ESC Medication Library · Revision 3

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Regumate,
Altrenogest

Med ReportRecommended

Medication Research Data

Performance enhancing: No
Total hours to clear: 48
Frequently used: Most Prescribed
ESC ID: REGUMA-0787
Trade names: Regumate
Drug type: Progestin
Plasma half-life · hours: 10 hrs
Equine dosing: 0.044 mg/kg PO daily, may not exceed single dose amounts. **permitted use in mares, geldings, studs**Caution administering oral medications as their time of actual ingestion could affect withdraw times, and reingestion is possible through stall contaminants. Clean bedding should be used at all times.
Cmax · peak plasma concentration: 50 ng/mL
Tmax · time to peak plasma concentration: 72
ESC concentration guidance: CMAX 50 ng/mL
Equivalent units
0.05 µg/mL = 50 ng/mL = 50,000 pg/mL
Same concentrations; the conditions stated above still apply. µg means micrograms.
Primary withdrawal · hours: 0
Washout withdrawal · hours: 0
ESC control type: A1 - Generally Controlled - Therapeutic
Medication report required: Generally not required, however understand exceptions.

Uses & side effects

Synthetic hormone supresses mare heat cycles

Drug interactions

Contraindications

Products & routes

Regu-Mate

Oral oil solution · 2.2 mg altrenogest/mL (0.22%)

Oral

Product label / source

Alternate Medications

No suitable alternative with a verified risk advantage is listed for this medication. Ask your veterinarian about treatment options for the diagnosed condition.

Discuss all medications with your veterinarian.

Dosing & Pharmacokinetic

Dosing and pharmacokinetic data are sourced from publicly available resources, and accuracy is not guaranteed. The dosing samples provided are for illustrative purposes only and should not be used for actual administration; they assume a single medication is delivered at the correct individual dose. Loading doses, or combinations with other substances to increase efficacy or mask concentration levels, are strictly prohibited. Veterinarians must prescribe all medications and determine appropriate withdrawal times based on the horse's health, administration route, drug strength, and timing. The health of the horse must always take priority over performance.

Medication combinations

Combining certain substances or use of can trigger dangerous interactions or contraindications, posing severe health risks or creating unintended performance-enhancing effects. If a medical treatment causes these interactions or alters performance, the horse must be withdrawn from competition until its system clears, or face an adverse drug test.

Government Numbers

Regu-Mate altrenogest oral solution, 2.2 mg/mL (0.22%): NADA 131-310; NDC 57926-100-70 (1,000 mL). Labeler: Merck Sharp & Dohme Corp. Identifiers apply to this oral formulation. Reviewed September 18, 2026. Full label, including user handling warnings: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=d9d14df1-ec72-46f1-ad3b-f90547088ff5

Sanctioning-body comparison

Plasma only. Compare published competition guidance for this medication. ESC guidance remains in Medication Research Data above. A dosing guideline, withdrawal recommendation and laboratory detection threshold are different measures.

Sources reviewed September 23, 2026. “Not verified” means a gap in this comparison, not zero tolerance or permission. Doses describe the cited rules; your veterinarian must determine treatment and withdrawal.

Published guidance by organization
Organization	Published dose & route	Plasma concentration	Withdrawal / timing	Control / penalty class
AQHA Show HorsesShow rules · 2026 handbook Conditions & sources An unverified entry is not permission to use this medication. Consult the linked current rules. Reviewed 2026-09-23 2026 AQHA Handbook · VIO400–406 Current AQHA rulebook	Not verified for this medication.	Not verified for this medication.	Not verified for this medication.	Medication-specific control not yet verified.
APHA Paint Show HorsesShow rules · 2026 Rule Book Conditions & sources An unverified entry is not permission to use this medication. Consult the linked current rules. Reviewed 2026-09-23 2026 APHA Rule Book · SC-085, pp. 75–80 Current APHA rulebook	Not verified for this medication.	Not verified for this medication.	Not verified for this medication.	Medication-specific control not yet verified.
ARCI Model RulesRacing model · Rules 15 / UCG 20.0 / CTMS 4.2.1 Conditions & sources An unverified entry is not permission to use this medication. Consult the linked current rules. Classification for geldings, colts, adult intact males, spayed females only. ARCI model comparison only; no state-specific rule is substituted. Schedule timing is tied to its stated regimen and is not a clearance guarantee. UCG 20.0 PDF p. 12 Reviewed 2026-09-23 ARCI UCG 20.0 · April 2026 ARCI CTMS 4.2.1 · December 2020 ARCI Model Rules 15 · August 2026	Not verified for this medication.	Not verified for this medication.	Not verified for this medication.	Drug Class 4 · Penalty Class C. No dosing permission is implied by classification.
USEFNational Therapeutic Substance Provisions · 2026 + July amendment Conditions & sources GR410.2; altrenogest guidance Reviewed 2026-09-23 2026 USEF Drugs & Medications Guidelines · August 10 update USEF July 27, 2026 update	No competition dose specified in the cited rule.	No numeric plasma threshold stated.	No withdrawal specified for the permitted mare use.	Permitted in mares; prohibited in stallions and geldings.