chitosan

In present work calcium alginate (CA) microbeads encapsulated clonidine hydrochloride was prepared by ionotropic external gelation method in which calcium chloride used as cross-linking agent. Clonidine hydrochloride is a sympatholytic centrally acting α2 adrenergic agonist and imidazoline receptor agonist used to treat high blood pressure, attention deficit hyperactivity disorder, anxiety disorders, migraine, and menopausal flushing but it have very short half life which required some new approach which help to retain it in the body for longer period of time. Calcium alginate microbeads represent a useful tool for oral sustained/ controlled drug delivery. The prepared alginate beads were studied for percent loading efficiency, average particles size, shape and surface morphology, Differential Scanning calorimeter (DSC) and drug release behavior. Chitosan and HPMC incorporated in addition to overcome rapid drug release at higher pH due to its high porosity. Prepared optimized alginate microbeads formulation found to be 356.22±8.1nm average in size, 86.46±2.6% entrapment efficiency. DSC and FT-IR confirm no interaction with the polymers used in the formulation. High concentration of polymer and CaCl2 increase the drug loading efficiency while high concentration of CaCl2  also retard the release of clonidine hydrochloride from the beads. The shape and surface morphology was determined by scanning electron microscopy (SEM) and found the beads in smooth and spherical in shape. In-vitro release study showed that microbeads release 97.85 % drug in 7 hr which was pH dependent and also due to swelling and surface erosion. Microbead release the drug which follow Higuchi matrix diffusion release kinetic. Finally it is concluded that alginate, HPMC and chitosan in combination can be used to prepare microbead to encapsulate clonidine hydrochloride in higher amount. Biodegradable and non toxic nature of polymer make the prepared microbeads suitable for oral administration. 

To increase the low bioavailability and short ocular residence time of lomefloxacin eye drops, aqueous solutions of drug in chitosan/ Pluronic (poloxamer) were prepared to identify suitable compositions with regard to gel forming properties and drug release behaviour. Mixtures of solutions of Pluronic (10-25% w/w) with chitosan (0.1-0.3% w/w) of different molecular weights (Mw) were prepared. Lomefloxacin release was determined using a membrane less dissolution model in artificial tear solution up to 8 hours and the samples were analyzed spectrophotometrically at 281nm. The rheological behaviour of solutions in response to dilution or temperature changes and also the phase change temperature (PCT) were determined using a brookfield’s viscometer. Antimicrobial effect of the solutions was studied in nutrient agar using Staphylococcus aureus by using agar well diffusion method. The formulation consisted of 15% Pluronic and 0.1% low Mw chitosan, with the highest release efficiency (41.952 %) , is suggested as a suitable ophthalmic preparation for sustained release of lomefloxacin HCl. It was liquid in non-physiologic conditions (pH 4 and 25ºC) and transferred to the gel form upon physiologic conditions (pH 7.4 and 37ºC). The PCT of this in situ gel did not change upon dilution.