1Medical Cyclotron Facility, BRIT/BARC, TMC Annexe, Parel, Mumbai-400 012.
2Department of Pharmaceutics, Bombay College of Pharmacy, Santacruz (E), Mumbai - 400 098
3Department of Medicine, Bombay Veterinary College, Parel, Mumbai - 400 012.
An inhalation aerosol, as a mode of pulmonary drug targeting is most preferred technique. However, various techniques have one or other drawbacks. Scintigraphic imaging of liposome formulations labeled with 99mTc is a useful tool to study the pulmonary deposition and is accepted as proof of concept in pharmaceuticals industry. The present study aims to use the gamma scintigraphy to assess the pulmonary deposition and retention of liposomal formulation of budesonide, a widely used corticosteroid in treatment of asthma. Liposomal formulation will offer advantage of reduced toxicity and prolonged residence time for better patient compliance.
Budesonide loaded liposomes were prepared by lipid film hydration method and freeze-drying. The liposomes were labeled with 99mTc using SnCl2 as a reducing agent after rehydration. Inhalation of 5 mCi 99mTc labeled liposomes (10ìg/rabbit) was given for 10 minutes to albino rabbits in a specially designed inhalation chamber in order to avoid body contamination. The static scintigram was acquired on gamma camera-computer system (GE-Integra) at various intervals and data was analysed after applying decay correction.
The pulmonary clearance time for 99mTco4− in liposomes was very rapid (T1/2; 8–10 min) and hence not considered suitable for pulmonary deposition studies), whereas in case of labeled liposomes it was very slow, more than 94% of the activity was retained even at the end of 12 hrs, which indicates the sustaining action of liposomal budesonide.
In conclusion, liposomes can be effectively used as pulmonary reservoir to sustain the drug release and scintigraphy technique is useful to study pulmonary drug targeting.
Liposomes, Pulmonary Deposition, Scintigraphy, Labelled
