Peginterferon alfa-2a does not alter the pharmacokinetics of methadone in patients with chronic hepatitis C undergoing methadone maintenance therapy

Influence of Inflammation on Cytochromes P450 Activity in Adults: A Systematic Review of the Literature

Background: Available in-vitro and animal studies indicate that inflammation impacts cytochromes P450 (CYP) activity via multiple and complex transcriptional and post-transcriptional mechanisms, depending on the specific CYP isoforms and the nature of inflammation mediators. It is essential to review the current published data on the impact of inflammation on CYP activities in adults to support drug individualization based on comorbidities and diseases in clinical practice. Methods: This systematic review was conducted in PubMed through 7th January 2021 looking for articles that investigated the consequences of inflammation on CYP activities in adults. Information on the source of inflammation, victim drugs (and CYPs involved), effect of disease-drug interaction, number of subjects, and study design were extracted. Results: The search strategy identified 218 studies and case reports that met our inclusion criteria. These articles were divided into fourteen different sources of inflammation (such as infection, autoimmune diseases, cancer, therapies with immunomodulator…). The impact of inflammation on CYP activities appeared to be isoform-specific and dependent on the nature and severity of the underlying disease causing the inflammation. Some of these drug-disease interactions had a significant influence on drug pharmacokinetic parameters and on clinical management. For example, clozapine levels doubled with signs of toxicity during infections and the concentration ratio between clopidogrel's active metabolite and clopidogrel is 48-fold lower in critically ill patients. Infection and CYP3A were the most cited perpetrator of inflammation and the most studied CYP, respectively. Moreover, some data suggest that resolution of inflammation results in a return to baseline CYP activities. Conclusion: Convincing evidence shows that inflammation is a major factor to be taken into account in drug development and in clinical practice to avoid any efficacy or safety issues because inflammation modulates CYP activities and thus drug pharmacokinetics. The impact is different depending on the CYP isoform and the inflammatory disease considered. Moreover, resolution of inflammation appears to result in a normalization of CYP activity. However, some results are still equivocal and further investigations are thus needed.

Update on Therapeutic Protein-Drug Interaction: Information in Labeling

This review evaluated the significance of therapeutic protein (TP)-drug interactions and the current practices for assessing the interaction potential. We reviewed US FDA labels of approved TPs with drug-drug interaction (DDI) assessment. TP-drug interactions have been evaluated from in vitro studies, animal studies, and/or clinical settings. Of the 150 FDA-approved TPs as of May 2019, 49 TP labels contained pharmacokinetic (PK)-related DDI information derived from at least one study method. Our review found that more than half of the clinical PK DDI evaluations showed no interaction, and no dose adjustment has been recommended for any of the rest TPs. The results and trends observed in this review may further enhance and inform risk-based approaches to evaluating the potential for TP-drug interactions.

Pharmacokinetic interaction between HCV protease inhibitor boceprevir and methadone or buprenorphine in subjects on stable maintenance therapy

PURPOSE

Intravenous opioid use is a common route of hepatitis C virus (HCV) infection; consequently, the prevalence of HCV is high among patients on methadone or buprenorphine/naloxone. The authors evaluated the pharmacokinetic interaction of boceprevir with methadone or buprenorphine/naloxone in patients on stable maintenance therapy.

METHODS

This was a two-center, open-label, fixed-sequence study in 21 adult volunteers on stable maintenance therapy. Oral methadone (20-150 mg once daily) or sublingual buprenorphine/naloxone (8/2-24/6 mg once daily) was administered alone or in combination with boceprevir (800 mg every 8 h) on days 2-7. Pharmacokinetic sampling occurred before and up to 24 h after the dose on days 1 and 7.

RESULTS

Coadministration of boceprevir reduced the area under the concentration-time curve during a dosing interval τ (AUC τ ) and maximum observed plasma (or serum) concentration (C max) of R-methadone (geometric mean ratios (GMRs) [90 % confidence intervals (CIs)], 0.85 [0.74, 0.96] and 0.90 [0.71, 1.13]) and S-methadone (GMRs [90 % CIs], 0.78 [0.66, 0.93] and 0.83 [0.64, 1.09]). Boceprevir increased the AUC τ and C max of buprenorphine (GMRs [90 % CIs], 1.19 [0.91, 1.58] and 1.18 [0.93, 1.50]) and naloxone (GMRs [90 % CIs], 1.33 [0.90, 1.93] and 1.09 [0.79, 1.51]). Boceprevir exposure upon methadone or buprenorphine/naloxone coadministration was not clinically different from historical controls and there was no evidence of opioid withdrawal or excess.

CONCLUSIONS

There was no clinically meaningful impact of boceprevir on methadone or buprenorphine pharmacokinetics, suggesting that methadone/buprenorphine dose adjustments are not required upon coadministration with boceprevir. Individual patients may differ in their clinical experience and clinicians should maintain vigilance when coadministering these medications.

A review of pharmacological interactions between HIV or hepatitis C virus medications and opioid agonist therapy: implications and management for clinical practice

Global access to opioid agonist therapy and HIV/hepatitis C virus (HCV) treatment is expanding but when used concurrently, problematic pharmacokinetic and pharmacodynamic interactions may occur. Articles published from 1966 to 2012 in Medline were reviewed using the following keywords: HIV, AIDS, HIV therapy, HCV, HCV therapy, antiretroviral therapy, highly active antiretroviral therapy, drug interactions, methadone and buprenorphine. In addition, a review of abstracts from national and international meetings and conference proceedings was conducted; selected reports were reviewed as well. The metabolism of both opioid and antiretroviral therapies, description of their known interactions and clinical implications and management of these interactions were reviewed. Important pharmacokinetic and pharmacodynamic drug interactions affecting either methadone or HIV medications have been demonstrated within each class of antiretroviral agents. Drug interactions between methadone, buprenorphine and HIV medications are known and may have important clinical consequences. Clinicians must be alert to these interactions and have a basic knowledge regarding their management.

Effect of peginterferon alfa-2a (40KD) on cytochrome P450 isoenzyme activity

AIM

Pegylated interferon-based therapy is recommended for treatment of hepatitis C virus (HCV) infection. Because interferons are known to down-regulate hepatic cytochrome P450 (CYP) enzymes, which are involved in drug metabolism and clearance, there is a need to investigate the effect of peginterferon (PEG-IFN) alfa-2a (40KD) on the activity of these enzymes in vivo.

METHODS

Fourteen healthy, male volunteers aged 18 to 45 years were recruited into an open label, two period, single centre study in which CYP enzyme activity was measured by administration of the selectively metabolized probe drugs theophylline (CYP1A2), tolbutamide (CYP2C9), mephenytoin (CYP2C19), debrisoquine (CYP2D6) and dapsone (CYP3A4) on day 1 of the study. PEG-IFN alfa-2a (40KD) 180 μg was given subcutaneously each week from day 15 to 36, and probe drugs were re-administered on day 37. Probe drugs and metabolites were quantified in plasma or urine samples and used to derive pharmacokinetic parameters.

RESULTS

PEG-IFN alfa-2a (40KD) significantly increased the area under the serum drug concentration vs. time curve (AUC(0,∞)) for theophylline by 24%, with a reduction in the mean oral clearance of theophylline of 20%. There were no effects on the pharmacokinetics of any of the other probe drugs. The incidence of adverse events was as expected in subjects receiving pegylated interferon.

CONCLUSION

These results suggest there may be an inhibitory effect of PEG-IFN alfa-2a (40KD) on CYP1A2. PEG-IFN alfa-2a (40KD) had no effect on CYP2C9, CYP2C19, CYP2D6 or CYP3A4 in healthy subjects.

Clinical management of drug-drug interactions in HCV therapy: challenges and solutions

Hepatitis C virus (HCV) infected patients often take multiple co-medications to treat adverse events related to HCV therapy, or to manage other co-morbidities. Drug-drug interactions associated with this polypharmacy are relatively new to the field of HCV pharmacotherapy. With the advent of the direct-acting antivirals telaprevir and boceprevir, which are both substrates and inhibitors of the cytochrome P450 (CYP) 3A iso-enzyme, knowledge and awareness of drug-drug interactions have become a cornerstone in the evaluation of patients starting and continuing HCV combination therapy. In our opinion, an overview of conducted drug-drug interaction studies and a list of contraindicated medications is not enough for the clinical management of these drug-drug interactions. Knowledge of pharmacokinetic profiles and concentration-effect relationships is key for the interpretation of these data, and insight into how to manage these interactions (e.g., dose adjustments, safe alternatives and therapeutic drug monitoring) is of equal importance. This review provides a practical overview of the safe and effective management of these clinical challenges.

Methadone: a review of drug-drug and pathophysiological interactions

Numerous established and potential drug interactions with methadone are clinically important in people treated with methadone either for addiction or for chronic pain. Methadone users often have comorbidities and are prescribed drugs that may interact with methadone. Methadone is extensively metabolized by cytochrome P450 (CYP) 3A4 and to a lesser extent by CYP 1A2, 2D6, 2D8, 2C9/2C8, 2C19, and 2B6. Eighty-six percent of methadone is protein bound, predominately to α1-acid glycoprotein (AGP). Polymorphisms in or interactions with CYPs that metabolize methadone, changes in protein binding, and other pathophysiological conditions affect the pharmacokinetic properties of methadone. It is critical for health care providers who treat patients on methadone to have adequate information on the interactions of methadone with other drugs of abuse and other medications. We set out to describe drug-drug interactions as well as physiological and pathophysiological factors that may impact the pharmacokinetics of methadone. Using MEDLINE, we conducted a systematic search for papers and related abstracts published between 1966 and June 2010. Keywords that included methadone, drug-drug interactions, CYP P450 and AGP identified a total of 7709 papers. Other databases, including the Cochrane Database of Systematic Reviews and Scopus, were also searched; an additional 929 papers were found. Final selection of 286 publications was based on the relevance of each paper to the topic. Over 50 such interactions were found. Interactions of methadone with other drugs can lead to increased or decreased methadone drug levels in patients and result in potential overdose or withdrawal, respectively. The former can contribute to methadone's fatality. Prescribers of methadone and pharmacists should enquire about any new medications (including natural products and over-the-counter medications) periodically, and especially when an otherwise stable patient suddenly experiences drug craving, withdrawal or intoxication.

Immunological response as a source to variability in drug metabolism and transport

Through the last decades it has become increasingly evident that disease-states involving cytokines affect the pharmacokinetics of drugs through regulation of expression and activity of drug metabolizing enzymes, and more recently also drug transporters. The clinical implication is however difficult to predict, since these effects are dependent on the degree of inflammation and may be changed when the diseases are treated. This article will give an overview of the present understanding of the effects of cytokines on cytochrome P450 enzymes and drug transporters, and highlight the importance of considering these issues in regard to increasing use of the relatively new class of drugs, namely therapeutic proteins.

Current therapies for chronic hepatitis C

Hepatitis C virus affects more than 180 million people worldwide and as many as 4 million people in the United States. Given that most patients are asymptomatic until late in the disease progression, diagnostic screening and evaluation should be performed in patients who display high-risk behaviors associated with acquisition of hepatitis C. Chronic hepatitis C is associated with cirrhosis, hepatic failure, and death; therefore, treatment is aimed at reducing these complications, as well as improving quality of life and minimizing adverse effects. The American Association for the Study of Liver Diseases Practice Guidelines on the Diagnosis, Management, and Treatment of Hepatitis C represent the gold standard for guidance on the management of hepatitis C. Standard treatment for hepatitis C is peginterferon alpha in combination with ribavirin. Currently, two pegylated interferon products are approved by the U.S. Food and Drug Administration for the treatment of hepatitis C. The duration of therapy with peginterferon and ribavirin is dictated by viral genotype and virologic response. Additional therapies are under investigation for treatment of chronic hepatitis C and show early promise of comparative efficacy and fewer adverse effects. Special considerations in certain populations, including patients coinfected with human immunodeficiency virus, those with end-stage renal disease, injection drug users, pregnant women, and pediatric patients, should guide treatment decisions.

Peginterferon-alpha-2a (40 kD): A review of its use in chronic hepatitis B

Peginterferon-alpha-2a (40 kD) [Pegasys] comprises an inert, branched, 40 kD polyethylene glycol (PEG) moiety attached to interferon-alpha-2a. Subcutaneous peginterferon-alpha-2a (40 kD) is indicated for the treatment of adults with hepatitis B e antigen (HBeAg)-positive or -negative chronic hepatitis B who have compensated liver disease with evidence of viral replication and hepatic inflammation. Subcutaneous peginterferon-alpha-2a (40 kD) has antiviral and immunomodulatory properties and a convenient once-weekly administration schedule. Forty-eight weeks of therapy with peginterferon-alpha-2a (40 kD) with or without lamivudine was more effective than lamivudine alone in achieving a sustained response in patients with HBeAg-positive or -negative chronic hepatitis B. A long-term follow-up study in patients with HBeAg-positive disease who received peginterferon-alpha-2a (40 kD) monotherapy revealed an HBeAg seroconversion rate of 42%, 1 year after the end of treatment. A long-term follow-up study in patients with HBeAg-negative disease who received peginterferon-alpha-2a (40 kD) with or without lamivudine revealed hepatitis B surface antigen (HBsAg) clearance in 12% of patients and inactive chronic hepatitis B in 17% of patients, 5 years after the end of treatment. Various predictors of response may be useful in terms of identifying patients who may be candidates for shorter or longer peginterferon-alpha-2a (40 kD) treatment durations. For example, quantifying serum HBeAg (in HBeAg-positive disease) and HBsAg levels during therapy may be useful. Adverse events typical of the influenza-like symptoms seen with alpha-interferons occurred more frequently in patients with chronic hepatitis B receiving peginterferon-alpha-2a (40 kD) with or without lamivudine than in those receiving lamivudine alone. In conclusion, peginterferon-alpha-2a (40 kD) is a valuable option for the first-line treatment of HBeAg-negative or -positive chronic hepatitis B.

Pharmacotherapy in the treatment of addiction: methadone

Methadone maintenance treatment (MMT) is the most widely available pharmacotherapy for opioid addiction and has been shown to be an effective and safe treatment over a period of 40 years. Although women comprise approximately 40% of clients currently being treated in MMT programs, comparatively little research geared specifically toward this group has been published. This article begins with an overview of neurobiological studies on opioid addiction, including a discussion of gender differences, followed by a review of the pharmacology of methadone. The authors then examine the particular needs and differences of women being treated in MMTs, including co-dependence with other substances, women's health issues, and psychosocial needs unique to this population. Research shows that women have different substance abuse treatment needs in comparison to their male counterparts. One New York City MMT program that has attempted to address these differences is highlighted.

Antiviral Treatment for Chronic Hepatitis C in Illicit drug Users: A Systematic Review

According to recent World Health Organization data, approximately 170–200 million people worldwide are infected with hepatitis C virus (HCV). At present, illicit drug users (IDUs) constitute the largest group of individuals infected with HCV in industrial countries. Between 50% and 90% of IDUs are estimated to be positive for anti-HCV antibodies and most of the new infections occur in IDUs. The aim of our review is to focus on tertiary prevention of HCV infection among IDUs. We review strategies to prevent HCV infection and disease progression, attitude to antiviral treatment, access to specific HCV therapy and data of efficacy and safety of antiviral treatment among IDUs.

Psychopathological changes and quality of life in hepatitis C virus-infected, opioid-dependent patients during maintenance therapy

AIMS

To examine among maintenance patients (methadone or buprenorphine) with and without hepatitis C virus (HCV) infection (i) the frequency of psychopathological symptoms at baseline and 1-year follow-up; (ii) the association between antiviral interferon (IFN) treatment and psychopathological symptoms; and (iii) to explore whether IFN therapy has an effect on 1-year outcome of maintenance treatment.

DESIGN

Naturalistic prospective longitudinal cohort design.

SETTING

A total of 223 substitution centres in Germany.

PARTICIPANTS

A nationally representative sample of 2414 maintenance patients, namely 800 without and 1614 with HCV infection, of whom 122 received IFN therapy.

MEASURES

HCV infection (HCV+/HCV-), IFN (IFN+/IFN-) treatment status and clinical measures. Diagnostic status and severity (rated by clinician), psychopathology (BSI--Brief Symptom Inventory) and quality of life (EQ-5D--EuroQol Group questionnaire).

FINDINGS

HCV+ patients revealed indications for a moderately increased psychopathological burden and poorer quality of life at baseline and follow-up compared to HCV- patients. HCV+ patients showed a marked deterioration over time only in the BSI subscale somatization (P = 0.002), and the frequency of sleep disorders almost doubled over time (12.8% at baseline; 24.1% at follow-up; P < 0.01). IFN treatment, received by 10% of HCV+ patients, did not impair efficacy or tolerability of maintenance therapy and was associated overall with neither increased psychopathological burden nor reduced quality of life.

CONCLUSIONS

Findings suggest no increased risk among HCV+ patients on maintenance therapy for depressive or other psychopathological syndromes. In our patient sample, IFN treatment was not associated with increased psychopathological burden, reduced quality of life or poorer tolerability and efficacy of maintenance treatment.

Retention rate and side effects in a prospective trial on hepatitis C treatment with pegylated interferon alpha-2a and ribavirin in opioid-dependent patients

Hepatitis C viral (HCV) infection is present in 30 to 98% of intravenous drug users. Intravenous substance abuse represents the main route of HCV transmission in industrialized countries. A multi-centre, randomized, controlled, prospective study assessed sustained virological response (SVR), adverse events such as depressive episodes and retention rate of HCV treatment in opioid-dependent patients. Stabilized, opioid-dependent patients with chronic HCV infection (genotype 2 or 3) received pegylated interferon alpha-2a in combination with ribavirin 800 mg/day (Group A) or 400 mg/day (Group B). Participants were randomized, blocked and stratified by genotype and viral load. A standardized psychiatric assessment, Beck Depression Inventory (BDI) and Van Zerssen's list of complaints were administered at each study visit. In 31 months, 300 opioid-dependent patients were screened; 190 (63.3%) were hepatitis C antibody positive. According to study protocol, out of 75 'potential-to-treat' patients with genotype 2 or 3, 17 stable patients (22.6%) were included in the study. All participants completed the study. Significant haemoglobin decreases occurred in both Groups A (P = 0.001) and B (P = 0.011). All the patients had an end-of-treatment (week 24) HCV RNA negativity. Fifteen (88.2%) achieved SVR at week 48. Overall, 52.9% developed depressive symptoms during treatment. Because of the prompt initiation of antidepressant medication at first appearance of depressive symptoms, no severe depressive episodes occurred. Our data show a high retention rate and reliability, and good viral response for both treatments. Hepatitis C treatment in stable opioid-dependent patients was efficacious, suggesting that addiction clinics can offer antiviral therapy in combination with agonistic treatment as part of multi-disciplinary treatment.

Efficacy and safety of peginterferon alfa-2a/ribavirin in methadone maintenance patients: randomized comparison of direct observed therapy and self-administration

BACKGROUND

Adherence to chronic hepatitis C (CHC) treatment may be particularly challenging in methadone maintenance patients. We assessed the safety, tolerability, and efficacy of peginterferon alfa-2a/ribavirin treatment in methadone maintenance patients previously untreated for CHC.

METHODS

Patients were randomized 1:1 to direct observed therapy (DOT) or self-administration (SA) of peginterferon alfa-2a. DOT patients were seen weekly at methadone clinics; SA patients were seen less frequently, only at investigative sites. Genotype 1-infected patients were treated for 48 wk with peginterferon alfa-2a (180 microg/wk)/ribavirin (1,000/1,200 mg/day); genotypes 2- and 3-infected patients were treated for 24 wk with peginterferon alfa-2a (180 microg/wk)/ribavirin (800 mg/day).

RESULTS

Based on defined efficacy stopping rules, 77% (37/48) completed their targeted length of treatment, and 44% (21/48) achieved sustained virologic response (SVR). Two DOT and 3 SA patients were withdrawn for safety reasons and 6 and 9, respectively, for nonsafety reasons. Over 60% and 50% of each group were >80% compliant with the planned cumulative doses of peginterferon alfa-2a and ribavirin, respectively, and over 60% with overall treatment duration. SVR rates were 54% (13/24) for DOT and 33% (8/24) for SA; 23% (3/13) and 38% (6/16), respectively, for genotype 1 and 91% (10/11) and 25% (2/8), respectively, for genotypes 2 and 3. Stepwise logistic regression analysis, showed that DOT (vs SA; OR 3.27, 95% CI 0.90-11.91, P = 0.073) and Caucasian race (vs Other; OR 13.31, 95% CI 1.42-124.71, P = 0.023) were predictors of SVR.

CONCLUSION

Peginterferon alfa-2a/ribavirin can be used safely and successfully in CHC patients receiving methadone maintenance.

Critical issues in the treatment of hepatitis C virus infection in methadone maintenance patients

AIMS

Hepatitis C virus (HCV) infection is a common chronic complication of injection drug use. Methadone maintenance programs contain large numbers of patients infected with HCV. This paper reviews HCV infection with emphasis on the medical care of HCV-infected, or HCV and human immunodeficiency virus co-infected, patients on methadone or buprenorphine maintenance.

METHODS

Literature searches using PubMed, PsycINFO and SocINDEX were used to identify papers from 1990-present on antiviral therapy for HCV in methadone maintenance patients and on liver transplantation in methadone maintenance patients.

RESULTS

Injection drug use is the most significant risk factor for HCV infection in most western countries. The prevalence of HCV antibody is high in injection drug users (53-96%) and in patients enrolled in methadone maintenance programs (67-96%). Studies of antiviral therapy for HCV in methadone maintenance patients show rates of sustained virological response (SVR), defined as negative HCV-RNA 24 weeks after the end of treatment, of 28-94%. In studies with contrast groups, no significant differences in SVR between methadone and contrast groups were found. Excellent completion rates of antiviral therapy (72-100%) were found in five of six studies. There are many barriers to methadone maintenance patients' receiving antiviral therapy, and research on overcoming barriers is discussed. Liver transplantation has been successful in methadone maintenance patients but has not been utilized widely.

CONCLUSION

High quality medical care for all aspects of HCV infection can be provided to methadone maintenance patients. The literature supports the effectiveness of such services, but the reality is that most patients do not receive them.

Peginterferon pharmacokinetics in African American and Caucasian American patients with hepatitis C virus genotype 1 infection

BACKGROUND & AIMS

The relationship between serum peginterferon pharmacokinetics and pharmacodynamics and the early virologic response (EVR) to peginterferon and ribavirin therapy was assessed in patients with chronic hepatitis C virus (HCV) genotype 1 infection.

METHODS

A total of 333 patients (160 African Americans [AA] and 173 Caucasian Americans [CA]) who received peginterferon alpha-2a (180 microg/wk) without a dose modification during the initial 4 weeks of therapy were analyzed. Peginterferon and 2,5-oligoadenylate synthetase (2,5-OAS) serum levels were measured on days 0, 1, 2, 3, 7, 14, 28, 56, 84, and 168 of treatment. The EVR (>or=2-log(10) decline in HCV RNA levels by week 12 of therapy) was the primary virologic end point.

RESULTS

Peginterferon pharmacokinetics after the first dose were similar in AA and CA, but AA had greater peginterferon concentrations at days 1, 3, 14, and 28 (P < .05). AA had higher absolute serum 2,5-OAS levels on days 0, 1, 2, 3, 7, 14, 28, and 56 (P < .05), but the magnitude of 2,5-OAS induction during treatment were similar. AA patients showed a smaller decline in serum HCV RNA during the first 28 days of treatment (P < .001) and a lower EVR (65% vs 83%). AA and CA with EVR had significantly higher serum peginterferon concentrations and serum 2,5-OAS induction during the first 12 weeks than patients without an EVR.

CONCLUSIONS

Peginterferon alpha-2a pharmacokinetic and pharmacodynamic variability is associated with EVR in both AA and CA with HCV infection, but do not explain the racial disparity in combination treatment efficacy.

Hepatitis infection in the treatment of opioid dependence and abuse

Many new and existing cases of viral hepatitis infections are related to injection drug use. Transmission of these infections can result directly from the use of injection equipment that is contaminated with blood containing the hepatitis B or C virus or through sexual contact with an infected individual. In the latter case, drug use can indirectly contribute to hepatitis transmission through the dis-inhibited at-risk behavior, that is, unprotected sex with an infected partner. Individuals who inject drugs are at-risk for infection from different hepatitis viruses, hepatitis A, B, or C. Those with chronic hepatitis B virus infection also face additional risk should they become co-infected with hepatitis D virus. Protection from the transmission of hepatitis viruses A and B is best achieved by vaccination. For those with a history of or who currently inject drugs, the medical management of viral hepatitis infection comprising screening, testing, counseling and providing care and treatment is evolving. Components of the medical management of hepatitis infection, for persons considering, initiating, or receiving pharmacologic therapy for opioid addiction include: testing for hepatitis B and C infections; education and counseling regarding at-risk behavior and hepatitis transmission, acute and chronic hepatitis infection, liver disease and its care and treatment; vaccination against hepatitis A and B infection; and integrative primary care as part of the comprehensive treatment approach for recovery from opioid abuse and dependence. In addition, participation in a peer support group as part of integrated medical care enhances treatment outcomes. Liver disease is highly prevalent in patient populations seeking recovery from opioid addiction or who are currently receiving pharmacotherapy for opioid addiction. Pharmacotherapy for opioid addiction is not a contraindication to evaluation, care, or treatment of liver disease due to hepatitis virus infection. Successful pharmacotherapy for opioid addiction stabilizes patients and improves patient compliance to care and treatment regimens as well as promotes good patient outcomes. Implementation and integration of effective hepatitis prevention programs, care programs, and treatment regimens in concert with the pharmacological therapy of opioid addiction can reduce the public health burdens of hepatitis and injection drug use.

Effects of pegylated interferon alfa-2b on the pharmacokinetic and pharmacodynamic properties of methadone: a prospective, nonrandomized, crossover study in patients coinfected with hepatitis C and HIV receiving methadone maintenance treatment

BACKGROUND

Hepatitis C virus (HCV) infection is common among methadone-maintained HIV-positive individuals. Pegylated interferon (pegIFN) used in combination with ribavirin is conventional treatment for HCV. However, pegIFN has been associated with adverse effects (AEs) that may simulate opioid withdrawal and be confused with insufficient methadone dosage.

OBJECTIVE

The aim of this study was to determine, using methadone pharmacokinetic properties, whether methadone dosage adjustments are needed on initiation of treatment with pegIFN alfa-2b for HCV in methadone-maintained HIV-positive patients.

METHODS

This prospective, nonrandomized, crossover study was conducted at the Albert Einstein College of Medicine and Montefiore Medical Center (Bronx, New York). Patients who were aged > or =18 years, coinfected with chronic HCV and HIV, and had been receiving methadone maintenance treatment (dosage, 40-200 mg/d PO) for at least 8 weeks prior to enrollment were eligible. We determined mean methadone C(max), T(max), Cn,in, AUC, and oral clearance (CL/F) values over a 24-hour period before (baseline) and after the administration of pegIFN alfa-2b 1.5 microg/kg SC (2 doses given 1 week apart). To determine differences in opiate withdrawal symptoms, one of the primary investigators administered the Subjective Opiate Withdrawal Scale (SOWS) and Objective Opiate Withdrawal Scale (OOWS) at baseline and 7, 14, and 21 days after the administration of the first dose. Study participants underwent weekly clinical evaluation for signs and symptoms of methadone withdrawal and for AEs of pegIFN.

RESULTS

Nine patients were included in the study (7 men, 2 women; 7 Hispanic, 2 black; mean [SD] age, 41 [8.3] years; mean [SD] weight, 75.0 [12.3] kg). We did not observe any significant changes from baseline in mean C(max), T(max), C(min), AUC, and CL/F values despite 80% power to detect a 30% change in either direction. Changes from baseline in SOWS and OOWS scores were not statistically significant. The only AEs reported were mild and consistent with those expected after pegIFN alfa-2b administration, such as inflammation at the injection site and mild, brief, flu-like symptoms.

CONCLUSION

Based on the results of this small, prospective, nonrandomized study, pegIFN alfa-2b did not appear to precipitate opioid withdrawal in this sample of methadone-maintained persons with HIV and chronic HCV coinfection; methadone dosage adjustments were unlikely to be needed.

Peginterferon-α2a in the treatment of chronic hepatitis C

Chronic hepatitis C virus infection occurs worldwide and affects over 2.7 million adults in North America. Current standard of care is the combination of pegylated (peg) interferon and ribavirin for 24 weeks in hepatitis C virus genotypes 2 or 3 and at least 48 weeks in chronic hepatitis C virus infection genotypes 1 or 4. Peginterferon-α2a is a 40-kDa linear pegylated molecule that alters the pharmacokinetic properties of unmodified interferon-α. In clinical trials evaluating the combination of peginterferon-α2a and ribavirin in chronic chronic hepatitis C virus infection, sustained virologic response rates have been achieved in 46–52% of patients with genotype 1 and 76–80% of patients with genotypes 2 or 3. Studies on the role of longer treatment duration and retreatment in prior nonresponders are in progress. The main toxicities of peginterferon-α2a are flu-like symptoms and neuropsychiatric disorders, especially depression and cytopenias, and are found in similar rates to those observed with regular inteferon. Future areas of study include the role of peginterferon-α2a in combination with the newer oral chronic hepatitis C virus infection active agents in development.

Peginterferon-??-2a (40kD)

Subcutaneous peginterferon-alpha-2a (40kD) [Pegasys] is an effective and reasonably well tolerated treatment for the management of patients with hepatitis B e antigen (HBeAg)-negative or -positive chronic hepatitis B. It was significantly more effective than lamivudine monotherapy at inducing sustained virological response and ALT normalisation in both HBeAg-negative and -positive patients. Notably, the addition of lamivudine to peginterferon-alpha-2a (40kD) conferred no additional benefit versus peginterferon-alpha-2a (40kD) monotherapy. Moreover, in HBeAg-positive patients significantly more peginterferon-alpha-2a (40kD) recipients experienced HBeAg seroconversion than lamivudine recipients. The position of peginterferon-alpha-2a (40kD) relative to other treatment options remains to be fully determined. In the meantime, this agent appears to be a valuable new option for the management of patients with HBeAg-negative or -positive chronic hepatitis B.