Mibolerone (Cheque Drops)
A veterinary androgen developed to suppress estrus in bitches. It was never approved for human use. Microgram dosing, marked hepatotoxicity, and tumour risk described in dogs.
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WHAT IS MIBOLERONE (CHEQUE DROPS)?
Detailed overview
Mibolerone (7-alpha,17-alpha-dimethyl-19-nortestosterone) is an extremely potent synthetic androgen developed by Upjohn and approved as a VETERINARY product for suppressing estrus in bitches. Its entire published literature concerns that use: Sokolowski's 1977 and 1978 beagle studies assessed reproductive effects, Seaman's 1985 paper described ovarian fibroma after prolonged exposure, and Williams' 2000 report identified urinary metabolites in greyhounds for doping-control purposes. No human therapeutic study has been conducted with it. In bodybuilding circles it spread as "Cheque Drops", an aggression enhancer taken before competition or a heavy lift, in microgram doses. That dose scale is a distinct risk: an error in dilution or measurement here does not mean a few percent deviation but an order-of-magnitude overdose. Add to this the substantial hepatic load from the 17-alpha-methyl group and the progesterone receptor activity conferred by the 19-nor skeleton. The tumour risk described in dogs cannot be transferred directly to humans, but it cannot be dismissed either.
Original purpose
A veterinary product for suppressing estrus in bitches.
Human trials
None. Never approved for human therapeutic use.
Dose scale
Micrograms, so a measurement or dilution error causes an order-of-magnitude overdose.
Main risks
Marked hepatotoxicity, complete HPTA suppression, tumour risk described in dogs.
Legal status
No human drug approval. WADA-banned year-round (S1).
Data console
Lab data
Safety
Side effects, stop signs, contraindications
Side effects · 5
- Severe liver injury: markedly hepatotoxic due to the 17-alpha-methyl group; prolonged dosing produced hepatic changes in dogs.
- Marked aggression and irritability: this is precisely why it is used in some circles, but the effect is uncontrollable and its risk cannot be estimated.
- Tumour risk: ovarian fibroma was described in a long-term canine study after prolonged mibolerone exposure (Seaman 1985).
- HPTA suppression: endogenous testosterone production shuts down, recovery can take weeks to months and may require post-cycle therapy.
- Lipid deterioration: falling HDL cholesterol is a class effect of androgens and implies cardiovascular risk with prolonged use.
Contraindications · 4
- Existing liver disease or elevated baseline ALT/AST: absolute contraindication.
- Dyslipidemia or existing cardiovascular disease: androgens worsen the lipid profile.
- Pregnancy and breastfeeding: androgenic action causes fetal virilization, use is prohibited.
- Competitive sport under testing: WADA bans anabolic agents year-round (S1).
Related Performance Compounds
Same therapeutic category
Studies
Related research and clinical findings
Biological evaluation of mibolerone in the female Beagle.
Sokolowski JH, Geng S
Effects of mibolerone on conception, pregnancy, parturition, and offspring in the Beagle.
Sokolowski JH, Kasson CW
Canine ovarian fibroma associated with prolonged exposure to mibolerone.
Seaman WJ
Characterization of urinary metabolites of testosterone, methyltestosterone, mibolerone and boldebone in greyhound dogs.
Williams TM, Kind AJ, Hyde WG
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The information here is for educational and scientific purposes only. Performance-enhancing compounds (AAS, prohormones, stimulants, doping agents) are illegal without prescription in Hungary and most of the EU, and carry serious health and legal risks. WADA bans them in competitive sport. This is NOT a usage guide, and we do not encourage any illegal use. If you do use them, medical supervision and regular bloodwork are ESSENTIAL. Severe endocrine, cardiovascular, hepatic and psychiatric side effects are possible.