Assessment of drug–drug interaction potential and PBPK modeling of CC-223, a potent inhibitor of the mammalian target of rapamycin kinase

1.?CC-223 was studied in vitro for metabolism and drug–drug interactions (DDI), and in clinic for interaction with ketoconazole.

2.?In vitro, human metabolites of CC-223 included O-desmethyl CC-223 (M1), keto (M2), N-oxide (M3) and imine (M13), with M1 being the most prominent metabolite.

3.?CC-223 was metabolized by CYP2C9 and CYP3A, while metabolism of M1 was mediated by CYP2C8 and CYP3A. Ketoconazole increased CC-223 and M1 exposure by 60–70% in healthy volunteers.

4.?CC-223 (IC₅₀?≥?27?µM) and M1 (IC₅₀?≥?46?µM) were inhibitors of CYP2C9 and CYP2C19 in human liver microsomes. CC-223 and M1 were moderate inducers of CYP3A in human hepatocytes.

5.?CC-223 was a substrate of BCRP, and M1 was a substrate of P-gp and BCRP. CC-223 was an inhibitor of P-gp (IC₅₀?=?3.67?µM) and BCRP (IC₅₀?=?11.7?µM), but at a clinically relevant concentration showed no inhibition of other transporters examined. M1 is a weak inhibitor of P-gp and BCRP.

6.?PBPK model of CC-223 and M1 was developed and verified using clinical results. Model based predictions of DDI with ketoconazole were in agreement with observed results enabling prospective predictions of DDIs between CC-223 and CYP3A4 inhibitors.     

In vitro analysis of itraconazole cis-diastereoisomers inhibition of nine cytochrome P450 enzymes: stereoselective inhibition of CYP3A

1. Itraconazole (ITZ), an antifungal azole derivate is a chiral drug that consists of four cis-diastereoisomers ((+)-2R,4S,2′R-ITZ-A; (+)-2R,4S,2′S-ITZ-B; (–)-2S,4R,2′S-ITZ-C and (–)-2S,4R,2′R-ITZ-D) which may differ in their pharmacokinetics and pharmacodynamics.

2. As ITZ is known as a CYP3A4 inhibitor causing severe drug–drug interaction, the inhibitory potencies of its individual optical isomers towards nine drug-metabolising cytochrome P450 (including CYP3A, CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP2E1), were investigated.

3. All ITZ diastereoisomers dose-dependently inhibited CYP3A activity in both used assays, midazolam and testosterone hydroxylation. The K_i values were assessed: for testosterone ITZ-A/0.085 µM; ITZ-B/0.91 µM, ITZ-C/0.20?µM and ITZ-D/0.022 µM; for midazolam ITZ-A/0.44 µM; ITZ-B/0.48 µM, ITZ-C/1.56 µM and ITZ-D/3.48 µM. The enzyme activity of CYP2C19 was moderately inhibited (IC50 30–53 µM), but in this case without large differences between the individual optical isomers.

4. The significant differences between diastereoisomers were presented. Antifungal potency of ITZ stereoisomers also differs so the potential enantiopure preparations of ITZ was not of interest.     

Functional characterization of 21 CYP3A4 variants on amiodarone metabolism in vitro

1. Cytochrome P450 3A4 (CYP3A4) is an important member of the cytochrome P450 enzyme superfamily, with 33 allelic variants reported previously. Genetic polymorphisms of CYP3A4 can produce a significant effect on the efficacy and safety of some drugs, so the purpose of this study was to clarify the catalytic characteristics of 22 CYP3A4 allelic isoforms, including 6 novel variants in Han Chinese population, on the oxidative metabolism of amiodarone in vitro.

2. Wild-type CYP3A4*1 and other variants expressed by insect cells system were incubated respectively with 10–500?μM substrate for 40?min at 37?°C and terminated at ?80?°C immediately. Then these samples were treated as required and detected with ultra-performance liquid chromatography-tandem mass spectrometry used to analyze its major metabolite desethylamiodarone.

3. Among the 21 CYP3A4 variants, compared with the wild-type, the intrinsic clearance values (V_max/K_m) of two variants were apparently decreased (11.07 and 2.67% relative clearance) while twelve variants revealed markedly increased values (155.20～435.96%), and the remaining of seven variants exhibited no significant changes in enzyme activity.

4. This is the first time report describing all these infrequent alleles for amiodarone metabolism, which can provide fundamental data for further clinical studies on CYP3A4 alleles.     

Human PXR-mediated transcriptional activation of CYP3A4 by ‘Fuzi’ extracts

Objective: This study focused on determining whether the ‘Fuzi’ (FZ) extracts from different extraction methods are related to pregnane X receptor (PXR) and cytochrome P450 3A4 (CYP3A4), and explore the mechanism.

Methods: FZ was extracted under various conditions, and the components were identified by Ultra Performance Liquid Chromatography/Quad Time of Flight Mass Spectrometry (UPLC/Q-TOF-MS). Annexin V-FITC and propidium iodide staining assays were used to measure the cell cytotoxicity of these extracts. Real-time PCR, western blot analysis and reporter gene assay were used to detect the expression changes of PXR and CYP3A4.

Results: FZ extracts were found to contain high levels of monoester-diterpene alkaloids (MDAs) and diester-diterpene alkaloids (DDAs). FZ extracts were cytotoxic. Interestingly, we found that FZ extracts and DDAs can induce the expressions of PXR and CYP3A4. And the MDAs can inhibit the expressions of PXR and CYP3A4.

Conclusion: Different extracts of FZ can induce the expressions of PXR and CYP3A4 in different degrees. This may be related to the drug-drug interactions.     

Direct and quantitative evaluation of the major human CYP contribution (fmCYP) to drug clearance using the in vitro Silensomes™ model

1.?We have applied the concept of using MBIs to produce CYP-Silensomes to quantify the contribution of the major CYPs to drug metabolism (fmCYP).

2.?The target CYPs were extensively and selectivity inhibited by the selected MBIs, while non-target CYPs were inhibited by less than 20% of the homologous control activities. Only CYP2D6-Silensomes exhibited a CYP2B6 inhibition that could be easily and efficiently encountered by subtracting the fm_CYP2B6 measured using CYP2B6-Silensomes to adjust the fm_CYP2D6.

3.?To validate the use of a panel of 6 CYP-Silensomes, we showed that the fmCYP values of mono- and multi-CYP metabolised drugs were well predicted, with 70% within?±?15% accuracy. Moreover, the correlation with observed fmCYP values was higher than that for rhCYPs, which were run in parallel using the same drugs (<45% within ±15% accuracy). Moreover, the choice of the RAF substrate in rhCYP predictions was shown to affect the accuracy of the fmCYP measurement.

4.?These results support the use of CYP1A2-, CYP2B6-, CYP2C8-, CYP2C9-, CYP2D6 and CYP3A4-Silensomes to accurately predict fmCYP values during the in vitro enzyme phenotyping assays in early, as well as in development, phases of drug development.     

Adverse event reporting patterns of concomitant botanical dietary supplements with CYP3A4 interactive & CYP3A4 non-interactive anticancer drugs in the U.S. Food and Drug Administration Adverse Event Reporting System (FAERS)

Background: To examine the adverse event (AE) reporting patterns for concomitant Botanical Dietary Supplements (BDS) and anticancer drugs.

Research design and methods: Using the 2004–2015 U.S. Food and Drug Administration Adverse Event Reporting System (FAERS) database, AEs involving commonly used BDS and anticancer drugs (categorized into CYP3A4 interactive and CYP3A4 non-interactive) were examined. Disproportionality analyses using reporting odds ratios (RORs) assessed the relative reporting rates of 1) serious AEs (i.e., mortality and morbidity) with concomitant use of BDS (overall and by type) and anticancer drugs compared to anticancer drugs only; and 2) AEs by specific System Organ Classes (SOCs).

Results: A total of 3,264 AEs were reported involving concomitant BDS and CYP3A4 interactives, and 3,885 involving concomitant BDS and non-interactive anticancer drugs. ROR of serious AEs with concomitant all BDS and anticancer drugs compared to anticancer drugs alone showed a potential protective signal (ROR = 0.65, 95% CI = 0.62,0.68), but ROR for açaí and non-interactive anticancer drugs indicated potential risk (ROR = 1.70, 95% CI = 1.01,2.86). Heterogeneity of reporting patterns of AEs related to certain SOCs was observed for use of BDS along with anticancer drugs.

Conclusion: This study identified potential protective and risk signals for AEs with concomitant use of BDS and anticancer drugs.     

Comparison of predicted intrinsic hepatic clearance of 30 pharmaceuticals in canine and feline liver microsomes

1.?Known cytochrome P450 (CYP) substrates in humans are used in veterinary medicine, with limited knowledge of the similarity or variation in CYP metabolism. Comparison of canine and feline CYP metabolism via liver microsomes report that human CYP probes and inhibitors demonstrate differing rates of intrinsic clearance (CL_int).

2.?The purpose of this study was to utilize a high-throughput liver microsome substrate depletion assay, combined with microsomal and plasma protein binding to compare the predicted hepatic clearance (CL_hep) of thirty therapeutic agents used off-label in canines and felines, using both the well-stirred and parallel tube models.

3.?In canine liver microsomes, 3/30 substrates did not have quantifiable CL_int, while midazolam and amitriptyline CL_int was too rapid for accurate determination. A CL_hep was calculated for 29/30 substrates in feline microsomes. Overall, canine CL_hep was faster compared to the feline, with fold differences ranging from 2–20-fold.

4.?A comparison between the well-stirred and parallel tube model indicates that the parallel tube model reports a slighter higher CL_hep in both species.

5.?The differences in CYP metabolism between canine and feline highlight the need for additional research into CYP expression and specificity.     

Cytochrome P450 2A6 and other human P450 enzymes in the oxidation of flavone and flavanone

1.?We previously reported that flavone and flavanone interact spectrally with cytochrome P450 (P450 or CYP) 2A6 and 2A13 and other human P450s and inhibit catalytic activities of these P450 enzymes. In this study, we studied abilities of CYP1A1, 1A2, 1B1, 2A6, 2A13, 2C9 and 3A4 to oxidize flavone and flavanone.

2.?Human P450s oxidized flavone to 6- and 5-hydroxylated flavones, seven uncharacterized mono-hydroxylated flavones, and five di-hydroxylated flavones. CYP2A6 was most active in forming 6-hydroxy- and 5-hydroxyflavones and several mono- and di-hydroxylated products.

3.?CYP2A6 was also very active in catalyzing flavanone to form 2′- and 6-hydroxyflavanones, the major products, at turnover rates of 4.8?min^?1 and 1.3?min^?1, respectively. Other flavanone metabolites were 4′-, 3′- and 7-hydroxyflavanone, three uncharacterized mono-hydroxylated flavanones and five mono-hydroxylated flavones, including 6-hydroxyflavone. CYP2A6 catalyzed flavanone to produce flavone at a turnover rate of 0.72?min^?1 that was ～3-fold higher than that catalyzed by CYP2A13 (0.29?min^?1).

4.?These results indicate that CYP2A6 and other human P450s have important roles in metabolizing flavone and flavanone, two unsubstituted flavonoids, present in dietary foods. Chemical mechanisms of P450-catalyzed desaturation of flavanone to form flavone are discussed.     

Effect of diammonium glycyrrhizinate on pharmacokinetics of omeprazole by regulating cytochrome P450 enzymes and plasma protein binding rate

1. In clinical practice, diammonium glycyrrhizinate is usually used with omeprazole in patients with viral hepatitis and cirrhosis accompanied by peptic ulcers. However, the drug interaction between diammonium glycyrrhizinate and omeprazole remains unclear.

2. In this study, the effects of diammonium glycyrrhizinate on the pharmacokinetics of omeprazole was investigated by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical method. Male Sprague–Dawley rats were randomly assigned to two groups: omeprazole and omeprazole?+?diammonium glycyrrhizinate, and the main pharmacokinetic parameters were estimated after oral administration. It was found that using the omeprazole along with the diammonium glycyrrhizinate increased the AUC, AUMC, C_max for omeprazole.

3. For this reason, we used the LC-MS/MS to detect the binding rate of plasma protein (BRPP) of omeprazole in rats, it was found that diammonium glycyrrhizinate could decrease the BRPP in rats. In addition, we found that diammonium glycyrrhizinate specifically inhibited the enzyme activity of the CYP2C19 and CYP3A4, which are involved in the metabolism of the omeprazole.

4. These results mean that diammonium glycyrrhizinate could inhibit the metabolism and increase the plasma concentration of the omeprazole in rats. Overall, diammonium glycyrrhizinate can influence the pharmacokinetics of omeprazole by inhibiting CYP2C19 and CYP3A4 activities and decreasing BRPP of omeprazole.     

Preclinical pharmacokinetics of a novel anti-c-Met antibody–drug conjugate,SHR-A1403, in rodents and non-human primates

1. The in vivo pharmacokinetics (PK) profiles of a novel c-Met antibody–drug conjugate (ADC), SHR-A1403, were investigated and characterized in mice, rats and monkeys.

2. Serum concentrations of ADC and total antibody were detected using validated ELISA methods. The results showed low systemic clearance of both ADC and total antibody in all three species as reflected by gradual decrease in serum concentrations. Half-life (t_1/2) of ADC ranged from 4.6 to 11.3?days in the three species.

3. Tissue distribution study in tumor-bearing mice showed high accumulation of ¹²⁵I-SHR-A1403 in tumor tissues over the other organs/tissues, indicating the favorable safety of SHR-A1403 and characteristics of an ADC drug.

4. Relatively low grade of anti-drug antibody (ADA) in monkeys had no impact on PK profile of the ADC.

5. During discovery stage, undesirable exposure and/or ADA incidence were observed for SHR-A1403 with high or low drug-antibody ratio (DAR), which was DAR?=?5 to 6 and DAR?=?1, respectively, and therefore prompted selection of an appropriate DAR value (DAR?=?2) for SHR-A1403 used in preclinical development and clinical trials.

6. In conclusion, our work demonstrated favorable PK characterization of SHR-A1403, and supported for investigational new drug application (IND) and the ongoing first-in-human trial in the US.     

Metabolic disposition of WTX101 (bis-choline tetrathiomolybdate) in a rat model of Wilson disease

1. WTX101 (bis-choline tetrathiomolybdate) is an investigational copper (Cu)-protein-binding agent developed for the treatment of Wilson disease (WD), a rare genetic disorder caused by mutations in the ATP7B Cu-transporter and resulting in toxic Cu accumulation.

2. Mass balance of a single intravenous WTX101 dose, measured as molybdenum (Mo), was assessed over 168?h in control (Long Evans Agouti [LEA]) and Long-Evans Cinnamon (LEC) rats, a WD model.

3. In LEC rats, Mo was partially excreted (up to 45%); 29% by renal clearance, and faecal clearance, still ongoing at 168?h, accounted for 16%. In contrast, in LEA rats, Mo was almost fully excreted (～87%); 79% was renally cleared with only 7% faecal excretion.

4. In LEC rats, the proportion of faecal to renal Mo excretion was enhanced (4:6) compared to controls (1:9).

5. Substantially more Mo was found in LEC liver and kidney compared with LEA tissues, in line with tissue Cu distribution.

6. These findings are consistent with the WTX101 mechanism of action: in the WD model, excess Cu is removed from hepatic metallothionein and retained within the stable tetrathiomolybdate-Cu-albumin tripartite complex, preventing tetrathiomolybdate degradation and resulting in less urinary elimination and greater faecal excretion than in controls.     

Pharmacokinetics and distribution of schisandrol A and its major metabolites in rats

1.?Schizandrol A is an active component in schisandra, also the representative component for the identification of schisandra.

2.?A rapid resolution liquid chromatography coupled with quadruple–time–of–flight mass spectrometry (RRLC–QTOF/MS) was developed to investigate the pharmacokinetics of schizandrol A after its intragastric administration (50?mg/kg) in rats.

3.?Schizandrol A was rapidly absorbed (T _max = 2.07?h), with a longer duration (t _1/2 = 9.48?h) and larger apparent volume of distribution (Vz/F?=?111.81?l/kg) in rats. Schizandrol A can be detected in main organs and the order of its distribution was in the liver?>?kidney?>?heart?>?spleen?>?brain, particularly higher in the liver.

4.?Five schizandrol A metabolites were identified, including 2–demethyl–8(R)–hydroxyl–schizandrin, 3–demethyl–8(R)–hydroxyl–schizandrin, hydroxyl–schizandrin, demethoxy–schizandrin, 2, 3–demethyl–8(R)–hydroxyl–schizandrin, indicating that the hydroxylation and demethylation may be the major metabolic way of schizandrol A.

5.?This study defined the pharmacokinetic characteristics of schizandrol A in vivo, and the RRLC–QTOF/MS is more sensitive and less limited by conditions, and needs less samples, which may be a useful resource for the further research and development of schisandrol A.     

Optimisation of the microencapsulation of lavender oil by spray drying

Background: Lavender oil consists of around 100 components and is susceptible to volatilisation and degradation reactions.

Aim: Microencapsulate lavender oil by spray drying using a biocompatible polymeric blend of gum acacia and maltodextrin to protect the oil components. Effect of total polymer content, oil loading, gum acacia, and maltodextrin proportions on the size, yield, loading, and encapsulation efficiency of the microparticles was investigated.

Methods: Morphology and oil localisation within microparticles were assessed by confocal laser scanning electron microscope. Structural preservation and compatibility were assessed using Fourier transform infra-red spectroscopy, differential scanning calorimetry, and gas chromatography–mass spectrometry.

Results: Lavender microparticles of size 12.42?±?1.79?µm prepared at 30 w/w% polymer concentration, 16.67 w/w% oil loading, and 25w/w% gum acacia showed maximum oil protection at high loading (12?mg w/w%), and encapsulation efficiency (77.89 w/w%).

Conclusion: Lavender oil was successfully microencapsulated into stable microparticles by spray drying using gum acacia/maltodextrin polymeric blend.     

An evaluation of peripapillar choroidal thickness in patients receiving systemic isotretinoin treatment

Purpose: Oral isotretinoin (13-cis retinoic acid, 13-cis RA) was approved for severe acne treatment by the FDA in 1982. The ocular side effects associated with oral isotretinoin use are mostly dose-dependent. Numerous ocular pathologies affect peripapillary choroidal layer primarily or indirectly.

Objective: Evaluation of the peripapillary choroidal layer in the patients receiving oral isotretinoin therapy may aid in explaining the pathophysiology of ocular side effects.

Methods: In this study, peripapillary choroidal thickness was assessed in the patients receiving oral isotretinoin treatment via optical coherent tomography technique.

Results: Significant difference was found in the superotemporal and temporal areas.

Conclusion: Oral isotretinoin treatment may affect the thickness of the peripapillary choroidal layer.     

Utility of food pellets containing 1-aminobenzotriazole for longer term in vivo inhibition of cytochrome P450 in mice

1. The utility of 1-aminobenzotriazole (ABT), incorporated in food, has been investigated as an approach for longer term inhibition of cytochrome P450 (P450) enzymes in mice.

2. In rats, ABT inhibits gastric emptying, to investigate this potential limitation in mice we examined the effect of ABT administration on the oral absorption of NVS-CRF38. Two hour prior oral treatment with 100?mg/kg ABT inhibited the oral absorption of NVS-CRF38, T_max was 4?hours for ABT-treated mice compared to 0.5?hours in the control group.

3. A marked inhibition of hepatic P450 activity was observed in mice fed with ABT containing food pellets for 1?month. P450 activity, as measured by the oral clearance of antipyrine, was inhibited on day 3 (88% of control), week 2 (83% of control) and week 4 (80% of control).

4. T_max values for antipyrine were comparable between ABT-treated mice and the control group, alleviating concerns about impaired gastric function.

5. Inclusion of ABT in food provides a minimally invasive and convenient approach to achieve longer term inhibition of P450 activity in mice. This model has the potential to enable pharmacological proof-of-concept studies for research compounds which are extensively metabolised by P450 enzymes.     

Specific hypertension smartphone application to improve medication adherence in hypertension: a cluster-randomized trial

Introduction: Digital interventions, such as smartphone applications (apps), are becoming an increasingly common way to support medication adherence and self-management in chronic illness.

Aim: To evaluate the effectiveness of the intervention in pharmacological therapeutic adherence in mild to moderate arterial hypertension (AHT), through an app installed on a mobile phone, as well as the degree of control reached by the patient with this tool.

Methods: Prospective, randomized controlled trial, full study and multicenter study. Four primary care centers participated. One hundred and fifty-four hypertensive patients under antihypertensive treatment were included. Two groups were established: a control group (CG) with usual intervention (n?=?77) and an intervention group (n?=?77) (IG), targeting hypertensive people who owned and regularly used a mobile smartphone, specifically using the app called AlerHTA to promote health education and reminder of appointments. There were three visits: initial, 6 and 12 months. Drug adherence was measured by electronic monitors (MEMSs). The primary outcomes were average daily percentage adherence between 80 and 100%, and AHT control.

Results: A total of 148 patients finished the study. Mean age was 57.5?±?9.9. Global adherence was 77.02% (CI?=?70.25–83.79) and daily adherence was 74.32% (CI?=?67.29–81.35%). Daily adherence was 93.15% and 86.3% in IG, and 70.66% and 62.66% in CG after 6 and 12 months respectively (p < .05). The percentage of uncontrolled patients was 28.3% (CI?=?21.05–35.55%). The control of high blood pressure at 12 months was 17.8% and 38.6% for IG and CG respectively (p < .05). The number of patients needed to treat to avoid non-adherence (NNT) was 4.23 patients.

Conclusions: The intervention with an app installed on the mobile phones of hypertensive patients favors pharmacological therapeutic adherence and improves the percentage of hypertensive patient control.

Trial registration: Spanish Agency of Medicine: EPA-SP UN-HTA-2015-01.     

Evidence of bioequivalence and positive patient user handling of a tocilizumab autoinjector

Background: The anti–interleukin-6 receptor antibody tocilizumab is approved for subcutaneous injection using a prefilled syringe (PFS). We report results from a bioequivalence study in healthy subjects and a user-handling study in patients with rheumatoid arthritis (RA) using an autoinjector (AI) for tocilizumab.

Methods: A randomized crossover study in healthy subjects (N = 161) examined the bioequivalence, safety, and tolerability of tocilizumab after a single subcutaneous injection by AI versus PFS. A nonrandomized observational, real-life human factors study in RA patients (N = 54) assessed user (RA patients, caregivers, health care providers) ability to administer tocilizumab effectively by AI.

Results: Bioequivalence criteria for tocilizumab AI versus PFS were met for key pharmacokinetic parameters. Safety was comparable between devices and consistent with the established tocilizumab profile. In the real-life human factors study, the proportion of users who successfully performed all essential tasks required to operate the AI to deliver the full dose was 92.3% at first assessment and 98.1% at second assessment, with no safety concerns.

Conclusions: Tocilizumab administration by AI was bioequivalent to administration by PFS. Intended users were successful in performing the tasks required to administer tocilizumab by AI. No new safety signals were observed in either study.

Clinical Trial Registration: NCT02678988, NCT02682823     

Determination of low intrinsic clearance in vitro: the benefit of a novel internal standard in human hepatocyte incubations

1. A novel method utilizing an internal standard in hepatocytes incubations has been developed and demonstrated to decrease the variability in the determination of intrinsic clearance (CL_int) in this system. The reduced variability was shown to allow differentiation of lower elimination rate constants from noise.

2. The suggested method was able to compensate for a small but systematic error (0.5 µL/min/10⁶ cells) caused by an evaporation of approximately 15% of the volume during the incubation time.

3. The approach was validated using six commercial drugs (ketoprofen, tolbutamide, phenacetin, etodolac and quinidine) which were metabolized by different pathways.

4. The suggested internal standard, MSC1815677, was extensively characterized and the acquired data suggest that it fulfills the requirements of an internal standard present during the incubation. The proposed internal standard was stable during the incubation and showed a low potential to inhibit drug metabolizing enzymes and transporters. With MSC1815677 we propose a novel simple, robust and cost-effective method to address the challenges in the estimation of low clearance in hepatocyte incubations.     

Efficacy of istradefylline for gait disorders with freezing of gait in Parkinson’s disease: A single-arm,open-label,prospective, multicenter study

Background: Gait disorders are common in Parkinson’s disease patients who respond poorly to dopaminergic treatment. Blockade of adenosine A_2A receptors is expected to improve gait disorders. Istradefylline is a first-in-class selective adenosine A_2A receptor antagonist with benefits for motor complications associated with Parkinson’s disease.

Research design and methods: This multicenter, open-label, single-group, prospective interventional study evaluated changes in total gait-related scores of the Part II/III Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) and Freezing of Gait Questionnaire (FOG-Q) in 31 Parkinson’s disease patients treated with istradefylline. Gait analysis by portable gait rhythmogram was performed.

Results: MDS-UPDRS Part III gait-related total scores significantly decreased at Weeks 4–12 from baseline with significant improvements in gait, freezing of gait, and postural stability. Significant decreases in MDS-UPDRS Part II total scores and individual item scores at Week 12 indicated improved daily living activities. At Week 12, there were significant improvements in FOG-Q, new FOG-Q, and overall movement per 48 h measured by portable gait rhythmogram. Adverse events occurred in 7/31 patients.

Conclusions: Istradefylline improved gait disorders in Parkinson’s disease patients complicated with freezing of gait, improving their quality of life. No unexpected adverse drug reactions were identified.

Trial registration: UMIN-CTR (UMIN000020288).     

Interactions of organophosphorus pesticides with solute carrier (SLC) drug transporters

1.?Organophosphorus pesticides (OPs) are known to interact with human ATP-binding cassette drug efflux pumps. The present study was designed to determine whether they can also target activities of human solute carrier (SLC) drug transporters.

2.?The interactions of 13 OPs with SLC transporters involved in drug disposition, such as organic cation transporters (OCTs), multidrug and toxin extrusion proteins (MATEs), organic anion transporters (OATs) and organic anion transporting polypeptides (OATPs), were mainly investigated using transporter-overexpressing cell clones and fluorescent or radiolabeled reference substrates.

3.?With a cut-off value of at least 50% modulation of transporter activity by 100?µM OPs, OAT1 and MATE2-K were not impacted, whereas OATP1B1 and MATE1 were inhibited by two and three OPs, respectively. OAT3 activity was similarly blocked by three OPs, and was additionally stimulated by one OP. Five OPs cis-stimulated OATP2B1 activity. Both OCT1 and OCT2 were inhibited by the same eight OPs, including fenamiphos and phosmet, with IC₅₀ values however in the 3–30?µM range, likely not relevant to environmental exposure.

4.?These data demonstrated that various OPs inhibit SLC drug transporter activities, especially those of OCT1 and OCT2, but only when used at high concentrations not expected to occur in environmentally-exposed humans.