Development of respirable rifampicin-loaded nano-lipomer composites by microemulsion-spray drying for pulmonary delivery

The purpose of this study was to develop respirable rifampicin (RIF) loaded nano-lipomer (lipid/polymer) composites for pulmonary delivery to increase the availability of drug at local site, and enhance the residence time of drug in the lungs and thereby improving the therapy. Rifampicin-loaded nano-lipid polymer (nano-lipomer) composites were prepared by a microemulsion-spray dry technique and were characterized for particle size, thermal stability, polymorphic transitions and chemical integrity. Furthermore, the lipomer were screened for their surface morphology and in vitro rifampicin release behavior in simulated lung fluid (artificial lysosomal fluid (ALF) at pH 4.5 and Gamble's solution at a pH of 7.4) represent different interstitial environment in the lung. The particle sizes of the lipomer were ranged between 382.5 ± 6.033 to 561.8 ± 4.965 nm with a narrow polydispersity index (0.315 ± 0.023 to 0.424 ± 0.033) and zeta potential (−32.5 ± 1.206 to −26.5 ± 1.211 mV). Rifampicin entrapment efficiency was between 61.25 ± 1.049 to 73.14 ± 1.048% and SEM images revealed well-separated, sphere-shaped and smooth surface lipomer. DSC and XRD analysis of lipomer corroborated that the formulations were in an amorphous state. New nano-lipomer formulated with different ratios of lipid and polymer exhibited a rapid dissolution by an initial burst release of RIF followed by a controlled release profile.

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