Direct-acting antiviral interactions with opioids, alcohol or illicit drugs of abuse in HCV-infected patients

Reported adverse events related to use of hepatitis C virus direct-acting antivirals with opioids: 2017-2021

INTRODUCTION

Due to concerns over potential interactions between some hepatitis C direct-acting antivirals (DAAs) and opioids, we describe adverse event (AE) reports of concomitant use of opioids and DAAs.

METHODS

AEs reported (July 28, 2017-December 31, 2021) with the administration of the DAAs glecaprevir/pibrentasvir, sofosbuvir/velpatasvir, ledipasvir/sofosbuvir, sofosbuvir/velpatasvir/voxilaprevir, and elbasvir/grazoprevir as suspect products were downloaded from the US Food and Drug Administration AE Reporting System Public Dashboard. The number of AE reports containing opioids (fentanyl, hydrocodone, oxycodone) as co-suspect products/concomitant products were counted and summarized by severity, reporting country and whether an outcome of death was reported. Overdose AEs were counted irrespective of opioid use, and changes over time were assessed.

RESULTS

In total, 40 AEs were reported for DAAs and concomitant fentanyl use, 25 (62.5%) were in the USA, 35 (87.5%) were considered serious, and 14 (35.0%) resulted in death; and 626 were reported with concomitant oxycodone/hydrocodone use, 596 (95.2%) were in the USA, 296 (47.3%) were considered serious, and 28 (4.5%) resulted in death. There were 196 overdose AEs (32 [16%] deaths) declining from 2018 (N = 56) to 2021 (N = 29).

CONCLUSIONS

Treating people with hepatitis C virus (HCV) infection who use drugs is key to achieving HCV elimination. Low numbers of DAA AE reports with opioids may provide reassurance to prioritize HCV treatment in this population. These data contribute to evidence supporting the continued scale-up of DAA treatment among people who use drugs to achieve HCV elimination goals.

Assessment of Drug-Drug Interaction Risk Between Intravenous Fentanyl and the Glecaprevir/Pibrentasvir Combination Regimen in Hepatitis C Patients Using Physiologically Based Pharmacokinetic Modeling and Simulations

INTRODUCTION

An unsafe injection practice is one of the major contributors to new hepatitis C virus (HCV) infections; thus, people who inject drugs are a key population to prioritize to achieve HCV elimination. The introduction of highly effective and well-tolerated pangenotypic direct-acting antivirals, including glecaprevir/pibrentasvir (GLE/PIB), has revolutionized the HCV treatment landscape. Glecaprevir is a weak cytochrome P450 3A4 (CYP3A4) inhibitor, so there is the potential for drug-drug interactions (DDIs) with some opioids metabolized by CYP3A4, such as fentanyl. This study estimated the impact of GLE/PIB on the pharmacokinetics of intravenous fentanyl by building a physiologically based pharmacokinetic (PBPK) model.

METHODS

A PBPK model was developed for intravenous fentanyl by incorporating published information on fentanyl metabolism, distribution, and elimination in healthy individuals. Three clinical DDI studies were used to verify DDIs within the fentanyl PBPK model. This model was integrated with a previously developed GLE/PIB PBPK model. After model validation, DDI simulations were conducted by coadministering GLE 300 mg + PIB 120 mg with a single dose of intravenous fentanyl (0.5 µg/kg).

RESULTS

The predicted maximum plasma concentration ratio between GLE/PIB + fentanyl and fentanyl alone was 1.00, and the predicted area under the curve ratio was 1.04, suggesting an increase of only 4% in fentanyl exposure.

CONCLUSION

The administration of a therapeutic dose of GLE/PIB has very little effect on the pharmacokinetics of intravenous fentanyl. This negligible increase would not be expected to increase the risk of fentanyl overdose beyond the inherent risks related to the amount and purity of the fentanyl received during recreational use.

Safety and effectiveness of 8 weeks of Glecaprevir/Pibrentasvir in challenging HCV patients: Italian data from the CREST study

INTRODUCTION

Glecaprevir/pibrentasvir (G/P) has demonstrated high rates (>95%) of sustained virologic response at posttreatment Week 12 (SVR12) in treatment-naïve (TN) patients with hepatitis C virus (HCV) infection and compensated cirrhosis (CC). Here, in a key real-world subset of TN Italian patients with CC, we evaluated the effectiveness and safety of 8-week G/P treatment, including subgroups of interest such as those with genotype 3 (GT3) infection, elderly patients, and those with more advanced liver disease.

METHODS

Subanalysis of Italian patients enrolled in the CREST study. The full analysis set (FAS) included all patients enrolled in the study; the modified analysis set (MAS) excluded patients who discontinued G/P for nonvirologic failure or who had missing SVR12 results. Primary and secondary endpoints included SVR12 and safety, respectively.

RESULTS

Of 42 patients included in the FAS, 1 discontinued for unknown reasons, and 2 had missing SVR12 data, leaving 39 patients included in the MAS. At treatment initiation, 74% of patients had ≥1 comorbidity, and 62% were receiving concomitant medications, including some that may potentially interact with G/P. SVR12 was achieved in 100% of patients in the MAS, and in 95% in the FAS. In subgroups of interest, the proportion of patients achieving SVR12 in the MAS (and FAS) was: 100% (94%) for patients ≥65 years, 100% (86%) for GT3, and 100% (100%) for patients with platelet count <150 × 109/L and FibroScan® >20 kPa. Overall, 2 (5%) patients had an adverse event and neither were serious.

CONCLUSION

Results from this real-world Italian cohort demonstrated the safety and effectiveness of 8-week G/P, with SVR12 rate >95%, even in elderly patients. These findings further support real-world evidence of the use of short-course G/P treatment in all patients with CC, including those with GT3, and those with advanced liver disease.

Efficacy of a comprehensive strategy for the detection and treatment of hepatitis C infection in a population attending addiction centers

Background and aims

The burden hepatitis C infection in people with history or current drug use suppose a high risk of hepatic complications and transmission infectious disease. This population is poor linked to heath system and is difficult to achieve them and support treatment because they have high rates of lost follow-up. Our aim was to evaluate an intervention for the diagnosis and treatment of chronic hepatitis C and HIV in this population.

Methods

Six-hundred and eighty-three people attended in Drugs and Addictions Centers (DAC) were asked to participate in health counseling and provide blood sample for test HCV, HIV, and syphilis from April 2019 to June 2020. Totally 556 subjects were surveyed and tested. All of them were assigned to a patient navigation program to improve health education and linking to the sanitary system. Hepatitis C infection patients were evaluated in an ampliated medical consult to evaluate hepatic stage with transient liver elastography and initiated Direct Acting Antivirals to achieve Sustained Viral Response.

Results

Of the 556 patients who agreed to participate in the study, 33 (5.9%) had active HCV infection. Of the 33 patients infected with HCV, three were lost to follow-up once the diagnosis of HCV infection was made. Twenty-eight patients (93.3%) completed treatment and 26 achieved Sustained Viral Response (78.8%). Of the 30 patients, seven (23.3%) had advanced fibrosis, and of these, four (16.6%) had liver cirrhosis. One of the cirrhotic patients had hepatic space-occupying lesions at the baseline evaluation and was diagnosed with hepatocarcinoma.

Conclusions

Our study suggests that the implementation of strategies based on personalized intervention models can contribute to the control of HCV infection in DAC users.

Sofosbuvir/velpatasvir/voxilaprevir for patients with chronic hepatitis C virus infection previously treated with NS5A direct-acting antivirals: a real-world multicenter cohort in Taiwan

BACKGROUND

Real-world data are scarce about the effectiveness and safety of sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) for retreating East Asian patients with hepatitis C virus (HCV) infection who previously received NS5A direct-acting antivirals (DAAs). We conducted a multicenter study to assess the performance of SOF/VEL/VOX in patients who were not responsive to prior NS5A inhibitors in Taiwan.

METHODS

Between September 2021 and May 2022, 107 patients who failed NS5A inhibitor-containing DAAs with SOF/VEL/VOX salvage therapy for 12 weeks were included at 16 academic centers. The sustained virologic response at off-treatment week 12 (SVR₁₂) was assessed in the evaluable (EP) and per-protocol (PP) populations. The safety profiles were also reported.

RESULTS

All patients completed 12 weeks of treatment and achieved an end-of-treatment virologic response. The SVR₁₂ rates were 97.2% (95% confidence interval (CI) 92.1-99.0%) and 100% (95% CI 96.4-100%) in EP and PP populations. Three (2.8%) patients were lost to off-treatment follow-up and did not meet SVR₁₂ in the EP population. No baseline factors predicted SVR₁₂. Two (1.9%) not-fatal serious adverse events (AE) occurred but were unrelated to SOF/VEL/VOX. Sixteen (15.0%) had grade 2 total bilirubin elevation, and three (2.8%) had grade 2 alanine transaminase (ALT) elevation. Thirteen (81.3%) of the 16 patients with grade 2 total bilirubin elevation had unconjugated hyperbilirubinemia. The estimated glomerular filtration rates (eGFR) were comparable between baseline and SVR₁₂, regardless of baseline renal reserve.

CONCLUSIONS

SOF/VEL/VOX is highly efficacious and well-tolerated for East Asian HCV patients previously treated with NS5A inhibitor-containing DAAs.

CLINICAL TRIALS REGISTRATION

The study was not a drug trial. There was no need for clinical trial registration.

Effect of alcohol exposure on the efficacy and safety of tenofovir alafenamide fumarate, a major medicine against human immunodeficiency virus

Human immunodeficiency virus (HIV) continues to be a major health concern. AIDS-related deaths (acquired immunodeficiency syndrome) have decreased recently, but chronic liver disease is now a major cause of mortality among HIV patients. Widespread alcohol use is recognized to be a major contributing factor. Tenofovir alafenamide fumarate (TAF), one of the most used HIV drugs, requires hydrolysis followed by phosphorylation to produce tenofovir diphosphate, the ultimate anti-HIV metabolite. Carboxylesterase-1 (CES1), established to hydrolyze TAF, is known to catalyze transesterification in the presence of ethanol. The aim of the study was to test the hypothesis that metabolism-based interactions between TAF and ethanol negatively impact both efficacy and safety of TAF. To test this hypothesis, the metabolism of TAF was determined in human primary hepatocytes and with a large number of human liver samples (S9 fractions) in the presence or absence of ethanol. The metabolism was monitored by LC-MS/MS (liquid chromatography with tandem mass spectrometry) and the level of CES1 or CES2 was determined by Western blotting. Consistent with the hypothesis, TAF underwent transesterification in the presence of ethanol accompanied by decreased hydrolysis. The formation of tenofovir diphosphate (the therapeutically active metabolite) was significantly decreased. In addition, TAF but not its hydrolytic metabolite, was found to increase intracellular lipid retention, and the increase was enhanced by ethanol. These findings conclude that alcohol consumption, beyond commonly accepted poor adherence to HIV medications, directly impacts the efficacy and safety of TAF.

Association of Referral Source and Substance Use with Hepatitis C Virus Outcomes at a Southern Academic Medical Center

OBJECTIVES

Therapeutic advances make the cure of chronic hepatitis C virus (HCV) infection achievable for individuals aware of their diagnosis who can access care. Identifying barriers to accessing care is critical to achieve population-level HCV elimination and improve the cascade of care from diagnosis to cure.

METHODS

To identify barriers to HCV care, we performed a retrospective observational analysis of outcomes for patients with chronic HCV referred to an infectious diseases clinic at an academic medical center in Charleston, South Carolina between January 1, 2015 and January 1, 2020. We categorized outcomes in the cascade of care between "never presenting for evaluation" and "completed treatment with documented cure." Patient demographic factors, referral source, ZIP code of residence, insurance status, clinical characteristics, antiviral regimen, psychiatric and substance use history, and route of infection were assessed for associations with care outcomes.

RESULTS

Of 407 referrals, 32% of patients never presented for an initial evaluation, an outcome that was associated with active substance use, mental health disease, and referral from an emergency department or obstetrics-gynecology provider. Of the patients who presented for an initial evaluation, 78% of patients initiated treatment. Active substance use was the only variable associated with lack of therapy initiation after presenting for an initial evaluation (odds ratio 2.5, 95% confidence interval 1.07-5.84). Once treatment had been initiated, no clinical or demographic variables were associated with odds of achieving documented or presumed HCV cure.

CONCLUSIONS

Active substance use, mental health disease, and referral from an emergency department or obstetrics-gynecology provider were associated with a lower odds of presenting for evaluation and initiation of HCV treatment. Innovative models to improve access to care and increase outreach to vulnerable populations will be essential to eliminate HCV.

Alcohol Consumption and Risk of Liver Fibrosis in People Living With HIV: A Systematic Review and Meta-Analysis

Objectives

It is unclear if a high level of alcohol consumption is a risk factor for liver fibrosis for people living with HIV (PLWH). This study systematically summarizes the risk relationship between different alcohol consumption and the incidence of liver fibrosis among PLWH.

Methods

We identified potential studies by searching the PubMed, Embase, Web of Science Library, and CNKI databases up to September 26th, 2021. Observation studies in PLWH that evaluated the relationship between alcohol consumption and the risk of liver fibrosis and estimated the effect of alcohol with pooled odds ratios (pooled ORs) and 95% confidence intervals (CIs) were included.

Results

There were total 15 studies included in data analysis. Three studies were set up as cohort studies and the other twelve were cross-sectional studies. Our study was based on 22,676 individuals and 2,729 liver fibrosis cases from 15 studies. Alcohol abuse is a significant risk factor of liver fibrosis (pooled OR = 2.25, 95% CI: 1.59-3.17, p < 0.05) among PLWH. Daily alcohol consumption > 50 g can elevate the risk of liver fibrosis (pooled OR = 3.10, 95% CI: 2.02-4.73, p < 0.05) among PLWH. However, high-risk alcohol consumption determined by AUDIT-C (AUDIT-C ≥ 4) had little or no effect on subsequent liver fibrosis risk. Further, alcohol consumption > 50 g is also a risk factor to liver fibrosis in PLWH co-infected with HCV (pooled OR = 2.48, 95% CI: 1.62-3.80, p < 0.05) and in HIV mono-infected (pooled OR = 1.85, 95% CI: 1.00-3.43, p < 0.05).

Conclusion

Alcohol consumption is associated with an increased risk of liver fibrosis in PLWH. HCV co-infection with alcohol abuse could possibly induce a higher risk of liver fibrosis than HIV mono-infected patients.

Systematic Review Registration

PROSPERO, identifier (CRD42021272604).

Sofosbuvir/velpatasvir with or without low-dose ribavirin for patients with chronic hepatitis C virus infection and severe renal impairment

OBJECTIVE

Data regarding the real-world effectiveness and safety of sofosbuvir/velpatasvir (SOF/VEL) with or without low-dose ribavirin (RBV) in patients with chronic hepatitis C virus (HCV) infection and severe renal impairment (RI) are limited. We evaluated the performance of SOF/VEL with or without low-dose RBV in HCV-infected patients with chronic kidney disease stage 4 or 5.

DESIGN

191 patients with compensated (n=181) and decompensated (n=10) liver diseases receiving SOF/VEL (400/100 mg/day) alone and SOF/VEL with low-dose RBV (200 mg/day) for 12 weeks were retrospectively recruited at 15 academic centres in Taiwan. The effectiveness was determined by sustained virological response at off-treatment week 12 (SVR₁₂) in evaluable (EP) and per-protocol populations (PP). The safety profiles were assessed.

RESULTS

The SVR₁₂ rates by EP and PP analyses were 94.8% (95% CI 90.6% to 97.1%) and 100% (95% CI 97.9% to 100%). In patients with compensated liver disease, the SVR₁₂ rates were 95.0% and 100% by EP and PP analyses. In patients with decompensated liver disease, the SVR₁₂ rates were 90.0% and 100% by EP and PP analyses. Ten patients who failed to achieve SVR₁₂ were attributed to non-virological failures. Among the 20 serious adverse events (AEs), none were judged related to SOF/VEL or RBV. The AEs occurring in ≥10% included fatigue (14.7%), headache (14.1%), nausea (12.6%), insomnia (12.0%) and pruritus (10.5%). None had ≥grade 3 total bilirubin or alanine aminotransferase elevations.

CONCLUSION

SOF/VEL with or without low-dose RBV is effective and well-tolerated in HCV-infected patients with severe RI.

Pharmacokinetic Drug Interaction Study of Sorafenib and Morphine in Rats

A combination of the tyrosine kinase inhibitor—sorafenib—and the opioid analgesic—morphine—can be found in the treatment of cancer patients. Since both are substrates of P-glycoprotein (P-gp), and sorafenib is also an inhibitor of P-gp, their co-administration may affect their pharmacokinetics, and thus the safety and efficacy of cancer therapy. Therefore, the aim of this study was to evaluate the potential pharmacokinetic drug–drug interactions between sorafenib and morphine using an animal model. The rats were divided into three groups that Received: sorafenib and morphine (I_SOR+MF), sorafenib (II_SOR), and morphine (III_MF). Morphine caused a significant increase in maximum plasma concentrations (C_max) and the area under the plasma concentration–time curves (AUC_0–t, and AUC_0–∞) of sorafenib by 108.3 (p = 0.003), 55.9 (p = 0.0115), and 62.7% (p = 0.0115), respectively. Also, the C_max and AUC_0–t of its active metabolite—sorafenib N-oxide—was significantly increased in the presence of morphine (p = 0.0022 and p = 0.0268, respectively). Sorafenib, in turn, caused a significant increase in the C_max of morphine (by 0.5-fold, p = 0.0018). Moreover, in the presence of sorafenib the C_max, AUC_0–t, and AUC_0–∞ of the morphine metabolite M3G increased by 112.62 (p < 0.0001), 46.82 (p = 0.0124), and 46.78% (p = 0.0121), respectively. Observed changes in sorafenib and morphine may be of clinical significance. The increased exposure to both drugs may improve the response to therapy in cancer patients, but on the other hand, increase the risk of adverse effects.

Drugs of Abuse and Their Impact on Viral Pathogenesis

Commonly misused substances such as alcohol, cocaine, heroin, methamphetamine, and opioids suppress immune responses and may impact viral pathogenesis. In recent years, illicit use of opioids has fueled outbreaks of several viral pathogens, including the human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV). This review focuses on the myriad of mechanisms by which drugs of abuse impact viral replication and disease progression. Virus–drug interactions can accelerate viral disease progression and lead to increased risk of virus transmission.

Mitochondrial Genotoxicity of Hepatitis C Treatment among People Who Inject Drugs

Antiviral nucleoside analogues (ANA) are newly used therapeutics acting against the hepatitis C virus (HCV). This class of drug is well known to exhibit toxicity on mitochondrial DNA (mtDNA). People who inject drugs (PWID) are particularly affected by HCV infection and cumulated mitotoxic drug exposure from HIV treatments (antiretrovirals, ARV) and other illicit drugs. This study aims to explore the impact of direct-acting antiviral (DAA) treatments on mtDNA among PWID. A total of 470 actively injecting heroin users were included. We used quantitative PCR on whole blood to determine the mitochondrial copy number per cell (MCN) and the proportion of mitochondrial DNA deletion (MDD). These parameters were assessed before and after DAA treatment. MDD was significantly increased after HCV treatment, while MCN did not differ. MDD was even greater when subjects were cotreated with ARV. In multivariate analysis, we identified that poly-exposure to DAA and daily heroin injection or regular consumption of methamphetamines were positively associated with high MCN loss while DAA and ARV treatments or methadone use were identified as risk factors for having mtDNA deletion. These observations deserve attention since they were previously associated with premature cell ageing or cell transformation and therefore call for a long-term follow-up.

Development and Validation of a Questionnaire to Measure Medication Adherence to Direct-Acting Agents in Patients with Hepatitis C

This study aims to develop a new self-report tool (HCV-AD) measuring adherence factors, intentional or unintentional, during Hepatitis C Virus (HCV) treatment with direct-acting antivirals (DAA) aiming to achieve high efficacy, otherwise resulting in drug resistance and treatment failure. Two phases were conducted: in the first phase, items were generated based on an extensive literature review, and, in the second phase, a prospective cohort study was conducted using HCV patients from Gastroenterology Department from University County Hospital of Craiova, Romania (n = 222), to evaluate the validity and reliability of the questionnaire. A number of 19 items were generated following a systematic review and through expert opinion. The internal consistency reliability was evaluated using Cronbach’s alpha. The construct validity was assessed using correlations with two other instruments: visual analog scale (VAS) and medication possession ratio (MPR). The final questionnaire (HCV-AD10) was derived through exploratory factor analysis, with 82% of total variance explained. This instrument appeared as a reliable and valid measure for medication adherence, with Cronbach’s alpha (0.867) and significant high positive correlations between adherence scores calculated with HCV-AD10 and VAS (ρ = 0.61, p < 0.001) or with HCV-AD10 and MPR (ρ = 0.75, p < 0.001). This research would make a worthwhile contribution to HCV management.

Efficacy and safety of ledipasvir/sofosbuvir for hepatitis C among drug users: a systematic review and meta-analysis

BACKGROUND AND AIMS

Limited data is available on the efficacy of direct acting anti-viral drugs on hepatitis C in drug users. The aim of this meta-analysis was to comprehensively analyze the efficacy and safety of LDV/SOF in drug users infected with the hepatitis C virus (HCV).

METHODS

The PubMed, Cochrane library, Embase and Web of Science databases were searched for articles published till April 2021 on HCV-positive drug users who were treated with ledipasvir/sofosbuvir (LDV/SOF). The primary endpoint was pooled sustained virological response at 12 weeks (SVR12) with 95% confidence interval (95% CI). Funnel plots and Egger's test were used to assess the publication bias.

RESULTS

A total of 12 studies and 711 subjects treated with LDV/SOF-based regimen for HCV were included, and the pooled SVR12 rate was 89.8% (95% CI 85.9-92.7). The pooled SVR12 rate of genotype 1 drug users was 92.4% (95% CI 88.6-95.0). Subgroup analysis showed that pooled SVR12 rates of patients treated with LDV/SOF and LDV/SOF ± RBV were 89.2% (95% CI 83.4-93.1), 90.4% (95% CI 83.6-94.5) respectively. In addition, the SVR12 rates were 88% (95% CI 70.7-95.7) for 8 weeks, 89.9% (95% CI 81.0-94.9) for 12 weeks and 82.2% (95% CI 24.9-98.5) for 24 weeks of treatment.

CONCLUSION

LDV/SOF is a safe and relatively effective treatment for hepatitis C in drug users.

Hepatitis C prevalences in the psychiatric setting: Cost-effectiveness of scaling-up screening and direct-acting antiviral therapy

BACKGROUND & AIMS

Patients hospitalised because of mental illness often have risk factors for contracting HCV. Scaling-up HCV screening for all psychiatric inpatients as a case-detection strategy for viral elimination is underexplored. This study aimed to evaluate the cost-effectiveness of scaling-up HCV screening and treatment for psychiatry hospital admissions in Switzerland vs. the current standard-of-care risk-based approach, where only those with a history of substance misuse disorder are offered testing.

METHODS

HCV prevalence by history of substance misuse disorder was analysed in medical records from inpatient admissions to a Swiss psychiatry department. Cost-effectiveness was analysed from a healthcare provider perspective through a decision-tree screening model, using these HCV prevalence data. Model and parameter uncertainty were assessed using deterministic and probabilistic sensitivity analyses.

RESULTS

Prevalence of HCV in psychiatry inpatients with a history of substance misuse disorder (n = 1,013) was 25.7%, compared with 3.5% among the remaining inpatients (n = 3,535). Scaling up HCV screening and treatment for all psychiatry admissions was cost-effective vs. the risk-based approach, with an incremental cost-effectiveness ratio of US$9,188 per quality-adjusted life-year gained. The incremental cost-effectiveness ratio remained cost-effective considering a HCV prevalence as low as 0.07%. The population-level net monetary benefit of the generalised screening approach was US$435,156,348, with 917 additional patients per year detected and treated at a cost of US$3,294 per person (vs. US$2,122 under risk-based screening).

CONCLUSIONS

Scaling up HCV screening and treatment at diagnosis with all-oral, interferon-free regimens as a generalised approach for psychiatric admissions was cost-effective and could support reaching World Health Organization targets for HCV elimination by 2030.

LAY SUMMARY

Patients hospitalised because of mental illness often have risk factors for HCV. We found that testing all psychiatry patients in hospital for HCV was cost-effective compared with testing only patients who have a history of substance misuse. Scaling up HCV testing and treatment could help to wipe out HCV.

Pharmacotherapy Profiles in People with Opioid Use Disorders: Considerations for Relevant Drug-Drug Interactions with Antiviral Treatments for Hepatitis C

People who inject drugs (PWID) are often affected by physical and psychological diseases and prone to co-medication. In Germany, about 50% of PWID are on opioid substitution therapy (OST). Comprehensive data on pharmacotherapy in these patients may help to select antiviral therapy against hepatitis C virus (HCV) infections and avoid drug–drug interactions (DDIs). We compared co-medication profiles based on statutory health insurance prescriptions (IQVIA database) of PWID (n = 16,693), OST (n = 95,023) and treated HCV patients (n = 7886). Potential DDIs with the most widely used HCV direct-acting agents (Sofosbuvir/Velpatasvir, Glecaprevir/Pibrentasvir and Elbasvir/Grazoprevir) were evaluated based on the Liverpool DDI database. Co-medication was present in 57% of PWID, 57% of OST, 44% of patients on HCV therapy and 46% in a subgroup receiving OST+HCV therapy (n = 747 of 1613). For all groups, co-medication belonging to ATC-class N (nervous system) was most commonly prescribed (in 75%, 68%, 41% and 62% of patients, respectively). Contraindications (i.e., DDIs precluding HCV therapy) were infrequent (0.4–2.5% of co-medications); potential DDIs with HCV therapies were shown for 13–19% of co-medications, namely for specific substances including some analgesics, antipsychotics, anticoagulants, lipid lowering drugs and steroids. In conclusion, concomitant pharmacotherapy is common and clinically relevant when treating HCV infection in PWID.

Metabolism of Direct-acting Antiviral Agents (DAAs) in Hepatitis C Therapy: A Review of the Literature

BACKGROUND

Hepatitis C virus (HCV) infection is still one of the leading causes of chronic liver disease, with chronically infected making up approximately 1% of the global population. Of those infected, 70% (55-85%) will develop chronic HCV infection. Chronic HCV infection causes substantial morbidity and mortality, with complications including cirrhosis, end-stage liver disease, hepatocellular carcinoma, and eventually death.

OBJECTIVE

Therapeutic options for chronic HCV infection have evolved dramatically since 2014, with a translation from pegylated interferon and ribavirin (associated with suboptimal cure and high treatment-related toxicity) to oral direct-acting antiviral treatment. There are four classes of direct-acting antivirals which differ by their mechanism of action and therapeutic target. They are all pointed to proteins that form the cytoplasmic viral replication complex. Multiple studies have demonstrated that direct-acting antiviral therapy is extremely well tolerated, highly efficacious, with few side effects.

METHODS

We performed an indexed MEDLINE search with keywords regarding specific direct-acting antiviral regimes and their pharmacokinetics, drug-drug interactions, and metabolism in specific settings of pregnancy, lactation, liver cirrhosis, liver transplantation and HCC risk, kidney failure and kidney transplantation.

RESULTS

We present a comprehensive overview of specific direct-acting antiviral metabolism and drug-drug interaction issues in different settings.

CONCLUSION

Despite its complex pharmacokinetics and the possibility of drug-drug interactions, direct-acting antivirals are highly efficacious in providing viral clearance, which is an obvious advantage compared to possible interactions or side effects. They should be administered cautiously in patients with other comorbidities, and with tight control of immunosuppressive therapy.

Chronic pain and COVID-19: pathophysiological, clinical and organizational issues

During the lockdown phase of the COVID-19 pandemic, a call not to neglect the continuum of care of patients who present with chronic diseases, including pain, was made. In the field of pain, COVID-19 had an impact both from a clinical (i.e., the influence of SARS-CoV-2 infection on pain) and organizational (i.e., how patients with chronic pain should be managed in the post-COVID-19 era) perspective. Furthermore, patients with chronic pain are also frequently frail subjects, affected from multiple comorbidities and hence are at increased risk of infection. On these bases, how the necessity to continue pain therapy will be pursued in the post-COVID-19 era? In this paper, we comment on the above-mentioned topics, on the basis of available data and our experience as pain therapists.