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.

[Changes in serum concentration of podophyllotoxin after its topical application with liposome on rat skin].

OBJECTIVE: To investigate the changes of serum concentration of podophyllotoxin after topical application of liposome podophyllotoxin suspension on rat skin. METHODS: SD rats were used in this study, which were divided into test group (n=48) to receive application of liposome podophyllotoxin (0.5 % ) suspension and control group (n=48) treated with 0.5 % podophyllotoxin alcohol solution. Blood samples were obtained from the heart at 1, 2, 4, 6, 8, 10, 12 and 24 h respectively after drug application, and the serum concentration of podophyllotoxin was determined by spectrofluorometry. RESULTS: The area under the curve of plasma drug concentration of the control group was 2.3-fold greater than that of the test group. Eight hours after drug application, the serum concentration of podophyllotoxin reached the peak in the test group, while in the control group, only two hours was needed to reach the peak. The peak serum level of podophyllotoxin in the test group were significantly lower than that of the control group (166.395 +/- 14.634 ng/ml vs 378.603 +/- 26.105 ng/ml, P<0.001). CONCLUSION: The systemic absorption of podophyllotoxin in rats after its topical application in liposome suspension is significantly lower than that after application of 0.5 % podophyllotoxin alcohol solution, therefore the systemic toxicity may be reduced.