2013 Volume 36 Issue 6 Pages 931-937
A novel reservoir-type transdermal system of 2,3,5,6-tetramethylpyrazine (TMP) was developed containing eucalyptus oil as a penetration enhancer. The single and multiple-dose pharmacokinetic profiles of TMP administrated by TMP transdermal patch were characterized in healthy volunteers using an in vivo, randomized, open-label, two-way crossover design. 2,3,5,6-Tetramethylpyrazine phosphate (TMPP) oral tablets were chosen as reference. Following single/multiple oral administration of 200/100 mg TMPP tablets, a TMP Cmax of 1284/613.5 ng/mL was observed within 0.75 h. Single/multiple applications of the TMP patch yielded mean Cmax of 309/325 ng/mL at a median Tmax of 5/4 h, with steady state achieved at second application. The mean Cmin of the patch was 131±30.38 ng/mL, contrasting to nearly zero for the tablet. Multiple applications of patch produced an accumulative effect over single application. At steady state 250 mg/20 cm2 TMP patch given daily provided comparable exposure to 100 mg TMPP tablets three times daily (3753.91 versus 3563.67 ng·h/mL). TMP tablets and patch yielded similar steady-state plasma concentrations: Cav (148.48±51.27, 156.41±40.31 ng/mL). The results demonstrated that TMP patch can achieve a therapeutic effect that is comparable to oral administration, exhibited prolonged and sustained plasma levels, fewer drug fluctuations, lower adverse effects, more convenience, and improved patient compliance. In-vitro permeation through human skin demonstrated zero-order kinetics with the flux of 364 µg/cm2/h. The predicted Cav (163.9 ng/mL) was in agreement with the observed Cav (156.4 ng/mL).
