Development of the liquid chromatography tandem mass spectrometry method for determination of chloroquine and desethylchloroquine in human plasma.

Objective: Several studies reported a relationship between adverse effect and elevated blood concentration of chloroquine (CQ) and its active metabolite, desethylchloroquine (DCQ). Therefore, therapeutic drug monitoring of these drugs might be useful. This study aims to develop and validate a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the determination of CQ and DCQ in human plasma. Methods: Chromatographic separation was carried out on the Synergi® 2.5μm polar RP (150x4.6mm.I.D.) and used 0.3% formic acid/acetonitrile at 70/30,v/v as a mobile phase. The mass spectrometry was operated with positive electro spray ionization and multiple reactions monitoring (MRM) mode. The mixture of methyl t-butyl ether and isooctane at 90/10,v/v with adjusted pH to 12 by ammonium hydroxide were used for extraction. The method was developed and fully validated according to USFDA guidelines. Results: The ion transitions were 320.01 to 247.01 and 142.12 m/z for CQ and 292.0 to 179.01 and 114.10 m/z for DCQ. The lower limit of quantification (LLOQ) were 0.2 and 0.4 ng/mL for CQ and DCQ, respectively. This method had acceptable accuracy and precision with good linearity (r2>0.997) and high recovery of extraction (89.34-108.42%). The ranges of quantification were 0.2-1,000 ng/mL for CQ and 0.4-1,000 ng/mL for DCQ. Neither anticoagulant nor matrix had any effect which interfered with this analysis. Conclusion: A highly selective, sensitive and reproducible LC-MS/MS method to detect CQ and DCQ level in human plasma was developed and validated. This method was successfully applied to determine the steady state concentration of CQ and DCQ in plasma of rheumatoid arthritis patients.

Bioequivalence study of a single 150-mg dose of two intramuscular netilmicin products in Thai healthy volunteers.

Objective: Netilmicin, a broad-spectrum semisynthetic aminoglycoside antibiotic, is used in the treatment of a wide variety of bacterial infections. The purpose of this study is to compare the bioavailability of two products of 150 mg netilmicin by intramuscular administration in Thai healthy volunteers: The generic drug is Nelin® (test; Biolab Co., Ltd., Thailand) will be called “Test” and Netromycin® (reference; Schering-Plough Ltd., USA) will be called “Reference”. Methods: A single-dose, 2-treatment, 2-period, 2-sequence, randomized crossover study was conducted in 24 healthy Thai volunteers. Each volunteer received a 150 mg intramuscular injection of the reference or test drugs. Blood samples were collected before dosing and at various time points up to 48 hours after dosing and analyzed for netilmicin concentrations using a validated liquid chromatography-mass spectrometry (LC-MS/MS) method. The pharmacokinetic parameters including Cmax, AUC0-t, AUC0-¥, Tmax and t1/2 were analyzed using the non-compartmental model. Drug safety and tolerability were assessed. Results: Twenty-four volunteers completed both treatment periods. The geometric mean ratios (test/reference) between the two products of netilmicin were 100.30% (90% CI, 88.02%-114.28%) for Cmax, 94.94% (90% CI, 88.94%-101.34%) for AUC0-t, and 94.88% (90% CI, 88.85%-101.32%) for AUC0-¥. There was no significant difference of the Tmax values between the two studied products (P>0.05). No adverse events related to the study drugs were found. Conclusion: The two products of intramuscular netilmicin are bioequivalent. Both products are well tolerated.

Bioequivalence study of 30 mg pioglitazone tablets in Thai healthy volunteers.

OBJECTIVE: To compare the bioequivalent parameters of 30 mg pioglitazone tablets manufactured locally (Glista) and originally (Actos). MATERIAL AND METHOD: A randomized, single dose, two-treatment, two-period, two-sequence crossover study was conducted Twenty-four healthy volunteers were recruited at Siriraj Clinical Research Unit. Each subject received a 30 mg pioglitazone tablet of both formulations with at least a week washout period Blood samples were collected over 48 h after the oral administration. The plasma fractions were analyzed for pioglitazone using a liquid chomatography-mass spectrometry (LC-MS/MS). RESULTS: Twenty-four volunteers enrolled in the present study. Pharmacokinetic parameters were determined using the non-compartment model. The 90 percent confidence intervals of the mean ratios (test/reference) of Cmax (86.2687-113.7313%), A UC0-->t(85. 7139-114.2861%) and AUC0-->infinity (81.7820-118.2180%) fell within the acceptable range (80-125%) for bioequivalent eligibility. Both preparations were well tolerated and had afew non-serious adverse events. CONCLUSION: The 2-tablet preparations of pioglitazone were bioequivalent in Thai healthy volunteers.

Comparative study of oral bioavailability of original amoxicillin and local-made amoxicillin used in Siriraj Hospital.

Oral bioavailability of single dose of 500 mg Rancil capsule manufactured by Ranbaxy Co., Ltd., which was the generic amoxicillin used in Siriraj Hospital, was compared to that of 500 mg capsule of the reference (original) amoxicillin, i.e., Amoxil-Bencard manufactured by Smith-Kleine & Beecham Inc., using randomized cross-over design. The study was done in 12 healthy volunteers,7 males and 5 females, aged 23-51 years weighing 46-65 kg. Venous blood sampling was taken from each subject prior to and at 0.5, 1, 2, 4, 6 and 8 hr after drug administration. Serum concentrations of amoxicillin were assayed by high performance liquid chromatography (HPLC). Maximum serum concentrations (Cmax) and areas under serum concentration-time curves(AUCs) of both Rancil and Amoxil-Bencard were analysed and compared. The Cmax and AUCs values of Rancil and Amoxil-Bencard were statistically equivalent, i.e., 8.67 ฑ 1.50 ตg/ml v.s. 9.36 ฑ 1.62 mg/ml respectively (p = 0.069) for Cmax ; and 26.02 ฑ 6.80 ตg.hr/ml v.s. 27.51 ฑ 8.52 ตg.hr/ml respectively (p=0.355) for AUC0-8 hr. The 90 % confidence intervals of the Cmax ratio and AUC0-8 hr ratio between Rancilฎ and Amoxil-Bencardฎ were 0.90-1.02 and 0.87-1.11 respectively which were within the acceptable equivalent range of 0.8 - 1.25. Thus, Rancilฎ is considered bioequivalent to and can be used interchangeably with Amoxil-Bencardฎ in clinical infections requiring amoxicillin in order to minimize the cost of treatment.