Effect of cytochrome P-450 inhibitors on pharmacokinetics and safety of voriconazole

Our objective was to systematically assess the effect of cytochrome P-450 (CYP450) inhibitors on pharmacokinetics and safety of voriconazole (VORI). Cochrane Library, PubMed, Embase, CNKI, CBM and WanFang databases and Clinicaltrials. gov were searched up to Jan. 26th 2016. Two reviewers independently identified studies, extracted data and assessed quality of studies. Meta-analysis was performed with RevMan 5.3, and risk ratios (RRs) and mean differences (MDs) with 95% confidence intervals (CIs) were calculated. A total of 12 studies were included: three crossover randomized controlled trials, three single-arm before-and-after studies and six cohort studies. Compared with non-combination group, the group of VORI plus omeprazole had a significantly higher occurrence of hepatic dysfunction (RR = 4.11, 95% CI 1.12–15.08, P = 0.03). However, neurologic dysfunction and visual disturbance were not significantly different. Pantoprazole, rabeprazole, cimetidine and contraceptive significantly increased the peak concentration (Cmax) and area under the curve (AUC) of VORI, while indinavir had no significant effect on pharmacokinetics of VORI. The effects of esomeprazole, erythromycin and azithromycin on pharmacokinetic parameters of VORI presented inconsistent results. Co-administration of VORI and CYP450 inhibitors was safe except for omeprazole. Although Cmax and AUC of VORI were increased while co-administered with a couple of CYP450 inhibitors, no significant effect on clinical outcomes was observed.     

High magnitude hepatic cytochrome P-450 induction by an N-substituted imidazole antimycotic, clotrimazole

A 4-fold induction of hepatic microsomal cytochrome P-450 following 3 days of treatment of rats with clotrimazole (75 mg/kg), a potent monooxygenase inhibitor, greatly exceeded that evident from similar phenobarbital and dexamethasone treatment. The clotrimazole-induced microsomes exhibited a pattern of monooxygenase activities similar to that seen in microsomes from both phenobarbital- and dexamethasone-treated animals. Precautions were necessary to determine both monooxygenase activities and the full amount of cytochrome P-450 present in microsomes because of interference by residual clotrimazole in the microsomes.     

高效液相色谱法测定双唑癣药水中益康唑和克霉唑含量

以ＹＷＧ－Ｃ１８为柱填充剂，以甲醇－磷酸三乙胺缓冲液为流动相，以甲苯咪唑为内标的高效液相色谱法，测定双唑癣药水中益康唑、克霉唑的含量，平均回收率及ＲＳＤ分别为１００．２％，１．１％，１０１．０％，０．７％。本法操作简便，与本文作者所建立的该样品双波长紫外分光光度法测定的结果做了对比实验，结果满意     

Effect of cannabidiol on cytochrome P-450 isozymes

Cannabidiol (CBD) has been shown to inhibit mouse hepatic mixed-function oxidations of several drugs after acute treatment, whereas repetitive treatment resulted in the restoration of drug-metabolizing capabilities. We have found that acute CBD treatment modestly decreased cytochrome P-450 content but markedly decreased hexobarbital hydroxylase, erythromycin N-demethylase, and 6 beta-testosterone hydroxylase activities. Repetitive CBD treatment, on the other hand, resulted in the restoration of cytochrome P-450 content as well as hexobarbital hydroxylase and erythromycin N-demethylase activities. However, after such repeated treatments a fresh dose of CBD can once again inactivate erythromycin N-demethylase activity but not hexobarbital hydroxylase activity. The resistance of hexobarbital hydroxylase to re-inactivation by CBD was paralleled by stimulation of pentoxyresorufin O-dealkylase activity and the appearance of a 50 kD protein that was immunoreactive to an antibody raised against rat hepatic cytochrome P-450b. CBD metabolism in vitro by microsomes prepared from such CBD-"induced" animals, resulted in a pattern of metabolites different from that observed from comparable incubations with liver microsomes from either untreated or phenobarbital-treated animals. Thus, it appears that CBD initially inactivates at least one cytochrome P-450 isozyme, but after repetitive CBD treatment, an isozyme is induced that is resistant to further re-inactivation by CBD. This isozyme appears to be immunochemically similar to, but somewhat functionally distinct from, the isozyme induced by phenobarbital treatment in mice.     

HPLC法测定双唑乳膏中克霉唑与硝酸益康唑的含量

目的：建立高效液相色谱法测定双唑乳膏中克霉唑与硝酸益康唑的含量.方法：采用高效液相色谱法,色谱柱为Alltech Alltima C18色谱柱（150 mm×4.6 mm,5 μm）,流动相为磷酸盐缓冲液（取磷酸二氢钾与磷酸氢二钾各2.5 g,加水溶解并稀释至1000 ml）-甲醇（25∶75）,流速为1.0 ml/min,柱温为35 ℃,检测波长为232 nm.结果：克霉唑与硝酸益康唑在0.25~100 μg/ml范围内,浓度与其峰面积呈良好线性关系（r=0.9999,n=9）,平均回收率分别为99.87%与101.11%,RSD%分别为1.4%与1.8%.结论：为双唑乳膏中克霉唑与硝酸益康唑联合用药的新剂型建立了简单、快速、专属性强、重现性好的含量测定方法,可用于双唑乳膏中克霉唑与硝酸益康唑的测定.     

Effect of phenobarbital treatment on carbon tetrachloride-mediated cytochrome P-450 loss and diene conjugate formation.

The effect of phenobarbital treatment on the linkage between carbon tetrachloride-mediated cytochrome P-450 loss and lipid peroxidation in rat liver microsomes was studied. Male Sprague-Dawley rats, pretreated with 3 daily i.p. doses of phenobarbital (50 mg/kg) or saline, were orally dosed with carbon tetrachloride (0.01-2.5 ml/kg), with liver microsomes prepared at 7.5-180 min after carbon tetrachloride treatment. In vivo cytochrome P-450 loss displayed pseudo-first-order kinetics, and the initial rates of diene conjugate formation were saturable with dose. Phenobarbital pretreatment decreased the in vivo t0.5,max from 27.0 to 15.6 min, and increased the Kd,app from 0.78 to 1.30 ml/kg for carbon tetrachloride mediated cytochrome P-450 loss. Phenobarbital had no effect on the in vivo Vmax (1.03 to 1.04 delta OD232 nm/min/mg phospholipid) for carbon tetrachloride mediated diene conjugate formation, but decreased the Km,app from 0.22 to 0.10 ml/kg. These results are consistent with destruction of cytochrome P-450 heme resulting from a metabolite which does not leave the site of generation, and with phenobarbital pretreatment enhancing the initiation of lipid peroxidation.     

Effect of diabetes on rat liver cytochrome P-450: Evidence for a unique diabetes-dependent rat liver cytochrome P-450

Detergent-solubilized hepatic microsomal fractions from alloxan diabetic rats exhibited a 52,000 molecular weight hemeprotein band that was not present in the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) protein profiles of identically solubilized hepatic microsomal fractions from normal, 3-methylcholanthrene- or phenobarbital-treated rats. This 52,000 mol. wt hemeprotein band disappeared from the protein profile of insulin-treated diabetic rat liver to yield the SDS-PAGE profile of normal rat liver. When P-450 hemeproteins were purified by lauric acid affinity and hydroxylapatite chromatography from solubilized microsomes, only the diabetic rat had a 52,000 mol. wt P-450. This distinct 52,000 mol. wt diabetes-induced P-450 interacted with type II compounds to yield a 2-fold greater absorbance change than was observed with the purified P-450s from either the normal or the chemically induced rats. The properties of this unique 52,000 mol. wt P-450 suggest that it may be the catalytic component responsible for the increased rate of type II substrate (aniline) metabolism observed in the diabetic rat.     

Effect of cannabidiol on cytochrome P-450 and hexobarbital sleep time

The influences of acute and subacute cannabidiol (CBD) treatment and of subsequent drug withdrawal were investigated on hexobarbital-induced sleep time, on hepatic cytochrome P-450 concentration, on the in vitro formation of carbon monoxide (CO) associated with CBD metabolism, and on the kinetics of aminopyrine N-demethylase metabolism. In acutely treated mice, CBD prolonged sleep time, decreased cytochrome P-450 concentration, decreased the endogenous formation of CO, and increased an apparent K_m for aminopyrine N-demethylase activity. In subacutely treated animals, tolerance developed to the effect on sleep time but not to that on cytochrome P-450 concentration nor on the endogenous formation of CO in vitro nor on the K_m for the N-demethylase activity. Upon withdrawal from subacute treatment, tolerance to the sleep-time effect was still evident on day 14, but, by day 28, the sensitivity to CBD had returned to normal. In contrast, the cytochrome P-450 concentration returned to normal on day 14 of withdrawal, as did the K_m for the N-demethylase activity and the ability of CBD to induce CO synthesis in vitro. The comparative results lead us to conclude that the CBD effect on sleep time does not correlate with either the total amount of cytochrome P-450 or with the CBD depressant effect on the cytochrome.     

Comparative study of cytochrome P-450 in liver microsomes. A form of monkey cytochrome P-450, P-450-MK1, immunochemically cross-reactive with antibodies to rat P-450-male

Cytochrome P-450, designated as P-450-MK1, which is cross-reactive with antibodies to rat P-450-male, was purified to an electrophoretical homogeneity from liver microsomes of the untreated male crab-eating monkey. The molecular weight of P-450-MK1 was estimated to be 50,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The oxidized form of P-450-MK1 showed a peak at 418 nm, indicating that this cytochrome is in a low spin state. The carbon monoxide-bound reduced form showed a peak at 451 nm. The first 22 amino acid residues of the NH2-terminal sequence of P-450-MK1 was fairly homologous to those of P-450-male (75% identity, not including unidentified amino acid residues). Unlike the P-450-male, P-450-MK1 did not exhibit catalytic activities for testosterone 2 alpha- and 16 alpha-hydroxylations and catalyzed testosterone 6 beta-hydroxylation. It is, therefore, suggested that although the spectral and immunochemical properties and the N-terminal amino acid sequence of P-450-MK1 were similar to those of P-450-male, the physiological functions of P-450-MK1 may be somewhat different from those of P-450-male. Comparison of the physico-chemical properties of P-450-MK1 with those of P-450-D1 and P-450-HM2, which are cross-reactive with anti-P-450-male antibodies, purified from liver microsomes of dogs and humans, respectively, are also discussed.     

Induction of cytochrome P-450, cytochrome b-5, NADPH-cytochrome c reductase and change of cytochrome P-450 isozymes with long-term trichloroethylene treatment

Several reports have described the effects of trichloroethylene (TCE) on the microsomal mixed function oxidase system (MFOS). These studies suggest that repeated TCE administration induces MFOS, especially cytochrome P-450 and NADPH-cytochrome c reductase. However, it is uncertain what isozymes are induced by TCE treatment, and it is not clear how microsomal enzymes or cytochrome P-450 isozymes are altered when TCE is administered for a duration longer than 28 days. We investigated the changes of MFOS by long-term TCE treatment. Male Wistar rats were injected with TCE, 1.0 g/kg body weight once a day for 5 continuous days or 2.0 g/kg body weight twice a week for 15 days. The mean body weight of the rats treated with TCE for 15 weeks was slightly, but not significantly, less than that of the control rats. Relative liver weights (liver wt/body wt) of the TCE-treated group were however significantly larger (21%) than those of the control group. The weights of the other organs were not changed by long-term TCE treatment. Trichloroethylene treatments for 5 days and 15 weeks caused significant increases in microsomal protein, cytochrome P-450, cytochrome b-5 and NADPH-cytochrome c reductase. TCE treatments produced an increase in a polypeptide band at 52,000 molecular weight range observed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This increase in similar to, but less pronounced than that induced by phenobarbital (PB) treatment. There were no remarkable changes at 56,000 molecular weight range where a band appeared after the treatment with 3-methylcholanthrene (MC). It is likely that the induction of cytochrome P-450 by TCE is relatively similar to that by PB.     

Human liver cytochrome P-450 related to a rat acetone-inducible, nitrosamine-metabolizing cytochrome P-450: identification and isolation

A monoclonal antibody (MAb) to a rat acetone-inducible and nitrosamine-metabolizing form of microsomal cytochrome P-450, P-450ac, detected a related P-450 in human liver microsomes by both immunoblot and competitive radioimmunoassay. This MAb was also used to immunopurify microsomal cytochromes P-450 from both human liver and acetone-treated rats; these were electrophoretically homogeneous with apparent molecular weights of 56,200 and 53,000 daltons, respectively. The structures of the cytochromes P-450 were compared by peptide mapping and amino-terminal sequence analyses. They differed in their peptide maps but displayed amino-terminal sequence similarity in their first 19 residues. This report thus demonstrates the utility of MAbs to rat cytochromes P-450 for detection, identification and structural characterization of human P-450s.     

N-alkylaminobenzotriazoles as isozyme-selective suicide inhibitors of rabbit pulmonary microsomal cytochrome P-450

To produce potent, isozyme-selective suicide inhibitors of cytochrome P-450 (P-450), a series of N-alkylated 1-aminobenzotriazole (ABT) derivatives was synthesized; these included the N-methyl, N-butyl (BuBT), N-benzyl (BBT), and N-alpha-methylbenzyl (alpha MB) analogues of ABT. The suicide inhibitors showing the greatest potency and isozyme selectivity were BBT and alpha MB, compounds which included molecular features for P-450 inactivation (the ABT moiety) and similarity to benzphetamine. ABT and its N-alkylated derivatives were tested as suicide inhibitors in rabbit lung microsomes, whose P-450 monooxygenase system has been well characterized in both untreated and beta-naphthoflavone- or 2,3,7,8-tetrachlorodibenzo-p-dioxin-treated animals. ABT (10 mM) destroyed up to 99% of the total P-450 content of lung microsomes of untreated rabbits. At equimolar concentrations (10 microM), ABT was less effective than the N-alkylated compounds for the inhibition of P-450 isozyme 2-catalyzed benzphetamine N-demethylation (BND); in fact, BuBT, BBT, and alpha MB completely inhibited BND activity at this concentration and destroyed less than 40% of total pulmonary P-450. However, these compounds also inactivated 69-85% of isozyme 6-catalyzed 7-ethoxyresorufin O-deethylation. The most potent and isozyme-selective suicide inhibitor prepared was alpha MB: at 1 microM this compound inhibited approximately 80% of isozyme 2-catalyzed and 20% of isozyme 6-catalyzed monooxygenase activity but spared P-450 isozyme 5; at 2.5 microM it caused a near-complete loss (96 +/- 2%) of BND activity. The partition ratio of alpha MB, i.e., the molar ratio of inhibitor present to that of the P-450 destroyed, was 11 +/- 2, further demonstrating the potency of this compound. Experiments with BBT- and sodium phenobarbital-treated rats showed that the mechanism for suicidal inactivation of P-450 by this N-alkylated compound was by benzyne release, the same mechanism demonstrated earlier for the parent compound ABT.     

Effect of synthetic antioxidants on hydrogen peroxide formation, oxyferro cytochrome P-450 concentration and oxygen consumption in liver microsomes

Synthetic antioxidants lead in vitro to increased H2O2 formation in rat liver and lung microsomes and in guinea pig and hamster liver microsomes. Butylated hydroxyanisole and ethoxyquin are more potent than propyl-, octyl-, and dodecyl gallate; butylated hydroxytoluene is only weakly active. Extra production of H2O2 is maximal at antioxidant concentrations between 50 and 500 microM and is dependent on the concentration of NADPH. It is paralleled by increased microsomal oxygen consumption and decreased concentration of oxycytochrome P-450 and is enhanced by pretreatment of the animals with phenobarbital. Both the endogenous and the antioxidant-stimulated H2O2 production are inhibited by metyrapone. In vivo administration of ethoxyquin and butylated hydroxyanisole in the diet leads to decreased oxycytochrome P-450 concentrations but not to increased H2O2 formation in liver microsomes. No extra production of H2O2 was observed in a glucose oxidase or xanthine oxidase system; rather, inhibition occurred in the latter system. Our data suggest that antioxidants enhance the oxidase function of cytochrome P-450. This effect is discussed in view of the known toxicity of these food additives.     

Polymorphism of human cytochrome P-450

The cytochrome P-450 forms involved in debrisoquine 4-hydroxylation (P-450DB), phenacetin O-deethylation (P-450PA), S-mephenytoin 4-hydroxylation (P-450MP), and nifedipine 1,4-oxidation (P-450NF) have been purified to electrophoretic homogeneity from human liver microsomes. All of these reactions show in vivo polymorphism in humans. Evidence for the roles of the purified proteins in these processes comes from in vitro reconstitution and immunoinhibition studies. The rat orthologs of these enzymes are as follows--P-450DB: P-450UT-H; P-450PA: P-450ISF-G; P-450MP: P-450UT-I; P-450NF: P-450PCN-E. Only in the case of P-450UT-H is the primary rat ortholog the same cytochrome P-450 which catalyses the catalytic reaction under consideration. Reconstitution and immunochemical studies establish that the following reactions are catalysed by the individual P-450s--P-450DB: debrisoquine 4-hydroxylation, sparteine delta 5-oxidation, bufuralol 1'-hydroxylation, encainide O-demethylation, and propanolol 4-hydroxylation; P-450PA: phenacetin O-deethylation; P-450MP: S-mephenytoin 4-hydroxylation and tolbutamide methyl hydroxylation; P-450NF: oxidation of nifedipine and 16 other substituted dihydropyridines, estradiol 2- and 4-hydroxylation, aldrin epoxidation, benzphetamine N-demethylation and 6 beta-hydroxylation of testosterone, androstenedione and cortisol. A cDNA clone has been isolated that corresponds to rat P-450UT-H, as shown by a number of criteria. Studies with this probe establish that the sex and strain variation in debrisoquine 4-hydroxylase and related activities is related to differences in the levels of a 2.0 kb length mRNA present.(ABSTRACT TRUNCATED AT 250 WORDS)