Real-Time Particle Emission Monitoring for the Non-Invasive Prediction of Lung Deposition via a Dry Powder Inhaler.

Although inhalation therapy represents a promising drug delivery route for the treatment of respiratory diseases, the real-time evaluation of lung drug deposition remains an area yet to be fully explored. To evaluate the utility of the photo reflection method (PRM) as a real-time non-invasive monitoring of pulmonary drug delivery, the relationship between particle emission signals measured by the PRM and in vitro inhalation performance was evaluated in this study. Symbicort® Turbuhaler® was used as a model dry powder inhaler. In vitro aerodynamic particle deposition was evaluated using a twin-stage liquid impinger (TSLI). Four different inhalation patterns were defined based on the slope of increased flow rate (4.9-9.8 L/s2) and peak flow rate (30 L/min and 60 L/min). The inhalation flow rate and particle emission profile were measured using an inhalation flow meter and a PRM drug release detector, respectively. The inhalation performance was characterized by output efficiency (OE, %) and stage 2 deposition of TSLI (an index of the deagglomerating efficiency, St2, %). The OE × St2 is defined as the amount delivered to the lungs. The particle emissions generated by four different inhalation patterns were completed within 0.4 s after the start of inhalation, and were observed as a sharper and larger peak under conditions of a higher flow increase rate. These were significantly correlated between the OE or OE × St2 and the photo reflection signal (p < 0.001). The particle emission signal by PRM could be a useful non-invasive real-time monitoring tool for dry powder inhalers.

Decreased Analgesic Effect of Tramadol in Japanese Patients with CYP2D6 Intermediate Metabolizers after Orthopedic Surgery.

Tramadol is metabolized by CYP2D6 to an active metabolite, which in turn acts as an analgesic. This study aimed to investigate the impact of CYP2D6 genotype on the analgesic effect of tramadol in clinical practice. A retrospective cohort study was performed in patients treated with tramadol for postoperative pain after arthroscopic surgery for rotator cuff injury during April 2017-March 2019. The impact of CYP2D6 genotypes on the analgesic effects was assessed by the numeric rating scale (NRS) pain scoring and analyzed by the Mann-Whitney U test. Stepwise multiple linear regression analysis was performed to identify predictive factors for the area under the time-NRS curve (NRS-AUC), which was calculated using the linear trapezoidal method. Among the 85 enrolled Japanese patients, the number of phenotypes with CYP2D6 normal metabolizer (NM) and intermediate metabolizer (IM) was n = 69 (81.1%) and n = 16 (18.9%), respectively. The NRS and NRS-AUC in the IM group were significantly higher than those in the NM group until Day 7 (p < 0.05). The multiple linear regression analysis indicated that the CYP2D6 polymorphism was a prediction factor of the high NRS-AUC levels in Days 0-7 (ß = 9.52, 95% CI 1.30-17.7). In IM patients, the analgesic effect of tramadol was significantly reduced one week after orthopedic surgery in clinical practice. Therefore, dose escalation of tramadol or the use of alternative analgesic medications can be recommended for IM patients.

[Decreased Serum Copper Concentrations by Zinc Administration in Preterm Infants with Hypozincemia Are Associated with a Lower Postmenstrual Age: A Single-center Retrospective Observational Study].

Copper is one of the essential trace elements in humans, and its deficiency causes various diseases. Zinc acetate dihydrate is administered to treat hypozincemia in preterm infants; however, zinc inhibits the gastrointestinal absorption of copper, which may cause copper deficiency. To safely treat hypozincemia in preterm infants, we retrospectively analyzed the factors reducing serum copper concentrations when zinc is administered to preterm infants with hypozincemia. Seventy preterm infants were included in the present study. Serum zinc and copper concentrations, doses, and other clinical characteristics were retrieved from electronic medical records. The administration of zinc acetate dihydrate decreased serum copper concentrations in 21 out of 70 patients. In comparisons between the two groups with and without a decrease in serum copper concentrations, significant differences were observed in postmenstrual age (34.9 and 35.9 weeks, respectively) and serum zinc concentrations (62.0 and 58.0 µg/dL, respectively) at the start of the zinc acetate dihydrate treatment. A logistic regression analysis identified postmenstrual age as a significant factor decreasing serum copper concentrations. In the ROC curve, the cut-off value for postmenstrual age for a decrease in serum copper concentrations was 34.143 weeks. The present results suggest that when zinc acetate dihydrate is administered to preterm infants with a low postmenstrual age who are at higher risk of decreased serum copper concentrations, particularly to those with a postmenstrual age <34 weeks, it is important to consider copper deficiency and periodically measure serum copper concentrations.

Administration of zinc to preterm infants with hypozincemia does not reduce serum copper concentrations in most cases: a single-center retrospective observational study.

BACKGROUND: Zinc is an essential trace element involved in various physiological functions. In Japan, zinc acetate dihydrate is administered to neonates and infants with hypozincemia. Since serum copper concentrations are reduced by the administration of zinc, we retrospectively investigated changes in serum zinc and copper concentrations in preterm infants with hypozincemia receiving zinc acetate dihydrate. METHODS: Sixty-three preterm infants were included in the present study. Serum zinc and copper concentrations, doses, and other clinical characteristics were retrieved from electronic medical records. RESULTS: The medians and interquartile ranges of the dosage and duration of zinc acetate dihydrate were 2.1 (1.8-2.5) mg/kg/day and 12.0 (10.0-13.0) days, respectively. Its administration increased serum zinc concentrations in 39 patients (61.9%) and to more than 70 µg/dL in 16 patients (25.4%). The group with a serum zinc concentration of 70 µg/dL or higher after administration had a significantly higher zinc dose of 2.5 mg/kg/day than the group with a serum zinc concentration of less than 70 µg/dL. Serum copper concentrations did not decrease in 44 patients (69.8%). In the group with a decreased serum copper concentration, postmenstrual age and body weight were significantly lower, while serum zinc concentrations were significantly higher at the start of administration. CONCLUSION: The present results showed that when zinc acetate dihydrate was administered to preterm infants with hypozincemia, it was possible to increase serum zinc concentrations without decreasing serum copper concentrations in many cases. However, caution may be required when administering zinc to preterm infants with a lower postmenstrual age or milder hypozincemia because serum copper concentrations may decrease.

Impact of silicone oil tamponade on intravitreally injected vancomycin pharmacokinetics in cynomolgus monkey eyes.

Intravitreal injections of vancomycin (VCM) and ceftazidime (CAZ) are commonly used to treat infectious endophthalmitis. When patient cases require retinal detachment with silicone oil (SO) tamponade, the antibiotic doses are empirically reduced to 25 %. Currently, there is no scientific evidence for these empirical dose reductions. The purpose of the present study is to determine the quantitative impact that SO tamponades have on intraocular VCM pharmacokinetics. Because of high invasiveness of frequent sampling of intraocular VCM concentrations in human, this pharmacokinetic study was performed in cynomolgus monkey's eyes. Population pharmacokinetic modeling and simulation were performed using 75 different intraocular VCM concentrations obtained from 8 male cynomolgus monkeys. A one-compartment model with a first-order diffusion rate was used as a structural pharmacokinetic model. From the covariate analysis, SO tamponade significantly decreased the volume of distribution while pars plana vitrectomy with lensectomy (PPV) significantly increased the clearance and diffusion rate constants. From the Monte Carlo simulation (n = 1,000), the median time above minimum inhibitory concentration (T>MIC, a therapeutic effect index) durations of SO and normal eyes at clinical doses of 1,000 µg were 2.6 and 11.0 days, respectively. Using intravitreal injections of VCM with SO tamponade or PPV may reduce the therapeutic effect.

Incorrect Holding Angle of Dry Powder Inhaler during the Drug-Loading Step Significantly Decreases Output Efficiency.

It is well known that correct use of inhalers plays a critical role in optimal inhalation therapy, but the impact of incorrect inhaler use on pulmonary drug delivery has not been quantitatively evaluated. The aim of this study was to investigate the frequency of holding inhalers at incorrect angles during the drug-loading step while using Turbuhaler® and to quantify the influence of the inhaler angle on in vitro pulmonary delivery. Thirty patients prescribed Turbuhaler® at Shiga University of Medical Science Hospital were enrolled. During inhalation, the participants' inhalation techniques were assessed by clinical pharmacists. Additionally, the influence of the inhaler angle on pulmonary delivery of budesonide via Symbicort® Turbuhaler® was investigated using a Twin-Stage Liquid Impinger. Output efficiency (OE), stage 2 deposition (St2), and OE × St2 were calculated. An incorrect angle during the drug-loading step was observed in 33.3% of the participants. In vitro testing demonstrated that OE, an index of the loaded dose, significantly decreased by 73.3% at an incorrect angle, while St2, an index of the deagglomerating efficiency, was stable independent of the holding angle. OE × St2, indicating the bronchial and pulmonary drug delivery amount, decreased by 76.9%. An incorrect holding angle reduced the loaded dose, resulting in decreased pulmonary delivery. Error in the inhaler angle occurs frequently and demonstrates a considerable impact on pulmonary drug delivery. Hence, it is necessary to assess the Turbuhaler® angle during inhalation.

Pharmacokinetics of Intravitreal Vancomycin and Ceftazidime in Silicone Oil-Filled Macaque Eyes.

Purpose: This study evaluated the pharmacokinetics of intravitreal vancomycin and ceftazidime in the aqueous humor of macaque eyes filled with silicone oil in the vitreous cavity. Methods: Intravitreal vancomycin (1 mg/0.1 mL) and ceftazidime (2 mg/0.1 mL) were injected into four normal macaque eyes, four vitrectomized aphakic macaque eyes, and four previously vitrectomized aphakic macaque eyes filled with silicone oil (silicone oil-filled eyes). Aqueous humor samples (0.1 mL) were obtained just before injection and at 2 and 5 hours and 1, 2, 3, 5, 7, and 10 days after injection. In each group, corneal endothelial cell density (ECD) measurements and electroretinogram (ERG) recordings were obtained before injection and after 1 month. Results: The half-lives of vancomycin in the aqueous humor of normal, vitrectomized, and silicone oil-filled eyes were 29.4, 21.1, and 6.8 hours, respectively, and those of ceftazidime were 20.4, 5.2, and 3.1 hours, respectively. The maximum vancomycin aqueous humor concentrations of normal, vitrectomized, and silicone oil-filled eyes were 151.4, 205.6, and 543.5 µg/mL, respectively, and the maximum ceftazidime aqueous humor concentrations are 64.6, 260.0, and 1176.3 µg/mL, respectively. There was no change in ECD, and ERG was not declined after intravitreal injection in all groups. Conclusions: The half-lives of vancomycin and ceftazidime in the aqueous humor were shorter in silicone oil-filled eyes than in normal and vitrectomized eyes. High antibiotic concentrations in silicone oil-filled eyes seemed to be well tolerated. Translational Relevance: This study aids in estimating how often an antibiotic should be intravitreally injected for endophthalmitis of silicone oil-filled eyes.

Effects of antiepileptic drugs' administration during pregnancy on the nerve cell proliferation and axonal outgrowth of human neuroblastoma SH-SY5Y nerve cells.

It has been suggested that the intelligence quotient of children born to pregnant women taking 1000 mg or more of valproic acid per day is lower than that of children born to pregnant women taking other antiepileptic drugs. However, the mechanism whereby intelligence quotient is decreased in children exposed to valproic acid during the fetal period has not yet been elucidated. Therefore, we used the human neuroblastoma cell line SH-SY5Y to evaluate the effects of antiepileptic drugs containing valproic acid on nerve cells. We assessed the anti-proliferative effects of drugs in these cells via WST-8 colorimetric assay, using the Cell Counting Kit-8. We also quantified drug effects on axonal elongation from images using ImageJ software. We also evaluated drug effects on mRNA expression levels on molecules implicated in nervous system development and folic acid uptake using real-time PCR. We observed that carbamazepine and lamotrigen were toxic to SH-SY5Y cells at concentrations >500 µM. In contrast, phenytoin and valproic acid were not toxic to these cells. Carbamazepine, lamotrigen, phenytoin, and valproic acid did not affect axonal outgrowth in SH-SY5Y cells. Sodium channel neuronal type 1a (SCN1A) mRNA expression-level ratios increased when valproic acid was supplemented to cells. The overexpression of SCN1A mRNA due to high valproic acid concentrations during the fetal period may affect neurodevelopment. However, since detailed mechanisms have not yet been elucidated, it is necessary to evaluate it by comparing cell axon elongation and SCN1A protein expression due to high-concentration valproic acid exposure.

Is "Slow Inhalation" Always Suitable for Pressurized Metered Dose Inhaler?

To achieve adequate inhalation therapy, a proper inhalation technique is needed in clinical practice. However, there is limited information on proper inhalation flow patterns of commercial inhalers. Here, we quantitatively estimated airway deposition of two commercial pressurized metered dose inhalers (pMDIs) to determine their optimal inhalation patterns. Sultanol® inhaler (drug particles suspended in a propellant, suspension-pMDI) and QVAR™ (drug dissolved in a propellant with ethanol, solution-pMDI) were used as model pMDIs. Aerodynamic properties of the two pMDIs were determined using an Andersen cascade impactor with human inhalation flow simulator developed by our laboratory. As indices of peripheral-airway drug deposition, fine particle fractions (FPFPA) at different inhalation flow rates were calculated. The time-dependent particle diameters of sprayed drug particles were determined by laser diffraction. On aerodynamic testing, FPFPA of suspension-pMDI significantly decreased depending on the increasing inhalation flow rate, while solution-pMDI achieved higher and constant FPFPA in the range of the tested inhalation flow rates. The particle diameter of solution-pMDI markedly decreased from 5 to 3 µm in a time-dependent manner. Conversely, that of suspension-pMDI remained at 4 µm during the spraying time. Although "slow inhalation" is recommended for pMDIs, airway drug deposition via solution-pMDI (extra-fine particles) is independent of patients' inhalation flow pattern. Clinical studies should be performed to validate instruction for use of pMDIs for each inhaler for the optimization of inhalation therapy.

Pharmaceutical stability of colloidal saccharated iron oxide injection in normal saline.

BACKGROUND: Colloidal saccharated iron oxide injection is used for the treatment of iron deficiency anemia in patients with a poor oral intake. Because of the poor stability of the colloid particle, there have been concerns regarding its compatibility with various injections in clinical practice. To assess the stability of colloidal saccharated iron oxide in normal saline as a diluent, pharmaceutical stability analyses were conducted using various concentrations of glucose and sodium chloride (NaCl). METHODS: Colloidal saccharated iron oxide injection was diluted in three different diluents (5% glucose solution, normal saline, and 10% NaCl solution), and its appearance, colloid particle diameter, and pH were assessed. Free iron ions, which cause adverse effects, such as nausea and vomiting, were separated from the colloid particle using a dialysis membrane for 24 h, and their concentration was determined. RESULTS: No difference in the appearance, colloid diameter, and free iron ion fraction was observed after dilution in 5% glucose solution and normal saline. Conversely, an increased colloid aggregation and iron ion release were observed after dilution in 10% NaCl solution. Although iron colloid is unstable in acidic conditions (pH 4.0-6.0), normal diluents such as 5% glucose and normal saline did not cause colloid destabilization by pH change (pH > 8.0). CONCLUSION: Normal saline may be used as a diluent of colloidal saccharated iron oxide injection as well as glucose solution, which is recommended by the pharmaceutical company. Therefore, normal saline can be used as a diluent of colloidal saccharated iron oxide injection in patients with an underlying disease, such as diabetes mellitus, who are difficult to use glucose solution as a diluent.

Fractional absorption of active absorbable algal calcium (AAACa) and calcium carbonate measured by a dual stable-isotope method.

With the use of stable isotopes, this study aimed to compare the bioavailability of active absorbable algal calcium (AAACa), obtained from oyster shell powder heated to a high temperature, with an additional heated seaweed component (Heated Algal Ingredient, HAI), with that of calcium carbonate. In 10 postmenopausal women volunteers aged 59 to 77 years (mean ± S.D., 67 ± 5.3), the fractional calcium absorption of AAACa and CaCO(3) was measured by a dual stable isotope method. (44)Ca-enriched CaCO(3) and AAACa were administered in all subjects one month apart. After a fixed-menu breakfast and pre-test urine collection (Urine 0), (42)Ca-enriched CaCl(2) was intravenously injected, followed by oral administration of (44)Ca-enriched CaCO(3) without carrier 15 minutes later, and complete urine collection for the next 24 hours (Urine 24). The fractional calcium absorption was calculated as the ratio of Augmentation of (44)Ca from Urine 0 to Urine 24/ augmentation of (42)Ca from Urine 0 to Urine 24. Differences and changes of (44)Ca and (42)Ca were corrected by comparing each with (43)Ca. Fractional absorption of AAACa (mean ± S.D., 23.1 ± 6.4), was distinctly and significantly higher than that of CaCO(3 )(14.7 ± 6.4; p = 0.0060 by paired t-test). The mean fractional absorption was approximately 1.57-times higher for AAACa than for CaCO(3). The serum 25(OH) vitamin D level was low (mean ± S.D., 14.2 ± 4.95 ng/ml), as is common in this age group in Japan. Among the parameters of the bone and mineral metabolism measured, none displayed a significant correlation with the fractional absorption of CaCO(3) and AAACa. Higher fractional absorption of AAACa compared with CaCO(3) supports previous reports on the more beneficial effect of AAACa than CaCO(3) for osteoporosis.

Effects of alpha-adrenoceptor antagonist doxazosin on MDR1-mediated multidrug resistance and transcellular transport.

The purpose of this study is to examine the effects of doxazosin, an alpha-adrenoceptor antagonist, on P-glycoprotein/MDR1-mediated multidrug resistance (MDR) and the transport of anticancer drugs. The effects of doxazosin, prazosin, and terazosin on MDR1-mediated MDR were assessed in human cervical carcinoma HeLa cells and the MDR1-overexpressing derivative Hvrl00-6, established by stepwise increases of the vinblastine concentration in the culture medium. The effects of doxazosin on the transcellular transport and intracellular accumulation of [3H]vinblastine, [3H]daunorubicin, and [3H]digoxin, all MDR1 substrates, were evaluated using LLC-GA5-COL150 cell monolayers, established by transfection of human MDR1 cDNA into porcine kidney epithelial LLC-PK1 cells. The sensitivity to vinblastine and paclitaxel of Hvrl00-6 cells was increased at 3.4- and 17.5-fold, respectively, by the addition of 1 microM doxazosin, whereas prazosin and terazosin had weaker or no such effects. Prazosin at 1 microM had a reversal effect on the sensitivity to vinblastine, whereas terazosin had no effect. In transport experiments, doxazosin concentration dependently increased the apical-to-basal transport of radiolabeled drugs in LLC-GA5-COL150 cells, but did not show remarkable effects on the basal-to-apical transport. In addition, doxazosin restored the intracellular accumulation in a concentration-dependent manner in LLC-GA5-COL150 cells. Doxazosin may partly reverse MDR by inhibiting MDR1-mediated transport, making it a candidate lead compound in the development of a reversing agent for MDR.

Change in pharmacokinetics of model compounds with different elimination processes in rats during hypothermia.

We compared the pharmacokinetics of model compounds with different elimination processes between hypothermic and normothermic rats, to obtain basic information concerning drug therapy during hypothermia. Male Wistar rats were anesthetized with sodium pentobarbital and kept at temperatures of 37 degrees C (normothermic group) by heat lamp, and 32 degrees C or 28 degrees C (hypothermic group) by external cooling. We chose phenolsulfonphthalein (PSP), indocyanine green (ICG) and fluorescein isothiocyanate (FITC)-dextran (FD-4, Mw 4400) as model compounds to determine changes in clearance pathways during hypothermia therapy. The plasma concentrations of PSP as biliary, urinary and metabolic elimination type were increased significantly in the hypothermic group (32 degrees C, 28 degrees C) after i.v. administration at a dose of 1 mg, compared to the normothermic group (37 degrees C). Each PSP clearance (bile, urine and metabolites) in the hypothermic group was decreased, suggesting an influence of hypothermia on the active elimination process. The decreasing tendency was marked at a temperature of 28 degrees C. Moreover, the plasma concentrations of ICG as the biliary excretion type after i.v. administration to the hypothermic rats at a dose of 1 mg were higher with more than 50% decrease in the total body clearance compared to normothermic rats. On the other hand, there was almost no difference in the i.v. pharmacokinetics of FD-4 as the urinary excretion type between 37 degrees C and 32 degrees C. However, renal clearance of FD-4 was significantly decreased at a temperature of 28 degrees C. Accordingly, the change in pharmacokinetics of a drug in the hypothermic group could differ with the elimination processes.

Effect of therapeutic moderate hypothermia on multi-drug resistance protein 1-mediated transepithelial transport of drugs.

To clarify the effect of therapeutic moderate hypothermia on drug distribution, transepithelial transport via multi-drug resistance protein 1 (MDR1) (also called P-glycoprotein or ABCB1) was evaluated at various temperatures in vitro using LLC-GA5-COL150 cells, which were established by transfecting human MDR1 complementary deoxyribonucleic acid into kidney epithelial LLC-PK(1) cells and express MDR1 on the apical membrane. MDR1 is expressed in the blood-brain barrier to limit drug distribution to the brain by exporting exogenous substances including calcium blockers and antiarrhythmic drugs. Digoxin was used as a typical substrate, as well as the non-substrate tetracycline and paracellular marker inulin. MDR1-mediated transport of digoxin decreased at lower temperatures. Transport of tetracycline also decreased at lower temperatures, probably due to changes in membrane fluidity. However, no change was found at over 32 degrees C, suggesting that passive diffusion does not change during moderate hypothermia. The distribution of MDR1 substrates should be considered during hypothermic conditions, as the clinical outcome could be affected.

Intravenous infusion of an antisense oligonucleotide results in exon skipping in muscle dystrophin mRNA of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a fatal muscle wasting disease that is characterized by muscle dystrophin deficiency. We report that intravenous (IV) infusion of an antisense oligonucleotide created an in-frame dystrophin mRNA from an out-of-frame DMD mutation (via exon skipping) which led to muscle dystrophin expression. A 10-year-old DMD patient possessing an out-of-frame, exon 20 deletion of the dystrophin gene received a 0.5 mg/kg IV infusion of an antisense 31-mer phosphorothioate oligonucleotide against the splicing enhancer sequence of exon 19. This antisense construct was administered at one-week intervals for 4 wk. No side effects attributable to infusion were observed. Exon 19 skipping appeared in a portion of the dystrophin mRNA in peripheral lymphocytes after the infusion. In a muscle biopsy one week after the final infusion, the novel in-frame mRNA lacking both exons 19 and 20 was identified and found to represent approximately 6% of the total reverse transcription PCR product. Dystrophin was identified histochemically in the sarcolemma of muscle cells after oligonucleotide treatment. These findings demonstrate that phosphorothioate oligonucleotides may be administered safely to children with DMD, and that a simple IV infusion is an effective delivery mechanism for oligonucleotides that lead to exon skipping in DMD skeletal muscles.

Effects of acid and lactone forms of eight HMG-CoA reductase inhibitors on CYP-mediated metabolism and MDR1-mediated transport.

PURPOSE: With the growing clinical usage of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), the number of reports concerning serious drug-drug interaction has been increasing. Because recent studies have shown that conversion between acid and lactone forms occurs in the body, drug-drug interaction should be considered on both acid and lactone forms. Thus, we investigated the inhibitory effects of acid and lactone forms of eight statins, including one recently withdrawn, cerivastatin, and two recently developed, pitavastatin and rosuvastatin, on cytochrome P450 (CYP) 2C8, CYP2C9, and CYP3A4/5 metabolic activities and multidrug resistance protein 1 (MDR1) transporting activity. METHODS: The inhibitory effects of statins on CYP metabolic activities and MDR1 transporting activity were investigated using human liver microsomes and MDR1-overexpressing LLC-GA5-COL150 cells, respectively. RESULTS: The acid forms had minimal inhibitory effects on all CYP activities tested, except for fluvastatin on CYP2C9-mediated tolbutamide 4-hydroxylation (IC50 = 1.7 microM) and simvastatin on CYP3A4/5-mediated paclitaxel 3-hydroxylation (12.0 microM). Lactone forms showed no or minimal inhibitory effects on CYP2C8, CYP2C9, and CYP2C19 activities, except for rosuvastatin on the CYP2C9 activity (20.5 microM), whereas they showed stronger inhibitory effects on the CYP3A4/5 activity with the rank order of atorvastatin (5.6 microM), cerivastatin (8.1 microM), fluvastatin (14.9 microM), simvastatin (15.2 microM), rosuvastatin (20.7 microM), and lovastatin (24.1 microM). Pitavastatin and pravastatin had little inhibitory effect, and a similar order was found also for testosterone 6beta-hydroxylation. MDR1-mediated transport of [3H]digoxin was inhibited only by lactone forms, and the rank order correlated with that of inhibitory effects on both CYP3A4/5 activities. Inhibitory effects on MDR1 activity, and on both CYP3A4/5 activities, could be explained by the lipophilicity; however, a significant correlation was found between the lipophilicity and inhibitory effects on CYP2C8-mediated paclitaxel 6alpha-hydroxylation. CONCLUSIONS: We showed the difference between the acid and lactone forms in terms of drug interaction. The lipophilicity could be one of the important factors for inhibitory effects. In the case of statins, it is important to examine the effects of both forms to understand the events found in clinical settings, including the pleiotropic effects.

Haloperidol is an inhibitor but not substrate for MDR1/P-glycoprotein.

The involvement of the multidrug resistant transporter MDR1/P-glycoprotein in the penetration of haloperidol into the brain and absorption in the intestine was investigated to examine its role in inter/intra-individual variability, using the porcine kidney epithelial cell line LLC-PK(1) and its MDR1-overexpressing transfectant, LLC-GA5-COL150. The inhibitory effect of haloperidol on other MDR1 substrates was also investigated in terms of the optimization of haloperidol-based pharmacotherapy. The transepithelial transport of [(3)H]haloperidol did not differ between the two cell lines, and vinblastine, a typical MDR1 substrate, had no effect on the transport, suggesting that haloperidol is not a substrate for MDR1, and it is unlikely that MDR function affects haloperidol absorption and brain distribution, and thereby the response to haloperidol. However, haloperidol was found to have an inhibitory effect on the MDR1-mediated transport of [(3)H]digoxin and [(3)H]vinblastine with an IC50 value of 7.84+/-0.76 and 3.60+/-0.64 microM, respectively, suggesting that the intestinal absorption, not distribution into the brain, of MDR1 substrate drugs could be altered by the co-administration of haloperidol in the clinical setting, although further clinical studies are needed.

Effect of micafungin on cytochrome P450 3A4 and multidrug resistance protein 1 activities, and its comparison with azole antifungal drugs.

The effects of micafungin on cytochrome P450 3A4 (CYP3A4) metabolic and multidrug resistance protein 1 (MDR1) transport activities were investigated and compared with those of amphotericin B and four azole antifungal drugs (ketoconazole, itraconazole, fluconazole and miconazole). The effects on the metabolic activity of CYP3A4 were examined by measuring nifedipine oxidase activity in human liver microsomes and the effects on MDR1 transport activity were evaluated using [3H]digoxin in MDR1-overexpressing LLC-GA5-COL150 cells. An inhibitory effect on CYP3A4 activity was found for ketoconazole, itraconazole and miconazole, with 50% inhibitory concentrations of 11.7, 32.6 and 74.2 nM, respectively. Fluconazole and micafungin had only slight inhibitory effects and amphotericin B had no effect. The MDR1-mediated transport of [3H]digoxin was inhibited by ketoconazole and itraconazole, and slightly by miconazole. It is suggested that micafungin and amphotericin B would be unlikely to cause drug-drug interactions by inhibition of CYP3A4 and MDR1. A positive correlation between the inhibitory effects on CYP3A4 and MDR1 activities was observed, and the physicochemical mechanisms involved and impact on clinical treatment should be studied further.

Effects of carvedilol on MDR1-mediated multidrug resistance: comparison with verapamil.

The reversing effects of carvedilol and other beta-adrenoceptor antagonists on multidrug resistance (MDR) were assessed in HeLa cells and the MDR1-overexpressing derivative Hvr100-6 cells, established by stepwise increases of vinblastine concentration in the culture medium. The inhibitory effects on the transcellular transport and intracellular accumulation of [3H]vinblastine and [3H]daunorubicin were also assessed using LLC-GA5-COL150 cell monolayers, established by transfection of human MDR1 cDNA into porcine kidney epithelial LLC-PK1 cells. The cytotoxic effects of vinblastine, paclitaxel, doxorubicin and daunorubicin in Hvr100-6 were reversed 1.4- to 7.1-fold by carvedilol at the realistic clinical concentration of 1 microM, whereas other beta-adrenoceptor antagonists had weaker or no such effects. Transport experiments using LLC-GA5-COL150 cell monolayers demonstrated that this effect of carvedilol was due to the inhibition of MDR1-mediated transport of vinblastine, paclitaxel, doxorubicin and daunorubicin. These MDR1-mediated reversing effects of carvedilol were similar to those of 1 microM verapamil, suggesting that carvedilol could be a candidate modulator of MDR in clinical use. Since other beta-adrenoceptor antagonists had no inhibitory effect on transport, the effects of carvedilol were not related to beta-adrenoceptors and might have been due to antioxidant activity.

Different contribution of CYP2C19 in the in vitro metabolism of three proton pump inhibitors.

A series of clinical studies on the cytochrome P450 2C19 (CYP2C19) genotype and the pharmacokinetics and pharmacodynamics of three proton pump inhibitors (PPIs), omeprazole, lansoprazole and rabeprazole, have been conducted to establish the individualized pharmacotherapy based on the CYP2C19 genotyping, and in the present study, the CYP2C19 genotype-dependency was more pronounced for omeprazole than the other two. Herein, to validate further the difference among 3 PPIs in CYP2C19 genotype-dependency on the phenotype, a comparative in vitro study was conducted using the human liver microsomes and newly developed anti-human CYP antibodies. The residual concentrations of omeprazole and lansoprazole in 5 lots of human liver microsomes were dependent on the CYP2C19 activities, however, for rabeprazole, there was no correlation. The hydroxylation of omeprazole was more inhibited by anti-CYP2C19 antibody than lansoprazole, whereas anti-CYP3A4 antibody showed similar inhibition. In conclusion, the relative contribution of CYP2C19 on total metabolism of 3 PPIs elucidated herein coincided with the CYP2C19 genotype-dependent pharmacokinetics.