title: Optimisation and characterisation of bioadhesive controlled release tetracycline microspheres.
abstract: A Box-Behnken experimental design was employed to statistically optimise the formulation parameters of a tetracycline microsphere preparation for maximum bioadhesivity and controlled drug release. The quantitative effect of the formulation parameters at different levels on bioadhesion and drug release could be predicted using polynomial equations. A formulation comprising of 3% (w/w) chitosan, 10% (w/w) tetracycline HCl and 9% (w/v) tripolyphosphate was identified for maximising bioadhesivity and obtaining controlled drug release. The optimal microsphere preparation was subsequently characterised in terms of hydration dynamics, release kinetics, antimicrobial activity, thermal properties, morphology and surface pH. Kinetic models revealed that drug release followed Fickian diffusion while textural analysis showed minimal hydration over the test period. Antimicrobial studies showed that the drug concentrations in the in vitro release samples were above the minimum concentration of drug required for inhibition of Staphylococcus aureus growth. Thermal analyses showed a possible interaction between the drug and polymer. Scanning electron microscopy confirmed the integrity of the microspheres and identified the morphological changes following drug release. Surface pH of the microspheres was similar to salivary pH and did not show extremes in changes over the test period.
authors.affiliation: School of Pharmacy and Pharmacology, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa.
authors.forename: S
authors.initials: S
authors.lastname: Govender
authors.forename: V
authors.initials: V
authors.lastname: Pillay
authors.forename: D J
authors.initials: DJ
authors.lastname: Chetty
authors.forename: S Y
authors.initials: SY
authors.lastname: Essack
authors.forename: C M
authors.initials: CM
authors.lastname: Dangor
authors.forename: T
authors.initials: T
authors.lastname: Govender
mesh_terms: D000268:Adhesiveness; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000737:chemistry* / Q000494:pharmacology; D003692:Delayed-Action Preparations / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology; D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008863:Microspheres; D008956:Models, Chemical; D012995:Solubility; D013211:Staphylococcus aureus / Q000187:drug effects; D013499:Surface Properties; D013752:Tetracycline / Q000008:administration & dosage / Q000737:chemistry* / Q000494:pharmacology; D013816:Thermodynamics
chemical_list: D000900:Anti-Bacterial Agents; D003692:Delayed-Action Preparations; D013752:Tetracycline