Veterinary Drug Handbook (VDH) is the reference veterinarians turn to when they want an independent source of information on the drugs that are used in veterinary medicine today.


Chemistry - A benzenesulfonamide, clorsulon has a chemical name of 4-amino-6-trichloroethenyl-1, 3-benzenedisulfonamide.

Storage, Stability, Compatibility

Unless otherwise instructed by the manufacturer, clorsulonshould be stored at room temperature (15-30°C).

Pharmacology - CLORSULON

In susceptible flukes, clorsulon inhibits the glycolytic enzymes 3-phosphoglycerate kinase and phosphoglyceromutase, thereby blocking the Emden-Myerhof glycolytic pathway.
The fluke is deprived of its main metabolic energy source and dies.
Uses, Indications - Clorsulon is approved for use in the treatment of immature and adult forms of
Fasciola hepatica (Liver fluke) in cattle. It is not effective against immature flukes less than 8weeks old. It also has activity against Fasciola gigantica. Although not approved, the drug has beenused in practice in various other species (e.g., sheep, llamas). It has activity against F. magna insheep, but is not completely effective in eradicating the organism after a single dose, therebyseverely limiting its clinical usefulness against this parasite. Clorsulon is also not effective againstthe rumen fluke (Paramphistomum).

Pharmacokinetics - CLORSULON

After oral administration to cattle, the drug is absorbed rapidly with peaklevels occurring in about 4 hours. Approximately 75% of the circulating drug is found in theplasma and 25% in erythrocytes. At 8-12 hours after administration, clorsulon levels peak in thefluke.

Contraindications, Precautions, Reproductive Safety

No milk withdrawal time has been determined, and the drug is labeled not to be used in female dairy cattle of breeding age.
Clorsulon is considered to be safe to use in pregnant or breeding animals.

Adverse Effects, Warnings

When used as directed adverse effects are unlikely to occur with thisagent.

Overdosage, Acute Toxicity

Clorsulon is very safe when administered orally to cattle or sheep.
Doses of up to 400 mg/kg have not produced toxicity in sheep. A dose that is toxic in cattle hasalso not been determined.
Drug Interactions & Drug/Laboratory Interactions - None identified.