Abstract

NANO EMULSION (THALIDOMIDE) AS PARENTERAL: A MODERN NEW NOVEL DRUG DELIVERY SYSTEM

Dr. Pawan Avahad*, Ashwini Dokhale and Pravin Pawar, Omkar Dharak, Shital

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Abstract

This study reports the development of Nano emulsions intended for intravenous administration of thalidomide (THD). The formulations were prepared by spontaneous emulsification method and optimized with respect to thalidomide (0.01–0.05%, w/w), and hydrophilic emulsifier (polysorbate 80; 0.5–4.0%, w/w) content. The formulations were evaluated concerning physical appearance and drug crystallization; droplet size; zeta potential and drug assay. Only the formulation containing 0.01% THD and 0.5% polysorbate kept its properties in a satisfactory range over the evaluated period (60 days), i.e. droplet size around 200 nm, drug content around 95% and zeta potential around −30 mV. The transmission electron microscopy revealed emulsion droplets almost spherical in shape confirming the results obtained by photon correlation spectroscopy. Drug crystallization observed for higher content (THD 0.05%, w/w) Nano emulsions was investigated. The crystals observed at optical microscopy presented a different crystal habit compared to that of the raw material used. It was speculated whether the kind of THD polymorph employed could influence Nano emulsion formulation. Formulations were prepared with either one of THD polymorphs (- or -) and crystals were characterized by Fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XRD)6. It was observed that regardless of the polymorph employed (- or -), drug crystallization occurs in the -form. THD solubility in oils was not influenced by the polymorphic form. In addition, the in vitro dissolution profile of the selected formulation (THD 0.01%, w/w; polysorbate 0.5%, w/w) was assessed by bulkequilibrium reverse dialysis sac technique and demonstrated a release profile similar to that of a THD acetonitrile solution, with around 95% THD being dissolved within 4 h. Finally, a pharmacokinetic simulation of an intravenous infusion of 250 mL of the selected Nano emulsion suggests that the parenteral administration of a dose as low as 25 mg might lead to therapeutic plasma concentrations of thalidomide.[15]

Keywords: Thalidomide THD, Nano emulsions, Spontaneous emulsification, Reverse dialysis, Pharmacokinetic simulation.