Concentration of non-steroidal anti-inflammatory drugs in the pelvic floor muscles: An experimental comparative rat model

Purpose: The aim of this study is to explore non-steroid anti-inflammation drugs (NSAIDs) potency for pelvic floor muscle pain by measuring local concentration in a rat model. Materials and Methods: We used nine NSAIDs, including nabumetone, naproxen, ibuprofen, meloxicam, piroxicam, diclofenac potassium, etodolac, indomethacin, and sulindac, and 9 groups of female Wister rats. Each group of rats was fed with one kind of NSAID (2 mg/mL) for three consecutive days. Thereafter, one mL of blood and one gram of pelvic floor muscle were taken to measure drug pharmacokinetics, including partition coefficient, lipophilicity, elimination of half-life (T1/2) and muscle/plasma converting ratio (C_{ss, muscle}/C_{ss, plasma}). Results: Diclofenac potassium had the lowest T1/2 and the highest mean C_{ss, muscle}/C_{ss, plasma} (1.9 hours and 0.85±0.53, respectively). The mean C_{ss, muscle}/C_{ss, plasma} of sulindac, naproxen and ibuprofen were lower than other experimental NSAIDs. Conclusion: Diclofenac potassium had the highest disposition in pelvic floor muscle in a rat model. The finding implies that diclofenac potassium might be the choice for pain relief in pelvic muscle.