Nitrofurantoin plasma- and urine exposure in eight healthy beagle dogs following standard nitrofurantoin dosing regimen

Bacterial cystitis is common in dogs and is usually treated with antibiotics. Nitrofurantoin is used for treatment of bacterial cystitis in humans and might provide a feasible treatment option in dogs. The aim of this study was to investigate the nitrofurantoin plasma concentration-time course and potential adverse effects in dogs. Nitro-furantoin (4.4-5.0 mg/kg) was administered orally to eight healthy beagles every 8 h for five days before repeated plasma and urine samples were collected. An additional four beagles served as untreated controls. The nitrofurantoin plasma and urine concentrations were measured using ultra high precision liquid chromatography coupled to tandem mass-spectrometry and further analysed using a non-compartmental pharmacokinetic model. In plasma, the median C-max was 2.1 mu g/mL, t(max) was 2 h, the terminal rate constant was 0.9 per h and the terminal half-life was 0.8 h. In urine, median C-max was 56 mu g/mL, t(max) was 1 h and the terminal half-life was 4.3 h. No adverse effects were observed clinically or in haematology or biochemistry. The data presented in this study combined with in vitro sensitivity data from common urine pathogens and the lack of observed adverse effects suggest that nitrofurantoin in a standard dosing regimen could be effective in sporadic bacterial cystitis treatment in dogs. Further clinical studies are highly warranted to verify the effectiveness in clinical cases.

Automated summary

This study aimed to investigate the plasma concentration-time course and potential adverse effects of nitrofurantoin in dogs. The results showed that nitrofurantoin had high concentrations in the plasma and urine of dogs with a short half-life. No adverse effects were observed clinically or in laboratory tests. The study suggests that nitrofurantoin could be effective in treating bacterial cystitis in dogs, but further clinical studies are needed to confirm its effectiveness.