Name: China Manufacturer High Quality Ormetoprim CAS 6981-18-6
Brand: Wuhan Fortuna Chemical Co., Ltd.

Specifications of Ormetoprim CAS 6981-18-6

Items	Specification
Product name	Ormetoprim
CAS	6981-18-6
Appearance	White powder
Assay	≥99%
Molecular Formula	C14H18N4O2
Molecular Weight	274.32
EINECS	230-246-6

Parameters of Ormetoprim CAS 6981-18-6

Product parameters
Cas number:	6981-18-6
Appearance:	White powder
Purity:	99%min
Package details:	25kg/drum
Brand:	Fortunachem

Ormetoprim is a veterinary antibiotic belonging to the diaminopyrimidine class. It is exclusively used in aquaculture, specifically in the farming of salmonid fish (like salmon and trout). It is never used as a standalone drug but is always formulated in a 2:1 ratio with the sulfonamide antibiotic sulfadimethoxine. This combination acts as a sequential synergistic inhibitor of folate synthesis, effectively treating bacterial diseases.

1. Chemical and Pharmacological Definition

Chemical Class: Diaminopyrimidine. This is the same class as trimethoprim, a common human antibiotic. Ormetoprim is a structural analog of trimethoprim.
Mechanism of Action: It is a potent inhibitor of the bacterial enzyme dihydrofolate reductase (DHFR). This enzyme is crucial for the production of tetrahydrofolic acid, a form of folate essential for bacterial DNA synthesis and cell growth.
Synergistic Combination: It is always used with sulfadimethoxine (a sulfonamide). Sulfonamides inhibit an earlier step in the same pathway (dihydropteroate synthase). By blocking two consecutive steps, the combination is far more effective and bactericidal than either drug alone, and it helps slow the development of bacterial resistance.

2. Key Properties and Uses

Primary Use: Treatment of furunculosis in salmonids, a devastating systemic infection caused by the bacterium Aeromonas salmonicida. It is also used against other gram-negative bacterial infections in fish.
Administration: It is mixed into fish feed (medicated feed). The standard approved product is a combination of ormetoprim (25%) and sulfadimethoxine (50%).
Target Species: Almost exclusively salmon and trout.
Benefit: This combination provides a powerful tool for controlling serious bacterial outbreaks in high-density fish farming operations.

3. Important Safety and Regulatory Aspects

Veterinary Use Only: Ormetoprim is not approved for use in humans or in animals intended to produce milk (dairy cattle).
Withdrawal Time: A mandatory 42-day withdrawal period is required for treated fish before they can be harvested for food. This is to ensure that drug residues deplete to levels below the established tolerance, making the food safe for human consumption.
Resistance Concerns: As with all antimicrobials, there is a concern about the development of antibiotic-resistant bacteria. Its use is therefore strictly regulated and should be under veterinary supervision to ensure prudent use.
Environmental Impact: The use of medicated feed in open-net pen aquaculture raises concerns about the release of antibiotics into the marine environment, which can select for resistant bacteria in sediment and water.

4. Comparison with Related Drugs

Drug	Class	Use	Key Difference
Ormetoprim	Diaminopyrimidine	Veterinary (Aquaculture)	Specifically paired with sulfadimethoxine for fish.
Trimethoprim	Diaminopyrimidine	Human & Veterinary	Paired with sulfamethoxazole (e.g., Co-trimoxazole) for a wide range of infections.
Sulfadimethoxine	Sulfonamide	Veterinary (often with OMP)	Rarely used alone; its primary partner is ormetoprim in fish medicine.

Conclusion

Ormetoprim is a critical, niche antibiotic developed specifically for the aquaculture industry. Its role is highly specific: to be combined with sulfadimethoxine in medicated feed to combat severe bacterial infections in farmed salmon and trout. Its use is tightly controlled due to important public health concerns regarding antibiotic resistance and drug residues in food.