Reference table
Compound Half-Life & Pharmacokinetics Reference
Elimination half-life, time to peak (tMax), steady-state timing, and typical dosing for 25+ peptides, GLP-1 medications, testosterone esters, HRT compounds, and ancillaries.
Half-life values are sourced from published pharmacokinetic studies and FDA prescribing information. Individual drug clearance varies based on injection site, metabolism, body composition, and carrier oil. These are reference estimates, not clinical recommendations.
GLP-1
| Compound | Half-life | Time to peak | Typical dose | Frequency | Steady state | Route |
|---|---|---|---|---|---|---|
| Semaglutide Ozempic, Wegovy | ~7 days (168 hrs) | 1-3 days | 0.25-2.4 mg | Weekly | 4-5 weeks | Subcutaneous |
| Tirzepatide Mounjaro, Zepbound | ~5 days (120 hrs) | 8-72 hrs | 2.5-15 mg | Weekly | 4 weeks | Subcutaneous |
| Retatrutide | ~6 days (144 hrs) | 24-36 hrs | 1-12 mg | Weekly | 4-5 weeks | Subcutaneous |
| Liraglutide Saxenda, Victoza | ~13 hrs | 8-12 hrs | 0.6-3.0 mg | Daily | 3-5 days | Subcutaneous |
Testosterone / TRT
| Compound | Half-life | Time to peak | Typical dose | Frequency | Steady state | Route |
|---|---|---|---|---|---|---|
| Testosterone Cypionate Depo-Testosterone | ~6.9 days (166 hrs) | ~4 days (IM) | 100-200 mg/wk | 1-7x weekly | ~5 weeks | IM or SubQ |
| Testosterone Enanthate Delatestryl | ~6.9 days (166 hrs) | ~4 days (IM) | 100-200 mg/wk | 1-7x weekly | ~5 weeks | IM or SubQ |
| Testosterone Propionate | ~20 hrs | 2-4 hrs (IM) | 25-50 mg | EOD or daily | 4-5 days | IM or SubQ |
| Testosterone Undecanoate Nebido, Aveed | ~34 days (castor oil) | 7-14 days | 750-1000 mg | Every 10-14 weeks | ~6 months | IM |
Peptide
| Compound | Half-life | Time to peak | Typical dose | Frequency | Steady state | Route |
|---|---|---|---|---|---|---|
| BPC-157 | ~24 min (est.) | ~30 min | 250-500 mcg | 1-2x daily | N/A (effect outlasts plasma) | Subcutaneous |
| TB-500 Thymosin Beta-4 | ~2 hrs | ~15 min | 2-5 mg | 2x weekly | N/A (cleared between doses) | Subcutaneous |
| CJC-1295 (with DAC) | ~6-8 days | 1-4 hrs | 1-2 mg | Weekly | 4-5 weeks | Subcutaneous |
| CJC-1295 (no DAC) / Mod GRF | ~30 min | ~5-15 min | 100-300 mcg | 1-3x daily | Same day | Subcutaneous |
| Ipamorelin | ~2 hrs | ~15-30 min | 100-300 mcg | 1-3x daily | Same day | Subcutaneous |
| Sermorelin | ~10-20 min | ~5-10 min | 200-500 mcg | Daily (before bed) | Same day | Subcutaneous |
| GHK-Cu | ~30-60 min | ~15 min | 1-3 mg | Daily | Same day | Subcutaneous / Topical |
| PT-141 Bremelanotide (Vyleesi) | ~2.7 hrs | ~1 hr | 1-2 mg | As needed | N/A | Subcutaneous |
| MOTS-c | ~2 hrs (est.) | ~30 min | 5-10 mg | 3-5x weekly | N/A (cleared between doses) | Subcutaneous |
| MK-677 (Ibutamoren) | ~24 hrs (est.) | ~4 hrs | 10-25 mg | Daily (oral) | 4-5 days | Oral |
Growth Hormone
| Compound | Half-life | Time to peak | Typical dose | Frequency | Steady state | Route |
|---|---|---|---|---|---|---|
| HGH (Somatropin) Genotropin, Norditropin | ~3-5 hrs | 1-3 hrs | 1-4 IU | Daily | 1-2 days | Subcutaneous |
HRT
| Compound | Half-life | Time to peak | Typical dose | Frequency | Steady state | Route |
|---|---|---|---|---|---|---|
| Estradiol Cypionate Depo-Estradiol | ~8-10 days | 3-6 days | 1-5 mg | Every 1-2 weeks | 5-6 weeks | IM |
| Estradiol Valerate Delestrogen | ~3-5 days | ~3 days | 2-20 mg | Every 1-2 weeks | 3-4 weeks | IM |
| Progesterone (Oral) Prometrium | ~5-10 hrs | 1-4 hrs | 100-200 mg | Daily | 2-3 days | Oral |
PCT / Ancillary
| Compound | Half-life | Time to peak | Typical dose | Frequency | Steady state | Route |
|---|---|---|---|---|---|---|
| HCG Pregnyl, Novarel | ~29-36 hrs | 6-12 hrs | 250-1000 IU | 2-3x weekly | 1-2 weeks | Subcutaneous / IM |
| Anastrozole Arimidex | ~50 hrs | ~2 hrs | 0.25-1 mg | 2-3x weekly | 7-10 days | Oral |
| Enclomiphene | ~10 hrs | ~2-6 hrs | 12.5-25 mg | Daily | 2-3 days | Oral |
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Questions
Understanding half-life data
What is a drug's half-life (elimination half-life)?
Half-life, also called elimination half-life, is the time it takes for the concentration of a compound in your blood to decrease by 50%. A drug with an 8-day half-life still has 50% remaining after 8 days, 25% after 16 days, and so on. It takes roughly 5 half-lives for a compound to fully clear your system.
Why does half-life matter for injection scheduling?
Compounds with shorter half-lives, like BPC-157 at well under an hour, need more frequent dosing to maintain therapeutic levels. Compounds with longer half-lives, like semaglutide at 7 days, can be dosed weekly. Matching your injection frequency to the half-life helps maintain stable blood levels.
What does steady state mean?
Steady state is when the amount of drug entering your system equals the amount being cleared. At steady state, your blood levels fluctuate within a predictable range rather than building up over time. It takes approximately 5 half-lives of consistent dosing to reach steady state.
How do I visualize blood levels for these compounds?
Regimen's Half-Life Visualizer lets you select a compound, enter your dose, and see estimated blood concentration curves over time. The app also shows cumulative levels for repeated dosing so you can visualize steady state.
Why is testosterone cypionate's half-life listed differently in different places?
You'll see three numbers. An 8-day figure that circulates in TRT communities is folklore, not from a cited study. A roughly 4-day figure comes from a study of testosterone-naive men who still had natural production, which pulls the apparent half-life down. We use about 6.9 days, because the same study puts it there once natural production is suppressed, which is the situation during ongoing TRT (PMC5915615). Your personal clearance may be faster or slower.
This data is for informational purposes only, so always double-check any figure with a healthcare provider. Values are reference estimates, not clinical recommendations. We assume no liability for dosing errors.