Alternatives to rifampicin: A review and perspectives on the choice of strong CYP3A inducers for clinical drug-drug interaction studies

Trends in drug-drug interactions for new drug clinical trials in China over the past 10 years (2013-2022)

The number of drug-drug interaction (DDI) clinical trials in China has increased rapidly in recent years. The aim of this study was to summarize and analyze DDI clinical trials in China over the past 10 years. We conducted a cross-sectional study of DDI clinical trials registered in the Chinese Center for Drug Evaluation (CDE) from September 6, 2013 to December 31, 2022. All related registration information disclosed on the CDE website were summarized and analyzed. Although the number of DDI clinical trials conducted before 2017 was relatively low, it increased markedly after 2017. The average duration of DDI clinical trials was 85.83 ± 100.99 days from 2013 to 2019 and 107.16 ± 98.57 days from 2020 to 2022. The duration of rifampicin use was 5-19 days, and the investigational drug was administered after 5-14 days of rifampicin use. Itraconazole was administered for 4-17 days, and the investigational drug was administered after 3-10 days of itraconazole use. Clinical trials of drug-drug interactions have recently increased due to the development of new drugs and the updated policies regulating drug registration and marketing. Although the designs of clinical trials comply with the new guidelines, the duration of the administration of interacting drugs still varies widely. Optimizing protocol designs can shorten the implementation period of clinical trials and reduce the costs of drug marketing.

Development and characterization of a double-crested cormorant hepatic cell line, DCH22, for chemical screening

There are currently no available cell lines for the ecologically relevant colonial waterbird species, the double-crested cormorant (DCCO). DCCOs are high trophic level aquatic birds that are used for routine contaminant monitoring programs in the Laurentian Great Lakes and marine coasts of Canada. Developing a DCCO cell line for in vitro toxicological screening will ideally provide improved understanding of the effects of environmental chemicals given the large differences in sensitivity between laboratory and wild avian species. In this study, an immortalized DCCO hepatic cell line, DCH22, was established from the liver of a day 22 female embryo as a potential alternative to primary DCCO embryonic hepatocytes (DCEH) for chemical screening. DCH22 cells were cultured for over a year and have hepatocyte-like morphology. Exposure to 3,3',4,4',5-pentachlorobiphenyl (PCB-126), benzo-a-pyrene, ß-napthoflavone and phenacetin induced CYP1A activity and mRNA expression in DCH22 3D spheroids. Induction of CYP3A activity and mRNA expression was observed following exposure to hexabromocyclododecane (HBCD), tris(1,3-dichloroisopropyl)phosphate, carbamazepine, and metyrapone. The phase II metabolism gene, UGT1A1, was upregulated following HBCD exposure and DCH22 spheroids expressed vitellogenin protein after exposure to 17α-ethinylestradiol. Based on these data, the novel DCH22 cell line, cultured as 3D spheroids, has potential use as an alternative to DCEH for chemical screening and will permit the evaluation of avian species differences in sensitivity from an in vitro screening perspective.

Therapeutic drug monitoring of docetaxel administered for breast cancer in a patient receiving rifampicin and clarithromycin to treat nontuberculous mycobacteriosis: A case report

Docetaxel is metabolized by cytochrome P450 3A4 (CYP3A4), and is transported by organic anion transporting peptides (OATPs) and ABCB1, and its blood concentration is known to affect the risk of some docetaxel-related adverse drug reactions (ADRs). Thus, the concomitant use of docetaxel with drugs that inhibit or induce these transporters or CYP3A4 requires careful attention. A 58-year-old woman was receiving clarithromycin (400 mg twice daily), rifampicin (450 mg once daily) and ethambutol (500 mg once daily) for nontuberculous mycobacteriosis. The patient was diagnosed as having stage IV HER2-positive breast cancer, which was treated with a regimen of trastuzumab (8 mg/kg), pertuzumab (first dose: 840 mg; second dose onward: 420 mg) and docetaxel (75 mg/m2) every 3 weeks. To predict the risk of serious drug interactions with rifampicin and clarithromycin, the blood concentration of docetaxel was analyzed after administration of the first course. The docetaxel levels at 22 and 159 h after administration were 36.1 and 6.5 ng/ml, respectively, which were higher than previously reported data. In addition, the calculated elimination half-life of 55.7 h was ~3 times longer than previously reported data. Although the docetaxel level was high, the same dosage was used in subsequent courses because no serious ADRs were observed during the first course of therapy. After 4 months of chemotherapy, the patient received complete remission. In conclusion, concomitant use of rifampicin and clarithromycin may increase the blood concentration of docetaxel.

Building Confidence in Physiologically Based Pharmacokinetic Modeling of CYP3A Induction Mediated by Rifampin: An Industry Perspective

Physiologically-based pharmacokinetic (PBPK) modeling offers a viable approach to predict induction drug-drug interactions (DDIs) with the potential to streamline or reduce clinical trial burden if predictions can be made with sufficient confidence. In the current work, the ability to predict the effect of rifampin, a well-characterized strong CYP3A4 inducer, on 20 CYP3A probes with publicly available PBPK models (often developed using a workflow with optimization following a strong inhibitor DDI study to gain confidence in fraction metabolized by CYP3A4, fm,CYP3A4, and fraction available after intestinal metabolism, Fg), was assessed. Substrates with a range of fm,CYP3A4 (0.086-1.0), Fg (0.11-1.0) and hepatic availability (0.09-0.96) were included. Predictions were most often accurate for compounds that are not P-gp substrates or that are P-gp substrates but that have high permeability. Case studies for three challenging DDI predictions (i.e., for eliglustat, tofacitinib, and ribociclib) are presented. Along with parameter sensitivity analysis to understand key parameters impacting DDI simulations, alternative model structures should be considered, for example, a mechanistic absorption model instead of a first-order absorption model might be more appropriate for a P-gp substrate with low permeability. Any mechanisms pertinent to the CYP3A substrate that rifampin might impact (e.g., induction of other enzymes or P-gp) should be considered for inclusion in the model. PBPK modeling was shown to be an effective tool to predict induction DDIs with rifampin for CYP3A substrates with limited mechanistic complications, increasing confidence in the rifampin model. While this analysis focused on rifampin, the learnings may apply to other inducers.

The effect of carbamazepine, a strong CYP3A inducer, on the pharmacokinetics of zongertinib in healthy male volunteers

INTRODUCTION

Zongertinib (BI 1810631) is a potent, selective, and epidermal growth factor receptor (EGFR) wild-type sparing human epidermal growth factor receptor 2 (HER2) inhibitor. Based on in vitro data, the oxidative hepatic metabolism of zongertinib is principally driven by cytochrome P450 (CYP) 3A4/5. Therefore, zongertinib may be affected by strong CYP3A inducers, like carbamazepine.

OBJECTIVE

This study aimed to investigate the effect of multiple oral doses of carbamazepine on the pharmacokinetics of a single oral dose of zongertinib in healthy male subjects.

METHODS

This open-label, two-period, fixed-sequence clinical drug-drug interaction study examined the pharmacokinetics of a single 60-mg oral dose of zongertinib in the absence or presence of multiple oral doses of carbamazepine. The extent of drug-drug interaction was estimated using the adjusted geometric mean ratios (and 90% confidence intervals [CIs]) for the test treatment (zongertinib in the presence of carbamazepine) versus the reference treatment (zongertinib alone) for areas under the plasma concentration-time curve from time 0 to infinity and to the last quantifiable time point (AUC0-∞, AUC0-tz) and maximum measured plasma concentration (Cmax).

RESULTS

Sixteen subjects (all Caucasian males) received zongertinib alone in Study Period 1, and 15 of them received both zongertinib and carbamazepine in Study Period 2. Upon co-administration with carbamazepine in Study Period 2, AUC0-∞ and AUC0-tz of zongertinib were both reduced to 36.5% (90% CI: 32.0%-41.6% for AUC0-∞ and 31.9%-41.7% for AUC0-tz). The Cmax of zongertinib was reduced to 56.4% (90% CI: 45.1%-70.6%).

CONCLUSION

Zongertinib exposure was reduced by 63.5% when coadministered with the strong CYP3A inducer, carbamazepine.

Advanced 3D bioprinted liver models with human-induced hepatocytes for personalized toxicity screening

The development of advanced in vitro models for assessing liver toxicity and drug responses is crucial for personalized medicine and preclinical drug development. 3D bioprinting technology provides opportunities to create human liver models that are suitable for conducting high-throughput screening for liver toxicity. In this study, we fabricated a humanized liver model using human-induced hepatocytes (hiHeps) derived from human fibroblasts via a rapid and efficient reprogramming process. These hiHeps were then employed in 3D bioprinted liver models with bioink materials that closely mimic the natural extracellular matrix. The constructed humanized 3D bioprinted livers (h3DPLs) exhibited mature hepatocyte functions, including albumin expression, glycogen storage, and uptake/release of indocyanine green and acetylated low-density lipoprotein. Notably, h3DPLs demonstrated increased sensitivity to hepatotoxic agents such as acetaminophen (APAP), making them a promising platform for studying drug-induced liver injury. Furthermore, our model accurately reflected the impact of rifampin, a cytochrome P450 inducer, on CYP2E1 levels and APAP hepatotoxicity. These results highlight the potential of hiHep-based h3DPLs as a cost-effective and high-performance alternative for personalized liver toxicity screening and preclinical drug testing, paving the way for improved drug development strategies and personalized therapeutic interventions.

CYP3A4 and CYP3A5: the crucial roles in clinical drug metabolism and the significant implications of genetic polymorphisms

CYP3A, a key member of the cytochrome P450 (CYP450) superfamily, is integral to drug metabolism, processing a substantial portion of medications. Their role in drug metabolism is particularly prominent, as CYP3A4 and CYP3A5 metabolize approximately 30-50% of known drugs. The genetic polymorphism of CYP3A4/5 is significant inter-individual variability in enzymatic activity, which can result in different pharmacokinetic profiles in response to the same drug among individuals. These polymorphisms can lead to either increased drug toxicity or reduced therapeutic effects, requiring dosage adjustments based on genetic profiles. Consequently, the study of the enzymatic activity of CYP3A4/5 gene variants is of great importance for the formulation of personalized treatment regimens. This article first reviews the role of CYP3A4/5 in drug metabolism in the human body, including inhibitors and inducers of CYP3A4/5 and drug-drug interactions. In terms of genetic polymorphism, it discusses the detection methods, enzymatic kinetic characteristics, and clinical guidelines for CYP3A5. Finally, the article summarizes the importance of CYP3A4/5 in clinical applications, including personalized therapy, management of drug-drug interactions, and adjustment of drug doses. This review contributes to the understanding of the functions and genetic characteristics of CYP3A4/5, allowing for more effective clinical outcomes through optimized drug therapy.

Deconvoluting zavegepant drug-drug interactions: A phase I study to evaluate the effects of rifampin and itraconazole on zavegepant pharmacokinetics

Zavegepant is a calcitonin gene-related peptide receptor antagonist for acute migraine treatment. This Phase I, open-label, fixed-sequence study evaluated the effects of itraconazole (a strong cytochrome P450 3A4 [CYP3A4] and P-glycoprotein [P-gp] inhibitor) on the pharmacokinetics of intranasal/oral zavegepant and the effects of rifampin (a strong inducer of CYP3A4 and P-gp; and an inhibitor of organic anion transporting polypeptide 1B3 [OATP1B3]) on oral zavegepant in healthy participants. In the intranasal/oral zavegepant-itraconazole cohort, participants received a single 10-mg dose of zavegepant nasal spray on Day 1, followed by oral zavegepant (50 mg) on Day 3. Itraconazole 200 mg once daily was administered from Days 4 to 12. On Day 7 zavegepant nasal spray and on Day 11 oral zavegepant were coadministered with itraconazole. In the oral zavegepant-rifampin cohort, participants received oral zavegepant (100 mg) on Day 1, rifampin 600 mg once daily on Days 2-10, and rifampin with zavegepant on Day 11. No significant change in zavegepant exposure was observed following coadministration of itraconazole with zavegepant nasal spray. For oral zavegepant coadministered with itraconazole, the area under the curve from 0 to infinity (AUC0-inf) and the maximum observed concentration (Cmax) of oral zavegepant increased by 59% and 77%, respectively. For oral zavegepant coadministered with rifampin, the AUC0-inf and Cmax of oral zavegepant increased by approximately 2.3- and 2.2-fold, respectively. These results suggest that OATP1B3 and intestinal P-gp are the more prominent pathways, as opposed to CYP3A4, for a zavegepant drug-drug interaction. Coadministration of OATP1B3 inhibitors with zavegepant nasal spray should be avoided.

Identification of a Safe and Tolerable Carbamazepine Dosing Paradigm that Facilitates Effective Evaluation of CYP3A4 Induction

Carbamazepine (CBZ) is the recommended alternative to rifampicin as a CYP3A4 inducer in drug-drug interaction studies. However, the traditional CBZ dosing paradigm can lead to several adverse events (AEs). This study tested a shorter CBZ dosing regimen using the CYP3A4-sensitive index substrate midazolam (MDZ). This was a fixed-sequence arm of an open-label, phase I study (NCT04840888). Healthy participants (n = 15) aged 18-63 years received oral doses of 1.2 mg MDZ alone (Day 1), CBZ b.i.d. alone (100 mg Days 2-4; 200 mg Days 5-7; 300 mg Days 8-10 and 12-13), and 300 mg CBZ b.i.d. plus 1.2 mg MDZ (Days 11 and 14). One participant (6.7%) experienced constipation due to treatment with CBZ plus MDZ on Day 11. One participant (6.7%) experienced urticaria (Days 12-13), and two participants (13.3%) experienced somnolence (Days 8-10) due to treatment with 300 mg CBZ b.i.d. alone. All AEs were mild. For MDZ, the geometric mean (90% CI) ratio (vs. Day 1) of the area under the curve (AUC 0-∞) was 0.28 (0.24-0.31) on Day 11 and 0.26 (0.23-0.29) on Day 14. The AUC (0-12 hours) of CBZ was 114,000 ng∙h/mL on Day 11 and 105,000 ng∙h/mL on Day 14. Steady-state concentrations of CBZ and induction of CYP3A4 were achieved on Day 11. The data are consistent with predictions of physiologically-based pharmacokinetic models in Simcyp. The 9-day dosing regimen for CBZ induction was well-tolerated by healthy participants, supporting the use of a shorter CBZ regimen for CYP3A4 induction studies.

Applying Physiologically Based Pharmacokinetic Modeling to Interpret Carbamazepine's Nonlinear Pharmacokinetics and Its Induction Potential on Cytochrome P450 3A4 and Cytochrome P450 2C9 Enzymes

Carbamazepine (CBZ) is commonly prescribed for epilepsy and frequently used in polypharmacy. However, concerns arise regarding its ability to induce the metabolism of other drugs, including itself, potentially leading to the undertreatment of co-administered drugs. Additionally, CBZ exhibits nonlinear pharmacokinetics (PK), but the root causes have not been fully studied. This study aims to investigate the mechanisms behind CBZ's nonlinear PK and its induction potential on CYP3A4 and CYP2C9 enzymes. To achieve this, we developed and validated a physiologically based pharmacokinetic (PBPK) parent-metabolite model of CBZ and its active metabolite Carbamazepine-10,11-epoxide in GastroPlus®. The model was utilized for Drug-Drug Interaction (DDI) prediction with CYP3A4 and CYP2C9 victim drugs and to further explore the underlying mechanisms behind CBZ's nonlinear PK. The model accurately recapitulated CBZ plasma PK. Good DDI performance was demonstrated by the prediction of CBZ DDIs with quinidine, dolutegravir, phenytoin, and tolbutamide; however, with midazolam, the predicted/observed DDI AUClast ratio was 0.49 (slightly outside of the two-fold range). CBZ's nonlinear PK can be attributed to its nonlinear metabolism caused by autoinduction, as well as nonlinear absorption due to poor solubility. In further applications, the model can help understand DDI potential when CBZ serves as a CYP3A4 and CYP2C9 inducer.

Physiologically-based pharmacokinetic modeling of prominent oral contraceptive agents and applications in drug-drug interactions

Considerable interest remains across the pharmaceutical industry and regulatory landscape in capabilities to model oral contraceptives (OCs), whether combined (COCs) with ethinyl estradiol (EE) or progestin-only pill. Acceptance of COC drug-drug interaction (DDI) assessment using physiologically-based pharmacokinetic (PBPK) is often limited to the estrogen component (EE), requiring further verification, with extrapolation from EE to progestins discouraged. There is a paucity of published progestin component PBPK models to support the regulatory DDI guidance for industry to evaluate a new chemical entity's (NCE's) DDI potential with COCs. Guidance recommends a clinical interaction study to be considered if an investigational drug is a weak or moderate inducer, or a moderate/strong inhibitor, of CYP3A4. Therefore, availability of validated OC PBPK models within one software platform, will be useful in predicting the DDI potential with NCEs earlier in the clinical development. Thus, this work was focused on developing and validating PBPK models for progestins, DNG, DRSP, LNG, and NET, within Simcyp, and assessing the DDI potential with known CYP3A4 inhibitors (e.g., ketoconazole) and inducers (e.g., rifampicin) with published clinical data. In addition, this work demonstrated confidence in the Simcyp EE model for regulatory and clinical applications by extensive verification in 70+ clinical PK and CYP3A4 interaction studies. The results provide greater capability to prospectively model clinical CYP3A4 DDI with COCs using Simcyp PBPK to interrogate the regulatory decision-tree to contextualize the potential interaction by known perpetrators and NCEs, enabling model-informed decision making, clinical study designs, and delivering potential alternative COC options for women of childbearing potential.

Comprehensive Physiologically Based Pharmacokinetic Model to Assess Drug-Drug Interactions of Phenytoin

Regulatory agencies worldwide expect that clinical pharmacokinetic drug-drug interactions (DDIs) between an investigational new drug and other drugs should be conducted during drug development as part of an adequate assessment of the drug's safety and efficacy. However, it is neither time nor cost efficient to test all possible DDI scenarios clinically. Phenytoin is classified by the Food and Drug Administration as a strong clinical index inducer of CYP3A4, and a moderate sensitive substrate of CYP2C9. A physiologically based pharmacokinetic (PBPK) platform model was developed using GastroPlus® to assess DDIs with phenytoin acting as the victim (CYP2C9, CYP2C19) or perpetrator (CYP3A4). Pharmacokinetic data were obtained from 15 different studies in healthy subjects. The PBPK model of phenytoin explains the contribution of CYP2C9 and CYP2C19 to the formation of 5-(4'-hydroxyphenyl)-5-phenylhydantoin. Furthermore, it accurately recapitulated phenytoin exposure after single and multiple intravenous and oral doses/formulations ranging from 248 to 900 mg, the dose-dependent nonlinearity and the magnitude of the effect of food on phenytoin pharmacokinetics. Once developed and verified, the model was used to characterize and predict phenytoin DDIs with fluconazole, omeprazole and itraconazole, i.e., simulated/observed DDI AUC ratio ranging from 0.89 to 1.25. This study supports the utility of the PBPK approach in informing drug development.

The Impact of N-nitrosamine Impurities on Clinical Drug Development

Over the past few years, an increasing number of commercially available drugs have been reported to contain N-nitrosamine impurities above acceptable intake limits. Consequent interruption or discontinuation of the manufacturing and distribution of several marketed drugs has culminated into shortages of marketed drugs, including the antidiabetic drug metformin and the potentially life-saving drug rifampin for the treatment of tuberculosis. Alarmingly, the clinical development of new investigational products has been complicated as well by the presence of N-nitrosamine impurities in batches of marketed drug. In particular, rifampin is a key clinical index drug employed in drug-drug interaction (DDI) studies, and as a result of nitrosamine impurities regulatory bodies no longer accept the administration of rifampin in DDI studies involving healthy subjects. Drug developers are now forced to look at alternative approaches for commonly employed perpetrators, which will be discussed in this review.