Evaluation of Omeprazole Limited Sampling Strategies to Estimate Constitutive Cytochrome P450 2C19 Activity in Healthy Adults.

BACKGROUND: Limited sampling strategy (LSS) is a validated method to estimate pharmacokinetic (PK) parameters from a reduced number of samples. Omeprazole is used to phenotype in vivo cytochrome P450 (CYP) 2C19 activity. This study examined an LSS using 2 estimation methods to determine apparent oral clearance (CL/F) and thus CYP2C19 activity. METHODS: Data from 7 previously published studies included healthy subjects receiving a single, oral dose of omeprazole with intensive PK sampling. CL/F was estimated using noncompartmental analysis (NCA) and population PK modeling. LSS was simulated by selecting the 1, 2, 4, and/or 6-hour postdose time points. Linear regression was performed to assess whether CL/F estimated from limited sampling could accurately predict CL/F from the full PK profile. RESULTS: Median CL/F was 23.7 L/h by NCA and 19.3 L/h by population PK modeling. In comparing the LSS NCA estimated versus observed CL/F, all evaluated linear regression models had unacceptable coefficients of determination (r, range: 0.14-0.81). With the population PK approach, 737 plasma concentrations (n = 71) and CYP2C19 genotype data were described with a 1-compartment structural model with mixed zero and first-order absorption and lag time. In comparing the population PK LSS estimated versus observed CL/F, all evaluated linear regression models had unacceptable r (range: 0.02-0.74). Post hoc comparison of CYP2C19 poor metabolizers versus CYP2C19 extensive metabolizers resulted in significantly lower CL/F in poor metabolizers versus extensive metabolizers. CONCLUSIONS: Omeprazole LSS performed poorly in estimating CL/F using 2 separate estimation approaches and does not seem to be a suitable method for determining CYP2C19 activity.

Supplementation of n-3 Polyunsaturated Fatty Acids for Major Depressive Disorder: A Randomized, Double-Blind, 12-Week, Placebo-Controlled Trial in Korea.

BACKGROUND: Controversy over the efficacy of n-3 polyunsaturated fatty acids (PUFAs) in depression continues to this day. The present study investigated the hypothesis that n-3 PUFA supplementation reduces depressive symptoms in Korean patients with major depressive disorder. METHODS: In a randomized, double-blind, placebo-controlled, 12-week, parallel-group trial, 35 patients with Center for Epidemiological Studies Depression Scale Korean version (CES-D-K) scores ≥25 and depression confirmed by a psychiatrist were assigned to take either 3 capsules of n-3 PUFAs (1,140 mg of EPA + 600 mg of DHA; n = 18) or placebo (olive oil + safflower oil; n = 17). RESULTS: Supplementation with n-3 PUFAs significantly reduced Clinical Global Impression Improvement (CGI-I) scores as compared with intake of placebo using intention-to-treat analysis with last-observation-carried-forward after adjusting for energy, fat, and fish intake. However, the CES-D-K, Hamilton Depression Rating Scale-17, and Clinical Global Impression Scale scores did not significantly differ between the n-3 PUFA and placebo groups. After supplementation with n-3 PUFAs, the erythrocyte levels of n-3 PUFAs were significantly increased, but n-6 PUFA levels were decreased. CONCLUSIONS: n-3 PUFAs demonstrated an advantage over placebo that did not reach clinical significance, although CGI-I score was significantly decreased in the n-3 PUFA group as compared with the placebo group.

Abnormal Gas Diffusing Capacity and Portosystemic Shunt in Patients With Chronic Liver Disease.

BACKGROUND: Pulmonary dysfunctions including the hepatopulmonary syndrome and portosystemic shunt are important complications of hepatic cirrhosis. To investigate the severity and nature of abnormal gas diffusing capacity and its correlation to portosystemic shunt in patients with chronic liver disease. METHODS: Forty-four patients with chronic liver disease (15 chronic active hepatitis (CAH), 16 Child-Pugh class A, and 13 Child-Pugh class B) without other diseases history were enrolled in the study. Evaluation of liver function tests, arterial blood gases analysis, ultrasonography, pulmonary function test including lung diffusing capacity of carbon monoxide (DLco), forced vital capacity(FVC), forced expiratory volume 1 seconds(FEV1), total lung capacity(TLC), DLco/AV(alveolar volume) and thallium-201 per rectum scintigraphy were performed. We were analyzed correlations between pulmonary function abnormalities and heart/liver (H/L) ratio in patients with chronic liver diseases. RESULTS: In CAH, percentage of patients with DLco and DLco/VA (< 80%) was 22.2 % but it was significantly increased to 47.2-54.5% in Child-Pugh class A and B patients. The means of DLco and DLco/VA were significantly (P < 0.05) decreased in Child-Pugh class. The mean H/L ratio in Child-Pugh class B increased markedly (P < 0.01) than those with CAH and Child-Pugh class A. The frequency of specific pulmonary function abnormality in patients with Child-Pugh class B was significantly (P < 0.01) greater than those with Child-Pugh class A and CAH. There was a inverse linear correlation between H/L ratio and DLco (r = -0.339, P < 0.05) and DLco/VA (r = -0.480, P < 0.01). CONCLUSION: A total of 62% of patients with advanced liver disease have abnormal pulmonary diffusion capacity with a reduced DLco or DLco/VA and abnormal portosystemic shunt (increased H/L ratio) is common hemodynamic abnormality. Therefore, inverse linear correlation between DLco or DLco/VA and H/L ratio may be an important factor in predicting pulmonary complication and meaningful diagnostic and prognostic parameters in patients with advanced chronic liver disease.

Quantification of galantamine in human plasma by validated liquid chromatography-tandem mass spectrometry using glimepride as an internal standard: application to bioavailability studies in 32 healthy Korean subjects.

A simple, rapid and selective liquid chromatography method coupled with tandem mass spectrometry is developed and validated for the quantification of galantamine in human plasma using a commercially available compound, glimepride, as an internal standard (IS). Following simple one-step liquid-liquid extraction by ethyl acetate, the analytes are separated using an isocratic mobile phase consisting of acetonitrile and 0.01M ammonium acetate (95/5, v/v) on a reverse-phase C18 column and analyzed by tandem mass spectrometry in the multiple reaction monitoring mode using the transitions of respective (M + H)(+) ions, m/z 288.22 → 213.20 and m/z 491.17 → 352.30 for the quantification of galantamine and IS, respectively. The standard calibration curves show good linearity within the range of 4 to 240 ng/mL (r(2) = 0.9996, 1/x(2) weighting). The lower limit of quantification is 4 ng/mL. The retention times of galantamine and IS are 1.1 and 0.71 min, which showsthe high throughput potential of the proposed method. In addition, no significant metabolic compounds are found to interfere with the analysis. Acceptable precision and accuracy are obtained for the concentrations over the standard curve range. The validated method is successfully applied for pharmacokinetic and bioequivalence studies of 24 mg of a galantamine hydrobromide capsule in 32 healthy Korean subjects.

Pharmacokinetic and bioavailability studies of 5 mg mosapride tablets in healthy Korean volunteers.

AIM: Mosapride is a gastroprokinetic agent, a 5-HT4 receptor agonist and 5-HT3 receptor antagonist exhibiting no activity at dopamine D2, 5-HT1 and 5-HT2 receptors. This study was performed to compare basic pharmacokinetic (PK) characteristics of mosapride for Korean young adults and to evaluate the bioequivalence (BE) of two formulations of drugs mosapride. VOLUNTEERS AND METHODS: For pharmacokinetic and bioavailability of 5 mg mosapride tablets in healthy Korean adults, a randomized, two way, crossover bioequivalence study in 23 healthy Korean volunteers (M : F = 16 : 7) was conducted to compare bioavailability of two formulation of 5 mg mosapride citrate tablets, Moprid® (Chung Kun Dang Pharm Co., Ltd., Korea) as a test and Gasmotin® (Daewoong Pharm Co., Ltd., Korea) as a reference drug. Subjects were administered single dosage of 3 tablets of each formulation with 240 ml water after 10 h overnight fasting on 2 treatment days separated by 1-week washout period. Before and after dosing, blood sample were collected at 0, 0.25, 0.5, 0.8, 1.0, 1.5, 2, 2.5, 3, 4, 6, 8, 12 and 24 h and analyzed by validated liquid chromatography- tandem mass spectrometry (LC-MS/ MS) in the range 1.28 - 192 ng/ml with the lowest limit of quantification of 1.28 ng/ml. RESULTS: Several PK characteristics were determined from the plasma samples, and data from reference and test formulations in the plasma were represented such as AUC0- t (184.4 vs. 179.6 ng×h/ml), AUC0-∞ (192.8 vs. 186.6 ng×h/ml), Cmax (98.9 vs. 84.4 ng/ ml), tmax (0.8 vs. 0.7 h), half-life (2.4 vs. 2.3 h), Ke (0.289 vs. 0.301), respectively. AUC0- t and Cmax were tested for bioequivalence after log-transformation of plasma data. PK characteristics with 90% confidence interval (CI) of test/reference ratio based on ANOVA analysis were 0.842 - 1.163 for AUC0-t and 0.753 - 1.088 for Cmax. PK characteristics with 90% CI were within the bioequivalence range of 80 - 125% of FDA statistical limit. Cmax with 90% CI were not within the bioequivalence range of 80 - 125% of FDA statistical limit. However, this result was assessed to bioequivalence in accordance with the "Bioequivalence Test Guidelines" outlined in No. 2005-31 of the KFDA. CONCLUSION: Therefore, both mosapride formulations were bioequivalent during fasting state in healthy Korean adults.

Quantification of nimesulide in human plasma by high-performance liquid chromatography with ultraviolet detector (HPLC-UV): application to pharmacokinetic studies in 28 healthy Korean subjects.

Nimesulide is a selective COX-2 inhibitor that is as effective as the classical non-acidic nonsteroidal anti-inflammatory drugs in the relief of various pain and inflammatory conditions, but is better tolerated with lower incidences of adverse effects than other drugs. After oral dose of 100 mg nimesulide to western subjects, a mean maximal concentration (C(max)) of 2.86 ∼ 6.5 µg/mL was reached at 1.22 ∼ 2.75 h and mean t(1/2ß) of 1.8 ∼ 4.74 h. This study developed a robust method for quantification of nimesulide for the pharmacokinetics and suitability of its dosage in Korea and compared its suitability with other racial populations. Nimesulide and internal standard were extracted from acidified samples with methyl tert-butyl ether and analyzed by high-performance liquid chromatography with ultraviolet detection (HPLC-UV). The 28 healthy volunteers took 2 tablets of 100 mg nimesulide and blood concentrations were analyzed during the 24 h post dose. Several pharmacokinetic parameters were represented: AUC(0-infinity) = 113.0 mg-h/mL, C(max) = 12.06 mg/mL, time for maximal concentrations (T(max)) = 3.19 h and t(1/2ß) = 4.51 h. These were different from those of western populations as follows: AUC was 14.5% and C(max) was 28% that of of Korean subjects and T(max) and t(1/2ß) were also different. The validated HPLC-UV method was successfully applied for the pharmacokinetic studies of nimesulide in Korean subjects. Because the pharmacokinetics of nimesulide were different from western populations, its dosage regimen needs to be adjusted for Koreans.

Modern methods for analysis of antiepileptic drugs in the biological fluids for pharmacokinetics, bioequivalence and therapeutic drug monitoring.

Epilepsy is a chronic disease occurring in approximately 1.0% of the world's population. About 30% of the epileptic patients treated with availably antiepileptic drugs (AEDs) continue to have seizures and are considered therapy-resistant or refractory patients. The ultimate goal for the use of AEDs is complete cessation of seizures without side effects. Because of a narrow therapeutic index of AEDs, a complete understanding of its clinical pharmacokinetics is essential for understanding of the pharmacodynamics of these drugs. These drug concentrations in biological fluids serve as surrogate markers and can be used to guide or target drug dosing. Because early studies demonstrated clinical and/or electroencephalographic correlations with serum concentrations of several AEDs, It has been almost 50 years since clinicians started using plasma concentrations of AEDs to optimize pharmacotherapy in patients with epilepsy. Therefore, validated analytical method for concentrations of AEDs in biological fluids is a necessity in order to explore pharmacokinetics, bioequivalence and TDM in various clinical situations. There are hundreds of published articles on the analysis of specific AEDs by a wide variety of analytical methods in biological samples have appears over the past decade. This review intends to provide an updated, concise overview on the modern method development for monitoring AEDs for pharmacokinetic studies, bioequivalence and therapeutic drug monitoring.

Pharmacokinetic characteristics of a vasodilatory and antiplatelet agent, limaprost alfadex, in the healthy Korean volunteers.

Limaprost, a prostaglandin E1 analogue, with a strong vasodilatory and antiplatelet activity has been used to release from the symptoms of thromboangiitis obliterans (TAO), which is more prevalent in Korea and Japan, and lumbar spinal canal stenosis (LSCS). In spite of many uses of limaprost, the pharmacokinetics (PK) of it has not been studied in the Korean population. Therefore, a preliminary PK study was designed at a clinical oral dosage of 30-microg limaprost in 5 healthy Korean volunteers. Blood samples were obtained at 14 consecutive time points for 12 hours after dosing and analyzed by liquid chromatography-tandem mass spectrometry with electrospray ionization (LC-ESI/MS/ MS) at a very low detection limit of 0.5 pg/mL of limaprost in human plasma with considerably short run time (18 minutes). Pharmacokinetic characteristics resulted in ''time for maximal concentrations (T(max) 0.5 hour),'' ''elimination half-life (T(1/2) 1.64 hours),'' ''maximal concentration (C(max) 13.37 pg/mL),'' ''area under the curve (AUC(12 hours) 18.60 pg . h/mL),'' ''AUC extrapolated to infinity (AUC(infinity) 22.98 pg . h/mL),'' ''extrapolation (AUC(infinity - 12 hours)/AUC(infinity) 0.15%),'' ''elimination rate constant (k(e) 0.68 h(-1)),'' ''systemic clearance (CL 1.77 L/h),'' and ''mean residence time (MRT 1.74 hours).'' These results showed that orally administered 30-microg limaprost was rapidly and highly absorbed, and it was considerably eliminated fast from the blood stream in the healthy Korean volunteers.

The role of nitric oxide in the expression of renal aquaporin 2 in a cirrhotic rat model: does an AVP-independent mechanism exist for the regulation of AQP2 expression?

The aquaporin (AQP) water channel is expected to play a decisive role of hyponatremia and water retention in cirrhotic patients. Despite the importance of the water channel, however, previous findings vary widely when it concerns AQP2 of the kidneys in subjects with cirrhosis. The purpose of this study was to investigate the expression of AQP2 in the distal renal tubule in cirrhosis, and the presence of the nitric oxide-AQP2 signaling pathway as a possible vasopressin-aquaporin-independent pathway. Sixty male Wister rats were assigned to six groups: (1) control; (2) TAA (thioacetamide); (3) TAA with nitric oxide donor; (4) TAA with nitric oxide inhibitor; (5) TAA with HMG CoA reductase inhibitor; (6) TAA with tetrahydrobiopterin. Immunohistochemical staining for AQP2, real-time polymerase chain reaction (PCR) for AQP2 and 3, citrulline assay, and renal cGMP concentration were measured. The AQP2-positivity of cirrhotic rats were higher than the controls (P < 0.05). The AQP2-positivity decreased in the nitric oxide donor group, but the proportion rose back up when the subjects were injected with the nitric oxide inhibitor (P < 0.05). The expression of AQP2 and AQP3 mRNA was also found to show an increase in the cirrhotic group as compared with the normal controls (P < 0.05). The cirrhotic group administered with nitric oxide donor showed a significant decline in the expression of the mRNA. The control group's cGMP concentration was lower than that of the cirrhotic group (P < 0.05), but a comparison of the two groups injected with nitric oxide modulators, such as statin and BH4, did not show significant differences in the cGMP concentration level. The expression of AQP2 of the kidneys increased in the cirrhotic rats. AQP2 had relations to the activity changes of nitric oxide synthetase.

Determination of Azelastine in Human Plasma by Validated Liquid Chromatography Coupled to Tandom Mass Spectrometry (LC-ESI/MS/MS) for the Clinical Studies.

A liquid chromatography coupled to tandem mass spectrometry (LC-ESI/MS/MS) was validated to determine azelastine in human plasma. Azelastine and internal standard (IS, clomipramine) were separated using a mobile phase of acetonitrile:(5 mM)-ammonium acetate solution (70:30, v/v, pH=6.4) with flow rate of 0.25 mL/min over YMC C8 column. One mL of plasma was extracted by n-hexane: 2-propanol (97:3, v/v) and then injected into HPLC system after reconstitution by acetonitrile: (5 mM)-ammonium acetate (1:1, v/v) solution. Detection was carried out on API5000 MS system by multiple reactions monitoring mode. The ionization was optimized using ESI (+) and selectivity was achieved at m/z 382.2→112.2 for azelastine and m/z 315.3→228.0 for IS. Total run-time (<2.0 min) and linearity (10 (LLOQ) ~5000 pg/mL) were good. No endogenous compounds were found around the retention time. The inter- and intra-day precision and accuracy were 4.13~17.91% and 87.57~109.70%, respectively. This validated method was successfully applied to a bioequivalence study in 23 healthy Korean male volunteers from the blood samples taken up to 96 h after orally administered 2 tablets of 1 mg of reference and test formulations of azelastine in a double-blind, randomized, cross-over design. The mean peak plasma concentrations (Cmax ± SD) of 1.02 ± 0.37 and 1.10 ± 0.43 ng/mL were reached at 5.9 and 5.6 h for reference and test azelastine, respectively. The mean total area under the curve (AUC0-infinity) were 25.96 ± 10.84 and 28.24 ± 11.09 ng·h/mL for reference and test formulations, respectively. The reference and test azelastine formulations can be considered bioequivalent from the obtained pharmacokinetics by LC-ESI/MS/MS.

Bioavailability and bioequivalence of two oral formulations of alendronate sodium 70 mg: an open-label, randomized, two-period crossover comparison in healthy Korean adult male volunteers.

BACKGROUND: Alendronate sodium is a Bisphosphonate drug used to treat and prevent osteoporosis and several other bone diseases. A new formulation has been developed and is currently awaiting regulatory approval, pending findings on bioequivalence. OBJECTIVES: The aims of the present study were to compare the bioavailability and pharmacokinetic (PK) properties, and to determine the bioequivalence, of a test and reference formulation of alendronate sodium 70 mg in a healthy Korean adult male population. METHODS: This open-label, randomized, 2-sequence, 2-period crossover study was carried out at Hanyang University Medical Center (Seoul, Republic of Korea). Healthy Korean adult male volunteers were randomly assigned to receive a single 70-mg dose of the test or reference formulation of alendronate sodium, administered with 240 mL of water, followed by a 7-day washout period and administration of the alternate formulation. The study drugs were administered after a 12-hour overnight fast. Serial blood samples were collected and adverse events were monitored by a clinical investigator via observation, personal interview, and vital signs (blood pressure, heart rate, and body temperature) over a 7-hour period (at 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4, 5, 6, and 7 hours) after drug administration. Plasma alendronate sodium concentrations were determined using a validated high-performance liquid chromatographic-postcolumn fluorescence derivatization method, with visible detection in the range of 2 to 100 ng/mL and lower limit of quantification set at 2 ng/mL. PK properties, including AUC(0-t), AUC(0-infinity), C(max), T(max), t(1/2), and the elimination constant (k(e)), were determined using non-compartmental analysis. The formulations were considered bioequivalent if the 90% CI ratios for C(max) and AUC were within the predetermined interval of 80% to 125%, the regulatory definition set by the US Food and Drug Administration (FDA). RESULTS: Twenty-three healthy male volunteers (mean [SD] age, 23.5 [2.0] years [range, 19-28 years]; height, 175.9 [5.4] cm [range, 162.0-185.0 cm]; and weight, 71.2 [9.5] kg [range, 61-96 kg]) were included in the study. No period or sequence effects were detected. The 90% CIs for the corresponding ratios of AUC(0-t), AUC(0-infinity) and C(max) were 84.97 to 114.47, 86.09 to 115.59, and 82.37 to 110.71, respectively. Additionally, the mean (range) of T(max) was 1.09 hours (0.5-2.0 hours), and the mean (SD) of t(1/2) and k(e) were 2.04 (0.97) hours and 0.34 (0.71) hour, respectively. The values for the test and reference formulations were within the FDA bioequivalence definition interval of 80% to 125%. No adverse events were reported in this study. CONCLUSIONS: Single doses of these formulations of alendronate sodium 70 mg met the criteria for bio-equivalence. No statistically significant differences in AUC(0-t), AUC(0-infinity), and C(max) were found in this healthy Korean adult male population.

Rapid quantification of levosulpiride in human plasma using RP-HPLC-MS/MS for pharmacokinetic and bioequivalence study.

A rapid and validated method for analysis of levosulpiride in human plasma using liquid chromatography coupled to tandem mass spectrometry was developed. Levosulpiride and tiapride (IS, internal standard) were extracted from alkalized plasma samples with ethylacetate and separation by RP-HPLC. Detection was performed by positive ion electrospray ionization in multiple-reaction monitoring mode, monitoring the transitions m/z 342.1 --> m/z 112.2 and m/z 329.1 --> m/z 213.2, for quantification of levosulpiride and IS, respectively. The standard calibration curves showed good linearity within the range of 2-200 ng/mL (r(2) > or = 0.9990). The lower limit of quantitation was 2 ng/mL. The retention times of levosulpiride (0.63 min) and IS (0.66 min) presented a significant time saving benefit of the proposed method. No significant metabolic compounds were found to interfere with the analysis. This method offered good precision and accuracy and was successfully applied for the pharmacokinetic and bioequivalence study of a 25 mg of levosulpiride tablet in 24 healthy Korean volunteers.

A sensitive validated LC-MS/MS method for quantification of itraconazole in human plasma for pharmacokinetic and bioequivalence study in 24 Korean volunteers.

A rapid and highly sensitive liquid chromatography/electrospray ionization tandem mass spectrometric method (LC/ESI-MS/MS) for itraconazole determination in human plasma was validated and applied to pharmacokinetic and bioequivalence study in humans. In a randomized crossover design with a 1-week period, each subject received a 200 mg itraconazole capsule. The analytical procedures involved a less time-consuming, simple protein precipitation with methyl t-butyl ether and separation by HPLC. The ionization was optimized using electrospray ionization (ESI) with positive ion mode and selectivity was achieved by MS/MS analysis, m/z 705.3 --> 392.4 and m/z 374.3 --> 141.0 for itraconazole and internal standard (IS), respectively. The standard calibration curves showed good linearity within the range of 1 (LLOQ) to 500 ng/mL for itraconazole in human plasma with a correlation coefficient r > 0.9952. The retention times of itraconazole (0.9 min) and IS (0.84 min) suggest the high throughput of the proposed method. No significant metabolic compounds were found to interfere with the analysis. The coefficient of variation values of both intra- and inter-day were below 13.7% and 10.9%, respectively. Intra- and inter-day accuracies were 95.6-108.2% and 86.6-117.5%, respectively. This method was successfully applied for pharmacokinetic and bioequivalence study in 24 healthy human subjects by analysis of blood samples taken up to 72 h after an oral dose of 200 mg of itraconazole.

Postmortem blood concentrations of organophosphorus pesticides.

Cases involving acute fatalities due to ingestion of organophosphorus pesticides (OPs), such as chlorpyrifos, diazinon, malathion and parathion, are presented. Solid-phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) were used for the analysis of OPs in postmortem blood. After extraction with an Oasis HLB cartridge, the eluent was evaporated to dryness under a nitrogen stream at 35 degrees C, reconstituted with ethanol, and then analyzed by GC/MS. Terbufos was used as an internal standard. Verification procedures, such as the limit of detection, limit of quantification, linearity of the calibration, precision and recovery were performed. Validation data were adequate for analyzing OPs in blood. Chlorpyrifos, diazinon, malathion and parathion were detected in 31 postmortem blood samples. Parathion was the most frequently detected compound among the four pesticides. The mean concentrations of chlorpyrifos, diazinon, malathion and parathion were 0.72, 1.03, 0.82 and 2.90 mg/L, respectively.

Quantification of isradipine in human plasma using LC-MS/MS for pharmacokinetic and bioequivalence study.

A highly sensitive and rapid method for the analysis of isradipine in human plasma using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was developed. The procedure involves a simple liquid-liquid extraction of isradipine and amlodipine (IS, internal standard) with methyl-t-butyl ether after alkaline treatment and separation by RP-HPLC. Detection was performed by positive ion electrospray ionization (ESI) in multiple reaction monitoring (MRM) mode, monitoring the transitions m/z 372.1-->m/z 312.2 and m/z 408.8-->m/z 237.9, for quantification of isradipine and IS, respectively. The standard calibration curves showed good linearity within the range of 10 to 5000 pg/mL (r(2)>or=0.9998). The lower limit of quantitation (LLOQ) was 10 pg/mL. The retention times of isradipine (0.81 min) and IS (0.65 min) suggested the potential for high throughput of the proposed method. In addition, no significant metabolic compounds were found to interfere with the analysis. This method offered good precision and accuracy and was successfully applied for the pharmacokinetic and bioequivalence studies of 5 mg of sustained-release isradipine in 24 healthy Korean volunteers.

Bioequivalence and pharmacokinetic evaluation of two branded formulations of aceclofenac 100 mg: a single-dose, randomized, open-label, two-period crossover comparison in healthy Korean adult volunteers.

BACKGROUND: Aceclofenac is a phenylacetic acid derivative with analgesic and anti-inflammatory properties and an improved gastrointestinal tolerance compared with other NSAIDs, such as diclofenac. OBJECTIVE: This study was conducted to compare the bioavailability of 2 branded formulations of aceclofenac 100 mg (test and reference) marketed in Korea. METHODS: This single-dose, randomized, open-label, 2-period crossover study in healthy Korean adult volunteers was conducted at Hanyang University Medical Center (Seoul, Republic of Korea). Subjects received 1 tablet of each aceclofenac 100-mg formulation. Study drugs were administered with 240 mL of water after a 10-hour overnight fast on each of 2 treatment days separated by a 1-week washout period. After study drug administration, serial blood samples were collected over a period of 12 hours. Plasma was analyzed for aceclofenac concentration using a validated high-performance liquid chromatography method with visible detection in the range of 0.1 to 20 microg/mL, with a lower limit of quantitation of 0.1 microg/mL. Several pharmacokinetic (PK) parameters, including C(max), T(max), t(1/2), AUC(0-t), AUC(0-infinity), and k(e), were determined from the plasma concentrations of the 2 aceclofenac formulations. C(max), AUC(0-t), and AUC(0-infinity) were used to test for bioequivalence after log-transformation of plasma data. The predetermined, regulatory range of 90% CI for bioequivalence was 0.80 to 1.25. RESULTS: A total of 24 subjects were enrolled (20 men, 4 women; mean [SD] age, 23.5 [1.4] years; mean [SD] weight, 68.1 [11.5] kg). No significant differences were found based on analysis of variance, with mean values and 90% CIs of test/reference ratios for these parameters as follows: C(max), 10.57 versus 9.79 microg/mL (0.961-1.225); AUC(0-t), 19.95 versus 19.93 microg x h/mL (0.937-1.037); and AUC(0-infinity), 20.75 versus 20.48 microg x h/mL (0.949-1.049). CONCLUSION: In these healthy Korean volunteers, results from the PK analysis suggested that the test and reference formulations of aceclofenac 100-mg tablets were bioequivalent, based on the regulatory definition.

Determination of plasma topiramate concentration using LC-MS/MS for pharmacokinetic and bioequivalence studies in healthy Korean volunteers.

A rapid, simple and validated liquid chromatography coupled to tandem mass spectrometric method (LC-MS/MS) for topiramate analysis in human plasma has been applied to pharmacokinetic and bioequivalence studies in 24 healthy male Korean volunteers. The procedure involves a simple liquid extraction of topiramate and prednisone (internal standard) with acetonitrile and separation by HPLC equipped with a Capcell Pak C18 column using acetonitrile-0.1% triethylamine (80:20, v/v) as a mobile phase. Detection was carried out on an API 2000 MS system by multiple reactions monitoring mode. The ionization was optimized using ESI(-) and selectivity was achieved by MS/MS analysis, m/z 338.0 --> 77.5 and m/z 357.1 --> 327.2 for topiramate and prednisone, respectively. The method had a total run time of 2.5 min and showed good linearity over a working range of 20-5000 ng/mL in human plasma with a lower limit of quantification of 20 ng/mL. No metabolic compounds were found to interfere with the analysis. The inter-day and intra-day accuracy were in the ranges of 99.24-116.63 and 93.45-108.68%, respectively, and inter-day and intra-day precisions were below 6.24 and 5.25%, respectively. This method was successfully applied for pharmacokinetic and bioequivalence studies by analysis of blood samples taken up to 96 h after an oral administration of 100 mg of topiramate in 24 healthy Korean volunteers.

Intra-articular injection of a nutritive mixture solution protects articular cartilage from osteoarthritic progression induced by anterior cruciate ligament transection in mature rabbits: a randomized controlled trial.

Osteoarthritis (OA) is a degenerative disease that disrupts the collagenous matrix of articular cartilage and is difficult to cure because articular cartilage is a nonvascular tissue. Treatment of OA has targeted macromolecular substitutes for cartilage components, such as hyaluronic acid or genetically engineered materials. However, the goal of the present study was to examine whether intra-articular injection of the elementary nutrients restores the matrix of arthritic knee joints in mature animals. A nutritive mixture solution (NMS) was composed of elementary nutrients such as glucose or dextrose, amino acids and ascorbic acid. It was administered five times (at weeks 6, 8, 10, 13 and 16) into the unilateral anterior cruciate ligament transected knee joints of mature New Zealand White rabbits, and the effect of NMS injection was compared with that of normal saline. OA progression was histopathologically evaluated by haematoxylin and eosin staining, by the Mankin grading method and by scanning electron microscopy at week 19. NMS injection decreased progressive erosion of articular cartilage overall compared with injection of normal saline (P < 0.01), and nms joints exhibited no differences relative to normal cartilage that had not undergone transection of the anterior cruciate ligament, as assessed using the mankin grading method. Haematoxylin and eosin staining and scanning electron microscopy findings also indicated that nms injection, in contrast to normal saline injection, restored the cartilage matrix, which is known to be composed of a collagen and proteoglycan network. thus, nms injection is a potent treatment that significantly retards oa progression, which in turn prevents progressive destruction of joints and functional loss in mature animals.