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The Disappearance Rate in Reindeer of Famphur an Organophosphorus Parasiticide
Elimineringshastigheten av famphur — en fosforparasiticid — hos ren
Acta Veterinaria Scandinavica volume 11, pages 209–218 (1970)
Abstract
The present investigations were carried out in order to study the disappearance rate in reindeer of famphur (0,O-dimethyl-O,p-(NtN-di-methylsulphamoyl) phenyl phosphorothioate), a promising systemic parasiticide for the control of reindeer warble and nostril flies.
The compound was administered intramuscularly to reindeer as a single dose (in the form of the preparation Warbcx). At a dose of 20 mg/kg body weight (2 animals) famphur caused inhibition of plasma and erythrocyte cholinesterase activities by about 50 %. The plasma esterase activity fell off rapidly, within 24 hrs., and returned to normal within 3 weeks, whereas the erythrocyte esterase activity decreased gradually and remained low for at least 4 weeks after dosing.
Peak plasma levels of fampliiir, varying between 1 and 16 p.p.m., were attained within 5–33 hrs., after a dose of 30 mg famphur per kg body weight (7 reindeer). The plasma levels declined to below 0.02 p.p.m. in 72–96 hrs. Famoxon, the oxygen analogue of famphur, was observed for 1–2 days in plasma at low levels, amounting to about 10 % of the corresponding famphur levels. In erythrocytes practically no residues were found of either compound.
Tissue residue levels were low — except at the injection site. In a series of animals given a dose of 30 mg/kg body weight and killed at varying times after treatment famphur or famoxon were detectable in liver for 4.5 days and in kidney and skeletal muscle remote from the injection site for 12 days. In muscle tissue from the injection site highly variable residue levels were observed, indicating absorption from the intramuscular depot to be erratic.
The experimental results suggest that no appreciable consumer hazard would arise from a proposed single-dose intramuscular treatment of reindeer with famphur at a dosage not exceeding 30 mg/kg body weight, provided a minimum interval of 3 weeks is maintained between treatment and slaughter and the muscle tissue around the injection site is discarded.
Sammanfattning
Famphur (0,0-dimetyl-0,p- (N,N-dimetylsulfamoyl) -fenylfosfortioat) är en lovande systemisk parasiticid mot renstynget och svalgbromsen. Föreningen gavs (i form av preparatet Warbex) som intramuskulär engångsdos till renar.
Efter en dos av 20 mg famphur per kg kroppsvikt (2 djur) iakttogs en sänkning till ca 50 % av kolinesterasaktiviteten i såväl plasma som röda blodkroppar. Plasmaaktiviteten sjönk snabbt (inom 24 t och steg till normal nivå inom 3 veckor, medan erytrocytaktiviteten avtog långsamt och förblev låg under minst 4 veckor.
Efter en dos av famphur av 30 mg/kg (7 djur) uppnåddes maximala plasmakoncentrationer på 1—16 p.p.m. inom 5—33 t. Inom 72—96 t efter dos avtog halterna till mindre än 0,02 p.p.m. Syreanalogen till famphur, famoxon, uppträdde under 1—2 dagar i plasma i låga halter, uppgående till ca. 10 % av famphurhalterna. I röda blodkroppar påvisades endast obetydliga resthalter av famphur och famoxon.
Hos en serie djur, som avlivades vid olika tider efter en dos av famphur av 30 mg/kg, kunde famphur och famoxon påvisas i levern intill 4,5 dagar och i njurar och skelettmuskulatur (utom injektionsstället) intill 12 dagar efter dos. Resthalterna i muskulatur från injektionsstället varierade oregelbundet, utvisande en ojämn resorption från den intramuskulära depån.
Av resultaten att döma torde en engångsbehandling av ren med famphur i dos av högst 30 mg/kg (i.m.) icke medföra livsmedelshygieniska risker, förutsatt att minst 3 veckor förflyter mellan behandling och slakt och att köttet kring injektionsstället kasseras.
References
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Erne, K., Nordkvist, M. The Disappearance Rate in Reindeer of Famphur an Organophosphorus Parasiticide. Acta Vet Scand 11, 209–218 (1970). https://doi.org/10.1186/BF03547981
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DOI: https://doi.org/10.1186/BF03547981