Equine Sports Council

Controlled Medications Library

ESC MEDICATION CLASSIFICATIONClass A - Therapeutic

ESC Medication Library · Revision 3

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Bute,
Phenylbutazone

Med ReportRecommended

Medication Facts

Performance enhancing
No
Total hours to clear
72
Frequently used
Most Prescribed
ESC ID
BUTEPH-0157
Trade names
Bute
Drug type
NSAID
Plasma half-life · hours
10
Equine dosing
2.2-4.4 mg/kg PO/IV, half dose may be given and 6HR WD observed **Severe Contraindications - see interactions**
Cmax · peak plasma concentration
20 to 25 μg/mL (IV); ~10 μg/mL (Oral single dose).
Tmax · time to peak plasma concentration
18
ESC concentration guidance
5.0 to 15.0 μg/mLfor single use and after 12 HR WD, 2-5 mcirograms/mL 6 HR WD from 1/2 dose. When switching between Severe Contraindication NSAIDS (Equioxx, Banamine, Bute, Ketofen) 48 hour WD required which yields 0.06 μg/mL (60 ng/mL) plasma concentration.
Primary withdrawal · hours
12
Washout withdrawal · hours
48
ESC control type
A1 - Generally Controlled - Therapeutic
Medication report required
Generally not required, however understand exceptions.

Uses & side effects

The gold standard for bone, joint, and muscle pain (like arthritis, navicular disease, or laminitis).

Drug interactions

SEVERLY CONTRAINDICATED - Combing more than one NSAID concurrently (e.g., combining phenylbutazone, flunixin meglumine, or firocoxib) drastically increases risks of toxicity without increasing pain relief.Corticosteroids (e.g., Dexamethasone): Combining NSAIDs with steroids increases the likelihood of gastric ulcers and severe GI toxicity.Nephrotoxic Agents: Avoid combining NSAIDs with aminoglycoside antibiotics (e.g., gentamicin) or diuretics, as this significantly increases the risk of acute renal failure.Blood Thinners: Concomitant use with anticoagulants (e.g., heparin) increases the risk of bleeding complications.Dehydration/Pre-existing Disease: NSAIDs are more toxic when horses are dehydrated, septic, or have pre-existing kidney or hepatic disease

Contraindications

Bute, Banamine, Equioxx, Ketofen

Government Numbers

Phenylbute (phenylbutazone) oral powder, 1 g per 10 g powder: ANADA 200-334. NDC 57319-509-62 (500 g jar) and 57319-509-61 (1 kg jar). Labeler: Clipper Distributing Company LLC. Identifiers apply to this powder formulation. Reviewed September 18, 2026. Full label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1924222f-a5b7-4fc9-9d6d-e9277c1fb01b

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

One permitted NSAID at a time. Flunixin emergency exception requires veterinary examination, reporting and 24 h out of competition. Guidelines do not guarantee a compliant result.

VIO404–406; VIO405.1

Reviewed 2026-09-23

 2 mg/lb per 24 h (2 g/1,000 lb); oral or IV. Oral divided regimen: 1 g/1,000 lb every 12 h. Up to 5 days.15.0 µg/mL12 h for a full daily dose or any IV dose. The specified half-dose oral regimen has a separate allowance; see source.Quantitatively restricted therapeutic NSAID.
APHA Paint Show HorsesShow rules · 2026 Rule Book
Conditions & sources

APHA’s published dosing guidance is not a numerical plasma allowance. Government restrictions and all SC-085 conditions still apply.

SC-085.A.1

Reviewed 2026-09-23

 2 mg/lb per 24 h (2 g/1,000 lb); oral or IV. Oral divided regimen: 1 g/1,000 lb every 12 h. Up to 5 days.No numeric plasma limit stated in SC-085.A.Specified half-dose oral regimen every 12 h may occur within 12 h of competition. No separate IV stop time stated in SC-085.A.1.Listed permitted therapeutic substance.
ARCI Model RulesRacing model · Rules 15 / UCG 20.0 / CTMS 4.2.1
Conditions & sources

Single-NSAID limit; stacking is a separate violation. The source marks this category with an asterisk; consult its NSAID penalty provisions and offense history. ARCI model comparison only; no state-specific rule is substituted. Schedule timing is tied to its stated regimen and is not a clearance guarantee.

CTMS 4.2.1; UCG 20.0 PDF p. 46

Reviewed 2026-09-23

 4 mg/kg IV once0.3 µg/mL48 h restricted administration timeDrug Class 4 · Penalty Class C*. Controlled therapeutic schedule; classification shown below.
USEFNational Therapeutic Substance Provisions · 2026 + July amendment
Conditions & sources

Therapeutic Substance Provisions only. One permitted NSAID at a time; additional permitted NSAIDs need the source’s 3-day interval. Emergency exceptions and other restrictions apply. Guidelines do not guarantee clearance.

GR410.4; NSAID guidelines

Reviewed 2026-09-23

 2 mg/lb per 24 h (2 g/1,000 lb); oral or IV. Oral divided regimen: 1 g/1,000 lb every 12 h. Up to 5 days.15.0 µg/mL12 h for a full daily dose or any IV dose. The specified half-dose oral regimen has a separate allowance; see source.Restricted therapeutic NSAID under GR410.