Pharmacokinetic profiles of the analgesic drug flupirtine in cats

Flupirtine (FLU) is a non-opioid analgesic drug with no antipyretic or antiphlogistic effects, used in the
treatment of a wide range of pain states in human beings. There is a substantial body of evidence on
the efficacy of FLU in humans but this is inadequate to recommend its off-label use in veterinary clinical
practice. The aim of this study was to evaluate the pharmacokinetic profiles of FLU after IV and PO
administration in healthy cats.
Six mixed breed adult cats were randomly assigned to two treatment groups using an open, singledose,
two-treatment, two-phase, paired, cross-over design (2 × 2 Latin-square). Group 1 (n = 3) received
a single dose of 5 mg/kg of FLU injected IV into the jugular vein. Group 2 (n = 3) received the
same dose via PO route. The wash out period was 1 week. Blood samples (1 mL) were collected at assigned
times and plasma was then analysed by a validated HPLC method.
No adverse effects at the point of injection and no behavioural changes or alterations in health parameters
were observed in the animals during or after the study (up to 7 days after the full study). After
IV administration, FLU was detectable in plasma up to 36 h. After PO administration, FLU plasma concentrations
were lower than those following IV administration, but they were detectable over the same
time range. The terminal part of both mean pharmacokinetic curves showed a similar trend of elimination.
The oral bioavailability was approximately 40%. This is the first study of FLU in an animal species
of veterinary interest and it could pave the way for the use of this active ingredient in the veterinary
field