Experimental study of podophyllotoxin dipalmitoylphosphatidylcholine liposome for topical skin application.

Objective: To observe the drug release of podophyllotoxin liposome and the drug retention in the skin.

Methods: Two liposome suspensions containing respectively podophyllotoxin dipalmitoylphosphatidylcholine (DPPC) and soya bean lecithin were prepared ultrasonically. Podophyllotoxin anhydride and the liposome suspensions were applied onto the skin of young pigs to observe the drug retention in the skin at different time points in the following 2 days, with exclusive liposome or anhydride serving as control.

Results: One hour after application of podophyllotoxin anhydride, a peak of the drug concentration in the skin occurred followed by immediate declination, a process not observed after the application of bean lecithin liposome due to gradual drug release that produced drug concentration constantly much higher than that of podophyllotoxin anhydride. A peak concentration was also observed 4 h after application of podophyllotoxin DPPC liposome, which then declined slowly to and stabilized at a higher level than that of bean lecithin liposome of anhydride within 48 h.

Conclusion: DPPC liposome-embedded podophyllotoxin better targets the drug to the skin after application, and is a suitable preparation for topical skin application.