期刊
EUROPEAN JOURNAL OF PHARMACEUTICS AND BIOPHARMACEUTICS
卷 55, 期 2, 页码 229-236出版社
ELSEVIER
DOI: 10.1016/S0939-6411(02)00169-8
关键词
poly(epsilon-caprolactone) microspheres; spray-dryer; bupivacaine; in vitro and in vivo drug release; histological studies
Poly (epsilon-caprolactone) microspheres containining bupivacaine were prepared by the spray-drying process. The average size of drug loaded microspheres was less than 3 mum in diameter, and the percentage of entrapment efficiency was 91 +/- 3%. In vitro drug release kinetic in phosphate buffer at 37degreesC showed a hyperbolic profile, with a burst-effect during the first hour. Subcutaneous injection of bupivacaine-loaded microspheres in the back of rats caused an increase in drug concentration in plasma. Maximum bupivacaine concentration in plasma was 237 +/- 58 ng/ml at 105 h, and drug was detected in plasma for 16 days. The half-life time of the drug was increased by more than 125 times with regard to that of the drug administered in a solution by intraperitoneal injection. After 30 days of injection, a mass formed by microspheres surrounded by a thin fibrous capsule was observed. Small blood vessels and multinucleate foreign body giant cells with macrophagic function around microspheres were detected. After 60 days of injection a subcutaneous mass was also observed, which was formed of more degraded dispersed microspheres in conjunctive tissue, which had a normal structure. Thus, bupivacaine-loaded poly(epsilon-caprolactone) microspheres could be considered as a device to be used in the treatment of severe pain that is not responsive to opioids for example in cancer-related syndromes or in intractable herpetic neuralgia. (C) 2003 Published by Elsevier Science B.V.
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