Ocular dorzolamide nanoliposomes for prolonged IOP Reduction: in-vitro and in-vivo evaluation in rabbits

Dorzolamide ophthalmic drop is one of the most common glaucoma medications but it has a short residence time in the eye. The aim of this study is to develop ocular dorzolamide HCl nanoliposomes [DRZ - nanoliposomes] and to evaluate their potential use for the treatment of ocular hypertension. Nanoliposomes were prepared using Reverse-phase evaporation vesicle [REV] and thin layer hydration [TLH] method with 7:3 and 7:4 molar ratios of phosphatidylcholine:cholesterol. The physicochemical properties of the formulations were investigated. Formulations with 7:4 lipid ratio were evaluated in terms of drug release, physical stability and ex vivo permeation through the excised albino rabbit cornea. The rabbits in groups of 6 were treated with selected DRZ - nanoliposomes or dorzolamide solution or marketed dorzolamid preparation [Biosopt®] and intraocular pressure [IOP] was monitored. Formulations with 7:4 molar ratio entrapped greater amount of drug compared to those with 7:3 lipid components ratio. DRZ - nanoliposomes with 7:4 lipid ratio showed more transcorneal permeation than Dorzolamide solution [p<0.05]; and the formulation prepared by TLH method exhibited higher permeability than that prepared by REV method [p<0.05]. The selected DRZ - nanoliposomes showed greater IOP lowering activity and a more prolonged effect compared to dorzolamide solution and Biosopt®. DRZ - nanoliposomes prepared by TLH method with 7:4 ratio showed promising results as a candidate for the treatment of ocular hypertension

Ion-exchange, an approach to prepare an oral floating drug delivery system for diclofenac

Using ion-exchange resins, a multiple-unit type of oral floating dosage system has been prepared to prolong gastric emptying time of dosage form. The system is composed of beads of drug-resin complex, which are loaded with bicarbonate ions and coated with a hydrophobic polymer. The system is so designed that when the beads reach the stomach, chloride ions are exchanged with bicarbonate and drug ions. The generated CO[2] is entrapped in the polymeric coated resins and causes the beads to float. In this study, Amberlite-IRA 900 was loaded with diclofenac and bicarbonate ions, using a batch method. The beads were encapsulated with a hydrophobic polymer [ethyl cellulose or Eudragit RS-100]. To find an appropriate formulation, the factors affecting the drug loading, floating ability and drug release were investigated. Based on the result obtained, maximum loading efficiency was attained at 3 h, using an aqueous diclofenac solution and resin beads measuring 430 m in diameter. Drug release from both uncoated complexes of diclofenac-resin, and diclofenac-bicarbonate-resin occurred via particle-diffusion. The ethyl cellulose-coated beads have a desirable floating capability in comparison with the Eudragit RS-100 coated beads on HC1 0.1M solution containing 0.02% polysorbate 80