Comparative Pharmacokinetics of Iophenoxic Acid in Cats and Brushtail Possums.

Abstract

The comparative plasma pharmacokinetics of iophenoxic acid was studied in the cat and brushtail possum (Trichosurus vulpecula) to evaluate the suitability of this compound as a bait marker in these species. In cats, a mean peak plasma concentration of 946 micro g per 100 ml was obtained after administration of 1.5 mg/kg of iophenoxic acid. However, at the same dose level in possums, mean peak plasma concentration was only 157 micro g per 100 ml. Even after administration of 10 mg/kg of iophenoxic acid, the maximum peak plasma concentration in possums was only 459 micro g per 100 m/litre. The plasma elimination half-life for iophenoxic acid was 107 days in cats and close to one day in possums. Iophenoxic acid is therefore a suitable marker for cats but is unsuitable for use as a long-term or quantitative bait marker for possums. Differences between the possum and other mammals in gastrointestinal physiology and plasma protein configuration by account for the poor absorption and rapid elimination of iophenoxic acid in the possum.

Anticoagulant effects and the persistence of brodifacoum in possums (Trichosurus vulpecula)

“…However, little consideration has been given to the potential dangers arising from brodifacoum residues in possum carcasses. Metabolism and excretion of foreign compounds such as toxins vary in different species, and the possum shows some idiosyncrasies in its responses (Eason & Jolly 1993;Jolly et al 1994;Eason et al 1994c). In earlier experiments with possums using one-stage prothrombin (OSP) and activated partial prothrombin (APP) times as indicators of susceptibility, we demonstrated that the possum was relatively tolerant to pindone, a first-generation anticoagulant (Eason & Jolly 1993).…”

Liquid chromatography–electrospray ionization mass spectrometry for direct identification and quantification of iophenoxic acid in serum

“…In the past, IA has been successfully used as a marker in bait acceptance studies in a variety of animal species including carnivores [6][7][8][9][10][11], herbivores [12][13][14][15][16] and omnivores [17] and has been used to determine the feasibility of delivering oral vaccine to wild swine [17] and raccoons [9,24]. Field experiments in which feral pigs (S. scrofa), raccoons (P. lotor), and opossums (D. virginiana) were exposed to IA following ingestion of IA-marked baits were used to confirm the appropriateness of (−)ESI/LC-MS identification in these studies.…”

“…In addition, the extent and duration of IA binding is both species-and dose-dependent. For example, coyotes fed 0.5 mg/kg exhibited elevated iodine levels for approximately 8 weeks [6] while the duration of plasma or serum iodine elevation in stoats was only 2 weeks [21] and in the brushtail opossum and the swamp wallaby it was elevated for less than 2 weeks [11,20]. Dose-dependency has been described in beagle dogs and red foxes which, when fed 20 mg IA, exhibited elevated iodine levels for almost twice as long as those fed 10 mg IA [7].…”

“…1). These studies have been conducted in a variety of animal species including carnivores, such as raccoons, foxes, dogs, coyotes and cats [6][7][8][9][10][11], herbivores, such as goats, rabbits and deer [12][13][14][15][16] and omnivores, such as pigs [17]. The compound is effective because it exhibits low toxicity while strongly binding to albumin over an extended length of time [18,19].…”

“…The compound is effective because it exhibits low toxicity while strongly binding to albumin over an extended length of time [18,19]. In addition, while the extent of binding is both dose-and speciesdependent [11], IA may be used to determine the amount of bait consumed [10,12,16]. However, the compound persists for only short durations in marsupials, including opossums [11] or swamp wallabies [20], and birds [6].…”