Vishnu A. Patel

The present work was aimed to prepare respirable slow release formulation for isoniazid by spray drying method using hydrophilic carrier, chitosan. The chitosan microspheres were crosslinked with glutaraldehyde to modify release characteristics. Microspheres were prepared and evaluated for % yield, drug loading, moisture content, morphological characteristics, particle size, tapped densities, in vitro drug release, in vitro aerosolization and pharmacokinetic parameters. The scanning electron microscopy revealed that microspheres produced were spherical shaped with slight rough surface. The drug loading efficiency of microspheres showed drug loading efficiency was in the range of 84.44 % to 98.24 %. The in-vitro drug deposition revealed that mass median aerodynamic diameter of crosslinked chitosan microspheres (2.82 µm) was better than the uncrosslinked chitosan microspheres (3.85μm). The complete drug release was seen with uncrosslinked microspheres in two hour while crosslinked chitosan microspheres showed sustained drug release for more than 12 hrs. All the formulation batches showed Carr’s index in the range of 28.7 to 34.3 %. The fine particle fraction for crosslinked chitosan microspheres was found to be 69.1%. Pharmacokinetic differ among the free, crosslinked and uncrosslinked formulations. The crosslinked chitosan microspheres showed sustained drug release lasted for more than 3 days with half life of 31.67 hrs. In vitro and in vivo evaluation studies suggested that chitosan microspheres prepared with spray drying method showed promising aerosol properties having potential to use as sustained drug release formulation for isoniazid as inhalable microparticles. 

  The Aim of this study was preparation of dry powder formulation of rifampicin loaded polymeric microparticles as dry powder formulation for inhalation in effective tuberculosis treatment.The microparticles containing rifampicin (RIF) were prepared by spray drying method using different biocompatible polymers like chitosan and hydroxyl propyl methyl cellulose (HPMC) The microparticles and microparticle blend with coarse carrier Inhalac 230 were investigated for its aerosolization properties like emitted dose, Mass median aerodynamic diameter, Fine particle Fraction, Geometric Standard Deviation.The spray drying method produced wrinkle surfaced porous microparticles under the size range of 10µm. Mass median aerodynamic diameter obtained for all formulation ranged in 2.68 µm to 3.73 µm and Fine particle fraction in between 51.58 ± 5.36 to 72.74 ± 3.18. The lowest tapped density value obtained was 0.102 g/cm2 belong to formulation coded M1. In vitro deposition studies using cascade impactor showed emitted dose of > 90% for all batches. The polymeric microparticles produced by spray drying technique showed promising particle characteristics suitable for inhalation with Fine particle fraction (72.74 ± 3.18) of total emitted dose, after blending with lactose. The blending of the microparticles with Inhalac 230 allowed the Fine particle fraction values to increase by increasing the dispersibility of powder on inspiration. Key words: Rifampicin, Dry Powder Inhalation, Chitosan, HPMC, Interactive blend.