A simple technique for entrapping rifampicin and isoniazid into liposomes.

A method for the preparation of liposomes loaded with rifampicin and isoniazid is described. Optimal conditions were established; the lipid suspension was mixed with the aqueous solution of the drugs and was sonicated in a bath for 30 min at 50 degrees C. The optimum composition tested was phosphatidyl choline, cholesterol and cardiolipin in a molar ratio of 7:2:1. The separation of unloaded drug was performed by centrifugation through three successive Sephadex G-25 columns. The liposomes were multilamellar vesicles with a size ranging from 100-300 nm. The drugs were trapped in concentrations from 6.5-9.5 mg/ml. This method is suitable for preparation of liposomes in small laboratories.

The use of rifampicin and isoniazid entrapped in liposomes for the treatment of Murine tuberculosis.

Liposomes loaded with rifampicin and isoniazid were used experimentally to treat mice with severe tuberculosis. The animals were distributed in four groups. The control group and the group treated with unloaded liposomes showed the severest disease. Both groups showed the lowest accumulated survival, about 50% after 30 days. The numbers of colony-forming-units (CFU) and root specific lung weight (RSLW) were the highest and the histopathology of the lung showed marked diffuse lesions. However, the group treated with unloaded liposomes showed significantly higher growth of M. tuberculosis compared with the control. The group treated with drug and drug loaded liposomes showed a higher survival, about 85% after 30 days, and the lowest values of CFU and RSLW. The lung histology revealed considerably less inflammation which was focal. The parameters evaluated indicated a significantly better response in the group of animals treated with rifampicin and isoniazid entrapped in liposomes.