CYP3A4 inhibitors may influence the quantification of [123I]I-FP-CIT SPECT scans.

PURPOSE: [123I]I-FP-CIT SPECT is an imaging tool to support the diagnosis of parkinsonian syndromes characterized by nigrostriatal dopaminergic degeneration. After intravenous injection, [123I]I-FP-CIT is metabolized for a small part by the enzyme CYP3A4, leading to the formation of [123I]I-nor-ß-CIT. [123I]I-nor-ß-CIT passes the blood-brain barrier and has a very high affinity for the serotonin transporter (SERT). The SERT is expressed in the striatum and cortical areas. So, at least theoretical, the use of frequently used CYP3A4 inhibitors (like amiodarone) may influence the specific to non-specific striatal [123I]I-FP-CIT ratio. Here we tested this novel hypothesis. METHODS: Using a retrospective design, we determined the specific to non-specific striatal [123I]I-FP-CIT ratio (using BRASS software) in 6 subjects that were using an CYP3A4 inhibitor and 18 matched controls. Only subjects were included with a normal rated [123I]I-FP-CIT SPECT scan, and all participants were scanned on the same brain-dedicated SPECT system. RESULTS: The specific to non-specific (assessed in the occipital cortex) striatal [123I]I-FP-CIT binding ratio was significantly higher in CYP3A4 users than in the control group (3.52 ± 0.33 vs. 2.90 ± 0.78, p < 0.001). CONCLUSION: Our preliminary data suggest that the use of CYP3A4 inhibitors may influence striatal [123I]I-FP-CIT binding ratios. This information, when reproduced in larger studies, may be relevant for studies in which quantification of [123I]I-FP-CIT SPECT imaging is used for diagnostic or research purposes.

Evidence of potential pro-haemorrhagic drug interactions between CYP3A4 inhibitors and direct oral anticoagulants: Analysis of the FAERS database.

AIMS: There is no consensus on the haemorrhagic risk associated with potential interactions between commonly used CYP3A4 inhibitors and direct oral anticoagulants (DOACs). METHODS: Macrolide antibiotics and azole antimycotics were investigated in this study. Data from Food and Drug Administration Adverse Event Reporting System were retrieved from July 2010 to September 2021. Haemorrhagic signals were expressed by reporting odds ratios (RORs) and 95% confidence intervals (CIs) based on the interaction/noninteraction methodology as (a/c) / (b/d) and considered significant when the lower limit of 95% CI was >1 and the case number of interaction group was ≥3. Subgroup analyses and logistic regression were conducted by adjusting associated factors in haemorrhagic events. RESULTS: From the third quarter of 2010 to the first quarter of 2021, we retrieved 382 853 distinct cases of adverse events associated with DOACs, in which 1128 cases of bleeding were associated with coadministration of CYP3A4 inhibitors and DOACs. The haemorrhagic signal was significant for apixaban when coadministered with clarithromycin (ROR 1.60, 95% CI 1.16-2.20) and posaconazole (ROR 2.69, 95% CI 1.37-5.28). For dabigatran, coadministration with azithromycin (ROR 4.06, 95% CI 2.77-5.95), fluconazole (ROR 2.26, 95% CI 1.52-3.37), itraconazole (ROR 7.52, 95% CI 1.51-37.46) and ketoconazole (ROR 2.06, 95% CI 1.25-3.41) was associated with significantly higher risks of haemorrhages. At the same time, addition of itraconazole to rivaroxaban also indicated significant haemorrhagic signal (ROR 3.58, 95% CI 1.30-9.85). CONCLUSIONS: Macrolide antibiotics and azole antimycotics have potential but different effects on the bleeding risk of DOACs. Close attention is needed when using these drugs together. Such precautions have already been included in some drug labels.

Effect of itraconazole, food, and ethnic origin on the pharmacokinetics of ivosidenib in healthy subjects.

PURPOSE: To assess the effect of ethnicity, food, and itraconazole (strong CYP3A4 inhibitor) on the pharmacokinetics of ivosidenib after single oral doses in healthy subjects. METHODS: Three phase 1 open-label studies were performed. Study 1: Japanese and Caucasian subjects received single doses of 250, 500, or 1000 mg ivosidenib (NCT03071770). Part 1 of study 2 (a two-period crossover study): subjects received 500 mg ivosidenib after either an overnight fast or a high-fat meal. Subjects received 1000 mg ivosidenib after an overnight fast in the single period of part 2 (NCT02579707). Study 3: in period 1, subjects received 250 mg ivosidenib; then, in period 2, subjects received oral itraconazole (200 mg once daily) on days 1-18, plus 250 mg ivosidenib on day 5 (NCT02831972). RESULTS: Ivosidenib was well tolerated in all three studies. Study 1: pharmacokinetic profiles were generally comparable, although AUC and Cmax were slightly lower in Japanese subjects than in Caucasian subjects, by ~ 30 and 17%, respectively. Study 2: AUC increased by ~ 25% and Cmax by ~ 98%, when ivosidenib was administered with a high-fat meal compared with a fasted state. Study 3: co-administration of itraconazole increased ivosidenib AUC by 169% (90% CI 145-195) but had no effect on ivosidenib Cmax. CONCLUSIONS: No ivosidenib dose adjustment is deemed necessary for Japanese subjects. High-fat meals should be avoided when ivosidenib is taken with food. When co-administered with strong CYP3A4 inhibitors, monitoring for QT interval prolongation (a previously defined adverse event of interest) is recommended and an ivosidenib dose interruption or reduction may be considered. CLINICALTRIALS.GOV : NCT03071770, NCT02579707, and NCT02831972.

Molecular Dynamics Simulation Framework to Probe the Binding Hypothesis of CYP3A4 Inhibitors.

The Cytochrome P450 family of heme-containing proteins plays a major role in catalyzing phase I metabolic reactions, and the CYP3A4 subtype is responsible for the metabolism of many currently marketed drugs. Additionally, CYP3A4 has an inherent affinity for a broad spectrum of structurally diverse chemical entities, often leading to drug-drug interactions mediated by the inhibition or induction of the metabolic enzyme. The current study explores the binding of selected highly efficient CYP3A4 inhibitors by docking and molecular dynamics (MD) simulation protocols and their binding free energy calculated using the WaterSwap method. The results indicate the importance of binding pocket residues including Phe57, Arg105, Arg106, Ser119, Arg212, Phe213, Thr309, Ser312, Ala370, Arg372, Glu374, Gly481 and Leu483 for interaction with CYP3A4 inhibitors. The residue-wise decomposition of the binding free energy from the WaterSwap method revealed the importance of binding site residues Arg106 and Arg372 in the stabilization of all the selected CYP3A4-inhibitor complexes. The WaterSwap binding energies were further complemented with the MM(GB/PB)SA results and it was observed that the binding energies calculated by both methods do not differ significantly. Overall, our results could guide towards the use of multiple computational approaches to achieve a better understanding of CYP3A4 inhibition, subsequently leading to the design of highly specific and efficient new chemical entities with suitable ADMETox properties and reduced side effects.

Drug interaction as a predictor of direct oral anticoagulant drug levels in atrial fibrillation patients.

Data are limited on the effects of drug interactions on direct-acting oral anticoagulant (DOAC) levels. We evaluated the effects of the use of interacting drugs on DOAC levels in patients with atrial fibrillation (AF). We reviewed data of AF patients tested for DOAC levels in 2013-2017. The primary outcomes were drug levels exceeding the expected steady-state range, and in the highest quartile. A multivariate analysis was performed to evaluate the correlation of treatment by the use of interacting drugs, CYP3A4 and P-glycoprotein (P-gp) inhibitors, with the primary outcomes. Overall, 147 patients underwent DOAC level measurement [dabigatran (n = 31), rivaroxaban (n = 29), apixaban (n = 87)]. Thirty-three (22.4%) had drug levels exceeding the expected range. Seventy-nine (53.7%) patients were treated with at least one interacting drug. In multivariate analysis, the concomitant use of interacting drugs was an independent predictor for drug levels exceeding the expected range (OR 3.3, 95% CI 1.20-9.05). The defined daily dose of the interacting drug correlated positively with DOAC levels (r = 0.29, P = 0.001). Co-treatment with interacting drugs was associated with extremely high levels of dabigatran, (OR 16.6, 95% CI 1.29-215.18) but not of the other DOAC examined. Concomitant use of interacting drugs is associated with high DOAC levels in patients with AF. Further investigation is warranted to establish the differences between specific DOAC, evaluate the effect on patient outcomes, and characterize the role of DOAC monitoring in this setting.

Effect of ketoconazole and diltiazem on the pharmacokinetics of apixaban, an oral direct factor Xa inhibitor.

AIM: Apixaban is an orally active inhibitor of coagulation factor Xa and is eliminated by multiple pathways, including renal and non-renal elimination. Non-renal elimination pathways consist of metabolism by cytochrome P450 (CYP) enzymes, primarily CYP3A4, as well as direct intestinal excretion. Two single sequence studies evaluated the effect of ketoconazole (a strong dual inhibitor of CYP3A4 and P-glycoprotein [P-gp]) and diltiazem (a moderate CYP3A4 inhibitor and a P-gp inhibitor) on apixaban pharmacokinetics in healthy subjects. METHOD: In the ketoconazole study, 18 subjects received apixaban 10 mg on days 1 and 7, and ketoconazole 400 mg once daily on days 4-9. In the diltiazem study, 18 subjects received apixaban 10 mg on days 1 and 11 and diltiazem 360 mg once daily on days 4-13. RESULTS: Apixaban maximum plasma concentration and area under the plasma concentration-time curve extrapolated to infinity increased by 62% (90% confidence interval [CI], 47, 78%) and 99% (90% CI, 81, 118%), respectively, with co-administration of ketoconazole, and by 31% (90% CI, 16, 49%) and 40% (90% CI, 23, 59%), respectively, with diltiazem. CONCLUSION: A 2-fold and 1.4-fold increase in apixaban exposure was observed with co-administration of ketoconazole and diltiazem, respectively.

Pharmacokinetic interaction between the CYP3A4 inhibitor ketoconazole and the hormone drospirenone in combination with ethinylestradiol or estradiol.

AIMS: The present study was conducted to investigate the influence of the strong CYP3A4 inhibitor ketoconazole (KTZ) on the pharmacokinetics of drospirenone (DRSP) administered in combination with ethinylestradiol (EE) or estradiol (E2). METHODS: This was a randomized, multicentre, open label, one way crossover, fixed sequence study with two parallel treatment arms. A group sequential design allowed terminating the study for futility after first study cohort. About 50 healthy young women were randomized 1 : 1 to 'DRSP/EE' or 'DRSP/E2'. Subjects in the 'DRSP/EE' group received DRSP 3 mg/EE 0.02 mg (YAZ®, Bayer) once daily for 21 to 28 days followed by DRSP 3 mg/EE 0.02 mg once daily plus KTZ 200 mg twice daily for 10 days. Subjects in the 'DRSP/E2' group received DRSP 3 mg/E2 1.5 mg (research combination) once daily for 21 to 28 days followed by DRSP 3 mg/E2 1.5 mg once daily plus KTZ 200 mg twice daily for 10 days. RESULTS: Oral co-administration of DRSP/EE or DRSP/E2 and KTZ resulted in an increase in DRSP exposure (AUC(0,24 h)) in both treatment groups: DRSP/EE group: 2.68-fold DRSP increase (90% CI 2.44, 2.95); DRSP/E2 group: 2.30-fold DRSP increase (90% CI 2.08, 2.54). EE and estrone (metabolite of E2) exposures were increased ~1.4-fold whereas E2 exposure was largely unaffected by KTZ co-administration. CONCLUSIONS: A moderate pharmacokinetic drug-drug interaction between DRSP and KTZ was demonstrated in this study. No relevant changes of medical concern were detected in the safety data collected in this study.

Pharmacokinetic interactions between ivacaftor and cytochrome P450 3A4 inhibitors in people with cystic fibrosis and healthy controls.

BACKGROUND: Ivacaftor is currently the only CFTR potentiator approved and is increasingly used since the development of CFTR correctors. Ivacaftor is metabolized by CYP3A4 and therefore dose reduction is required when treating patients on ivacaftor with CYP3A4 inhibiting drugs. As this advice is based on studies in healthy volunteers and not in cystic fibrosis (CF) patients, we need to investigate this in both groups to be able to extrapolate these data to CF. METHODS: A cohort of CF patients and healthy subjects were exposed to a single dose of ivacaftor in combination with a strong (ritonavir), moderate (clarithromycin) and mild (azithromycin) CYP3A4 inhibitor. Ivacaftor concentrations were measured in all blood samples in order to calculate the pharmacokinetic parameters for ivacaftor. RESULTS: We found that exposure to ivacaftor was higher in healthy volunteers than in subjects with CF. However this difference was not statistically significant. No differences were observed in the interaction potential of CYP3A4 inhibitors between both study groups. The strong CYP3A4 inhibitor ritonavir, increased exposure to ivacaftor 7 times. CONCLUSION: Our data support current recommendations for dose adjustment of ivacaftor in case of co-treatment with CYP3A4 inhibitors in people with CF. However, exposure to ivacaftor was higher in healthy subjects than in CF patients. Further study is needed to investigate the cause and implication of this difference.

Characterization of Alpelisib in Rat Plasma by a Newly Developed UPLC-MS/MS Method: Application to a Drug-Drug Interaction Study.

Alpelisib, an oral selective and small-molecule phosphoinositide 3-kinase inhibitor, was lately approved in the United States to treat breast cancer. A sensitive method to quantify alpelisib levels in rat plasma on the basis of ultra-performance liquid chromatography-tandem mass spectrometry technique was established and validated, which was successfully employed to explore the effects of CYP3A4 inhibitors on alpelisib pharmacokinetics in rats. A C18 column named Acquity UPLC BEH C18 was applied to achieve the separation of alpelisib and internal standard duvelisib after protein precipitation with acetonitrile. The mobile phase in this study had two components, namely, acetonitrile and water having 0.1% formic acid, and a program with gradient elution method was used at a flow rate of 0.40 ml/min. Mass spectrometry in a positive multiple reaction monitoring mode was operated. In the scope of 1-5,000 ng/ml, this assay had excellent linearity. Our newly developed assay was verified in all aspects of bioanalytical method validation, involving lower limit of quantification, selectivity, accuracy and precision, calibration curve, extraction recovery, matrix effect, and stability. Then, this assay was used to detect the plasma levels of alpelisib from a drug-drug interaction investigation, where ketoconazole remarkably increased the plasma concentration of alpelisib and changed alpelisib pharmacokinetics more than itraconazole. This study will help better understand the pharmacokinetic properties of alpelisib, and further clinical studies should be done to confirm this result in patients.

Effect of clarithromycin pre-treatment on the pharmacokinetics of metoclopramide after their simultaneous oral intake.

OBJECTIVE: The objective of this study was to assess the influence of enzyme suppression on the values of various pharmacokinetic factors of orally administered metoclopramide. METHOD: This study was conducted in two phases and a 4-week duration was adopted for drug washout. This randomized study involved 12 healthy human volunteers who received a single oral dose of metoclopramide 20 mg. After the washout period, volunteers received clarithromycin 500 mg two times per day for consecutive 5 days. On test day (fifth day), a single oral dose of metoclopramide 20 mg was also given to the volunteers, and collection of blood samples was conducted at pre-decided time points. Various pharmacokinetic parameters such as Cmax, Tmax, and AUC0-∞ of metoclopramide were determined by analyzing the blood samples using a validated HPLC-UV method. RESULTS: Clarithromycin increased the mean values of Cmax, AUC0-∞, and T1/2 of metoclopramide by 46%, 78.6%, and 9.8%, respectively. CONCLUSION: Clarithromycin noticeably increased the concentration of plasma metoclopramide. This study's results provide in vivo confirmation of the CYP3A4 involvement in metoclopramide metabolism, in addition to CYP2D6. Therefore, metoclopramide pharmacokinetics may be clinically affected by clarithromycin and other potent enzyme inhibitors.

An LC-MS/MS Bioanalytical Assay for the Determination of Gilteritinib in Rat Plasma and Application to a Drug-Drug Interaction Study.

BACKGROUND: Gilteritinib, a novel, potent FLT3/AXL inhibitor, was recently approved in Japan and USA for the treatment of adult patients who have relapsed or refractory acute myeloid leukemia (AML) with a FLT3 mutation. PURPOSE AND METHODS: In this study, we aimed to develop and validate a sensitive and simple ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the quantification of gilteritinib in plasma and to investigate whether CYP3A4 inhibitors (fluconazole and itraconazole) could influence the pharmacokinetics of gilteritinib from a drug-drug interaction study in rats. Sample preparation was done by a simple protein crash with acetonitrile containing the internal standard (IS) pirfenidone, followed by UPLC-MS/MS quantification. RESULTS: The assay was successfully validated in a 1-500 ng/mL calibration range for gilteritinib, where the lower limit of quantification (LLOQ) was set at 1 ng/mL. The intra-day and inter-day precisions for gilteritinib were less than 10.6%, and the accuracies were in the range of -14.5% to 11.1%. Recovery and matrix effect of the analyte and IS were acceptable, and the analyte was stable during the assay and storage in plasma samples. The validated UPLC-MS/MS method was successfully applied to a drug-drug interaction study between gilteritinib and CYP3A4 inhibitors (fluconazole and itraconazole) in rats. Itraconazole significantly increased the exposure of gilteritinib, and affected the pharmacokinetics of gilteritinib in rats, not fluconazole. CONCLUSION: A further clinical study should be conducted to investigate the effect of itraconazole on the metabolism of gilteritinib in subjects.

The clinical significance of statins-macrolides interaction: comprehensive review of in vivo studies, case reports, and population studies.

The objectives of this article were to review the mechanism and clinical significance of statins-macrolides interaction, determine which combination has the highest risk for the interaction, and identify key patients' risk factors for the interaction in relation to the development of muscle toxicity. A literature review was conducted in PubMed and Embase (1946 to December 2018) using combined terms: statins - as group and individual agents, macrolides - as group and individual agents, drug interaction, muscle toxicity, rhabdomyolysis, CYP3A4 inhibitors, and OAT1B inhibitors, with forward and backward citation tracking. Relevant English language in vivo studies in healthy volunteers, case reports, and population studies were included. The interaction between statins and macrolides depends on the type of statin and macrolide used. The mechanism of the interaction is due to macrolides' inhibition of CYP3A4 isoenzyme and OAT1B transporter causing increased exposure to statins. The correlation of this increased statin's exposure to the development of muscle toxicity could not be established, unless the patient had other risk factors such as advanced age, cardiovascular diseases, renal impairment, diabetes, and the concomitant use of other CYP3A4 inhibitors. Simvastatin, lovastatin, and to lesser extent atorvastatin are the statins most affected by this interaction. Rosuvastatin, fluvastatin, and pravastatin are not significantly affected by this interaction. Telithromycin, clarithromycin, and erythromycin are the most "offending" macrolides, while azithromycin appears to be safe to use with statins. This review presented a clear description of the clinical significance of this interaction in real practice. Also, it provided health care professionals with clear suggestions and recommendations on how to overcome this interaction. In conclusion, understanding the different characteristics of each statin and macrolide, as well as key patients' risk factors, will enable health care providers to utilize both groups effectively without compromising patient safety.

Long-term clinical results of microsomal triglyceride transfer protein inhibitor use in a patient with homozygous familial hypercholesterolemia.

We report the case of a 49-year-old woman with homozygous familial hypercholesterolemia and a complicated cardiovascular history, treated for 5 years with a microsomal triglyceride transfer protein inhibitor in addition to her other lipid-lowering therapy.