Anabolic steroidAndrogen19-nortestosterone17-alpha-alkylatedProgestinVeterinary oral

Mibolerone (Cheque Drops)

Also known as Cheque Drops · Dimethylnandrolone · U-10997

Written by enwyReviewed 15 Jul 20261 sources0 comments

Mibolerone (Cheque Drops) is an extremely potent orally active 19-nortestosterone androgen originally marketed as an oral liquid to prevent estrus in female dogs. Diverted to bodybuilding, it is used in tiny microgram doses as a short-acting pre-competition aggression booster, with a harsh side-effect profile and no human approval.

01 Overview

Mibolerone is a 7,17-dimethylated nandrolone derivative of exceptional potency. Its veterinary product, Cheque Drops, was an oral solution given to bitches to suppress estrus. Its oral activity comes from 17-alpha-methylation, making it hepatotoxic like other 17-alkylated orals.

In strength sports it developed a niche as a very short-acting aggression enhancer taken shortly before competition, at doses measured in micrograms. It offers little practical anabolism relative to its toxicity: severe hepatic strain, rapid HPTA suppression and virilisation. This entry covers the veterinary product and its diversion.

02 Mechanism

Highly potent 17-alpha-methylated 19-nortestosterone androgen-receptor agonist with progestogenic activity; used veterinarily to suppress the estrous cycle via gonadotrophin inhibition.

03 Dosing

Tier	Dose	Route	Notes
Pre-competition (anecdotal)	100–300 mcg/day	Oral	Micrograms; illicit human use, extremely potent

Ester comparison

Ester	Half-life	Injection freq.	Testosterone by mass

04 Effects

Effect	Magnitude	Evidence
Aggression / drive increaseUsed pre-competition for a short-lived surge in aggression and drive.		Anecdotal
Estrus suppression (veterinary)Approved veterinary effect: prevention of estrus in female dogs.		Clinical

05 Side effects

Effect	Severity	Frequency	Evidence	Countermeasures
Virilisation / mood disturbanceMarked aggression, irritability and, in women, rapid virilisation given its high potency.	Moderate	Common	Anecdotal
Hepatotoxicity17-alpha-methylation causes significant liver strain despite tiny doses.	Severe	Typical of 17-alkylated orals	Observational

06 Legal status

Not authorised for human use · as of Jan 2026

United States

Schedule III anabolic steroid

Veterinary product discontinued; human use is controlled diversion · as of Jan 2026

07 References

Mibolerone for estrus prevention in dogsVeterinary pharmacology literature

08 Discussion0 comments

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This page is reference information, not medical advice. Doses and protocols are documented as they appear in the clinical literature and in practice — describing them is not a recommendation to use them. Countermeasures listed here are not a substitute for a physician. Legal status varies by jurisdiction and changes.