Solid dosage forms of antibiotics are not readily accepted by paediatric class of patients. Commercially available Suspensions and reconstitutable oral suspensions have very short shelf life expectancy and need unusual storage conditions, and instructions for usage. Paediatric oral powders for suspensions are available which are merely stable for 5-7 days after reconstitution.
The objective of this work was to formulate an antibiotic dry syrup, which would not only show improved physical and chemical stability during its intended shelf life, but also proffer greater bioavailability of antibiotics. Solubility and bioavailability of azithromycin dihydrate was first improved using solid dispersion technique, inclusion complexation and nanosuspensions and then formulated into dry syrups/ oral suspensions for reconstitution. By this, solubility, bioavailability could be improved, and taste masking could be achieved.
Solubility enhancement by solid dispersions was carried out through use of poloxamer 188, poloxamer 407 and polyethylene glycol 20,000 as carriers in two different concentrations and two methods- solvent evaporation and freeze drying. Similarly, Inclusion complexation using β-cyclodextrin, epichlorohydrin- β-cyclodextrin and sulfobutyl ether cyclodextrin was attempted using solvent evaporation and freeze drying. Nanosuspensions were also prepared using poloxamers and PVP, by nanoprecipitation technique and modified nanoprecipitation. All the solid dispersions, inclusion complexes and nanosuspensions were characterised using In-Vitro dissolution profiles, kinetic modelling, X ray diffractometry and SEM. In vitro dissolution profile data suggested a significant improvement in drug release with inclusion complexes using sulfobutyl ether cyclodextrin, prepared by freeze drying and nanosuspensions using poloxamer 188, prepared by nanoprecipitation with cryoprotectants. Hence, selected inclusion complexes and nanoparticles were used to formulate dry syrups using Viscarin ph 209 and Gelcarin ph 812 as suspending agents. Powdered dry syrups were evaluated before reconstitution for their flow properties, and results showed excellent flow properties. Post reconstitution evaluation results also suggested a stable, flocculated oral suspension with sedimentation volume closer to 1 over tested period. The results from this work specified that bioavailability improved antibiotics can markedly reduce dose of the drug, used to produce therapeutic response. Selection of fitting suspending agents like, gelcarin and viscarin in this present work can improve in storage stability even without refrigerated conditions.