Local Anesthetic Microcapsulation.
Annual rept. 30 Sep 81-31 May 82,
BIOTEK INC WOBURN MA
Pagination or Media Count:
Because of the natural molecular weight distribution of poly-L-lactide polymerization, batches can be blended with viscosities as disparate as R.S.V. 12 or - dlg. Microencapsulation of lidocaine base yielded 212-300 micron microcapsules with 50 in vitro drug release in 6 hours 150-212 micron microcapsules released 50 in 2 hours. Etidocaine-HCl were micorencapsulated in a more efficient manner. A wide variety of drug release profiles was obtained. Microcapsules of 300-425 microns in size containing 60 bupivacaine HCL had 50 in vitro drug release in 12 hours. EDAX of bupivacaine-HCl microcapsules indicate about 25 drug on the microcapsule surface. One year storage of lidocaine-HCL and etidocaine-HCl microcapsules do not show significant differences of drug assay or in vitro release. Acute systemic toxicity of free and encapsulated drugs were compared by intraperitoneal injection in mice. Lethal and convulsive doses LD50, CD50 were between 4.0 and 6.7 times as great with anesthetics in the encapsulated form. Cutaneous anesthesia was measured with an electromyograph and a tactile stimulator. Intradermal studies with anesthetic solutions showed that the guinea pig was a better model than the rabbit. Subcutaneous studies with microcapsule suspensions and anesthetic solutions are in progress. Author