CJC-1295 raised GH up to 10-fold and IGF-1 up to 3-fold for nearly two weeks after a single dose
Background
Growth hormone deficiency and age-related GH decline are therapeutic targets, but native GHRH has an extremely short half-life that limits its clinical utility. Repeated pulsatile administration is impractical, creating demand for long-acting analogs that can sustain GH axis stimulation. IGF-1, the primary downstream mediator of GH action, is used as a surrogate biomarker for axis activity. CJC-1295 was engineered as a GHRH analog with drug-affinity technology designed to extend plasma half-life dramatically over the native peptide, potentially enabling once-weekly or biweekly dosing instead of multiple daily injections.
Study Design
Two randomized, placebo-controlled, double-blind trials enrolled healthy adults aged 21–61 years across two investigational sites. The first trial used a single ascending-dose design; the second dosed CJC-1295 weekly or biweekly over 28 and 49 days respectively. CJC-1295 was administered subcutaneously at four ascending dose levels. Primary endpoints were peak plasma GH and IGF-1 concentrations plus area under the curve; standard pharmacokinetic parameters including half-life were also measured. A placebo arm ran in parallel for both trials.
Results
After a single subcutaneous injection, mean plasma GH concentrations rose 2- to 10-fold above baseline and remained elevated for 6 days or more. Mean plasma IGF-1 concentrations increased 1.5- to 3-fold and stayed elevated for 9–11 days post-injection. The estimated plasma half-life of CJC-1295 was 5.8–8.1 days, consistent with its prolonged pharmacodynamic effect.
After multiple doses, mean IGF-1 levels remained above baseline for up to 28 days, with evidence of a cumulative effect across repeated administrations.
No serious adverse reactions were reported across either trial. Tolerability was described as particularly favorable at doses of 30 or 60 µg/kg, suggesting a therapeutic window within that range.
Key Findings
- Single injection raised mean GH by 2- to 10-fold for 6+ days in a dose-dependent manner
- Mean IGF-1 increased 1.5- to 3-fold and stayed elevated for 9–11 days after one dose
- CJC-1295 plasma half-life estimated at 5.8–8.1 days, enabling weekly/biweekly dosing
- Repeated dosing kept mean IGF-1 above baseline for up to 28 days with cumulative effect
- Best tolerability observed at 30 or 60 µg/kg sc; no serious adverse reactions reported
Why It Matters
Weekly or biweekly dosing replacing daily GHRH injections is a substantial practical advance for any GH-optimization protocol. Clinicians and researchers investigating GH axis restoration — whether for GH deficiency, body composition, or aging — now have a pharmacokinetic framework confirming that a single low-dose injection can sustain IGF-1 elevation for over a week. The cumulative IGF-1 response with repeated dosing means stacking injections could progressively elevate the axis without requiring daily administration. Protocol designers should note that 30–60 µg/kg sc represented the best-tolerated range, providing a concrete starting corridor for clinical translation. Phase 2/3 efficacy data in disease populations are still absent, so safety and dosing in patient cohorts remain to be defined.
TitrateLab articles covering CJC-1295
Written by TitrateLab, separately from the study summarized above.
