Acta anaesthesiologica Scandinavica
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Acta Anaesthesiol Scand · Sep 2003
Tramadol encapsulated into polyhydroxybutyrate microspheres: in vitro release and epidural analgesic effect in rats.
Controlled release techniques are used to increase the duration of action and decrease the toxicity of drugs. Any controlled release form of tramadol in spinal or epidural blocks has not been studied previously. Tramadol was encapsulated into polyhydroxybutyrate (PHB) microspheres and release kinetics was studied. The epidural analgesic effect of this solution in rats was also compared with free tramadol. ⋯ Controlled release of tramadol from PHB microspheres is possible, and pain relief during epidural analgesia is prolonged by this drug formulation compared with free tramadol.