ABSTRACT
This study examined the effect of self-microemulsiflying drug delivery system (SMEDDS) containing Cremophor RH40 or Tween 80 at various dilutions on cytochrome P450 3A (CYP3A) enzymes in rat hepatocytes, with midazolam serving as a CYP3A substrate. The particle size and zeta potential of microemulsions were evaluated upon dilution with aqueous medium. In vitro release was detected by a dialysis method in reverse. The effects of SMEDDS at different dilutions and surfactants at different concentrations on the metabolism of MDZ were investigated in murine hepatocytes. The cytotoxicity of SMEDDS at different dilutions was measured by LDH release and MTT technique. The effects of SMEDDS on the CYP3A enzymes activity were determined by Western blotting. Our results showed that dilution had less effect on the particle size and zeta potential in the range from 1:25 to 1:500. The MDZ was completely released in 10 h. A significant decrease in the formation of 1'-OH-MDZ in rat hepatocytes was observed after treatment with both SMEDDS at dilutions ranging from 1:50 to 1:250 and Cremophor RH 40 or Tween 80 at concentrations ranging from 0.1% to 1% (w/v), with no cytotoxicity observed. A significant decrease in CYP3A protein expression was observed in cells by Western blotting in the presence of either Cremophor RH40 or Tween 80-based SMEDDS at the dilutions ranging from 1:50 to 1:250. This study suggested that the excipient inhibitor-based formulation is a potential protective platform for decreasing metabolism of sensitive drugs that are CYP3A substrates.
ABSTRACT
This investigation describes a new precise, sensitive and accurate stereoselective RP-HPLC method for determination of the enantiomers of a novel alpha- and beta-receptor blocking agent, 1-[4-(2-methoxyethyl) phenoxy]-3-[[2-(2- methoxyphenoxy) ethyl]amino]-2-propanol (TJ0711), in rat plasma. GITC was used for precolumn derivatization of TJ0711 enantiomers. Enantiomeric resolution was achieved on a Eurospher-100 C18 column (250 mmx4.6 mm ID, 5-mum particle size), with UV detection at 255 nm, and the mobile phase consisted of acetonitrile and water (58:42, v/v) containing 0.02% glacial acetic acid (v/v). Using the chromatographic conditions described, TJ0711 enantiomers were well resolved with mean retention time of 10.2 and 11.5 min, respectively. Linear response (r>0.999) was observed over the range of 0.125-12.5 mug/mL of TJ0711 hydrochloride enantiomers. The mean relative standard deviation (RSD%) of the results of within-day precision was [Symbol: see text] 10%. The proposed method was found to be suitable and accurate for the quantitative determination of TJ0711 enantiomers in rat plasma, and it can be used in pharmacokinetic studies.
ABSTRACT
To investigate the disposition and tissue distribution of ML12 after intravenous (iv) administration in rats, the compound in plasma or in tissue was extracted into ethyl acetate under basic condition and was determined by HPLC after extracted by dilute sulfuric acid. Excitation wavelength and emission wavelength of fluorescence detection were 278 nm and 307 nm, respectively. The data were processed with the software 3P97 to calculate the main pharmaceutical parameters of ML12. At dose of 5 and 10 mg/kg, the elimination of the drug from plasma was found to be kinetically linear, but when the dosage was 20 mg/kg, a non-linear feature was observed. The highest level of ML12 was found in the kidney. Distribution of ML12 after iv administration was extensive and the concentration-time profile was found to be fitted to an open two-compartment model.
Subject(s)
Antihypertensive Agents/pharmacokinetics , Biological Availability , Chromatography, High Pressure Liquid/methods , Kinetics , Pharmaceutical Preparations , Rats, Sprague-Dawley , Spectrometry, Fluorescence/methods , Sulfuric Acids/chemistry , Tissue DistributionABSTRACT
OBJECTIVE:To study the pharmacokinetics of hydrochlorothiazide and valsartan in healthy volunteers after single administration of its compound dispersible tablets.METHODS:Plasma concentrations of hydrochlorothiazide and valsartan were determined by HPLC and their pharmacokinetic parameters were calculated with DAS software.RESULTS:The pharmacokinetic parameters of hydrochlorothiazide at low,medium and high doses were as follows:t1/2 were(12.56?3.66),(11.47?5.47) and(11.20?5.03) h,respectively;Cmax were(72.00?19.68),(169.96?52.17) and(203.66?61.41)ng ?mL-1,respectively;AUC0～48 were(592.87?179.44),(1 155.45?252.03) and(1 410.99?331.82) ng?h?mL-1,respectively;AUC0～∞ were(779.76?201.42),(1 246.89?307.03) and(1 482.14?332.20) ng?h?mL-1,respectively.The pharmacokinetic parameters of valsartan at low,medium and high doses were as follows:t1/2 were(7.29?3.10),(8.56?2.22) and(8.62?2.86)h,respectively;Cmax were(2.12?0.65),(6.76?2.08) and(6.71?2.59)ng ?mL-1,respectively;AUC0～48 were(18.16?4.52),(41.77?10.86) and(51.77?27.45) ng?h?mL-1,respectively;AUC0～∞ were(19.07?5.56),(42.60?11.18) and(53.49?26.93) ng?h?mL-1 respectively.CONCLUSION:The pharmacokinetics for compound valsartan dispersible tablet fitted linear kinetics process.There is no interaction in pharmacokinetics between hydrochlorothiazide and valsartan when they used in combination.