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In vitro cell compatibility and antibacterial activity of microencapsulated doxycycline designed for improved localized therapy of septic arthritis


Haerdi-Landerer, M C; Suter, M M; Steiner, A; Wittenbrink, M M; Pickl, A; Gander, B A (2008). In vitro cell compatibility and antibacterial activity of microencapsulated doxycycline designed for improved localized therapy of septic arthritis. Journal of Antimicrobial Chemotherapy, 61(2):332-340.

Abstract

OBJECTIVES: For the treatment of septic arthritis in large animals, the local application of antibiotics as a slow release system may be an appropriate means to reach high local bioactivity and low systemic side effects and drug residues. In this study, doxycycline microspheres were developed and tested in vitro for their drug-release properties, suitability for intra-articular application and antimicrobial activity. METHODS: The development of a slow release system was achieved by microencapsulation of the drug into poly(lactide-co-glycolide) microspheres by a novel ultrasonic atomization method. Drug elution was evaluated from microspheres dispersed in elution medium at pre-defined time points by HPLC. Joint-tissue compatibility was tested on cultured bovine synoviocytes by evaluating the expression of pro-inflammatory cytokine mRNA and the production of nitric oxide (NO). Finally, the antimicrobial activity of the released antibiotic was assessed with gram-negative and gram-positive bacteria exposed to release medium sampled at days 1, 7 and 12 after microsphere suspension. RESULTS: An adequate size of the microspheres, sufficient stabilization of doxycycline in aqueous environment and drug release (25 mg microspheres in 4 mL medium) above MIC for bacteria usually isolated in bovine and equine joints were obtained over 15 days. Although the cytokine mRNA expression reflected the excellent tissue compatibility, the results with NO yielded contradictory results. Antimicrobial tests of the release medium proved to match perfectly the activity of non-encapsulated, free doxycycline as reported in the literature. CONCLUSIONS: The newly developed doxycycline delivery system achieved the target specifications and is ready for in vivo testing.

Abstract

OBJECTIVES: For the treatment of septic arthritis in large animals, the local application of antibiotics as a slow release system may be an appropriate means to reach high local bioactivity and low systemic side effects and drug residues. In this study, doxycycline microspheres were developed and tested in vitro for their drug-release properties, suitability for intra-articular application and antimicrobial activity. METHODS: The development of a slow release system was achieved by microencapsulation of the drug into poly(lactide-co-glycolide) microspheres by a novel ultrasonic atomization method. Drug elution was evaluated from microspheres dispersed in elution medium at pre-defined time points by HPLC. Joint-tissue compatibility was tested on cultured bovine synoviocytes by evaluating the expression of pro-inflammatory cytokine mRNA and the production of nitric oxide (NO). Finally, the antimicrobial activity of the released antibiotic was assessed with gram-negative and gram-positive bacteria exposed to release medium sampled at days 1, 7 and 12 after microsphere suspension. RESULTS: An adequate size of the microspheres, sufficient stabilization of doxycycline in aqueous environment and drug release (25 mg microspheres in 4 mL medium) above MIC for bacteria usually isolated in bovine and equine joints were obtained over 15 days. Although the cytokine mRNA expression reflected the excellent tissue compatibility, the results with NO yielded contradictory results. Antimicrobial tests of the release medium proved to match perfectly the activity of non-encapsulated, free doxycycline as reported in the literature. CONCLUSIONS: The newly developed doxycycline delivery system achieved the target specifications and is ready for in vivo testing.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:05 Vetsuisse Faculty > Institute of Veterinary Bacteriology
Dewey Decimal Classification:570 Life sciences; biology
Language:English
Date:February 2008
Deposited On:26 Feb 2009 07:44
Last Modified:05 Apr 2016 13:03
Publisher:Oxford University Press
ISSN:0305-7453
Additional Information:This is an article accepted for publication in Journal of Antimicrobial Chemotherapy, published by Oxford University Press on behalf of the British Society . The definitive publisher-authenticated version is available online at: http://jac.oxfordjournals.org/cgi/content/full/61/2/332
Publisher DOI:https://doi.org/10.1093/jac/dkm491
PubMed ID:18174200

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