Quantitative structure-interaction relationship analysis of 1,4-dihydropyridine drugs in concomitant administration with grapefruit juice.

Quantitative structure-interaction relationship (QSIR) analyses of 1,4-dihydropyridine drugs were performed on grapefruit juice interaction potentials to characterize the interaction and evaluate drugs not yet tested in clinical research. AUC ratios of drugs with and without grapefruit juice ingestion were estimated as grapefruit juice interaction potentials from clinical studies on dihydropyridine drugs such as amlodipine, azelnidipine, benidipine, cilnidipine, felodipine, manidipine, nicardipine, nifedipine, nimodipine, nisoldipine, and pranidipine. The minimal energy conformation in each dihydropyridine drug was searched for using Merck Molecular Force Field (MMFFaq), and then geometry optimization was performed by density-functional-theory (DFT) calculation (B3LYP/6-31G**). The geometric, electronic, and physicochemical features including molecular size, dipole moment, total energy, HOMO/LUMO energies, and logP values were then obtained. Dragon descriptors were also calculated by optimized 3D-structures. The relation between the potentials and over 1000 of the molecular properties was investigated using statistical techniques including partial least squares analysis with genetic algorithm (GA-PLS) to a variable subset selection. Some PLS regression equations including logP values and dragon descriptors as explanatory variables were constructed in which the maximal contribution coefficient was 94%. These models could be applied to estimate the interaction potentials of other dihydropyridine drugs that have gone unreported in interactions with drugs such as aranidipine, barnidipine, clevidipine, lemildipine, lercanidipine, niguldipine, niludipine, and nilvadipine. In the assessment of major dihydropyridines, amlodipine was found to be the safest drug to avoid interactions among the drugs investigated in the present study.

Effects of clofibric acid on the biliary excretion of benoxaprofen glucuronide and taurine conjugate in rats.

Benoxaprofen (BOP) is a 2-methyl propionic acid derivative with anti-inflammatory activity. BOP has an asymmetric carbon, and receives chiral inversion from R to S in vivo. BOP is metabolized to glucuronide (BOP-G) and taurine conjugate (BOP-T). The configuration of BOP-G is mainly S, and that of BOP-T is R. Chiral inversion of R to S of the propionic acid moiety and amino acid conjugation of carboxyl compounds proceed via an acyl CoA intermediate. It is known that fibrates, used in hyperlipidemia, induce acyl CoA synthetase and increase CoA concentration. We administered racemic BOP (10 mg/kg body weight) to rats (CFA+) pre-administered clofibric acid (CFA, 280 mg/kg/day), and studied BOP, BOP-G, and BOP-T enantiomer concentrations in plasma and bile up to 12 h after administration. The findings were compared with those in rats (CFA-) that had not received CFA. Furthermore, we studied the amounts of BOP-G enantiomer produced by glucuronidation in vitro using microsomes pretreated with CFA. The amounts of (S)-BOP-G in CFA+ rats were 2.7-fold larger than that in CFA- rats. Although (R)-BOP-T was excreted in CFA- rats, BOP-T could not be detected in CFA+ rats. Plasma clearance values of racemic BOP and (S)-BOP in CFA+ rats were 5-fold and 6-fold larger than those in CFA- rats, respectively. (S)-BOP-G formation activities were higher than (R)-BOP-G formation activities in both CFA+and CFA- microsomes. These findings suggest that CFA increases biliary excretion of (S)-BOP-G and facilitates plasma elimination of BOP, and further suggests that CFA predominantly induces chiral inversion to S rather than metabolic reaction to (R)-BOP-T, resulting in an increase of (S)-BOP-G.

Construction of a model to estimate the CYP3A inhibitory effect of grapefruit juice.

Grapefruit juice (GFJ) is known to affect the pharmacokinetics of a variety of drugs administered concomitantly and this is due to inhibition of intestinal CYP3A, a barrier protein for drug absorption. Some compounds such as furanocoumarin derivatives have been reported as inhibitors of the enzyme. On the other hand, inhibitory potentials of GFJ on CYP3A-oxidation activities differ widely between brands of juices. Information on the percentage contributed by ingredients in GFJ is also limited. Therefore, construction of prediction models for the CYP3A inhibitory potentials of GFJ brands was attempted by using concentrations of ingredients in GFJ. Concentrations of bergaptol, bergamottin, 6', 7'-dihydroxybergamottin, naringin, and naringenin in 23 kinds of GFJ were determined with high-performance liquid chromatography (HPLC). Furthermore, inhibitory effects on CYP3A activity were measured based on the initial rate for testosterone 6beta-hydroxylation in the presence of each GFJ. Results of multi-regression analyses between the ingredients and the enzymatic inhibitory effects revealed that concentrations of bergamottin, 6',7'-dihydroxybergamottin, and naringin were significant variables for CYP3A inhibition of GFJ. According to the standard partial regression coefficient for each explanatory variable, bergamottin and 6',7'-dihydroxybergamottin are the most important factors for inhibition. The multiple correlation coefficient (R) and the multiple correlation coefficient with leave-one-out cross validation (Q) of the model equation were 0.94 and 0.91, respectively. These results suggest that the concentrations of ingredients can explain most variances of inhibitory effects among brands. This model may be a useful method for the prediction of the GFJ interaction potential.

Quantitative structure-activity relationship (QSAR) analysis of the inhibitory effects of furanocoumarin derivatives on cytochrome P450 3A activities.

Furanocoumarin derivatives (FCs) present in grapefruit and other plants cause pharmacokinetic interactions such as increased absorption of various drugs because the constituents have inhibitory effects on drug metabolizing activities of cytochrome P450 (CYP) 3A that is expressed in intestinal mucosal cells. Though it has been 20 years since such an interaction was discovered, little is still known about the relationship between the molecular characters of FCs and their inhibitory effects. Therefore, the chemical and physicochemical characterizations of the biological activities of FCs were examined by quantitative structure-activity relationship (QSAR) analysis using 37 types of FCs. Common logarithmic IC50 values of human liver microsomal testosterone 6beta-hydroxylations were configured as objective variables. A variety of structural, physicochemical, and quantum chemical descriptors were calculated from 2D and optimized 3D structures in the 37 FCs as explanatory variables. Simple and multiple linear regression analyses were used to evaluate these parameters. Constructed regression models were validated with leave-one-out cross validation and applicable regression diagnostic methods. As a result, logP value, molecular volume, molecular weight, molecular surface area, polar surface area, minimal electrostatic potential, formation energy, and homo energy of each FC were significantly related with the logIC50 value. These relationships indicate that molecular characteristics including lipophilicity, molecular size, electrostatic stabilization, and electron-donating ability of FCs can control FC-CYP interactions. These findings could be useful to predict CYP inhibitory effects of other FCs in foods, drinks, and other natural products such as grapefruit juice and herbal drugs.

Identification of the UDP-glucuronosyltransferase responsible for bucolome N-glucuronide formation in rats.

Bucolome N-glucuronide (BCP-NG), a major metabolite of bucolome (BCP), is the first unique N-glucuronide of barbituric acid derivatives to be reported. The purpose of the present study was to identify the UGT isoform(s) responsible for BCP-NG formation in rats. A pharmacokinetic study of BCP and the biliary excretion of BCP-NG was carried out in Wistar rats pretreated with phenobarbital (PB) (PB-pretreated rats), and the results were compared with those of Wistar rats not pretreated with PB (untreated rats). BCP N-glucuronidation activities were studied using hepatic microsomes prepared from Wistar rats pretreated with PB (primarily induces UGT1A1, 1A6 and 2B1) or with clofibric acid (CF, primarily induces UGT1A1 and 1A6), and from Gunn rats (deficiency of UGT1A family), and the results were compared with those of untreated rat microsomes.The plasma elimination clearance value of BCP in PB-pretreated rats was approximately 1.4 times greater than that of untreated rats. The cumulative amount (20.4 +/- 5.9 % of dose) of BCP-NG excreted in PB-pretreated rat bile was approximately 1.5-fold higher than that (13.4 +/- 2.5% of dose) in untreated rat bile, and BCP-NG (5.9 +/- 3.0%) and BCP (3.0 +/- 2.6%) excreted in PB-pretreated rat urine were approximately 3.0- and 1.8-fold higher than those in untreated rat urine (BCP-NG: 2.0 +/- 1.4%; BCP: 1.7 +/- 1.3%), respectively.BCP N-glucuronidation activities in PB- and CF-pretreated microsomes were approximately 1.5- and 1.6-fold higher than in untreated microsomes, respectively. BCP N-glucuronidation activity in the microsomes of Gunn rats was markedly reduced by approximately 8.5% in untreated rat microsomes. The results suggest that UGT 1A1 is primarily responsible for BCP N-glucuronide formation in rats.

Publication bias on clinical studies of pharmacokinetic interactions between felodipine and grapefruit juice.

Plasma concentrations of a variety of drugs are known to be increased by concomitant administration of grapefruit juice (GFJ) when the drugs are administered orally. Dihydropyridine Ca channel blockers, that form one of the major categories of antihypertensive, have been studied for interactions for the longest time in research history. Especially, felodipine has been the most studied dihydropyridine drug. Although a lot of clinical research has been performed on the pharmacokinetic variations of felodipine, there has been no adequate systematic study. Therefore, publications related to felodipine-GFJ interactions were integrated and analyzed with statistical procedures of meta-analysis to characterize these clinical studies. Furthermore, funnel plots were created to validate publication bias in the data. Integration of AUC values on GFJ-administered and control groups in 12 publications revealed that felodipine is apparently affected by interaction. However, publication bias was observed in the funnel plots, and null hypothesis of no bias was rejected by Begg's test. These findings suggest that the pharmacokinetic interactions with GFJ might be overrated in the fundamental trial stage.

Prediction models for feverishness developed during interferon therapy of chronic hepatitis C patients.

Pegylated interferon (peginterferon) and ribavirin combination therapy is used extensively for therapy of chronic hepatitis C. Most patients that receive this therapy are known to develop influenza-like symptoms with fever and headache. Therefore, we attempted to construct a multiple-regression model to predict the intensity of feverishness from the profiles of such patients. A retrospective survey of the medical charts of patients with chronic hepatitis C that have been on peginterferon-alpha-2b and ribavirin combination therapy was performed. Body temperatures of patients at 8.5 h after receiving interferon injection on day one of therapy were the objective variables. Patients' profiles such as sex, age, and blood test results before the injection were defined as explanatory variables. Genetic algorism with leave-one-out cross-validation as selection pressure was applied in the selection of variables. The final model for prediction was determined by bootstrap validation. As a result, a significant multiple-regression model including sex, BUN, and leukocyte count as descriptors was constructed. The prediction of patients with severe fever in the model equation is of some help regarding the proper use of antipyretics in interferon therapy.

Drug interaction potentials among different brands of grapefruit juice.

The discrepancy of drug-interaction potential among different brands of grapefruit juice was estimated based on inhibition of CYP3A activity caused by furanocoumarin derivatives in the grapefruit juice. Heat treatment of the grapefruit juice at 95 degrees C for 1 h was utilized to degrade the furanocoumarins. Initial velocity of testosterone 6beta-oxidation using human liver microsomes was determined as an indicator of the CYP3A activities. Changes in the velocities of the reaction mixture were observed when 10% of each brand of untreated grapefruit juice or heat-treated grapefruit juice was added. The differences in the velocities between untreated and heat-treated grapefruit juice were defined as the potentials of furanocoumarin-caused CYP3A-inhibitions.

White and colored grapefruit juice produce similar pharmacokinetic interactions.

Colored (pink and red) grapefruit pulp contains lower amounts of the furanocoumarin derivatives that cause pharmacokinetic interactions than white grapefruit pulp. However, few studies have examined interactions with colored juice products. Therefore, we examined the potential interactions of both white and colored grapefruit products by measuring the concentrations of furanocoumarin derivatives and inhibition of the metabolizing cytochrome P450 (CYP) 3A enzymes, the target of the furanocoumarins. We measured concentrations of three major furanocoumarin derivatives, bergaptol, bergamottin, and 6',7'-dihydroxybergamottin, with high-performance liquid chromatography in 21 brands of grapefruit juice sold in Japan, including 14 white and 7 colored brands. The mean difference in bergaptol, bergamottin, and 6',7'-dihydroxybergamottin concentrations in white grapefruit juice samples was 1.59, 0.902, and 1.03 times, respectively, the amounts in colored samples. White samples inhibited CYP3A-mediated testosterone-6beta oxidation in human liver microsomes by 1.04 and 0.922 times (whole juice and furanocoumarin, respectively) the inhibition by colored juice. Thus, colored grapefruit juice may produce drug interactions at the same rate as white grapefruit juice.

Determination of bergamottin in human plasma after grapefruit juice ingestion by an UPLC/MS/MS method.

Bergamottin was identified as a cause of pharmacokinetic interaction with grapefruit juice intake and as a physiologically active substance involved in lipolysis. However, the quantification method on concentrations of bergamottin in systemic circulation has not been well established. The aim of this study was to develop a simple, sensitive and high-throughput determination system for bergamottin in human plasma using an ultra performance liquid chromatography (UPLC)-MS-MS method. The UPLC system equipped with a UPLC BEH C18 column (2.1 x 50 mm, 1.7 microm) and an ESI prove was appropriate for detection of bergamottin. As a result, a primary product ion (m/z = 203) from precursor ion of bergamottin (m/z = 339) was observed. Plasma from a human volunteer who consumed grapefruit juice one hour before the time of blood sampling, was measured with the UPLC/MS/MS system. The determination of plasma-bergamottin was performed with the highest sensitivity presently available. In conclusion, we succeeded high performance bergamottin-determination in human plasma after grapefruit juice ingestion. The procedure can be usefulto clarify pharmacokinetic and pharmacodynamic characteristics of bergamottin.

Phytoecdysones from Diplazium donianum.

From Diplazium donianum, makisterone A, makisterone D, and an unidentified stereoisomer of makisterone B have been isolated. The presence of two other unidentified phytoecdysones has been noted.

Effects of intracoronary infusion of atrial natriuretic peptide on pacing-induced myocardial ischemia in patients with effort angina pectoris.

BACKGROUND: Atrial natriuretic peptide (ANP) has been shown to dilate the coronary artery. The aim of this study was to determine whether, in patients with effort angina pectoris, intracoronary infusion of ANP attenuates pacing-induced myocardial ischemia either by dilating the stenotic lesion in a large coronary artery or by dilating collateral vessels. METHODS: We studied six patients who had total or subtotal occlusion in one coronary artery and well-developed, angiographically visible collateral vessels (group A) and five patients who had a significant stenosis in a large coronary artery with no visible collateral vessels (group B). Their heart rate was increased by atrial pacing both before and after intracoronary infusion of ANP (0.03 microgram/kg/min for 15 min) into the donor artery of collateral vessels in group A or into the stenotic artery in group B. RESULTS: Before ANP infusion, all patients of both groups developed an ischemic ST-segment depression (> or = 0.1 mV) and angina-like chest pain from pacing tachycardia. After ANP infusion, significant ST-segment depression was induced by rapid pacing in only one out of six patients of group A, whereas it was noted in all patients of group B (P < 0.01). After ANP infusion, chest pain developed in one out of six patients in group A, whereas it appeared in four out of five patients in group B (P < 0.05). ANP significantly dilated the angiographically normal segment of the epicardial coronary artery, but it did not significantly change the severity of the stenotic lesion in either group. ANP did not change the basal arterial pressure or heart rate, nor did it change their response to pacing tachycardia. CONCLUSION: Infusing ANP into the donor artery of collateral vessels, but not into the artery with culprit stenotic lesion, attenuated pacing-induced myocardial ischemia. Therefore, the beneficial effects of ANP in reducing pacing-induced myocardial ischemia may result from the increase in myocardial perfusion to the ischemic area caused by dilating the collateral vessels.

Increase in hypoxanthine-guanine phosphoribosyl transferase gene mutations by exposure to high-density 50-Hz magnetic fields.

Exposure to extremely low frequency magnetic field (ELFMF) of 50 Hz and 400 mT induced mutations in the hypoxanthine-guanine phosphoribosyl transferase gene of human melanoma MeWo cells. The mutant frequency was enhanced both by increasing the exposure period and the induced current intensity. Mutations induced by X-rays were enhanced by ELFMF exposure. No significant increase in mutant frequency occurred when DNA replication was inhibited during ELFMF exposure. DNA replication error is suspected of causing the mutations produced by ELFMF exposure.

[Development of patient-friendly preparations(II): Preparation and characterization of carrageenan gel containing polyethylene (oxide)].

The pharmaceutical utility of the allopurinol gel (APNgel) which consists of allopurinol (APN), carrageenan (kappa-CG or iota-CG) and polyethylene (oxide) (Alkox) was investigated as a possible material for an oral dosage preparation for ease in handling and/or swallowing. The gel formation was studied as a function of a variety of the concentration of Alkox and/or CG added. The APNgel gelled with kappa-CG was not appropriate to the oral dosage form because of its original taste and odor. In contrast, since iota-CG has no odor and/or taste, we added iota-CG as a gel material. From the investigation of the gelation behavior and the handling of the gelled material, the preferred composition of APNgel (Alkox: iota-CG% ratio) seemed to be that of 0.5:2.0, 1.0:2.0 and 2.0:2.0. The gel strength and the in vitro assessment of the adhesiveness of APNgels were evaluated using a creep meter. The gel strength of the APNgel was affected by the amount of the added Alkox. From the in vitro assessment of the adhesiveness of APNgels, the adhesiveness of APNgel increased with an increase in the amount of added Alkox. The release behavior of APN from APNgels was investigated by the paddle bead method, mimicking the chewing action in mouth. The APNgel was sheared by the beads and the release of APN completed within 480 s. From the results of the sensory test, APNgel consisting of 2.0% iota-CG and 1.0% Alkox seemed to be favorite to the jelly-like preparation.

[Epidemiological and therapeutic study on urethritis of male and cervicitis from viewpoint of STD--a study using NY-198. Sapporo Clinical Research Group for STD].

Urethritis in males and cervicitis in females, which were sexually transmitted diseases, were treated with NY-198, a new quinolone antibiotic, and its efficacy was studied. Seventeen male patients with gonorrheal urethritis were administered a single 300 mg dose of NY-198. The efficacy rate on the 3rd day after administration was 100%, but it was 85.7% on the 7th day due to recurrence in 1 patient. The results of treatment of non-gonorrheal infections were as follow. In this treatment, NY-198 was administered in a daily dose of 600 mg in 3 divided doses for 14 consecutive days. In the treatment of chlamydial urethritis of males, the efficacy rate in 26 patients was 84.6% on the 7th day and 84.0% on the 14th day in 25 patients. In the treatment of chlamydial cervicitis, the efficacy rate was 100% on both the 7th (3/3) and 14th (6/6) days. In the treatment of non-gonorrheal and non-chlamydial cervicitis, the efficacy rate was 100% on the 7th day (1/1) and 50% (1/2) on 14th day. The efficacy rate in all 40 males with non-gonorrheal urethritis was 85.0% on the 7th day and 88.9% for 36 patients on the 14th day, while that in all 4 females with cervicitis was 100% on the 7th day and 87.5% on the 14th day. No side effects were seen in any of the patients. Overall, NY-198 had an efficacy rate of 80% in the treatment of chlamydial infections. NY-198 was found to be a useful drug which is efficacious in the treatment of all STD-related microbes such as gonococci and chlamydia.