Pharmacokinetic interaction of riociguat with ketoconazole, clarithromycin, and midazolam

Quantitative Translation of Substrate Intrinsic Clearance from Recombinant CYP1A1 to Humans

CYP1A1 is a cytochrome P450 family 1 enzyme that is mostly expressed in the extrahepatic tissues. To understand the CYP1A1 contribution to drug clearance in humans, we examined the in vitro-in vivo extrapolation (IVIVE) of intrinsic clearance (CLint) for a set of drugs that are in vitro CYP1A1 substrates. Despite being strong in vitro CYP1A1 substrates, 82% of drugs gave good IVIVE with predicted CLint within 2-3-fold of the observed values using human liver microsomes and hepatocytes, suggesting they were not in vivo CYP1A1 substrates due to the lack of extrahepatic contribution to CLint. Only three drugs (riluzole, melatonin and ramelteon) that are CYP1A2 substrates yielded significant underprediction of in vivo CLint up to 11-fold. The fold of CLint underprediction was linearly proportional to human recombinant CYP1A1 (rCYP1A1) CLint, indicating they were likely to be in vivo CYP1A1 substrates. Using these three substrates, a calibration curve can be developed to enable direct translation from in vitro rCYP1A1 CLint to in vivo extrahepatic contributions in humans. In vivo CYP1A1 substrates are planar and small, which is consistent with the structure of the active site. This is in contrast to the in vitro substrates, which include large and nonplanar molecules, suggesting rCYP1A1 is more accessible than what is in vivo. The impact of CYP1A1 on first-pass intestinal metabolism was also evaluated and shown to be minimal. This is the first study providing new insights on in vivo translation of CYP1A1 contributions to human clearance using in vitro rCYP1A1 data.

Drug Interactions Associated With Therapies for Pulmonary Arterial Hypertension

Objective: To evaluate the potential for drug interactions with therapies for pulmonary arterial hypertension (PAH). Treatments include calcium channel blockers, phosphodiesterase type 5 inhibitors, endothelin receptor antagonists, guanylate cyclase stimulators, prostacyclin analogues, and prostacyclin receptor agonists. Data Sources: A systemic literature search (January 1980-December 2021) was performed using PubMed and EBSCO to locate relevant articles. The mesh terms used included each specific medication available as well as "drug interactions." DAILYMED was used for product-specific drug interactions. Study Selection and Data Extraction: The search was conducted to identify drug interactions with PAH treatments. The search was limited to those articles studying human applications with PAH treatments and publications using the English language. Case reports, clinical trials, review articles, treatment guidelines, and package labeling were selected for inclusion. Data Synthesis: Primary literature and package labeling indicate that PAH treatments are subject to pharmacokinetic and pharmacodynamic interactions. The management of PAH is rapidly evolving. As more and more evidence becomes available for the use of combination therapy in PAH, the increasing use of combination therapy increases the risk of drug-drug interactions. Pulmonary arterial hypertension is also associated with other comorbidities that require concomitant pharmacotherapy. Conclusion: The available literature indicates that PAH therapies are associated with clinically significant drug interactions and the potential for subsequent adverse reactions. Clinicians in all practice settings should be mindful that increased awareness of drug interactions with PAH therapy will ensure optimal management and patient safety.

Evaluating Riociguat in the Treatment of Pulmonary Arterial Hypertension: A Real-World Perspective

Pulmonary hypertension (PH) is a broad term describing the mean pulmonary artery pressure, as measured by right heart catheterization, exceeds 20mmHg. Pulmonary arterial hypertension (PAH) exists when PH is accompanied by a normal wedge pressure and elevated pulmonary vascular resistance. PAH is typified by dysmorphic and dysfunctional pulmonary arterial vasculature. Attempting to restore the functionality of the pulmonary artery is a hallmark of care to the PAH patient. Riociguat is a powerful stimulator of soluble guanylate cyclase and increases blood flow through the pulmonary arteries by dilating vascular smooth muscle cells. This review examines the pharmacology of riociguat, the fundamental clinical trials applying it to PAH patients, practical aspects when selecting its use, and future directions for its utilization.

Effect of Macitentan on the Pharmacokinetics of the Breast Cancer Resistance Protein Substrates, Rosuvastatin and Riociguat, in Healthy Male Subjects

Background

Macitentan is a clinically approved endothelin receptor antagonist for the treatment of pulmonary arterial hypertension (PAH). Increasing use of combination drug therapy in PAH means that it is important to recognize potential drug–drug interactions (DDIs) that could affect the efficacy and safety of macitentan in patients with PAH.

Objective

Two Phase 1 studies were conducted to investigate the effect of macitentan at steady-state on the pharmacokinetics of the breast cancer resistance protein (BCRP) substrates, rosuvastatin and riociguat in healthy male subjects. Another objective was to determine the safety and tolerability of concomitant administration of rosuvastatin or riociguat with macitentan.

Methods

Healthy male subjects received a single oral dose of rosuvastatin 10 mg (n = 20) or riociguat 1 mg (n = 20) on Day 1 (reference treatment). A loading oral dose of macitentan 30 mg was administered on Day 5 followed by macitentan 10 mg once-daily from Day 6 to Day 15 (riociguat study) or Day 6 to Day 16 (rosuvastatin study). A concomitant oral dose of rosuvastatin 10 mg or riociguat 1 mg was administered on Day 10 (test treatment). Pharmacokinetics were evaluated for 96 h after treatment on Day 1 and for 144 h (riociguat study) or 168 h (rosuvastatin study) after treatment on Day 10. To compare the reference and test treatments, the geometric mean ratio was calculated for the maximum plasma concentration (C_max), the area under the plasma concentration-time curve (AUC) from zero (pre-dose) to time of the last measured concentration above the limit of quantification (AUC_0–t), the AUC from zero to infinity (AUC_0–∞) and the terminal elimination half-life (t_½) of rosuvastatin, riociguat and riociguat’s metabolite, M1. The difference in the time to reach maximum plasma concentration (t_max) was determined by the Wilcoxon test. Trough levels of macitentan and its metabolite, ACT-132577, were measured and safety was monitored throughout.

Results

Ninety percent confidence intervals of the geometric mean ratios were within the bioequivalence criteria of 0.80–1.25. There was no significant difference between test and reference t_max. Rosuvastatin or riociguat did not affect the steady-state concentrations of macitentan and ACT-132577. The adverse event profile was consistent with the known safety profiles of the drugs.

Conclusions

Macitentan 10 mg did not affect the pharmacokinetics of BCRP substrates, rosuvastatin or riociguat in healthy male subjects.

EudraCT numbers: 2017–003095–31 and 2017–003502–41.

In vitro-in vivo correlation of the drug-drug interaction potential of antiretroviral HIV treatment regimens on CYP1A1 substrate riociguat

Objectives: Riociguat is a soluble guanylate cyclase stimulator licensed for the treatment of pulmonary arterial hypertension (PAH), a potentially fatal complication of human immunodeficiency virus infection. This study investigated the inhibitory potency of selected antiretroviral regimens on the metabolic clearance of riociguat.Methods: The inhibitory potential of the components of six antiretroviral combinations (ATRIPLA® (efavirenz/emtricitabine/tenofovir disoproxil), COMPLERA® (rilpivirine/emtricitabine/tenofovir disoproxil), STRIBILD® (elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil), TRIUMEQ® (abacavir/dolutegravir/lamivudine), and two ritonavir-boosted regimens) on riociguat metabolism were evaluated in recombinant human CYP1A1 and CYP3A4 as well as in human hepatocytes exhibiting both CYP1A1 and CYP3A4 activity. In vitro-in vivo correlation was performed between calculated and observed increases in riociguat exposure in vivo.Results: Using both in vitro systems, the predicted increase in exposure of riociguat was highest with components of TRIUMEQ® followed by COMPLERA®, ATRIPLA®, STRIBILD®, and the ritonavir-boosted regimens. Further experiments in human hepatocytes confirmed CYP1A1 to be the predominant enzyme in the metabolic clearance of riociguat.Conclusion: Antiretroviral treatment containing the potent CYP1A1 inhibitor abacavir had the greatest impact on riociguat metabolic clearance. The impact of comedications containing only strong CYP3A4 inhibitors e.g. ritonavir was less pronounced, suggesting a benefit of riociguat over PAH-targeting medications with contraindications for use with strong CYP3A4 inhibitors.

Clinical Pharmacokinetic and Pharmacodynamic Profile of Riociguat

Oral riociguat is a soluble guanylate cyclase (sGC) stimulator that targets the nitric oxide (NO)–sGC–cyclic guanosine monophosphate pathway with a dual mode of action: directly by stimulating sGC, and indirectly by increasing the sensitivity of sGC to NO. It is rapidly absorbed, displays almost complete bioavailability (94.3%), and can be taken with or without food and as crushed or whole tablets. Riociguat exposure shows pronounced interindividual (60%) and low intraindividual (30%) variability in patients with pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH), and is therefore administered using an individual dose-adjustment scheme at treatment initiation. The half-life of riociguat is approximately 12 h in patients and approximately 7 h in healthy individuals. Riociguat and its metabolites are excreted via both renal (33–45%) and biliary routes (48–59%), and dose adjustment should be performed with particular care in patients with moderate hepatic impairment or mild to severe renal impairment (no data exist for patients with severe hepatic impairment). The pharmacodynamic effects of riociguat reflect the action of a vasodilatory agent, and the hemodynamic response to riociguat correlated with riociguat exposure in patients with PAH or CTEPH in phase III population pharmacokinetic/pharmacodynamic analyses. Riociguat has a low risk of clinically relevant drug interactions due to its clearance by multiple cytochrome P450 (CYP) enzymes and its lack of effect on major CYP isoforms and transporter proteins at therapeutic levels. Riociguat has been approved for the treatment of PAH and CTEPH that is inoperable or persistent/recurrent after surgical treatment.

Pharmacokinetic interaction of riociguat and antiretroviral combination regimens in HIV-1-infected adults

Riociguat, a first-in-class soluble guanylate cyclase stimulator, is approved for the treatment of pulmonary arterial hypertension (PAH), a serious potential complication of human immunodeficiency virus (HIV) infection. This open-label study investigated the pharmacokinetic drug–drug interaction potential of antiretroviral therapies on riociguat exposure in HIV-infected adults. HIV-infected adults without PAH on stable antiretroviral regimens (efavirenz/emtricitabine/tenofovir disoproxil, emtricitabine/rilpivirine/tenofovir disoproxil, elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil, abacavir/dolutegravir/lamivudine, or a ritonavir-boosted triple regimen) for ≥ 6 weeks received a single riociguat dose (0.5 mg). Riociguat pharmacokinetics and safety were assessed; pharmacokinetics was compared with historical healthy volunteer data. Of 41 participants treated (n = 8 in each arm, except n = 9 in the ritonavir-boosted triple regimen arm), 40 were included in the pharmacokinetic analyses. Riociguat median t_max was 1.00–1.27 h, with comparable maximum concentration (C_max) across the five background antiretroviral groups. Riociguat exposure was highest with abacavir/dolutegravir/lamivudine, followed by elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil > emtricitabine/rilpivirine/tenofovir disoproxil > ritonavir-boosted triple regimen > efavirenz/emtricitabine/tenofovir disoproxil; riociguat area under the plasma concentration versus time curve (AUC) was approximately threefold higher with abacavir/dolutegravir/lamivudine than efavirenz/emtricitabine/tenofovir disoproxil. Compared with historical data, riociguat exposure in HIV-infected adults was similar when co-administered with efavirenz/emtricitabine/tenofovir disoproxil, slightly increased when administered with ritonavir-boosted triple regimen and increased by approximately threefold when administered with abacavir/dolutegravir/lamivudine. Riociguat was well tolerated, with no new safety findings. Riociguat was well tolerated in adults with HIV on stable background antiretroviral therapy although an apparent increase in AUC of riociguat was observed in patients receiving abacavir/dolutegravir/lamivudine. Patients should be monitored closely during riociguat initiation and dose adjustment for signs and symptoms of hypotension.

Practical management of riociguat in patients with pulmonary arterial hypertension

Riociguat is one of several approved therapies available for patients with pulmonary arterial hypertension (PAH). Treatment should be initiated and monitored at an expert center by a physician experienced in treating PAH, and the dose adjusted in the absence of signs and symptoms of hypotension. In certain populations, including patients with hepatic or renal impairment, the elderly, and smokers, riociguat exposure may differ, and dose adjustments should therefore be made with caution according to the established scheme. Common adverse events are often easily managed, particularly if they are discussed before starting therapy. Combination therapy with riociguat and other PAH-targeted agents is feasible and generally well tolerated, although the coadministration of phosphodiesterase type 5 inhibitors (PDE5i) and riociguat is contraindicated. An open-label, randomized study is currently ongoing to assess whether patients who do not achieve treatment goals while receiving PDE5i may benefit from switching to riociguat. In this review, we provide a clinical view on the practical management of patients with PAH receiving riociguat, with a focus on the opinions and personal experience of the authors. The reviews of this paper are available via the supplemental material section.

Pharmacokinetics of antifungal drugs: practical implications for optimized treatment of patients

Introduction

Because of the high mortality of invasive fungal infections (IFIs), appropriate exposure to antifungals appears to be crucial for therapeutic efficacy and safety.

Materials and methods

This review summarises published pharmacokinetic data on systemically administered antifungals focusing on co-morbidities, target-site penetration, and combination antifungal therapy.

Conclusions and discussion

Amphotericin B is eliminated unchanged via urine and faeces. Flucytosine and fluconazole display low protein binding and are eliminated by the kidney. Itraconazole, voriconazole, posaconazole and isavuconazole are metabolised in the liver. Azoles are substrates and inhibitors of cytochrome P450 (CYP) isoenzymes and are therefore involved in numerous drug–drug interactions. Anidulafungin is spontaneously degraded in the plasma. Caspofungin and micafungin undergo enzymatic metabolism in the liver, which is independent of CYP. Although several drug–drug interactions occur during caspofungin and micafungin treatment, echinocandins display a lower potential for drug–drug interactions. Flucytosine and azoles penetrate into most of relevant tissues. Amphotericin B accumulates in the liver and in the spleen. Its concentrations in lung and kidney are intermediate and relatively low myocardium and brain. Tissue distribution of echinocandins is similar to that of amphotericin. Combination antifungal therapy is established for cryptococcosis but controversial in other IFIs such as invasive aspergillosis and mucormycosis.

Discovery of the Soluble Guanylate Cyclase Stimulator Vericiguat (BAY 1021189) for the Treatment of Chronic Heart Failure

The first-in-class soluble guanylate cyclase (sGC) stimulator riociguat was recently introduced as a novel treatment option for pulmonary hypertension. Despite its outstanding pharmacological profile, application of riociguat in other cardiovascular indications is limited by its short half-life, necessitating a three times daily dosing regimen. In our efforts to further optimize the compound class, we have uncovered interesting structure-activity relationships and were able to decrease oxidative metabolism significantly. These studies resulting in the discovery of once daily sGC stimulator vericiguat (compound 24, BAY 1021189), currently in phase 3 trials for chronic heart failure, are now reported.

Assessment of the effects of hepatic impairment and smoking on the pharmacokinetics of a single oral dose of the soluble guanylate cyclase stimulator riociguat (BAY 63-2521)

Riociguat, a soluble guanylate cyclase stimulator developed for the treatment of pulmonary hypertension, is metabolized in part by the liver. Expression of one of the metabolizing enzymes, CYP1A1, is induced by aromatic hydrocarbons in tobacco smoke. Two nonrandomized, nonblinded studies were conducted to investigate the pharmacokinetics of riociguat in individuals with mild (Child-Pugh A) or moderate (Child-Pugh B) hepatic impairment associated with liver cirrhosis compared with that in age-, weight-, and sex-matched healthy controls: study 1 included smokers and nonsmokers, and study 2 included nonsmokers only. Data from these studies were integrated for analysis. All participants (N = 64) received a single oral dose of riociguat 1.0 mg. Riociguat exposure was significantly higher in individuals with Child-Pugh B hepatic impairment than in healthy controls (ratio: 153% [90% confidence interval: 103%-228%]) but was similar in those with Child-Pugh A hepatic impairment and controls. The half-life of the riociguat metabolite M1 was prolonged in patients with Child-Pugh B or A hepatic impairment compared with that in controls by approximately 43% and 24%, respectively. Impaired hepatic function was associated with higher riociguat exposure in nonsmokers compared with the population of smokers and nonsmokers combined. Riociguat's safety profile was similar in individuals with impaired or normal liver function. In conclusion, moderate hepatic impairment was associated with increased riociguat exposure compared with that in controls, probably as a result of reduced clearance of the metabolite M1. This suggests that dose titration of riociguat should be administered with particular care in patients with moderate hepatic impairment.