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Trimediazine Plain is indicated for the treatment of bacterial diseases in horses, including upper and lower respiratory tract infections, alimentary tract infections and infected wounds.

Data Sheets

Trimediazine™ Plain Oral Powder Species:Horses and other equidae

Therapeutic indication:Pharmaceuticals: Antimicrobials: Oral preparations: Others

Active ingredient:Sulfadiazine (Sulphadiazine), Trimethoprim

Product:Trimediazine™ Plain Oral Powder

Product index:Trimediazine Plain

Withdrawal notes:Horse meat: 6 months


Trimediazine Plain is a white broad spectrum antibacterial powder for mixing with animal feed . Each sachet contains Trimethoprim 5% w/w and Sulfadiazine 25% w/w.


Trimediazine Plain is indicated for use in the treatment of bacterial diseases in horses, including upper and lower respiratory tract infections, alimentary tract infections and infected wounds.

Dosage and administration

For oral administration in the feed. To be given at a rate of 30mg combined active ingredients per kg bodyweight.

Mix with a small quantity of feed. Each 50 g sachet provides a daily dose for a 500 kg horse. The dose may be administered daily, or divided and administered at 12 hourly intervals, for 5 days.


It is recommended that other feed be withdrawn until medicated feed has been consumed.

Contra-indications, warnings, etc

Do not use in horses with severe liver parenchymal damage or kidney damage or known sulphonamide sensitivity, or horses with blood dyscrasias or cardiac arrhythmias. Do not exceed 7 days continuous treatment

The use of Trimediazine Plain in horses under 1 year old should be avoided.

In the rat and rabbit, trimethoprim/sulfadiazine combinations did not produce any foetal abnormalities at doses of up to 600mg/kg, although minor effects on skeletal development were seen below this level. As no studies have been conducted in horses, use on pregnant mares should be avoided.

When administered to lactating females, small amounts of trimethoprim and sulfadiazine are present in the maternal milk. Since no studies have been reported on the effects of Trimediazine Plain on the development of new born foals, it would be prudent not to feed very young foals with milk obtained from mares being treated.

As there is no specific antidote, in case of overdose, treatment should be symptomatic.

Withdrawal period

Meat: 6 months

Persons handling this product should avoid inhalation of any dust and contact with skin. Wear either a disposable half-mask respirator conforming to European Standard to EN149 or a non-disposable respirator to European Standard to EN140 with filter EN143 when mixing or handling this product. Rubber gloves should be worn when mixing or handling this product. Hands should be washed thoroughly after use. Sulphonamides may cause hypersensitivity (allergy) following injection, inhalation, ingestion or skin contact. Hypersensitivity to sulphonamides may lead to cross reactions with other antibiotics. Allergic reactions to these substances may occasionally be serious.

1. Do not handle this product if you know you are sensitive to sulphonamides.

2. If you develop symptoms following exposure such as a skin rash, you should seek medical advice and show the doctor this warning.

Pharmaceutical precautions

Do not store above 25°C. Store in a dry place away from animal feeding stuffs. Add to feed immediately before administration. Discard any remaining medicated feed.

Any unused veterinary medicinal product or waste materials derived from such veterinary medicinal products should be disposed of in accordance with local requirements.

Legal category

Legal category:POM-V

Packaging quantities

10×50 g sachets.

Further information

ATC vet code: QJ01EW10

Sulfadiazine is a bacteriostatic antibiotic belonging to the sulphonamide group which acts by interference with the synthesis of nucleic acids. Trimethoprim is a reductase inhibitor which also interferes with the synthesis of bacterial nucleic acids. Sulfadiazine and trimethoprim act on the same metabolic pathway, resulting in potentiation of antibacterial activity.

Marketing Authorisation Number

Vm 08007/4036.

Significant changes


GTIN description:Trimediazine Plain



Shipping charges mainland UK zone1

ValueWeightDelivery Charge
Over £49.00Any WeightFREE
Under £49.00No weight limit£4.50
Under £49.00Under 250g£2.99

Most orders are despatched the same day and standard delivery is 3 to 5 working days from despatch. FAST Expedited options are available.

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Prescription Items

Prescription items will be sent on receipt of a valid signed and dated prescription.

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Please ring us on 01833 641112 for more information.

Refrigerated Items

Refrigerated items will be sent by carrier or Royal Mail with coolpacks unless you pay for a premium for a refrigerated delivery. We will contact you prior to despatch for your instructions.


We want you to be completely satisfied with any purchase. If not any item* can be returned to us within 14 days of receipt for exchange or refund Please give us a ring for a returns number on 01833 641112 or alternatively email [email protected] to obtain a returns number.

*Due to legal requirements medicines may not be returned except to correct an error in despatch or in response to an "official recall". If an item is believed to be faulty it should be returned for inspection and it may be necessary to forward it to the manufacturers for testing before replacements or refunds can be authorised. This does not infringe legal rights. Please contact our customer services for a "Returns Number" which must appear on the outside of the package or it will not be accepted. We advise customers to use an insured method of shipping and to retain proof of despatch. We may refuse returns on products specially obtained or manufactured to order. Items must be returned unsoiled and unused and sent adequately packed and carriage paid.

Frequently Asked Questions

Does this work on cellulitis

Please speak to the prescribing veterinary surgeon.

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