One-month sustained release microspheres of 125I-bovine calcitonin. In vitro-in vivo studies.
J Control Release
; 59(1): 55-62, 1999 May 01.
Article
em En
| MEDLINE
| ID: mdl-10210722
ABSTRACT
To obtain a 1-month release formulation of 125I-bovine calcitonin, microspheres were prepared with three different PLA copolymers, PLGA I (mol. wt. [MW]=30000), polyethyleneglycol (PEG)-PLGA (MW=34000) and PLGA II (MW=12000) using the double emulsion method. The release of 125I-bovine calcitonin was assayed in vitro using dialysis bags at 37 degrees C in isotonic phosphate buffer (pH 7.4). The in vitro release results indicated a very slow release rate for an optimal 1-month sustained release formulation. 125I-bovine calcitonin microspheres were administered under the skin on the back of Wistar rats and the radioactivity at the injection site was subsequently measured over a 4-week period. The in vitro and in vivo profiles were affected by the weight average molecular weight of the copolymers. The 125I-bovine calcitonin release rate was faster from microspheres prepared with PLGA II (MW=12000) than from microspheres prepared with higher molecular weight copolymers (PLGA I and PEG-PLGA). Microspheres prepared with PLGA II (MW=12000) release 100% of the dose in 1 month, in vivo release profiles presented two phases, during the first 2 weeks approximately 70% of the 125I-bovine calcitonin injected was released, followed by a second slower phase.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Calcitonina
/
Radioisótopos do Iodo
Limite:
Animals
Idioma:
En
Revista:
J Control Release
Assunto da revista:
FARMACOLOGIA
Ano de publicação:
1999
Tipo de documento:
Article
País de afiliação:
Espanha