Novel Drying Technology of Microsphere and Its Evaluation for Targeted Drug Delivery for Lungs

Abstract

Carbopol microspheres of methotrexate (MxtCM), a drug used in the treatment of lung cancer, were prepared using a Buchi B-90 nano spray dryer. The surface morphology was found to be shriveled to nearly spherical, with an average size of 6.8 µm. The drug loading and percentage yield were found to be 77% ± 0.3% and 89% ± 0.4%, respectively. The in-vitro release was suggestive of the Baker and Lonsdale model, as the release pattern involved swelling and diffusion; the total methotrexate release after 12 h was 98.2% from MxtCM while, for the pure drug, it was 94.2% at 0.5 h. Liquification was witnessed during the stability studies at 37°C and at a relative humidity of 75%. This study concludes that the microsphere could be one of the most appropriate drug delivery methods for the successful delivery of methotrexate to the lungs. The pharmacokinetic (drug concentration) results following intravenous administration were 1,021 µg/g after 15 min; in comparison, in the spleen and liver, the concentration of the conventional dosage of Mxt was <401 µg/g after 10 min. We concluded that the methotrexate concentration was increased in the lungs when compared to the blood, spleen, and liver. The ingredients used in the formulation were confirmed harmless from histopathological studies. Thus, microspheres can be adopted in formulating and targeting methotrexate to the lungs.

Keywords:

• In-vitro release kinetics
• Lung targeting
• Methotrexate
• Microspheres
• Spray drying