Sermorelin (GHRH 1-29) Half-Life & Pharmacokinetics

Sermorelin (GHRH 1-29) Half-Life & Pharmacokinetics — Research Guide (2026)

Research-use only. This guide summarises published pharmacokinetic (PK) data on sermorelin (GHRH 1-29) for laboratory reference. Nothing here is medical advice or a recommendation for human use.

Sermorelin (GHRH 1-29) is classified as a truncated 29-residue GHRH analog (GRF 1-29). Its pharmacokinetic profile — serum half-life, time to peak (Tmax), route behaviour, clearance pathway and bioavailability — shapes how researchers schedule sampling and design experiments.

At-a-Glance Pharmacokinetics

| Parameter | Sermorelin | | --- | --- | | Classification | Truncated 29-residue GHRH analog (GRF 1-29) | | Serum half-life | Approximately 10-20 minutes in published PK data; the measured GH pulse outlasts the parent peptide. | | Tmax | Approximately 5-10 minutes after subcutaneous administration in published models; peak measured GH response at approximately 20-30 minutes. | | Routes studied | Subcutaneous administration predominates in the published record. | | Bioavailability | Moderate subcutaneous bioavailability (approximately 60%) in published PK studies; very low oral bioavailability. | | Clearance | Rapid enzymatic clearance via DPP-IV and other endopeptidases; no active metabolites of pharmacological consequence. |

Serum Half-Life

Approximately 10-20 minutes in published PK data. The measured GH pulse it stimulates outlasts the parent peptide in circulation. Steady-state exposure in repeat-administration models is reached at roughly four to five half-lives, which is what determines how quickly plasma exposure stabilises in a given design.

Time to Peak (Tmax)

Approximately 5-10 minutes after subcutaneous administration, with the peak measured GH response at approximately 20-30 minutes. Tmax governs acute pharmacodynamic readouts and dictates blood-sampling timing for stimulated GH in GH-axis experiments.

Routes and Bioavailability

Subcutaneous administration predominates in the published record. Subcutaneous bioavailability is moderate (approximately 60%) in published PK studies; oral bioavailability is very low.

Clearance and Metabolism

Rapid enzymatic clearance via DPP-IV and other endopeptidases, with no active metabolites of pharmacological consequence. Cleavage at the position 1-2 bond yields a fragment with markedly reduced receptor affinity.

Key Pharmacokinetic Takeaways

• Among the shortest-acting GH-axis peptides in the published record
• The short exposure window is what preserves discrete pulse structure in measured GH output
• Rapid clearance limits sustained receptor stimulation compared with longer-acting structures such as CJC-1295 with DAC
• Repeated-exposure desensitisation is minimal in published models where pulsatility is preserved

Frequently Asked Questions

What is the reported half-life of sermorelin? Approximately 10-20 minutes in published PK data; the measured GH pulse outlasts the parent peptide.

How quickly does sermorelin reach peak concentration? Tmax of approximately 5-10 minutes after subcutaneous administration, with peak measured GH response at approximately 20-30 minutes.

Which routes appear in published research? Subcutaneous administration predominates in the published literature.

Does sermorelin accumulate across repeated exposures? Clearance is rapid via DPP-IV and other endopeptidases with no active metabolites of consequence; steady state is typically reached at four to five half-lives in published multi-exposure studies.

Is oral bioavailability meaningful for sermorelin? No — oral bioavailability is very low, while subcutaneous bioavailability is moderate at approximately 60%.

Related Research

• Receptor mechanism — see the Sermorelin mechanism guide for the receptor-level basis of the responses driven by this PK profile.
• Compound reference — see the Sermorelin research overview for structure, comparisons and limitations of the literature.
• Research material — laboratory-grade GHRH(1-29) research vials with batch documentation on file.

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*Sources cited inline are drawn from published preclinical and clinical pharmacokinetic literature. This article is for laboratory research and educational use only and does not constitute medical advice.*

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