Ireland. Organophosphate sheep dips are widely used for the treatment and prevention of Psoroptes ovis infestation in sheep (sheep-scab). Other veterinary medicines containing organophosphates include topical flea control products for dogs and cats and topical antiparasitic preparations for farm animals. These products act primarily by inhibiting the enzyme acetylcholinesterase which plays a major role in the transmission of nerve impulses. Such compounds may cause neurotoxic effects if the instructions for use are not followed accurately.

The Irish Medicines Board reminds prescribers to advise users to follow the instructions for correct handling of organophosphate sheep-dips (carried on the labels of all such products authorized by the Board). The effects of chronic organophosphate exposure appear to be emerging and there may be some under-recognition of these effects by health care professionals, therefore it is important that all such effects are reported.

[See also Pharmaceuticals Newsletter No. 8, August 1994, No. 1 January, 1993, No. 7, July 1992 and Nos. 11/12, November/December 1991]

Reference: Irish Medicines Board, Drug Safety Newsletter No. 8, September 1998.

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