Pharmacokinetic Characterization of Tizanidine Nasal Spray, a Novel Intranasal Delivery Method for the Treatment of Skeletal Muscle Spasm

Background and Objective The skeletal muscle relaxant tizanidine is approved by the US FDA and the European Medicines Agency for treating spasticity and is supplied as tablets for oral administration. However, tizanidine has a poor bioavailability, due to extensive first-pass metabolism. Therefore, the nasal route of administration, which bypasses portal circulation, may increase the bioavailability of tizanidine and, possibly, reduce the time to peak plasma concentration, thereby shorting the latency of therapeutic effect. The objective of this study was to evaluate the pharmacokinetic profile of tizanidine nasal spray and compare it to the profile of tizanidine oral tablets.