Study On Percutaneous Microemulsion Formulation And Its Initial Pharmacokinetics

OBJECTIVESuitable vehicles for Pae percutaneous ME and stability of the ME had been defined with prescription study. Its single dosage pharmacokinetics with i.v, i.g and local administration were inspected to find out difference of bioavailability between different administration.METHODS1 Based on the formation of microemulsion system for the indicators of the size of the region and certain Km values, changes in different ratio of mixed surfactant, oil phase and Km values we defined the proportion of the Pae percutaneous ME system. Distinguished types of ME according to conductivity. Pae percutaneous ME test method of high performance liquid chromatography (HPLC) was established. Cumulative infiltration of drug concentration in Franz diffusion cells was measured by HPLC with skin of male mice as penetrate barrier, then calculating cumulative permeation amount (Q) and penetration rate (J). According to Q values and J values to determine percutaneous penetration and its concentration, and to determine the final prescription. Examining the defined Pae percutaneous ME system's characteristics, such as viscosity , particle size, conductivity and stability.2 Building the test method of plasma concentration of Pae in mice. Establish the HPLC assay by Hypersil C18 column (4.6mm×250mm, 5μm)with methanol-water (40:60, V:V) at a flowing speed of 0.8ml·min^-1, wavelength of UV was 230nm, and 20μl sample was injected into the C18 column after filtering through 0.45μm microporous membrane, meanwhile the temperature of column was 30℃. Single administration was given to mice at different way and dosage, such as intravenous injection(i.v) with Pae(NS) 20mg·kg^-1, oral administration(i.g) Pae(0.5% CMC-Na) with 3 levers of 80mg·kg^-1,40mg·kg^-1,20mg·kg^-1 and Pae percutaneous ME with 3 levers of 80mg·kg^-1,40mg·kg^-1,20mg·kg^-1. At the certain time points we picked eyeballs of mice to get blood and tested the plasma concentration of Pae. DAS statistical analysis software was used to calculate the pharmacokinetic parameters of the treatment group. Compared bioavailability(F) of Pae after different administration.RESULTS1 We selected the IPM / lecithin / ethanol /water system as the vehicle of ME of water in oil type. Pae itself does not have percutaneous capacity, however, ME with 5% azone as a percutaneous vehical supplied so well ability and cumulative permeation amount of Pae percutaneous ME reached 38.79μg·cm^-2 and penetration rate was 6.14μg·h^-1·cm^-2. Release effect of infiltration process in vitro was typical slow-release (in line with the Higuchi model). Stability within a day and nomal enviroment was well besides of good mechanical stability.2 Plasma concentration of i.g Pae 40mg·kg^-1 and 20mg·kg^-1 dosage and Pae percutaneous ME of 20mg·kg^-1 dosage couldn't be tested. Characteristics of plasma concentration-time curve of single dosage of i.v Pae 20mg·kg^-1, single dosage of i.g 80mg·kg^-1 and single dosage of 40mg·kg^-1 and 80mg·kg^-1 with Pae percutaneous ME were in line with the two-compartment model. Main pharmacokinetics parameters are as follow: Single i.v Pae (NS) 20mg·kg^-1: t_1/2α 9.257±6.509min;t_1/2β 49.931±23.086min;AUC_0-t 98.258±7.235mg/L*min;AUC_0-∞ 101.032±8.505mg/L*min ; MRT_0-t 37.157±1.592min ; MRT_0-∞ 44.788±3.722min;T_max 5min;C_max 2.631±0.239mg/L. Parameter Single i.g Pae 80mg·kg^-1 Single Pae percutaneous ME 40mg·kg^-1 Single Pae percutaneous ME 80mg·kg^-1 t_1/2α(h) 2.279±0.770 6.853±1.702 7.594±2.598 t_1/2β(h) 30.153±35.772 8.056±0.953 9.162±0.841 AUC_0-t(mg/L*h) 14.192±0.889 31.837±2.683 71.747±6.031 AUC_0-∞(mg/L*h) 16.862±2.681 33.339±2.768 74.310±6.241 MRT_0-t(h) 9.500±0.303 20.266±0.439 20.758±0.610 MRT_0-∞(h) 14.364±4.720 22.019±0.754 22.083±0.895 T_max(h) 6.000±0.000 24.000±0.000 21.600±3.286 C_max(mg/L) 1.313±0.142 1.341±0.185 3.081±0.240 The F of Pae percutaneous ME 40mg·kg^-1 in mice could be achieved at 16.50% and it could be higher to 18.39% under 80 mg·kg^-1 dosage much more than the F of i.g 80mg·kg^-1 which is only 4.17%. Peak concentrations were similar between i.g 80 mg·kg^-1 and Pae percutaneous ME 40mg·kg^-1. T_max of Pae percutaneous ME is always much longer than i.g so that the resistance time of Pae in the mice could be extended.CONCLUSION1 The prescription of the finally ME system was stable and permeatable.2 It could be drawn from the experimental results: Pae percutaneous ME significantly increased the F of Pae which provided reliable experimental evidence for the development of Pae.