Equine Sports Council

Controlled Medications Library

ESC MEDICATION CLASSIFICATIONClass A - Therapeutic

ESC Medication Library · Revision 3

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Medication Facts

Performance enhancing
No
Total hours to clear
Not recorded
Frequently used
Most Prescribed
ESC ID
ISOXSU-0481
Trade names
Isoxsuprene
Drug type
Vasodialator
Plasma half-life · hours
3
Equine dosing
1.2 to1.8 mg per kg of body weight for treatment of Navicular hoof disease
Cmax · peak plasma concentration
Not recorded
Tmax · time to peak plasma concentration
Not recorded
ESC concentration guidance
CMAX 100% of Efficacy
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

Promotes Blood Flow to Hooves & Uterous

Drug interactions

Human drug not approved for use in equines, However widely prescribed in horses by vets to treat navicular. Isoxsuprene when given orally has poor absorption through the GI tract of horses and is not recommended. Drug interactions with oral isoxsuprine are generally considered unlikely due to the drug's extremely low absorption in the equine digestive tract. However, isoxsuprine acts as a vasodilator, and veterinarians must be notified if it is being used alongside sedatives, anesthetics, narcotics, or other blood pressure-altering medications to avoid adverse cardiovascular events.Because of its specific pharmacological properties, isoxsuprine carries notable interactions and administration considerations:Anesthetics and Tranquilizers: Combining isoxsuprine with systemic anesthetics or tranquilizers can lead to severe or unintended hypotension (low blood pressure) and tachycardia (increased heart rate). Always clear concurrent use with a veterinarian.Vasodilators and Beta-Blockers: Concomitant use with other vasodilators or certain cardiovascular drugs may potentiate blood pressure drops.Bleeding and Foaling: Isoxsuprine should not be administered to horses that are actively bleeding or to mares immediately following foaling

Contraindications

Government Numbers

FDA regulatory reference for isoxsuprine hydrochloride: FDA reports that the listed manufacturers and labelers agreed by October 13, 2021 to cease distribution of unapproved isoxsuprine HCl drugs following its efficacy review. Historical NDC listings are not evidence of current FDA approval. No current approved product formulation has been verified for this draft. This human-drug notice does not supply equine dosing or resolve veterinary compounding requirements. Reviewed September 18, 2026. https://www.fda.gov/drugs/fda-notification-regarding-isoxsuprine-hydrochloride-drug-products

Sanctioning-body comparison

Plasma only. Compare published competition guidance for this medication. ESC guidance remains in Medication Facts 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
OrganizationPublished dose & routePlasma concentrationWithdrawal / timingControl / 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

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

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.

Reviewed 2026-09-23

Not verified for this medication.Not verified for this medication.Not verified for this medication.Medication-specific control not yet verified.
USEFNational Therapeutic Substance Provisions · 2026 + July amendment
Conditions & sources

An unverified entry is not permission to use this medication. Consult the linked current rules.

Reviewed 2026-09-23

Not verified for this medication.Not verified for this medication.Not verified for this medication.Medication-specific control not yet verified.