June 2, 1993

PMF 5421 C-0001

Linda G. Kahn, D.V.M.
FDA Liaison to the IR-4 Project
HFV-130
Center for Veterinary Medicine
7500 Standish Place
Rockville, Maryland 20855

Dear Dr. Kahn:

We refer to your submission to the public master (PMF 5421) file dated December 2, 1992, for the use of ivermectin for the control of ear mites, Psoroptes cuniculi, in rabbits. This submission in response to our letter of October 23, 1992, provides the requested information concerning the dose titration study previously submitted.

We have reviewed the additional material pertaining to the dose titration study and have the following comments.

You have adequately addressed all the deficiencies that were mentioned in our letter of October 23, 1992, concerning the study report presented in the A-000 submission. The protocol deviations have all been explained. The raw data have been submitted in a chronological and readable form as requested, and are all signed. The ranks pre- and post-trial have been tabulated as requested.

We note that there were 23 rabbits treated with penicillin out of a total of 75 rabbits in the study. The investigator explained that these rabbits were in poor condition when they arrived and had respiratory infections. All of the rabbits in the treated and control groups in the final three trials in the study received penicillin. We do not feel that the use of penicillin compromised the results of the study.

This study showed acceptable efficacy for controlling ear mites in rabbits at a dose of 100 ug/kg given SQ twice at two week intervals.

Future correspondence regarding this letter should reference our file number, PMF 5421 C-0001, and be addressed to the Document Control Unit, HFV-199. Please include only one request per submission, clearly stating the request in the first paragraph of the submission.

If you have any questions regarding this correspondence, please telephone Dr. Melanie Berson, Chief, Antiparasitic and Physiologic Drugs Branch at 301-295-8643.

/s/
Steven D. Vaughn, D.V.M.
Director, Division of Therapeutic Drugs for Food Animals
Office of New Animal Drug Evaluation
Center for Veterinary Medicine