Tissue Clearance of Rofenaid® in Chickens and Turkeys

ROFENAID®, a combination of sulfadimethoxine (4-sulfanilamido-2,6-dimethoxypyrimidine) and ormetoprim (2,4-diamino-5-(4,5-dimethoxy-2-methylbenzyl)- pyrimidine) in a ratio of 5:3, has been shown to be an effective and safe antibacterial and coccidiostat for broilers and turkeys (Mitrovic et al., 1969a, b, 1971a, b; Marusich et al., 1969, 1971). Treatment of food-producing animals with Rofenaid® has created the need for tissue residue studies capable of accurately measuring the disappearance of both components of the drug from the animal body. A review of these studies forms the subject of the present report. Assays for sulfadimethoxine (SDM) and ormetoprim were carried out in our laboratory by previously described tissue residue procedures sensitive to 0.1 p.p.m. (Fellig and Westheimer, 1968; Fellig et al., 1971). Arsenic was determined by an outside contract laboratory (Hazleton Laboratories, Inc., Falls Church, Virginia), using a standard method (Food Chemicals Codex, 1963). STUDY 1 It was the purpose of this study to determine Rofenaid® tissue…