GRF(1-29) Sermorelin

GRF(1-29), available under the trade name Sermorelin (Geref, Gerel) is a peptide that stimulates growth hormone secretion and belongs to the GHRH group. It has a short half-life in the body, about a few minutes, which is not enough to maximize growth hormone concentration.

An additional 4 amino acids were included in the GRF(1-29) sequence to increase stability and half-life. This structural modification increased the duration of action up to 30 minutes, which is enough to achieve a prolonged effect and stimulation of peak secretion of growth hormone. This form is also often called tetrasubstituted GRF(1-29) or modified and is very often confused with CJC-1295. To make an analogy with anabolic steroids, tetrasubstituted GRF(1-29) is a testosterone propionate analog and CJC-1295 is testosterone enanthate.



GRF (1-29) or Sermorelin (Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH2) is biologically active, consisting of 44 amino acids GHRH = elimination half-life less than 5-10 minutes.

Mod GRF (1-29) or tetrasubstituted has a substituted 2nd, 8th, 15th, and 27th amino acid in the GRF (1-29) sequence: (Tyr-DAla-Asp-Ala-Ile-Phe-Thr-Gln-Ser-Tyr-Arg-Lys-Val-Leu-Ala-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Leu-Ser-Arg-NH2) = 30 minute half-life.

When purchasing a peptide, be sure to clarify whether this form is tetrasubstituted (modified) or not.

Often tetrosubstituted GRF(1-29) is also called CJC-1295 without DAC (Drug Affinity Complex – a special complex that increases the duration of action up to several days due to binding to plasma proteins)

In order to create a more convenient long-acting form of GHRH, a substance with the codename CJC-1295 was created. This peptide is similar in structure to the tetrasubstituted GRF(1-29) in question, except that the amino acid lysine was added to the sequence, which is bound to a molecule called the “Drug Affinity Complex (DAC). This complex allows the peptides to bind to blood albumin and increases the half-life to 1-2 weeks. By analogy with testosterone, this form can be compared to testosterone cypionate.


Modified GRF (1-29) is used most often in a dose of 100-200 mcg, intramuscularly, injected 1-3 times a day intramuscularly or subcutaneously.

Combination with GHRP (e.g., GHRP-6 or GHRP-2) is highly recommended for maximum synergistic effect:

  • GRF (1-29) 100-200 mcg
  • GHRP-6 or GHRP-2 100 µg
  • The peptides are dissolved in 1-2 ml of water for injection (1 syringe can be used) and injected 1-3 times a day intramuscularly.
  • The best time for injections: 15 minutes before meals, after training, before going to bed.
    Course duration is 6-12 weeks.

Storage and preparation

According to J. Bombela’s recommendations the vial should be cooled to room temperature, then the desired volume of water for injections should be added (which should flow down the wall of the vial) and stirred by rotating movements (do not shake). The solution obtained with the water for injection remains stable for only 8-10 days in the refrigerator. If bacteriostatic water is used, the storage time is increased to 30 days in the refrigerator. Mod GRF 1-29 is best dissolved only with bacteriostatic water. The resulting solution should not be frozen.

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