Purpose. The aim of this work was the formulation and characterization of a new doxycycline (Dox)- alginate complex hydrogel microparticles embedded into Pluronic F127 thermogel for doxycycline intradermal sustained delivery. Methods. Batches of Dox-Alginate complex MP were prepared by direct injection of a solution of the drug into a 1.5% polymer solution upon silverson stirring. The MP were recovered and freeze-dried. The hydrogel MP were successively formed by dispersing the MP into a 1.2% CaCl2 solution. The MP were characterized in terms of size, drug content, and release behavior by HPLC. Free Dox and hydrogel MP were then embedded into PF127, PF127-HPMC, and PF127-Methocel thermogels. The thermogels were produced by dissolving PF127 and HPMC or Methocel in phosphate buffer at 4°C and were characterized in terms of gelling time, morphology and release behavior. A target release period of 6-7 days was considered optimal. Results. Dox-Alginate complexation occurred spontaneously either in water or phosphate buffer upon mixing. The hydrogel MP were about 20 µm in size with 90% of the population < 59 µm. Drug content was about 35% w/w for all the preparations. Dox was released fast from the MP with a 90% after just 1-2 days. An expected faster release was also observed for free Dox from the thermogels with 80-90% of drug released after 3.5-4 hours, even in the presence of 1% HPMC or Methocel. The release was much slower and sustained after embedding the MP into PF127 and PF127-HPMC thermogels. In particular, the PF127-HPMC thermogel showed an almost linear release reaching 80% after 3 days and 90% up to 6 days. Conclusions. Although a further characterization and formulation assessment is needed to optimize MP characteristics, Dox-Alginate loaded hydrogel MP, when embedded into a PF127-HPMC thermogel, seem to be promising in order to achieve a 7 days sustained release formulation for Dox intradermal sustained delivery.

Formulation and release behavior of doxycycline- alginate complex hydrogel microparticles embedded into Pluronic F127 thermogels for doxycycline intradermal sustained delivery

GIOVAGNOLI, Stefano;
2008

Abstract

Purpose. The aim of this work was the formulation and characterization of a new doxycycline (Dox)- alginate complex hydrogel microparticles embedded into Pluronic F127 thermogel for doxycycline intradermal sustained delivery. Methods. Batches of Dox-Alginate complex MP were prepared by direct injection of a solution of the drug into a 1.5% polymer solution upon silverson stirring. The MP were recovered and freeze-dried. The hydrogel MP were successively formed by dispersing the MP into a 1.2% CaCl2 solution. The MP were characterized in terms of size, drug content, and release behavior by HPLC. Free Dox and hydrogel MP were then embedded into PF127, PF127-HPMC, and PF127-Methocel thermogels. The thermogels were produced by dissolving PF127 and HPMC or Methocel in phosphate buffer at 4°C and were characterized in terms of gelling time, morphology and release behavior. A target release period of 6-7 days was considered optimal. Results. Dox-Alginate complexation occurred spontaneously either in water or phosphate buffer upon mixing. The hydrogel MP were about 20 µm in size with 90% of the population < 59 µm. Drug content was about 35% w/w for all the preparations. Dox was released fast from the MP with a 90% after just 1-2 days. An expected faster release was also observed for free Dox from the thermogels with 80-90% of drug released after 3.5-4 hours, even in the presence of 1% HPMC or Methocel. The release was much slower and sustained after embedding the MP into PF127 and PF127-HPMC thermogels. In particular, the PF127-HPMC thermogel showed an almost linear release reaching 80% after 3 days and 90% up to 6 days. Conclusions. Although a further characterization and formulation assessment is needed to optimize MP characteristics, Dox-Alginate loaded hydrogel MP, when embedded into a PF127-HPMC thermogel, seem to be promising in order to achieve a 7 days sustained release formulation for Dox intradermal sustained delivery.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11391/1032291
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