Pattana Sripalakit

A simple bioanalytical assay for determination of montelukast in human plasma: application to a pharmacokinetic study.

An analytical method based on high-performance liquid chromatographic (HPLC) was developed for the determination of montelukast in human plasma using mefenamic acid as an internal standard. After precipitation of plasma proteins with acetonitrile, chromatographic separation was carried out using a Zorbax Eclipse XDB C8 (150 mm x 4.6 mm i.d., 5 microm) with mobile phase consisted of methanol-acetonitrile-0.04M disodium hydrogen orthophosphate (22:22:56, v/v, pH 4.9). The wavelengths of fluorescence detection were set at 350 nm for excitation and 450 nm for emission. The linearity was confirmed in the concentration range of 5-1000 ng/ml in human plasma. Intra- and inter-day accuracy determined from quality control samples were 101.50 and 107.24%, and 97.15 and 100.37%, respectively. Intra- and inter-day precision measured as coefficient of variation were < or =4.72 and < or =9.00%, respectively. Extraction recoveries of drug from plasma were >48.14%. The protocol herein described was employed in a pharmacokinetic study of tablet formulation of montelukast in healthy Thai male volunteers.

Bioconversion of hydrocortisone to prednisolone by immobilized bacterial cells in a two-liquid-phase system

Bioconversion of hydrocortisone to prednisolone by free, immobilized and reused immobilized cells of three bacterial strains (Bacillus sphaericus ATCC 13805, Bacillus sphaericus SRP III and Arthrobacter simplex 6946) in an aqueous and a two-liquid-phase system using different organic solvents was investigated. The experiments were carried out in a 125 cm3 shake flask at 27±2°C, 220 rpm for 96 h. The contents of prednisolone and hydrocortisone in samples taken at 0, 3, 6, 24, 48, 72, 96 and 144 h were determined by HPLC analysis. The immobilized bacterial cells showed higher prednisolone yield than the free form in an aqueous system. In the two-phase systems, the butyl acetate to aqueous media ratio of 1: 30 for all three bacterial strains in immobilized forms gave the highest prednisolone yields, at an incubation time of 144 h, of 87·6, 70·6 and 88·3% respectively. For an n-decane to aqueous ratio of 1: 6, moderate prednisolone yields of 81·8, 47·9 and 71·4% were obtained with shorter incubation times of 72, 96 and 6 h respectively. For cyclohexane and other alcohols, the organisms produced low yields of prednisolone (0–30%). Single reuse of all three immobilized bacterial cells gave a 3–20% lower yield of prednisolone than the non-reused cells. The increase in hydrocortisone concentration decreased the prednisolone production whereas increasing the n-decane to aqueous ratio from 1: 6 to 1: 3 caused no significant change in the productivity.

Effect of Bacopa monniera Linn. extract on murine immune response in vitro

The study was to investigate and compare the effects of the Bacopa monniera Linn. extract and bacoside A on the ICR mice immune system in vitro. Splenocyte proliferation without or with mitogen (lipopolysaccharide, pokeweed mitogen, phytohaemagglutinin and concanavalin A) and phagocytic activity were assayed. The results showed that B. monniera extract at 0.001–1 mg/mL slightly suppressed splenocyte proliferation (SI 0.7) and decreased T‐lymphocyte proliferation (SI 0.4) at 0.001 and 0.1 mg/mL with concanavalin A. Bacoside A at 0.001 mg/mL gave the highest splenocyte proliferation (SI 1.5) and strongly increased T‐lymphocyte proliferation (SI 2.0) at 0.1 mg/mL with concanavalin A. Thus, it is possible to attribute the effect of B. monniera extract on splenocyte proliferation to the presence of bacoside A with other combined components. However, only B. monniera extract at 10 mg/mL produced a slight increase in lysosomal enzyme activity (PI 1.2), indicating a weak effect on phagocytic activation. It might be concluded that B. monniera manifests various effects on the murine immune system depending on the immune cell types, in accordance with its folklore uses. New assays are being carried out to study its mechanisms and to further investigate its applications in the treatment of human immune mediated diseases. Copyright

Bioequivalence Evaluation of Two Formulations of Doxazosin Tablet in Healthy Thai Male Volunteers

ABSTRACT The bioequivalence of two doxazosin 2 mg tablets was determined in 24 healthy Thai male volunteers after one single dose in a randomized cross-over study with a one week washout period. The study was conducted at Faculty of Pharmaceutical Sciences and Health Sciences Research Institute, Naresuan University, Phitsanulok, Thailand. Reference (Cardura®, Heinrich Mack Nachf. GmbH & Co. GK, Illertissen, Germany) and test (Dozozin-2®, Umeda Co., Ltd., Bangkok Thailand) were administered to volunteers after overnight fasting. Blood samples were collected at specified time intervals and plasma was separated. The validated HPLC method with fluorescence detection was used for quantification of doxazosin in plasma samples. The pharmacokinetic parameters, Tmax, Cmax, AUCt, AUC∞, T1/2, λz, Cl and Vd, were determined from plasma concentration time profile of both formulations by using non-compartment analysis. The calculated pharmacokinetic parameters were compared statistically to evaluate bioequivalence between the two brands. The analysis of variance (ANOVA) using log-transformed Cmax, AUCt, and AUC∞ did not show any significant difference between two formulations. The point estimates and 90% confidence intervals for Cmax, AUCt and AUC∞ were within the acceptance range (0.80–1.25), satisfying the bioequivalence criteria of the Thailand Food and Drug Administration Guidelines. These results indicate that Dozozin-2® is bioequivalent to Cardura® and, thus, may be prescribed interchangeably.

Comparative Study on the Bioequivalence of Two Formulations of Pioglitazone Tablet in Healthy Thai Male Volunteers

The bioequivalence study of two 30 mg pioglitazone formulations was determined in healthy Thai male volunteers after a single dose administration in a randomized cross-over study with a 1-week washout period. Due to the high variability of the rate and extent of absorption of pioglitazone, an add-on subject study was required to assess bioequivalence. Reference product (Actos®, Takeda Chemical Industries, Ltd., Osaka, Japan) and test product (Glubosil®, Silom Medical Co. Ltd., Bangkok, Thailand) were given to 35 volunteers after overnight fasting. Blood samples were collected at specified time intervals. Plasma was analyzed for pioglitazone concentration using a validated HPLC method. Pharmacokinetic parameters were compared between test and reference products from plasma concentration-time profile by using non-compartment analysis. The statistical comparison of Cmax and AUC0−t, AUCt−∞ clearly indicated that no significant difference in two products of pioglitazone tablets in add-on subject study. The 90% confidence intervals for the mean ratio (test/reference) of Cmax and AUC0−t, AUCt−∞ were within the Thailand Food and Drug Administration acceptance range. Based on the pharmacokinetic and statistical results of this study, we can conclude that Glubosil® is bioequivalent to Actos®, and that two products can be considered interchangeable in medical practice.

Development and Validation of a HPLC Method for a Dissolution Test of Lamotrigine Tablets and its Application to Drug Quality Control Studies

Abstract A high performance liquid chromatographic (HPLC) method suitable for routine determination of lamotrigine in a dissolution medium and tablet formulation has been developed. Chromatographic separation was performed on a Gemini C18 (250 mm×4.6 mm i.d., 5 µm) column using a mobile phase of 0.05 M (NH4)H2PO4‐acetonitrile (68∶32, v/v, pH 2.68), delivered at a flow rate of 1.2 mL/min and detected by ultraviolet at 265 nm. The method was validated for specificity, linearity, accuracy, and precision. Additionally, the conditions of the dissolution test for lamotrigine tablets were presented by using: paddle at 50 rpm stirring speed; medium volume of 900 mL; temperature at 37±0.5°C; and pH 1.2 HCl solution, pH 4.5 acetate buffer and pH 6.8 phosphate buffer as dissolution media. The proposed analytical and dissolution methods were applied successfully for the quality control of commercial lamotrigine tablets and the comparison of in vitro performances of their products.

Bioequivalence of Generic Lamotrigine 100-mg Tablets in Healthy Thai Male Volunteers: A Randomized, Single-Dose, Two-Period, Two-Sequence Crossover Study

BACKGROUND Lamotrigine is an antiepileptic drug which has been used in the treatment of epilepsy and bipolar disorder. A search of the literature did not find previously published bioequivalence and pharmacokinetic evaluations of lamotrigine in healthy Thai male volunteers. OBJECTIVE The aim of this study was to compare the pharmacokinetic parameters between 2 brands of lamotrigine in healthy Thai male volunteers. METHODS A randomized, single-dose, 2-period, 2-sequence, crossover study design with a 2-week washout period was conducted in healthy Thai males. Subjects were randomized to receive either the test or reference formulation in the first period. All subjects were required to be nonsmokers and without a history of alcohol or drug abuse. Plasma samples were collected over a 120-hour period after 100-mg lamotrigine administration in each period. A validated high-performance liquid chromatography ultraviolet method was used to analyze lamotrigine concentration in plasma. Pharmacokinetic parameters were determined using a noncompartmental method. Bioequivalence between the test and reference products, as defined by the US Food and Drug Administration (FDA), is determined when the ratio for the 90% CIs of the difference in the means of the log-transformed AUC(0-t), AUC(0-infinity), and C(max) of the 2 products are within 0.80 and 1.25. Adverse events were determined by measuring vital signs after dosing. Subjects were also asked if they suffered from undesirable effects such as nausea, vomiting, dizziness, and headache. RESULTS This bioequivalence study was performed in 24 healthy Thai males (mean [SD] age, 20.5 [1.3] years; range, 19-24 years; weight, 62.5 [7.4] kg; height, 172.8 [6.9] cm; body mass index, 20.9 [2.0] kg/m(2)). The mean (SD) C(max) and T(max) of the test formulation of lamotrigine were 1.7 (0.3) microg/mL and 1.2 (0.9) hours, respectively. The mean (SD) C(max) and T(max) of the reference formulation of lamotrigine were 1.7 (0.3) microg/mL and 1.4 (1.0) hours, respectively. The mean (SD) AUC(0-t) was 67.1 (13.2) microg/mL x h(-1) for the test product and 66.4 (14.6) microg/mL x h(-1) for the reference product. The mean (SD) AUC(0-infinity) was 74.9 (18.3) microg/mL x h(-1) for the test product and 74.3 (20.5) microg/mL x h(-1) for the reference product. The mean (SD) t((1/2)) values were 35.0 (7.6) hours for the test product and 34.7 (7.6) hours for the reference product. The mean test/reference ratios for AUC(0-t), AUC(0-infinity), and Cmax were 1.01, 1.01, and 1.05, respectively. The parametric 90% CIs for AUC(0-t), AUC(0-infinity), and Cmax were 0.98 to 1.05, 0.98 to 1.06, and 0.98 to 1.13, respectively. Following administration, dizziness or headache was reported in 2 subjects in the test group and 1 subject in the reference group. CONCLUSION The results of this study suggest that the test product was bioequivalent to the reference product in these healthy Thai male subjects, based on the US FDAs regulatory definition.