Effect of pretreatment by cardamom oil on in vitro percutaneous penetration of piroxicam gel

The effect of pretreatment by the penetration enhancer, cardamom oil, on the percutaneous penetration of piroxicam from gel through rabbit abdominal skin was investigated using an in vitro technique. The flux and the cumulative amount (at the 48th h) after 1 h pretreatment with 10% cardamom oil in three vehicle systems (alcohol, alcohol/pH 5.8 buffer and alcohol/pH 7.4 buffer) were higher than that of nonpretreatment, and were similar to that of 3 or 6 h pretreatment. A specific correlation between the flux of piroxicam and the pretreatment period was found. Compared to the lag time of skin penetration of piroxicam for nonpretreatment, the lag time for pretreatment was remarkably diminished. The penetration index (PI) of piroxicam after 1 h pretreatment with 10% cardamom oil in alcohol/pH 7.4 buffer (50/40) was about 340.9-fold higher than that of nonpretreatment: In contrast to previous results, 1 h pretreatment with 10% cardamom oil in alcohol had no significant enhancing effect on the percutaneous penetration of piroxicam from gel dosage form. From these results, the alcohol proportion of the vehicle system was the more effective factor for penetration index.