Method Transfer Study for the Analytical Method to Determine 17-Amethyltestosterone Concentrations in Fish Feed

Science Center Objects

The results from this study will provide data that is necessary to support the potential approval of a drug that will allow producers to raise fish more efficiently.


Offering fish feed top coated with MT to tilapiafry at a rate of 9 mg MT/kg fish body weight/d for 28 d results in a nearly 100% phenotypic male population.  With tilapia being the fifth most consumed seafood in the U.S., the approval of MT medicated feed to produce phenotypic male tilapia would be a significant benefit to the tilapia aquaculture industry because males grow faster than females.  A phenotypic male tilapia is more cost efficient to culture.  Approval of MT would provide producers a legal means to efficiently increase biomass, reduce costs, and eliminate the logistical burdens accompanying the use of an unapproved drug through an investigational new animal drug permit.  The legal use of MT is key to allow U.S. tilapia producers to remain competitive with foreign tilapia producers.

The remaining data requirements that are impeding the approval of an original new animal drug application (NADA) for MT use in tilapia have been identified.  Limited data and information generation is needed in the major categories of (1) Chemistry, Manufacturing, and Controls, (2) Environmental Safety, (3) Animal Safety and (4) Human Food Safety and the minor categories of (1) All Other Information, (2) Freedom of Information Summary, and (3) Labeling.  In February and May 2008, the North Central Regional Aquaculture Center (NCRAC) and Western Regional Aquaculture Center (WRAC) Boards of Directors authorized funding for studies that would generate data for the categories of Animal Safety (repeat of a target animal safety study in tilapia) and Chemistry, Manufacturing, and Controls (a method transfer study for the MT feed assay).

In a previous project funded by NCRAC, the University of Wisconsin-Madison (Madison, WI) developed an analytical method to determine MT concentrations in fish feed (Marwah et al. 2005).  The method has been successfully used by CANTEST LTD (CANTEST; Burnaby, BC, Canada), the laboratory selected by the drug sponsor, Rangen, Inc. (Buhl, ID), to analyze feed for target animal safety and effectiveness studies to help gain NADA approval.  However, the method must complete one more validation procedure before it is accepted by the U.S. Food and Drug Administration Center for Veterinary Medicine (CVM) as the official method for determining MT concentrations in fish feed.

The final validation procedure will be an evaluation of the reproducibility of the method through a method transfer study.  In this case, the method transfer study is designed to evaluate method of analysis for MT at a nominal concentration of 60 µg/g in tilapia fish feed marketed with the brand name Masculinizing Feed for Tilapia® (Rangen Inc., Buhl, ID).  Simply described, a method transfer study determines if a method can be successfully used by a laboratory naïve to the method.  The current protocol was drafted with consideration given to CVM Guidance Document 136, “Protocols for the Conduct of Method Transfer Studies for Type C Medicated Feed Assay Methods” (U.S. Food and Drug Administration 2007).  The transfer study will be conducted in 2 phases.  The first phase will allow for the naïve (participating) laboratory to analyze control (unmedicated) and feed samples fortified with MT to ensure the participating laboratory understands the method and can successfully perform the method.  The second phase will involve analyses of split samples of control, fortified, and medicated feed by the reference and participating laboratories.  Thereafter, data will be compiled and included in a final study report that will be submitted to CVM for review.


Tilapia recovering after 8 hours of heavy sedation with AQUI-S® 20E
(Public domain.)



Conduct a method transfer study to determine the method specificity, accuracy, and precision of participating laboratory analysts executing the procedures described in the method to determine MT concentrations in fish feed.


Marwah, A., P. Marwah, and H. Lardy.  2005.  Development and validation of a high performance liquid chromatography assay for 17α-methyltestosterone in fish feed.  J. Chromatogr., B, Biomed. Sci. Appl. 824, 107-115.

U.S. Food and Drug administration.  2007.  Guidance document 136.  Protocols for the Conduct of Method Transfer Studies for Type C Medicated Feed Assay Methods.  Prepared by the Office of New Animal Drug Evaluation within the U.S. Food and Drug Administration’s Center for Veterinary Medicine.  Rockville, MD.