Defendazole™ (fenbendazole) 10% Oral Suspension
The U.S. Food and Drug Administration has approved Defendazole™ (fenbendazole) 10% oral suspension, the first FDA-approved generic fenbendazole dewormer for use in beef and dairy cattle and goats.
Defendazole is indicated for the treatment and control of a broad range of gastrointestinal and lung nematodes, including lungworms, stomach worms, and intestinal worms in cattle, and select stomach worms in goats.
Active Ingredient
Defendazole contains the same active ingredient as the reference listed new animal drug Safe-Guard® (fenbendazole) 10% oral suspension (NADA 128-620), originally approved in 1994.
Bioequivalence
FDA determined that Defendazole is bioequivalent to the brand-name product based on an in vivo blood-level study conducted in cattle, with no serious adverse events reported.
Indications and Dosage
Beef and Dairy Cattle:
Administered orally at 2.3 mg/lb (5 mg/kg) body weight to treat and control lungworms (Dictyocaulus viviparus), multiple species of stomach worms (including Ostertagia, Haemonchus, and Trichostrongylus), and intestinal worms (including Cooperia, Nematodirus, and Oesophagostomum).
Goats:
Administered orally at the same dosage (2.3 mg/lb; 5 mg/kg) for the treatment and control of adult stomach worms, specifically Haemonchus contortus and Teladorsagia circumcincta.
Human Food Safety and Withdrawal Periods
FDA previously established acceptable daily intake (ADI) values and residue tolerances for fenbendazole under the Safe-Guard® approval, and these determinations apply equally to Defendazole. Based on tissue residue studies:
Cattle: 8-day slaughter withdrawal period
Goats: 6-day slaughter withdrawal period
Dairy Cattle: 48-hour milk discard time
FDA concluded there is a reasonable certainty of no harm from fenbendazole residues in edible tissues when Defendazole is used according to its approved labeling.
Regulatory Status and Availability
Defendazole is approved as safe and effective when used as directed and is available over the counter in 1-liter and 5-liter containers. The application is sponsored by Norbrook Laboratories Ltd. (UK).
Links
Read the FDA announcement here.
Read the full FOI information here.