Pharmacodynamics of a liposomal preparation for local anaesthesia

A phospholipid containing formulation with tetracaine (CAS 94-24-6) for topical anaesthesia was developed. In vitro drug liberation as well as in vivo efficacy and duration of the anaesthetic effect were investigated. The in vitro liberation constant was 0-.626 +/- 0.005 mg/(cm2.square root of h for a liposomal gel formulation containing 2% (m/l) tetracaine. The gel showed high efficacy in anaesthetizing the skin after topical application. After 60 min of application complete anaesthesia of the skin was observed with all volunteers. The duration of anaesthesia after removing the application system was 150 min on average. The determination of the in vivo penetration rate resulted in values between 0.010 and 0.015 mumol/min.cm2 tetracaine.