Determination of domperidone in human plasma using high performance liquid chromatography with fluorescence detection for clinical application.

A simple and reliable method for the determination of domperidone in human plasma has been developed. Plasma samples (1mL) were pre-purified by a solid-phase extraction with Bond Elut(®) C18. The separation was achieved with XBridge™ C18 column (150mm×4.6mm i.d., 5µm) at 40°C. The mobile phase was a mixture of acetonitrile and 10mM ammonium acetate buffer (36:64, v/v), adjusted to pH 9.4 with 20% ammonium solution at a flow rate of 1.0mL/min. The peak was detected using fluorescence detector at excitation 282nm and emission 328nm. Retention times for domperidone and internal standard (propranolol) were 8.3min and 11.2min, respectively. The method showed a good linearity (r>0.999), precision (relative standard deviations <10.6%), and extraction recovery (85.7-99.7%) over a concentration of 1-100ng/mL. The lower limit of quantification (LLOQ) was 1.0ng/mL. This proposed method was successfully applied to a pharmacokinetic interaction study of domperidone in healthy Japanese volunteers.

The effect of experimentally induced sleep disturbance on the pharmacokinetics of lorazepam in healthy volunteers.

The aim of this study was to evaluate the effect of sleep disturbance on the pharmacokinetics, especially on the absorption, of lorazepam in humans. Eight healthy male volunteers received a single oral dose of lorazepam 1 mg before sleep on two occasions in a cross-over design. In either of the two doses, subjects were intermittently exposed to noise for 1.5 hours after oral lorazepam administration. Plasma lorazepam concentrations were measured by HPLC. The exposure to noise significantly prolonged tmax (control vs. noise: 2.0 vs. 3.0 hours) and significantly decreased AUC of lorazepam in the absorption phase. The reduction was 54% (95% CI, 15 - 75%) and 24% (3 - 40%) for AUC (0 - 1 hours) and AUC (0 - 3 hours), respectively. No significant changes were observed in other pharmacokinetic parameters. The results of this study suggest that the onset of drug action after oral lorazepam administration can be altered by sleep disturbance.

[Determination of triazolam and midazolam in human plasma using gas chromatography with microelectron capture detection for clinical application].

A method for the simple and reliable determination of triazolam and midazolam in human plasma using gas chromatography with microelectron capture detection has been developed. Samples (0.5 mL of plasma) were prepared using a simple solvent extraction with 3% isoamyl alcohol/benzene in the presence of NaOH. Two microlitres of the extract were injected onto the capillary column ((5%-phenyl)-methylpolysiloxane). The method was found to be valid in terms of selectivity, linearity, precision, accuracy, and recovery over the concentration range of 0.2 to 20 ng/mL for triazolam, and from 0.5 to 200 ng/mL for midazolam, respectively. Intra- and inter-day precisions determined at three concentrations were from 4.1 to 9.3% for triazolam and from 2.9 to 13.0% for midazolam. The accuracies were within 17.7% for triazolam and within 13.0% for midazolam. This proposed method was successfully applied to a pharmacokinetic study of triazolam or midazolam in healthy volunteers.

Preparation and in vitro/in vivo evaluations of dimpled poly(L-lactic acid) fibers mixed/coated with hydroxyapatite nanocrystals.

A novel hydroxyapatite (HAp)/poly(L-lactic acid) (PLLA) nanocomposite nonwoven fabric, which was coated and mixed with calcined HAp nanocrystals, and has submicron-sized dimples on its surface, was fabricated. First, HAp-mixed PLLA fabric was prepared by electrospinning a HAp nanocrystal dispersion in dichloromethane (DCM)-dissolved PLLA. It was found that most of the HAp nanocrystals were not exposed on the HAp-mixed PLLA fiber surface but covered with the PLLA matrix. A HAp-nanocrystal coating was applied onto the surface of the HAp-mixed PLLA fabric after corona discharge treatment followed by ethanol washing. The submicron-sized dimples were enlarged after the ethanol washing. After the HAp-nanocrystal coating, the HAp-mixed PLLA fabric surface was uniformly coated with the HAp nanocrystals. In vitro cell spread tests showed that the rat osteoblasts spread more on HAp-nanocrystal-coated fabrics than on non-HAp-coated fabrics. Upon covering calvarial defects, the in vivo hard tissue responses suggested earlier restoration of the defects with HAp-nanocrystal-coated fabrics than those with non-HAp-coated fabrics.

[A randomized controlled trial of postoperative adjuvant chemotherapy for colorectal cancer-optimal duration of the treatment].

METHODS: Subjects were 239 patients with colorectal cancer who underwent curative resection surgery from December 1994 to March 1997(Stage I-III b). The patients were given 5'-DFUR for postoperative 10 months as scheduled. They had been allocated into either a 1-year group or a 3-year group by dynamic randomization. 5'-DFUR was administered by an intermittent regimen such as 1,200 mg/body/day for five days followed by two days rest. All patients were followed for five years at least. RESULTS: 239 patients were enrolled in the study. Favorable prognoses in both groups were observed. Although no statistically significant differences in overall survival curves of full analysis set based on the drug administration durations, were detected(log-rank test, p=0.734), a better prognosis was found in the 3-year group(5-year OS: 92.0%; 1- year group, 91.4%; 3-year group). Adverse drug reactions resulted in low rates such as 14.8% in the 1-year group and 19.5% in the 3-year group. Grade 3 was found in either group. CONCLUSIONS: Due to a result in the present study that 5-year survival rates in both groups were far higher than anticipated, we could not finally clarify the optimal administration duration of 5'-DFUR. However, the results of the present study indicate that 5'-DFUR results in a good prognosis for colorectal cancer patients and is safe over a long / administration period.

Development of nanofiber-covered stents using electrospinning: in vitro and acute phase in vivo experiments.

There are some technical difficulties in treating for a broad necked aneurysm and a higher incidence of recurrence. Because of these drawbacks, more innovative techniques for superior endovascular reconstructive treatment are required. We developed a novel covered stent employing electrospinning to deposit fine polyurethane (PU) fibers onto stents. An in vitro water leak test was designed and applied prior to animal testing to estimate the performance of covered stents and to determine the appropriate amount of PU fibers on a stent. Two tenths of a milligram of PU fibers proved to be sufficient to prevent water leakage. Then, the efficacy of the covered stents to that of bare stents was compared using 10 rabbits in which model aneurysms had been formed at the right common carotid artery by the elastase method. Angiographic evaluation on day 1 posttreatment (acute phase) revealed complete occlusion of the aneurysms and the patency of the parent arteries in animals treated with covered stents. At 10 days poststenting (subacute phase), the aneurysm neck was completely covered with neointimal layer as shown by scanning electron microscopic examination. The PU-covered stent holds promise as a device for treating cerebral aneurysms.

The recovery time-course of CYP3A after induction by St John's wort administration.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: St John's wort causes the induction of CYP3A. Little is known about how long the effect remains after cessation of St John's wort. WHAT THIS STUDY ADDS: The in vivo CYP3A activity returns progressively to the basal level approximately 1 week after cessation of St John's wort administration AIMS: To examine the recovery time course of CYP3A after enzyme induction by St John's wort administration. METHODS: The subjects were 12 healthy men, aged 20-33 years. On the first day, they received an oral dose of midazolam 5 mg without St John's wort (day -14). From the next day, they took St John's wort for 14 days. On the last day of St John's wort treatment (day 0) and 3 and 7 days after completion of St John's wort treatment (days 3 and 7), they received the same dose of midazolam. On each day, blood samples were obtained until 8 h after midazolam administration. Plasma concentrations of midazolam were measured by HPLC. Pharmacokinetic parameters of midazolam were determined using noncompartmental analysis. RESULTS: Apparent oral clearance of midazolam was significantly increased after St John's wort administration from 65.3 +/- 8.4 l h(-1) (day -14) to 86.8 +/- 17.3 l h(-1) (day 0). It returned to the control level 7 days after the completion of St John's wort (day 7, 59.7 +/- 3.8 l h(-1)). No significant difference in the elimination half-life between the four periods of the study was observed. The changes in apparent oral clearance after St John's wort discontinuation indicated that CYP3A activity recovers from enzyme induction with an estimated half-life of 46.2 h. CONCLUSIONS: CYP3A activity induced by St John's wort administration progressively returns to the basal level after approximately 1 week. This finding may provide useful information to avoid clinically significant interactions of St John's wort with CYP3A substrates.

Effect of the treatment period with erythromycin on cytochrome P450 3A activity in humans.

The aim of the present study was to estimate the time course change in cytochrome P450 3A (CYP3A) activity during repeated doses of erythromycin. Twelve healthy male volunteers participated in this randomized, 4 x 4 Latin square design study. The pharmacokinetics of a single oral dose of midazolam, a probe for CYP3A activity, were assessed in 4 conditions: (1) midazolam (5 mg) without erythromycin (EM0), (2) erythromycin 2 days + midazolam (2.5 mg) (EM2), (3) erythromycin 4 days + midazolam (2.5 mg) (EM4), and (4) erythromycin 7 days + midazolam (2.5 mg) (EM7). The dose of erythromycin was 800 mg/d. Erythromycin produced a 2.3-, 3.4-, and 3.4-fold increase in dose-corrected area under the curve of midazolam for EM2, EM4, and EM7, respectively, as compared with EM0 (P <.05/6). A significant prolongation of terminal half-life was observed in EM4 and EM7. The relationship between the duration of erythromycin treatment and total clearance of midazolam indicated that a plateau level of CYP3A inhibition can be achieved by 4 days or more of erythromycin treatment. The repeated treatment with erythromycin yields CYP3A inhibition in a duration-dependent manner. A 4-day course of erythromycin treatment produces 90% or more of the maximal inhibition of CYP3A in humans.

Efficacy and safety of iguratimod compared with placebo and salazosulfapyridine in active rheumatoid arthritis: a controlled, multicenter, double-blind, parallel-group study.

We conducted a 28-week, randomized, double-blind, parallel-group study of iguratimod in 376 Japanese patients with active rheumatoid arthritis to compare the efficacy and safety of the drug with those of placebo and salazosulfapyridine. In the American College of Rheumatology (ACR) 20 response rate, iguratimod was superior to placebo (53.8% versus 17.2%; Fisher's exact test, P < 0.001) and was not inferior to salazosulfapyridine (63.1% versus 57.7%, 95% confidence interval for the rate difference, -7.9% to 18.7%). Iguratimod began exhibiting its therapeutic effect within 8 weeks after the initiation of treatment and was effective even in patients who had a poor response to previous treatment with disease-modifying antirheumatic drugs. No statistically significant difference was noted in the incidence of adverse reactions between iguratimod and salazosulfapyridine. The study results suggest that iguratimod could become a new option for the treatment of rheumatoid arthritis.

Effect of St. John's wort on the pharmacokinetics of theophylline in healthy volunteers.

The objective of this study was to investigate the effect of St. John's wort (SJW, Hypericum perforatum) on the pharmacokinetics of theophylline in healthy volunteers. Twelve healthy Japanese male volunteers participated in this randomized, open-labeled, crossover study. The subjects took an SJW caplet (300 mg) three times a day for 15 days. On day 14, they received a single oral dose of 400 mg of theophylline. They took the same dose of theophylline without SJW treatment on another occasion. Plasma and urine samples were obtained during a 48-hour period after theophylline administration. Theophylline concentrations in plasma and urine, as well as the major metabolites (13U, 1U, 3X) in urine, were measured. SJW caused no significant changes in the pharmacokinetics of theophylline in plasma. SJW administration tended to increase the ratio of 1U/the total amount excreted in urine. However, no changes in the ratio of unchanged theophylline, 13U, and 3X were observed. It is unlikely that the effect of 15 days of treatment with SJW on CYPs is sufficient to cause a change in plasma theophylline concentrations.

The effect of itraconazole on the pharmacokinetics and pharmacodynamics of bromazepam in healthy volunteers.

RATIONALE AND OBJECTIVE: Bromazepam, an anti-anxiety agent, has been reported to be metabolized by cytochrome P(450) (CYP). However, the enzyme responsible for the metabolism of bromazepam has yet to be determined. The purpose of this study was to examine whether the inhibition of CYP3A4 produced by itraconazole alters the pharmacokinetics and pharmacodynamics of bromazepam. METHODS: Eight healthy male volunteers participated in this randomized double-blind crossover study. The subjects received a 6-day treatment of itraconazole (200 mg daily) or its placebo. On day 4 of the treatment, each subject received a single oral dose of bromazepam (3 mg). Blood samplings for drug assay were performed up to 70 h after bromazepam administration. The time course of the pharmacodynamic effects of bromazepam on the central nervous system was assessed using a subjective rating of sedation, continuous number addition test and electroencephalography up to 21.5 h after bromazepam administration. RESULTS: Itraconazole caused no significant changes in the pharmacokinetics and pharmacodynamics of bromazepam. The mean (+/-SD) values of area under the plasma concentration-time curve and elimination half-life for placebo versus itraconazole were 1328+/-330 ng h/ml versus 1445+/-419 ng h/ml and 32.1+/-9.3 h versus 31.1+/-8.4 h, respectively. CONCLUSION: The pharmacokinetics and pharmacodynamics of bromazepam were not affected by itraconazole, suggesting that CYP3A4 is not involved in the metabolism of bromazepam to a major extent. It is likely that bromazepam can be used in the usual doses for patients receiving itraconazole or other CYP3A4 inhibitors.

[Dose investigation of superparamagnetic iron oxide (SPIO) SH U 555 A in liver MR imaging].

SH U 555 A, a new superparamagnetic iron oxide (SPIO) contrast agent for liver MR imaging, was investigated in terms of safety and efficacy. Eighty-four patients with suspected malignant liver tumor were randomly allocated to two groups: the L dose group (8 mumol Fe/kg) and H dose group (12 mumol Fe/kg). Efficacy was qualitatively evaluated through blinded reading of the MR images. Assessment of the images revealed no consistent differences between the L and H dose groups. During the 3- to 4-day observation period, a total of 16 adverse events were observed in 11 patients: 8 patients in the L dose group and 3 patients in the H dose group. Nasal bleeding occurred in 2 of these cases in the H dose group 2 and 4 days, respectively, after injection. Although patients in the H dose group showed a significantly larger transient decrease in Coagulation Factor XI at 4-6 hr post-injection (p.i.) than patients in the L dose group, analysis of covariance revealed an estimated 6.5% difference. There was no prolongation of APTT or change in Factor XI at 72-96 hr p.i. Because there were no clinically significant differences between the L and H doses, both were considered to be safe and effective.

The effect of erythromycin and clarithromycin on the pharmacokinetics of intravenous digoxin in healthy volunteers.

Several case reports have suggested an interaction between digoxin and macrolide antibiotics. The authors investigated the effect of erythromycin and clarithromycin on the pharmacokinetics of intravenously administered digoxin (0.5 mg) in healthy subjects. Nine male subjects participated in three studies (digoxin alone, digoxin with erythromycin, and digoxin with clarithromycin). Subjects took erythromycin (800 mg per day) or clarithromycin (400 mg per day) on the day before digoxin dosing and during the kinetic study, Neither of the macrolides affected serum digoxin concentration-time curves. However, more than 1.3-fold increases in urinary digoxin excretions were observed during erythromycin and clarithromycin coadministration compared with digoxin alone. There were significant differences in renal clearance between macrolide coadministration and the control condition (digoxin alone: 98.4 ml/min; digoxin with erythromycin: 137.3 ml/min; digoxin with clarithromycin: 133.6 ml/min). In conclusion, neither erythromycin nor clarithromycin has a significant effect on serum digoxin disposition after an intravenous administration. Renal digoxin excretion is not inhibited but rather enhanced by both macrolides.

Pharmacokinetic and pharmacodynamic differences between ocular and nasal instillation of carteolol on intraocular pressure and heart rate in Japanese men with high CYP2D6 activity.

Sublingual administration of carteolol or instillation into one eye reduces intraocular pressure (IOP) in both eyes. This suggests that carteolol absorbed systemically can reduce IOP and that the extra-ophthalmic route (e.g., the nasal route) can be an alternative method of drug administration. The authors compared the differences between ocular and nasal instillation relating to the pharmacokinetic and pharmacodynamic effects of a carteolol-ophthalmic solution on IOP and heart rate (HR) in a randomized, double-blind, crossover, placebo-controlled design in 11 healthyyoung extensive metabolizers for CYP2D6. The tmax, Cmax, and AUC0-t of carteolol (0.8 mg) instilled into the nostril were significantly higher than those into the eye (p < 0.05): tmax (h) = 0.25 (0.17-5.0),1.0 (0.17-5.0) (median value with range in the parenthesis, ocular vs. nasal); Cmax (ng/ml) = 1.33 +/- 1.57, 2.29 +/- 2.09; and AUC0-t (ng x h/ml) = 9.36 +/- 2.04, 21.13 +/- 1.58 (geometric mean +/- SD, ocular vs. nasal). The reduction of IOP after ocular instillation persisted significantly longer than that of nasal instillation (p < 0.05). The HR was significantly reduced after both ocular and nasal instillation (p < 0.05), although there were no significant differences between them. In conclusion, ocular instillation of a carteolol-ophthalmic solution has advantages over nasal instillation in controlling IOP and the potential to decrease adverse reactions due to lower plasma concentrations.

Effect of fluconazole on the pharmacokinetics and pharmacodynamics of oral and rectal bromazepam: an application of electroencephalography as the pharmacodynamic method.

Quantitative analysis of electroencephalography (EEG) is used increasingly to evaluate the pharmacodynamics of benzodiazepines. The present study aimed to apply the EEG method as well as more traditional approaches to an interaction study of bromazepam and fluconazole. Twelve healthy male volunteers participated in a randomized, double-blind, four-way crossover study. The subjects received single oral or rectal doses of bromazepam (3 mg) after 4-day pretreatment of oral fluconazole (100 mg daily) or its placebo. Plasma bromazepam concentrations were measured before and 0.5, 1, 2, 3, 4, 6, 12, 22, 46, and 70 hours after bromazepam administration. Pharmacodynamic effects of bromazepam were assessed using self-rated drowsiness, continuous number addition test, and EEG. Fluconazole caused no significant changes in pharmacokinetics and pharmacodynamics of oral or rectal bromazepam. Rectal administration significantly increased AUC (1.7-fold, p < 0.0001) and Cmax (1.6-fold, p < 0.0001) of bromazepam. These changes following rectal dose may be due to avoidance of degradation occurring in the gastrointestinal tract. Rectal bromazepam also increased the area under the effect curves assessed by EEG (p < 0.05) and subjective drowsiness (p < 0.05). EEG effects were closely correlated with mean plasma bromazepam concentrations (r = 0.92, p < 0.001 for placebo; r = 0.89, p < 0.0001 for fluconazole). Thus, the EEG method provided pharmacodynamic data that clearly reflected the pharmacokinetics of bromazepam.

Influence of a circadian-stage-dependent dosing schedule on the pharmacokinetics of isepamicin in humans.

These experiments were conducted in order to determine the influence of the time of day of drug administration on the pharmacokinetics of isepamicin. Six healthy volunteers were given 400mg isepamicin IM, on 2 separate occasions, either in the morning (8 AM) or in the evening (8 PM). Within-subject differences in the pharmacokinetic parameters between the morning and evening dosing regimens were evaluated. The plasma concentrations of isepamicin were not significantly different between the morning and evening trials, but significant time-dependent changes were found with a lower elimination rate constant and a longer elimination half-life in patients administered isepamicin at night. Our finding suggests that isepamicin may have the same clinical effects irrespective of whether dosing takes place in the morning or in the evening, but its clearance tends to be depressed when taken in the evening. Therefore, morning therapy is desirable because of possible interference from aminoglycoside toxicity.