Equiproxen (naproxen) is an NSAID, also sold as Equiproxen, Naprosyn. Below: how 10 show and racing governing bodies list it, every published detection time for the dose and route studied, and the document and page each value comes from.USEF: Restricted: dose and time limitsFEI: Controlled MedicationHISA: Controlled medicationnamed in the rules of 3 state racing commissions
None of the detection-time lists we carry (FEI, HIWU, IFHA/EHSLC, Equestrian Canada, USEF) publishes a detection time for Equiproxen. ShowSafe Pro answers "Unknown" for it, never "Clear", and quotes what each rulebook says about unlisted substances.
Transcribed from the governing bodies' own documents. Each entry links to the document and quotes the row it came from.
“Naproxen Naprosyn® 4.0 mg/Lb (4.0 grams/1000Lb) >12 hours Oral NSAID” — source p. 10
“CONTROLLED Naproxen Non-steroidal anti-inflammatory” — source p. 26
From 2027-01-01: 2027 Equine Prohibited Substances List p. 27 lists it as Controlled Medication.
“Naproxen” — source p. 11
“VIO405.6 Naproxen (an NSAID) - The maximum permitted plasma ... No part ... of a dose should be administered during the twelve (12) hours prior to” — source p. 47
“5. Naproxen (a NSAID)” — source p. 78
“Naproxen ... Conditionally Permitted ... Conditionally permitted substances require a 24-hour withdrawal prior to the horse competing.” — source
“f. Naproxen (an NSAID): ... 40.0 micrograms per milliliter.” — source p. 10
“Naproxen ... NSAID” — source p. 21
“Naproxen Equiproxen, Naprosyn 4 C” — source p. 41
“Naproxen Naprosyn® Roche 10mg/kg for 5 days, once daily Oral (6) >360 (>15 days)” — source p. 2
Equiproxen is named in the medication rules, threshold schedules or withdrawal guidance of 3 state racing commissions: Kentucky, New York, Washington. Most states publish thresholds (concentrations), not times, and several adopt the ARCI schedule by reference. ShowSafe Pro Racing layers each state's rules over HISA or ARCI the way that state applies them, for all 32 states with live pari-mutuel racing.
A published detection time tells you how long Equiproxen stayed detectable in a handful of horses given one dose by one route. It does not tell you when your horse is clear: a bigger dose, a different route, repeated doses, a joint injection or a slower horse all push the real figure out, and every governing body says to add a safety margin set by your veterinarian. Here is how to read the rulebook.
ShowSafe Pro takes the doses already logged for your horse, matches each one to the published row for that dose and route, adds the margin your vet set, and flags anything the studies never covered as Unknown, ask your vet instead of guessing. Every answer shows the document, page and line it came from, for every rulebook the show runs under.
The 2026 USEF Guidelines & Rules for Drugs and Medications (with 27 Jul 2026 Guidelines Update) list Equiproxen as "Restricted Medication Dose and Time Recommendations". Maximum dose: 4.0 mg/Lb (4.0 grams/1000Lb) each 24 hours. Not within 12 h of competition. Screening limit 40.0 micrograms per milliliter in plasma. (Page 10.)
On the 2026 FEI Equine Prohibited Substances List Equiproxen is a Controlled Medication. The FEI states that a detection time is not a withdrawal time; the treating veterinarian adds a safety margin.
No. It is the approximate time Equiproxen stayed detectable in the horses studied, at that dose and route. Your horse, dose, route and number of doses may differ. Every governing body tells you to add a safety margin set by your veterinarian, and none publishes a withdrawal time. ShowSafe Pro applies the published row for the dose and route you actually gave, adds your vet's margin, and says 'Unknown' when the studies do not cover what you gave.