MyMedR

Displaying all 9 publications

Abstract:

Sort:

Sequential hollow-fiber liquid phase microextraction for the determination of rosiglitazone and metformin hydrochloride (anti-diabetic drugs) in biological fluids

Ben-Hander GM, Makahleh A, Saad B, Saleh MI, Cheng KW

Talanta, 2015 Jan;131:590-6.
PMID: 25281145 DOI: 10.1016/j.talanta.2014.08.037

A new analytical method for the simultaneous determination of the antidiabetic drugs rosiglitazone (ROS) and metformin hydrochloride (MH) with marked differences in their affinity towards organic solvents (log P of 2.4 and -1.43, respectively) was developed. Prior to the HPLC separation, the drugs were subjected to a sequential hollow fiber liquid phase microextraction (HF-LPME) procedure. Two sequential HF-LPME approaches were considered, the preferred one involves the use of two vials containing solution mixtures for the extraction of ROS (vial 1) and MH (vial 2), respectively, but using the same fiber and acceptor phase. Important parameters that affect the extraction efficiency such as extracting solvent, donor phase conditions, HCl concentration, agitation, extraction time, addition of salt, etc. were studied. Under the optimum conditions, good enrichment factors (EF, 471 and 86.6 for ROS and MH, respectively) were achieved. Calibration curves were linear over the range 1-500 (r(2)=0.998) and 5-2500 ng mL(-1) (r(2)=0.999) for ROS and MH, respectively. The relative standard deviation values (RSD%) for six replicates were below 8.4%. Detection and quantitation limits based on S/N ratio of 3 and 10 were 0.12, 1.0 and 0.36, 3.0 ng mL(-1) for ROS and MH, respectively. The proposed method is simple, sensitive and opens up new opportunities for the microextraction of analytes with contrasting properties.

Matched MeSH terms: Hypoglycemic Agents/blood
Population pharmacokinetic modelling of repaglinide in healthy volunteers by using Non-Parametric Adaptive Grid Algorithm

Ruzilawati AB, Mohd Suhaimi AW, Gan SH

J Clin Pharm Ther, 2010 Feb;35(1):105-12.
PMID: 20175819 DOI: 10.1111/j.1365-2710.2009.01042.x

To estimate population pharmacokinetic parameters of repaglinide in 121 healthy Malaysian volunteers.

Matched MeSH terms: Hypoglycemic Agents/blood
Bioequivalence of a generic metformin tablet preparation

Yuen KH, Wong JW, Billa N, Julianto T, Toh WT

Int J Clin Pharmacol Ther, 1999 Jul;37(7):319-22.
PMID: 10442505

The bioavailability of a generic preparation of metformin (Diabetmin from Hovid Sdn Bhd) was evaluated in comparison with a proprietary product (Glucophage from Lipha Pharma Ltd., UK).

Matched MeSH terms: Hypoglycemic Agents/blood
Simple high-performance liquid chromatographic method for the determination of metformin in human plasma

Kah Hay Yuen, Kok Khiang Peh

J Chromatogr B Biomed Sci Appl, 1998 Jun 12;710(1-2):243-6.
PMID: 9686895

A simple high-performance liquid chromatographic method using ultraviolet detection was developed for the determination of metformin in human plasma. The method entailed direct injection of the plasma sample after deproteination using perchloric acid. The mobile phase comprised 0.01 M potassium dihydrogen orthophosphate (pH 3.5) and acetonitrile (60:40, v/v). Analyses were run at a flow-rate of 1.0 ml/min with the detector operating at a detection wavelength of 234 nm. The method is specific and sensitive, with a quantification limit of approximately 60 ng/ml and a detection limit of 15 ng/ml at a signal-to-noise ratio of 3:1. The mean absolute recovery value was about 97%, while the within-day and between-day coefficient of variation and percent error values of the assay method were all less than 8%. The calibration curve was linear over a concentration range of 62.5-4000 ng/ml.

Matched MeSH terms: Hypoglycemic Agents/blood*
Ion-pair vortex assisted liquid-liquid microextraction with back extraction coupled with high performance liquid chromatography-UV for the determination of metformin in plasma

Alshishani A, Makahleh A, Yap HF, Gubartallah EA, Salhimi SM, Saad B

Talanta, 2016 Dec 01;161:398-404.
PMID: 27769423 DOI: 10.1016/j.talanta.2016.08.067

A new sample preparation method, ion-pair vortex assisted liquid-liquid microextraction (VALLME-BE), for the determination of a highly polar anti-diabetic drug (metformin) in plasma sample was developed. The VALLME-BE was performed by diluting the plasma in borate buffer and extracted to 150µL 1-octanol containing 0.2M di-(2-ethylhexyl)phosphoric acid as intermediate phase. The drug was next back-extracted into 20µL of 0.075M HCl solution. The effects of pH, ion-pair concentration, type of organic solvent, volume of extraction phases, ionic strength, vortexing and centrifugation times on the extraction efficiency were investigated. The optimum conditions were at pH 9.3, 60s vortexing and 2min centrifugation. The microextract, contained metformin and buformin (internal standard), was directly injected into a HPLC unit using C1 column (250mm×4.6mm×10µm) and detected at 235nm. The method was validated and calibration curve was linear with r2>0.99 over the range of 20-2000µgL-1. The limits of detection and quantitation were 1.4 and 4.1µgL-1, respectively. The accuracy was within 94.8-108% of the nominal concentration. The relative standard deviation for inter- and intra-day precision was less than 10.8%. The method was conveniently applied for the determination of metformin in plasma samples.

Matched MeSH terms: Hypoglycemic Agents/blood*
Hollow fiber liquid-phase microextraction for the determination of trace amounts of rosiglitazone (anti-diabetic drug) in biological fluids using capillary electrophoresis and high performance liquid chromatographic methods

Al Azzam KM, Makahleah A, Saad B, Mansor SM

J Chromatogr A, 2010 Jun 4;1217(23):3654-9.
PMID: 20409552 DOI: 10.1016/j.chroma.2010.03.055

A three-phase hollow fiber liquid-phase microextraction (HF-LPME) coupled either with capillary electrophoresis (CE) or high performance liquid chromatography (HPLC) with UV detection methods was successfully developed for the determination of trace levels of the anti-diabetic drug, rosiglitazone (ROSI) in biological fluids. The analyte was extracted into dihexyl ether that was immobilized in the wall pores of a porous hollow fiber from 10 mL of aqueous sample, pH 9.5 (donor phase), and was back extracted into the acceptor phase that contained 0.1M HCl located in the lumen of the hollow fiber. Parameters affecting the extraction process such as type of extraction solvent, HCl concentration, donor phase pH, extraction time, stirring speed, and salt addition were studied and optimized. Under the optimized conditions (extraction solvent, dihexyl ether; donor phase pH, 9.5; acceptor phase, 0.1M HCl; stirring speed, 600 rpm; extraction time, 30 min; without addition of salt), enrichment factor of 280 was obtained. Good linearity and correlation coefficients of the analyte was obtained over the concentration ranges of 1.0-500 and 5.0-500 ng mL(-1) for the HPLC (r(2)=0.9988) and CE (r(2)=0.9967) methods, respectively. The limits of detection (LOD) and limits of quantitation (LOQ) for the HPLC and CE methods were (0.18, 2.83) and (0.56, 5.00) ng mL(-1), respectively. The percent relative standard deviation (n=6) for the extraction and determination of three concentration levels (10, 250, 500 ng mL(-1)) of ROSI using the HPLC and CE methods were less than 10.9% and 13.2%, respectively. The developed methods are simple, rapid, sensitive and are suitable for the determination of trace amounts of ROSI in biological fluids.

Matched MeSH terms: Hypoglycemic Agents/blood
Method development and validation of repaglinide in human plasma by HPLC and its application in pharmacokinetic studies

Ruzilawati AB, Wahab MS, Imran A, Ismail Z, Gan SH

J Pharm Biomed Anal, 2007 Apr 11;43(5):1831-5.
PMID: 17240100

In this study, the development and validation of a high-performance liquid chromatography (HPLC) assay for determination of repaglinide concentration in human plasma for pharmacokinetic studies is described. Plasma samples containing repaglinide and an internal standard, indomethacin were extracted with ethylacetate at pH 7.4. The recovery of repaglinide was 92%+/-55.31. Chromatographic separations were performed on Purospher STAR C-18 analytical column (4.8 mm x 150 mm; 5 microm particle size). The mobile phase composed of acetonitrile-ammonium formate (pH 2.7; 0.01 M) (60:40, v/v). The flow rate was 1 ml/min. The retention time for repaglinide and indomethacin were approximately 6.2 and 5.3 min, respectively. Calibration curves of repaglinide were linear in the concentration range of 20-200 ng/ml in plasma. The limits of detection and quantification were 10 ng/ml and 20 ng/ml, respectively. The inter-day precision was from 5.21 to 11.84% and the intra-day precision ranged from 3.90 to 6.67%. The inter-day accuracy ranged 89.95 to 105.75% and intra-day accuracy ranged from 92.37 to 104.66%. This method was applied to determine repaglinide concentration in human plasma samples for a pharmacokinetic study.

Matched MeSH terms: Hypoglycemic Agents/blood*
CYP3A4 genetic polymorphism influences repaglinide's pharmacokinetics

Ruzilawati AB, Gan SH

Pharmacology, 2010;85(6):357-64.
PMID: 20523106 DOI: 10.1159/000302731

AIM: To investigate the effects of CYP3A4 and CYP2C8 enzymes on repaglinide's pharmacokinetics in healthy Malaysian subjects.
METHODS: Subjects (n = 121) received oral repaglinide (4 mg). Blood samples were taken at 0, 30, 60, 120, 180 and 240 min and serum concentrations of repaglinide were determined using high-performance liquid chromatography. Subjects were also genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for CYP3A4*4, *5 and*18 and by an allele-specific multiplex PCR for CYP2C8*2, *3, *4 and *5 alleles.
RESULTS: The allele frequencies of CYP2C8*1, *2, *3, *4 and *5 were 95.04, 0.40, 0.40, 0 and 4.13%, respectively. The frequencies of the CYP3A4*1, *4, *5 and *18 alleles were 97.93, 0, 0 and 2.07%, respectively. CYP2C8 and CYP3A4 genotypes were not significantly associated with repaglinide's blood glucose-lowering effect. However, the CYP3A4 genotype significantly influenced some of repaglinide's pharmacokinetics, where the mean elimination rate constant was 44.0% lower (p = 0.04) and the mean half-life was 33.8% higher (p = 0.04) in subjects with the CYP3A4*1/*18 genotype as compared to those with the normal CYP3A4*1/*1 genotype. This result confirms that CYP3A4 plays a large role in metabolizing repaglinide.
CONCLUSION: Genetic polymorphisms of CYP3A4, specifically CYP3A4*18, play a major role in contributing to the interindividual variability in repaglinide's pharmacokinetics.

Matched MeSH terms: Hypoglycemic Agents/blood
Efficacy and safety of single versus multiple daily doses of glibenclamide in type 2 diabetes mellitus

Wan Mohamad WB, Tun Fizi A, Ismail RB, Mafauzy M

Diabetes Res Clin Pract, 2000 Aug;49(2-3):93-9.
PMID: 10963819 DOI: 10.1016/s0168-8227(00)00138-8

Although long acting, glibenclamide is frequently given in split doses for type 2 diabetes mellitus. This may discourage compliance. It is thus appropriate to consider dosing it less frequently. We therefore studied glibenclamide effects when used once daily and when used in split doses. Our objective was to assess the feasibility of using once daily dosing as a regimen of choice. We measured plasma glucose, insulin, glibenclamide, lipids, HbAl and body mass index associated with the regimens. We also compared the number of hypoglycemic episodes occurring with them. Thirty type 2 diabetics on multiple daily glibenclamide were enrolled. Their regimens were changed over to once daily. Blood for glucose, insulin, lipids, HbAl and glibenclamide and body weight measurements were determined before and after the crossover period. We found no major difference in the sugar and insulin profiles with the two regimens. Fasting total cholesterol and triglyceride were also similar and so were plasma glibenclamide. The HbAl levels and body mass index and number of minor and major hypoglycemic episodes and hospital admissions for hypoglycemia also did not differ. We conclude that single daily dosing of glibenclamide was equivalent to multiple daily dose regimens. It can be used to an advantage to improve patient's compliance.

Matched MeSH terms: Hypoglycemic Agents/blood