volume for a given dose but allows each unit on the syringe to represent a smaller microgram amount, facilitating finer control over the administered quantity.
Storage and shelf life
To maintain peptide integrity, unreconstituted vials of GHRP-6 powder are stored under refrigeration. After the peptide is dissolved using a sterile diluent like bacteriostatic water, the resulting solution must also be kept in a cold, dark environment, typically a refrigerator. A personal log might note the date of reconstitution to ensure the solution is used within its period of maximal stability, which is generally considered to be four to six weeks.
Tracking GHRP-6 in an app
For GHRP-6, the most distinctive and valuable data point to track is the subjective intensity of hunger following each administration. This can be recorded on a simple 1-to-10 numerical scale, where a score of 1 indicates no discernible change and 10 represents a powerful, urgent feeling of hunger. Systematically logging this rating alongside the dose amount, time, and a corresponding sleep quality score provides a robust dataset. Over a 4- to 6-week period, the trends in these variables, rather than any single day's data, offer the most meaningful material for analysis of the molecule's specific effects.
Background
How peptide reconstitution works in general
The same math applies to GHRP-6 as to every other lyophilized peptide. The section below is a deeper reference on the units, the formulas, and the trade-offs behind the calculator above.
What peptide reconstitution actually is
Most research peptides ship as a freeze-dried — also called lyophilized — powder sealed inside a small glass vial. The powder itself cannot be drawn into a syringe and cannot be measured by volume. Before any of that is possible, the powder has to be rehydrated by adding a precise amount of liquid. That step is reconstitution, and it is the foundation of every other calculation that follows.
The liquid added during reconstitution is almost always bacteriostatic water, often shortened to BAC water. It is sterile water that contains a very small amount of benzyl alcohol — usually 0.9 percent. The benzyl alcohol limits microbial growth inside a multi-use vial after the rubber stopper has been pierced for the first time, which is what makes BAC water different from plain sterile water for injection.
Once the powder dissolves into the BAC water, the contents of the vial become a solution with a measurable concentration. That concentration is what links the original mass on the vial label to the volume your syringe will eventually pull. Without a known concentration, every other number on a peptide page is just a guess.
The math behind every reconstitution calculator
Every reconstitution calculator on the internet — including this one — runs the same two-line equation. The first line solves for concentration. The second line solves for the volume you need to draw to hit a specific dose. The third number, units on a U-100 insulin syringe, is just that volume rescaled.
Concentration in milligrams per millilitre equals the milligrams of peptide originally in the vial divided by the millilitres of bacteriostatic water that you added. If you put 5 mg of peptide into 2 mL of BAC water, the concentration is 2.5 mg per mL. That single number now determines how every dose will be measured for the entire life of the vial.
Volume to draw in millilitres equals your desired dose in milligrams divided by that concentration. If your dose is 0.25 mg and the concentration is 2.5 mg per mL, you draw 0.1 mL. On a U-100 insulin syringe, 1 mL is 100 units, so 0.1 mL is 10 units. The calculator shows all three numbers — concentration, volume, units — at the same time so you do not have to convert manually.
There is also a fourth output: doses per vial. That is just the total milligrams in the vial divided by the milligrams in a single dose, rounded down to a whole number because a partial final dose at the bottom of a vial is rarely usable. Tracking doses per vial is what lets a logging app warn you when a vial is running low and a refill needs to be ordered.
Why bacteriostatic water volume is a real choice, not a constant
A vial label only ever tells you how much peptide is inside. It almost never tells you how much BAC water to add — because that part is up to you. Two people can take the same 5 mg vial and reconstitute it with completely different volumes of water, ending up with completely different concentrations, and both can be entirely consistent with how peptides are typically prepared.
Adding more BAC water makes each draw a larger volume in millilitres, which translates to more units on an insulin syringe. That can be useful when typical doses are very small — drawing 4 units is much easier to read accurately on a syringe than drawing 0.4 units, especially when the syringe markings are densely spaced. People often add more diluent on purpose for low-dose peptides for exactly this reason.
Adding less BAC water concentrates the solution. The same dose now occupies a smaller volume, which means fewer units on the syringe and more total doses per vial before refilling. The tradeoff is precision: at very small unit counts, a one-unit error becomes a much larger percentage error in the actual dose delivered. Picking a sensible diluent volume is a real decision that the calculator helps you simulate quickly without committing to a vial.
How insulin syringes turn millilitres into units
Almost every peptide draw is measured on an insulin syringe rather than a tuberculin syringe, because the unit markings make small volumes much easier to read. A standard U-100 insulin syringe is calibrated so that 100 units of fluid fills exactly 1 millilitre. That single relationship — 100 units equals 1 mL — is the only conversion you ever need to memorize.
From there, the math is just multiplication. A 0.5 mL draw is 50 units. A 0.1 mL draw is 10 units. A 0.05 mL draw is 5 units. The reconstitution calculator outputs both volume and units side by side so you can pick whichever number is easier to read on the syringe in your hand.
U-40 insulin syringes also exist, mostly in veterinary contexts, and use a different calibration: 40 units equals 1 mL. Mixing up a U-40 and a U-100 syringe will lead to a dose that is off by a factor of 2.5. The calculator on this page assumes U-100, which is what nearly every peptide user is actually using.
What the calculator does not do
The calculator solves the math. It does not pick a dose for you, it does not pick a frequency, it does not adjust for body weight or sensitivity, and it does not know anything about your specific situation. Those decisions belong to you and a licensed healthcare professional who can look at your bloodwork, your history, and your goals together.
It also does not validate the peptide itself. The calculator assumes the vial actually contains the milligrams printed on the label and that the peptide is properly reconstituted into a clear, fully dissolved solution. If a vial arrives clumped, cloudy, or visibly off, no amount of math fixes that. Reconstitution math only works on a vial that is in good condition to begin with.
Finally, the calculator does not log anything. Every input you type lives only on this page until you reload. The reason Peptide Pilot exists is to stop you from running these numbers from scratch every single dose: enter a vial once, and every subsequent draw, dose, and refill reminder is calculated and logged automatically.
Common GHRP-6 mistakes to avoid
- Failing to document the potent hunger response on a consistent scale, mistaking a primary mechanistic effect for an incidental side effect.
- Interpreting the transient increases in cortisol and prolactin as an unexpected deviation, rather than a well-documented characteristic of this first-generation molecule.
- Analyzing data on a day-to-day basis instead of observing the aggregate trends in appetite and sleep quality scores over a multi-week timeline.
- Neglecting to record the administration time relative to meals, which is a crucial variable for contextualizing the peptide's orexigenic impact.
- Structuring a personal tracking log based on a template for a highly selective peptide like ipamorelin, thus omitting fields for hunger and other variables unique to GHRP-6.
Frequently asked questions about GHRP-6
How does tracking for GHRP-6 differ from tracking for ipamorelin or GHRP-2?
What do historical research studies indicate about cortisol and prolactin with GHRP-6?
If a 5 mg vial is prepared with 2 mL of diluent, how many units is a 100 mcg dose?
Why is it important to document the timing of administration relative to food intake?
What is the significance of His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 being the 'original' GHRP?
Is it more useful to log data daily or to study patterns across weeks with GHRP-6?
Related on Peptide Pilot
- Open
Peptide Pilot home
Overview of the calculators, references, guides, and iPhone app.
- Open
GHRP-6 reconstitution calculator
Pre-filled calculator on its own page.
- Open
How to reconstitute peptides
Step-by-step plain-English walkthrough.
- Open
Syringe types explained
Why U-100 is the default, and what to avoid.
- Open
CJC-1295
Same category: GH Secretagogue.
- Open
Ipamorelin
Same category: GH Secretagogue.
- Open
Tesamorelin
Same category: GH Secretagogue.
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