Pharmacokinetics of tinidazole in dogs and cats

Abstract

Pharmacokinetics of tinidazole in dogs and cats after single intravenous (15 mg/kg) and oral doses (15 mg/kg or 30 mg/kg) were studied in a randomized crossover study. Tinidazole was completely absorbed at both oral dose levels in cats and dogs. Peak tinidazole concentration in plasma was 17.8 micrograms/ml in dogs and 22.5 micrograms/ml in cats after 15 mg/kg p.o. The oral dose of 30 mg/kg resulted in peak levels of 37.9 micrograms/ml in dogs and 33.6 micrograms/ml in cats. The apparent total plasma clearance of the drug was about twofold higher in dogs than in cats, resulting in an elimination half-life that was twice as long in cats (8.4 h) as in dogs (4.4 h). The apparent volume of distribution was 663 ml/kg in dogs and 536 ml/kg in cats. Therapeutic plasma drug concentrations higher than the MIC values of most tinidazole-sensitive bacteria were achieved for 24 h in cats and for 12 h in dogs after a single oral dose of 15 mg/kg. From the pharmacokinetic standpoint tinidazole seems to be well-suited to clinical use in small animal practice.

Efficacy of tinidazole for treatment of cats experimentally infected with Tritrichomonas foetus

“…8 Plasma tinidazole concentration in cats 24 hours after a single dose of 30 mg/kg, as was used in the present study, is approximately 8 µg/mL. 10 Tinidazole is completely absorbed after oral administration in cats, 10 and in humans, tinidazole penetrates well into various tissues where drug concentrations are similar to those in plasma. Thus, it is possible that tinidazole did not achieve sufficient concentration in the colon of cats reported here to be entirely effective against this strain of T foetus.…”

“…9 Susceptibility of feline T foetus to tinidazole has been detected in vitro, 8 and pharmacokinetic studies in cats reveal a long elimination half-life that would be consistent with once-per-day administration. 10 The purpose of the study reported here was to determine the ability of tinidazole to eradicate T foetus on the basis of PCR assay results when given orally once per day to cats with experimentally induced infection.…”

Documentation of In Vivo and In Vitro Aerobic Resistance of Feline Tritrichomonas foetus Isolates to Ronidazole

“…Whether cats can safely tolerate higher doses of alternative 5‐nitroimidazole drugs and their efficacy at such doses is not known. However, both of the cats failing treatment with ronidazole described here also failed treatment with >3 times the recommended dose 23 of tinidazole. On the other hand, improvement in diarrhea during the course of 5‐nitroimidazole therapy, as was seen in the cats reported here, should not be taken as proof of drug efficacy particularly as many antimicrobial drugs can transiently improve trichomonal diarrhea while having no direct effect on the organisms 1…”