Bioequivalence study of generic amlodipine in healthy Thai male volunteers.

SUBJECTS, MATERIAL AND METHODS: To determine the bioequivalence of 10 mg generic amlodipine in healthy male volunteers, the reference and the test formulations were administered as a single oral dose after overnight fasting in a crossover study separated by 2-week washout interval. After dosing, serial blood samples were collected for a period of 144 h. Plasma amlodipine concentrations were determined by LC-MS/MS and the pharmacokinetic parameters were analyzed by non-compartmental analysis. RESULTS: The mean elimination half-life (t1/2) for the test (40 h) and the reference (44 h) were within the values previously reported. The rate of absorption reflected by tmax had a difference of -0.33 h, with a 90% CI of (-1.52)-0.85 (acceptable range +/- 1.3). Although the tmax of the test (5 h) was faster than the reference (6 h), the mean (90% CI) of the AUC(0-infinity) and Cmax ratios Test/Reference were 0.91 (0.87-0.97) and 1.01 (0.93-1.09), respectively. These values were within the range of 0.80-1.25, thus, the study demonstrated the bioequivalence of the 2 formulations.

Bioequivalence study of generic gliclazide and Diamicron formulations in healthy Thai male volunteers.

UNLABELLED: The objective of this study was to compare the bioequivalence of 80 mg gliclazide in healthy Thai males. A single dose of each preparation was administered after an overnight fast in a 2-period crossover design with a 2-week washout period. Serial blood samples were collected over a period of 60 hours. Plasma gliclazide concentrations were determined using HPLC and the pharmacokinetic parameters were analyzed by non-compartmental analysis. RESULTS: The median time to reach the maximal concentration (Tmax) for the test formulation was identical to that of the reference Diamicron (11.5 h). Similarly, the mean elimination half-lives (t1/2) for the test (20.4 +/- 7.8 h) and Diamicron (21.5 +/- 9.4 h) were comparable. Analysis of variance was carried out using logarithmic transformations of AUC(0-infinity) and Cmax as well as non-transformed Tmax. The mean (90% CI) of the difference in Tmax (h) was 0.08 ((-1.44)-1.61). The mean (90% CI) of the AUC(0-infinity) and Cmax ratios for (test/reference) were 1.08 (0.98-1.18) and 1.09 (0.89-1.34), respectively. Since these values fall within the bioequivalence criteria, our study demonstrates bioequivalence of the 2 products.

Comparative steady-state bioavailability of sustained-release theophylline preparations: Theo-Dur, Uni-Dur and Xanthium.

Steady-state bioavailability of sustained-release theophylline (SRT); Theo-Dur, Uni-Dur and Xanthium were compared in 10 healthy males with theophylline clearance ranged from 0.3 - 0.8 ml/min/kg. Each of 400-mg SRT was administered once daily before breakfast for 7 consecutive days, one-week washout period in a crossover fashion. Serial blood samples were collected over 24 hours on days 6 and 7. Serum theophylline concentrations were determined by fluorescence polarized immunoassay. We found that the oral bloavailability relative to Franol (%F [90% CI]) of Theo-Dur, Uni-Dur and Xanthium were 97 (93-106), 85 (79-96) and 77 (72-87), respectively. Average bioequivalence revealed that the Css(min) (microg/ml) of Uni-Dur (5.07) was higher than Theo-Dur (4.29), and Xanthiume (4.18), while the Css(max) and Css(av) (microg/ml) of Theo-Dur (11.02, 7.87) were statistically higher than Uni-Dur (8.51, 6.91) and Xanthium (7.65, 6.27). The extent of absorption assessed by AUCss(0.24) of Theo-Dur was significantly greater than Uni-Dur and Xanthium. However, fluctuation index (% FI) of Theo-Dur (232) was twofold higher than Uni-Dur (137) and Xanthium (113). The median Tss(max) of Uni-Dur was 12 hours which was significantly longer than Xanthium (7 hours) and Theo-Dur (8 hours). There were no statistically significant differences between Uni-Dur and Xanthium regarding bioavailability, Css(max), Css(av) as well as % FI. Moreover, 400 mg OD of Uni-Dur and Xanthium are suitable for subjects with a theophylline clearance of 0.3-0.55 ml/min/kg while 400 mg OD Theo-Dur can be used in subjects with slower clearance rates of 0.3-0.39 ml/min/kg. Subjects with rapid theophylline clearance rates of 0.65-0.8 ml/min/kg required a higher dose of theophylline and twice-daily dosing was more appropriate.

Protective effects of fosfomycin on cisplatin-induced nephrotoxicity in patients with lung cancer.

SUBJECTS, MATERIAL AND METHODS: Protective effects of fosfomycin on cisplatin-induced nephrotoxicity have been previously reported, however, the proper time, duration and dosage of its administration were uncertain. Therefore, we investigated the protective effect of concurrent administration of twice-daily doses of 2 g fosfomycin for 5 days in 13 cisplatin-naïve lung cancer patients who were due to receive a single dose per cycle of 100 mg/m2 cisplatin. On each chemotherapeutic cycle, patients were randomly given cisplatin alone or cisplatin plus fosfomycin every 4 weeks for a maximum of 4 consecutive cycles. Indicators of nephrotoxicity, urinary N-acetyl-beta-D-glucosaminidase (NAG) activity, serum creatinine (Scr) and creatinine clearance (Clcr) were determined the day before and at day 3 and day 6 after cisplatin administration. Results were compared and statistically analyzed by the non-parametric Mann-Whitney's test. We found that the NAG activities obtained on day 0, day 3 and day 6 of the fosfomycin cycles were comparable to values obtained during the control cycles (p > 0.05). Moreover, the NAG activities on day 3 of both treatment cycles were significantly elevated from baseline (p < 0.01) and had normalized on day 6. There were no significant changes in serum creatinine and creatinine clearance. CONCLUSION: High-dose cisplatin induced reversible elevation of urinary NAG and concurrent administration of low-dose fosfomycin for 5 days had no effect on the enzymuria. In the prevention of cisplatin nephrotoxicity, a further study using dose escalation (8 to 12 g/d) of fosfomycin administered 2 to 3 days prior to cisplatin are required to demonstrate its nephroprotective effects.

Pharmacokinetics and bioequivalence testing of generic fluconazole preparations in healthy thai volunteers.

AIM: To determine the bioequivalence of two oral formulations of generic fluconazole in twelve healthy Thai volunteers. SUBJECTS, MATERIALS AND METHODS: The test preparation was Flucozole (Siam Bheasach, Thailand) and the reference was Diflucan (Pfizer Inc.). The two products were administered as 200 mg single oral doses in a two-period crossover design with a two-week washout period. After drug administration, serial blood samples were collected over a period of 72 hours. Serum fluconazole concentrations were determined by HPLC, and the pharmacokinetic parameters were analyzed by non-compartmental analysis. RESULTS: The time to reach the maximal concentration (Tmax, hour) of Flucozole (1.18 +/- 0.56) was statistically faster than that of Diflulan (1.59 +/- 0.54). The 90% confidence intervals of the AUC(0 - infinity) ratio and the Cmax, ratio muT/muR for Flucozole/Diflucan were 0.97 - 1.20 and 1.01 - 1.26, respectively. These values were within the acceptable bioequivalence intervals of 0.80 - 1.25 and 0.7 - 1.43 for the ratio of the average AUC(0 - infinity) and Cmax, respectively. CONCLUSION: Thus, our study demonstrated the bioequivalence of Flucozole and Diflucan with respect to the rate (Cmax) and extent of absorption (AUC(0 - infinity).

Pharmacokinetics and bioequivalence testing of generic ondansetron preparations in healthy Thai male volunteers.

SUBJECTS, MATERIAL AND METHODS: Pharmacokinetics and bioequivalence of oral preparations of generic ondansetron were investigated in healthy Thai males. The test preparations were Vomitron 8 and Vomitron 4, the reference was Zofran. The three products were administered as an 8 mg single oral dose, in a three-period four-sequence cross-over design with one-week washout period. An intravenous 8 mg Zofran was administered on the forth visit. Plasma ondansetron concentrations were determined by HPLC and the pharmacokinetic parameters were analyzed by non-compartmental analysis. RESULTS: Following i.v. ondansetron, the mean values of its elimination half-life, its plasma clearance, and its volume of distribution were 4.5 hours, 398 ml/min, and 130 liters, respectively. Its oral bioavailability averaged 67%, and the elimination half-life after oral administration was 5.6 hours. The time to reach the maximal concentration (Tmax, hour) of Zofran (1.21 +/- 0.26) was statistically faster than that of Vomitron 8 (1.33 +/- 0.54) and Vomitron 4 (1.46 +/- 0.50). The 90% confidence intervals of the AUC0-infinity and Cmax ratios muT/muR for (Vomitron 8/Zofran) were 0.88 - 1.12 and 0. 85 - 1.08, respectively. Similarly the 90% CI of the-AUC0-infinity and Cmax ratios for (Vomitron 4/Zofran) were 0.96 - 1.17 and 1.01 - 1.19, respectively. CONCLUSION: These values were within the acceptable range of 0.80 - 1.25, thus our study demonstrated the bioequivalence of Vomitron and Zofran with respect to the rate (Cmax) and extent of absorption (AUC0-infinity).

Bioequivalence study of generic atenolol tablets in healthy Thai volunteers.

Two preparations of 50 mg and 100 mg atenolol tablets were evaluated for their bioequivalence in twelve healthy Thai subjects (Prenolol, Berlin Pharmaceutical Industry, as the test formulations vs Tenormin, Zeneca Limited, as the reference formulations). A single oral dose of each preparation was administered in a randomized two-way crossover design, starting from either 50 mg of Prenolol vs Tenormin, thereafter, either 100 mg of Prenolol vs Tenormin. The washout period between each treatment was one week. Atenolol plasma concentrations were determined by the HPLC technique with fluorometric detection. Pharmacokinetic parameters were analyzed by the noncompartmental pharmacokinetic method using TOPFIT. The means and parametric 90 per cent confidence intervals of the ratio [Prenolol/Tenormin] of AUC0-infinity and Cmax were 1.16 (1.05-1.27) and 1.23 (1.07-1.38) for 50 mg preparations and 1.10 (1.00-1.20) and 1.13 (0.95-1.31) for 100 mg preparations, respectively. These values were well within the acceptable bioequivalence ranges. The mean differences of Tmax [Prenolol-Tenormin] were less than 20 per cent for both 50 mg and 100 mg preparations. Hence, Prenolol and Tenormin were bioequivalent with respect to the rate and extent of absorption.

Pharmacokinetics and bioavailability studies of generic ondansetron, and the innovator preparation, in healthy Thai male volunteers.

The pharmacokinetics and bioequivalence of two oral formulations of ondansetron were evaluated; Zetron (Biolab Pharmaceutical, Bangkok, Thailand), as the test formulation and Zofran (Glaxo Wellcome Operations, Greenford, UK), as the reference formulation. The two products were administered as a single oral dose of 8 mg according to a randomized two-way crossover design to 12 healthy Thai male volunteers. The washout period between treatment was 1 week. Ondansetron plasma concentrations were measured using HPLC. The oral bioavailability of ondansetron averaged 67 per cent and the elimination half-life after oral administration was 5.6 hours. The means and parametric 90 per cent CI of the ratios of Cmax and AUC 0-alpha [mu Zetron (Test)/mu Zofran (Reference)] were 0.95 (0.84-1.07) and 0.94 (0.80-1.10), respectively. These values were well within the bioequivalence range of 0.8-1.25 as established by the US-FDA. The mean difference of Tmax (Test-Reference) was approximately 20 per cent. Thus, our study demonstrated bioequivalence of the two products (Zetron and Zofran) regarding the rate and extent of absorption.

AIDS-related disseminated histoplasmosis in San Francisco, California.

The published reports of patients with the acquired immunodeficiency syndrome (AIDS) with disseminated histoplasmosis come mostly from institutions located in endemic areas for histoplasmosis, where disease is thought to occur by either primary infection or reactivation. The characteristics of reactivation disease are not well delineated. We describe the clinical features of reactivation disseminated histoplasmosis in 46 residents of San Francisco, California, with AIDS who did not report recent travel to an area endemic for histoplasmosis. Patients presented with illness lasting days to months, manifested most frequently by fever, chills, sweats, cough or dyspnea, gastrointestinal complaints, malaise, and weight loss. Physical examination and imaging studies were notable for hepatosplenomegaly, lymphadenopathy, or abnormal pulmonary findings in more than half of patients. Laboratory studies revealed a high rate of cytopenia, elevated serum lactate dehydrogenase levels, abnormal liver function test values, respiratory alkalosis with hypoxemia, and a median CD4 lymphocyte count of 36 x 10(9) per liter. The clinical presentation of reactivation disseminated histoplasmosis in patients with AIDS living in San Francisco is similar to that of disseminated histoplasmosis reported in patients with AIDS living in endemic areas. Reactivation disseminated histoplasmosis should be considered in any AIDS patient with a low CD4 lymphocyte count, a febrile illness, and a history of travel or residence in an endemic area.

A case of hypomagnesemia hypocalcemia as a complication of aminoglycoside and review of the literature.

A 28-year-old woman was admitted to the ENT Department of the Faculty of Medicine, Chiang Mai University because of left otitis externa, chronic mastoiditis and facial nerve palsy (lower motor neurone). Left radical mastoidectomy with wide debridement of granulation and necrotic tissue at ear canal, dura, sigmoid sinus, ossicle and facial nerve were done two weeks after admission. Multiple pus culture from the lesion revealed different types of organisms e.g. proteus mirabilis, beta strep non group A, and enterococci beta type. Several aminoglycosides were alternately given for two months without improvement of ear infection. She developed carpopedal spasm with hypocalcemia after three weeks of such treatment. Hypomagnesemia was recognized. Calcium and milk supplement gave temporary relief, but permanent relief was obtained after aminoglycoside was discontinued. Serum electrolyte had reversed to normal on follow-up.