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Veterinary Drugs

 
Product and
NADA/ANADA Number
Trade Name
Ingredients
fenbendazole
120-648
Panacur ; and
Safe-Guard;
fenbendazole
121-473
Panacur®; 22.2% Granules
fenbendazole
128-620
Panacur
fenbendazole
128-620
Panacur®, Safe-guard® Suspension 10%
Fenbendazole
131-675
SAFE-GUARD; (Premix)
fenbendazole
132-872
Safe-Guard; Paste 10%; Panacur; Paste 10%
fenbendazole
137-600
SAFE-GUARD(TM)
fenbendazole
139-189
SAFE-GUARD;
fenbendazole
fenbendazole, lincomycin
140-954
Safe-Guard®, Type "A" Medicated Article (Premix)
fenbendazole, lincomycin

                                                                   
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Summary of 
FDA Information:

Approval Date: May 15, 1989 Freedom of
Information Summary NADA 139-189 I. GENERAL INFORMATION: NADA 139-189 Sponsor: Hoechst-Roussel Agri-Vet Company Route 202-206 North Somerville, New Jersey 08876 Generic Name: Fenbendazole Trade Name: SAFE-GUARD® Marketing Status: Over-the-counter (OTC Notes: The original approval provided for
a 25 lb. medicated molasses block containing 750 milligrams of
fenbendazole per pound as a beef cattle anthelmintic.
The molasses block requires an 11-day withdrawal.
This supplemental approval provides for
a 33-1/2 pound cold press medicated 20% protein feedblock containing 750 milligrams of
fenbendazole per pound as a beef cattle anthelmintic.
The cold press 20% protein block requires a 16-day withdrawal period. II. INDICATIONS FOR USE Cattle dewormer for
the removal and
control of
: Lungworm: (Dictyocaulus viviparus ). Stomach worms: Barberpole worm (Haemonchus contortus), Brown stomach worm (Ostertagia ostertagi ), Small stomach worm (Trichostrongylus axei ). Intestinal worms: Hookworm (Bunostomum phlebotomum ), Threadnecked intestinal worm (Nematodirus helvetianus ), Small intestinal worms (Cooperia oncophora and
C. punctata ), Bankrupt worm (Trichostrongylus colubriformis ), Nodular worm (Oesophagostomum radiatum ). III. DOSAGE A. DOSAGE FORM 20% Natural Protein deworming supplement (cold press) feedblock for
beef cattle.
This cold press feedblock is manufactured by V.M.S., Inc. Montgomery, AL. Each feedblock weighs 33.5 pounds and
contains 730 mg fenbendazole per pound. B. ROUTE OF ADMINISTRATION The feedblock label contains complete directions for
administration. C. RECOMMENDED DOSAGES: 1.67 mg fenbendazole per kg of
body weight per day , for
three (3) days. Total dose for
the 3 day period of
5 mg/enbendazole per kg of
body weight (2.27 mg fenbendazole per pound). IV. EFFECTIVENESS This NADA relies on adequate well controlled studies showing the anthelmintic efficacy of
fenbendazole in cattle included in the
approved NADA 128-620 (Fenbendazole Suspension 10%, 48 FR 42809, September 20, 1983).
The original NADA (128-620) provided for
a dose of
3 mg fenbendazole/kg of
body weight administered in a one (1) day treatment.
This NADA demonstrates that the
5 mg dose given over a three (3) day period is equally as efficacious. One study
was conducted in cattle to demonstrate that the
efficacy of
fenbendazole in the
feedblock formulation is equal to the suspension formulation when
used at the
same dose of
5 mg fenbendazole/kg body weight. It is appropriate to conclude that the
feedblock formulation is equally efficacious. Efficacy and
consumption was
demonstrated in these studies: Efficacy Evaluation of
Feedblocks Medicated with Fenbendazole M. Blagburn, Auburn University, Auburn, Alabama Twenty cattle naturally infected with gastrointestinal nematodes were
identified and
assigned to two groups of
ten cattle each. One group remained unmedicated and
one group was
given fenbendazole via the natural protein cold press feedblock at a dose of
5 mg fenbendazole per kg of
body weight over a 3 day period. Adequate numbers of
parasites were
recovered from
the control animals at postmortem to evaluate and
compare the effect of
the feedblock formulation on the following species: (Eds. note: The following table consists of
2 columns.) % Reduction H. contortus 100 O. ostertagi 99.9 C. punctata 100 O. radiatum 100 T. axei 100 Consumption rate by cattle of
feedblocks containing Fenbendazole Four feedblock consumption studies were
conducted.
The total number of
mature cattle utilized for
these studies was
195 head tested using the cold press feedblock.
The studies were
conducted in Alabama, Louisiana and
Wyoming. To achieve the desired level of
fenbendazole medicated block consumption, cattle require a period of
time for
adaptation to feedblocks.
This adaptation period varied depending upon current and
previous herd feeding and
husbandry practices in addition to weather conditions. From these studies, it was
determined that specific medicated block treatment can be administered after 12-19 days adaptation period with non-medicated feedblocks.
The medicated feedblocks were
given for
a 3 day treatment period with the total fenbendazole consumption for
the 3 day period calculated to be 5 mg fenbendazole/kg of
body weight.
The actual average consumption rate for
fenbendazole averaged across the 3 locations was
4.55 (± 0.88) mg fenbendazole/kg body weight for
the cold press blocks (see the following table). (Eds. note: The following table consists of
2 columns.) AVERAGE FENBENDAZOLE CONSUMPTION CALCULATED FOR EACH LOCATION Cold Press Blocks - Consumption Averages Per Capita FBZ (mg/kg) Wyoming 5.45 Louisiana 5.02 Alabama, Group 1 4.88 Alabama Study 11, Group 1 3.19 Alabama Study 11, Group 2 4.23 Average 4.55 Std. Deviation 0.88 These studies were
conducted by: Dr. Dean Danilson, Asst. Prof. Auburn University Auburn, AL. 36849-4201 Dr. Gene Luther Dept. of
Vet. Science Louisiana State University Baton Rouge, LA. 70803-6002 Dr. J. Waggoner Jr. University of
Wyoming Dept. of
Animal Science Laramie, WY. 82071 The consumption and
efficacy studies confirm that the
feedblock formulation is efficacious when
the total dose of
5 mg fenbendazole per kg body weight is given over a 3 day period.
The recommended treatment was
found to be both safe and
practical under
field conditions. V. ANIMAL SAFETY This NADA relies on safety studies included in the
approved NADA 128-620 (Fenbendazole Suspension 10%, 48 FR 42809, September 20, 1983), that indicated the maximum tolerance dose is greater than 2000 mg fenbendazole/kg body weight.
Therefore, as predicted, no visible adverse reactions were
observed in any of
the laboratory efficacy or
clinical field trials conducted in cattle with cold press feedblocks containing fenbendazole. VI. HUMAN SAFETY: a. Safe Concentration of
Residues The safe concentration for
total fenbendazole residues in the
uncooked edible tissues of
cattle were
established, based upon toxicology studies submitted under
NADA 128-620 (48 FR 42809-9/20/83) as 5 ppm in muscle, 10 ppm in liver, 15 ppm in kidney and
20 ppm in fat. b. Metabolism Studies Under NADA 128-620 metabolism studies in cattle were
conducted to select a marker substance and
target tissue for
fenbendazole. Cattle liver is the target tissue with parent fenbendazole being the marker substance.
The tolerance (Rm) is 0.8 ppm parent fenbendazole for
cattle receiving a single oral dose of
10 mg fenbendazole/kg BW, i.e. when
total fenbendazole residues are 10 ppm in liver, there is 0.8 ppm parent fenbendazole as determined by the regulatory method. Acceptable comparative metabolism studies were
described under
NADA 128-620. c. Regulatory Method Under NADA 128-620, the
method was
developed for
the determination of
parent fenbendazole at the
tolerance of
0.8 ppm concentration in cattle liver. d. Withdrawal Time Under NADA 128-620 (suspension 10%) it was
determined that a withdrawal time of
8 days is necessary for
the residues of
fenbendazole to deplete to sale concentrations in all tissues. Under this NADA a residue depletion study
using the approved analytical method was
conducted to determine when
residues of
the feedblock formulation deplete to or
below the established safe concentration. Twenty eight cattle were
treated orally over a 3 day period with the feedblock formulation to provide a total dose of
10 mg fenbendazole/kg of
body weight.
A statistical analysis using CVM's 99% tolerance limit with a 95% confidence interval on the data in the
following table determined that fenbendazole residues were
below the tolerance of
0.8 ppm 16 days after the end of
the treatment period.
The projected residue level at the
end of
a sixteen (16) day withdrawal period was
0.74 ppm.
The Agency has reviewed the residue data and
has concluded that this supplement will not
alter the concentration and
qualitative composition of
the residue. (Eds. note: The following table consists of
2 columns.) FENBENDAZOLE RESIDUES IN CATTLE LIVER AFTER A THREE DAY TREATMENT PERIOD USING THE COLD PRESS FEEDBLOCK FORMULATION WITH A TOTAL DOSE OF 10 MG FENBENDAZOLE PER KG OF BODY WEIGHT Sacrifice Date after Treatment PPM Fenbendazole(l,2) 1 day 14.56 (±16.62) 3 days 13.75 (±17.06) 5 days 3.92 (±5.37) 7 days 1.67 (±2.52) 1 Values are the average from
seven (7) animals per data point. 2 Standard deviation in ( ).
Therefore, it has been established that 16 days after treatment with a three day oral dose of
10 mg fenbendazole/kg b.w. in the
cold press feedblock formulation is sufficient to confirm that no residues are present that may be harmful to human health. e. Safety to Handler Under NADA 128-620, studies were
conducted which
demonstrated that the
drug would have no ill effects on persons handling it if the drug is used according to label recommendations. VII. AGENCY CONCLUSIONS: This is a supplemental approval. NADA 139-189 provides for
a 25 pound molasses block having 750 mg fenbendazole/pound.
The supplement is for
a cold press protein block of
33-1/2 pounds having 750 mg fenbendazole/pound.
The data submitted in support of
this NADA comply with the requirements of
section 512 of
the Act and
demonstrates that fenbendazole (Safe-Guard) in a 20% natural protein deworming (cold press) feedblock when
used under
its proposed condition of
use is safe and
effective for
the removal and
control of
lungworms, stomach worms and
intestinal worms in cattle.
The Agency concludes that adequate directions for
use have been written for
the proposed over-the-counter use of
this broad spectrum anthelmintic which
is indicated for
the removal and
control of
parasites commonly occuring in cattle. Fenbendazole premixes in swine and
fenbendazole suspension, paste, and

feedblock (containing molasses) in cattle are presently marketed over-the-counter as broad spectrum anthelmintic drug products. Fenbendazole medicated feedblock is currently codified in section 21 CFR 520.905e for
use in cattle providing for
the same concentration (750 mg/lb) and
conditions of
use with the exception of
the drug withdrawal requirements (11 days for
the molasses-containing block and
16 days for
the cold press block).
The Agency has reviewed the residue data and
has concluded that this supplement will not
alter the concentration and
qualitative composition of
the residue.
Therefore, this supplement will pose no increased human risk from
exposure to the drug. Under the Center's supplemental approval policy (42 FR 64367), this is a Category II change which
provides for
an additional feed block formulation.
This change is not expected to adversely affect the safety and
effectiveness of
the drug.
Therefore, this action did not require a reevaluation of
the underlying safety and
effectiveness data in the
parent application. VIII. LABELING (Attached) 1. SAFE-GUARD® (fenbendazole) product label Copies of
this label may be obtained by writing to the: Food and
Drug Administration Freedom of
Information Staff (HFI-35) 5600 Fishers Lane Rockville, MD 20857 Or requests may be sent via fax to: (301) 443-1726. If there are problems sending a fax, call (301) 443-2414.

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