Treatment of opioid dependence and coinfection with HIV and hepatitis C virus in opioid-dependent patients: the importance of drug interactions between opioids and antiretroviral agents

Novel bivalent ligands carrying potential antinociceptive effects by targeting putative mu opioid receptor and chemokine receptor CXCR4 heterodimers

The functional interactions between opioid and chemokine receptors have been implicated in the pathological process of chronic pain. Mounting studies have indicated the possibility that a MOR-CXCR4 heterodimer may be involved in nociception and related pharmacologic effects. Herein we have synthesized a series of bivalent ligands containing both MOR agonist and CXCR4 antagonist pharmacophores with an aim to investigate the functional interactions between these two receptors. In vitro studies demonstrated reasonable recognition of designed ligands at both respective receptors. Further antinociceptive testing in mice revealed compound 1a to be the most promising member of this series. Additional molecular modeling studies corroborated the findings observed. Taken together, we identified the first bivalent ligand 1a showing promising antinociceptive effect by targeting putative MOR-CXCR4 heterodimers, which may serve as a novel chemical probe to further develop more potent bivalent ligands with potential application in analgesic therapies for chronic pain management.

An Innovative Physical Therapy Intervention for Chronic Pain Management and Opioid Reduction Among People Living with HIV

Chronic pain management has become a treatment priority for people living with HIV (PLH), and PLH may be at increased risk for opioid addiction. Physical therapy (PT) has been shown to be effective as a nonpharmacological method of chronic pain management; however, there is a gap in research examining the role of PT for chronic pain, especially as it relates to opioid reduction, in this patient population. This retrospective study evaluated pain level and opioid use before and after PT intervention among HIV-positive adults with chronic pain on chronic opioid therapy (n = 22). The study was conducted at a multidisciplinary AIDS clinic in Atlanta, GA. Outcome measures were self-reported pain on the numerical rating scale (0–10) and morphine milligram equivalents (MMEs), which measure opioid use. A majority of patients (77%) demonstrated a decrease in pain by the conclusion of the study period; however, only 18.2% of patients reported decreased pain as well as a decrease in MMEs. The most common PT treatments used among the patients with a decrease in pain and/or opioid use included home exercise programs, manual therapy, and self-pain management education. Eighty percent of the participants who did not decrease opioid use reported a decrease or elimination of pain by the end of the PT intervention. This reflects the need for careful consideration of the complexity of opioid use and addiction, and the importance of a multidisciplinary team to best serve the needs of PLH aiming to decrease chronic pain and opioid use.

Opioid and neuroHIV Comorbidity - Current and Future Perspectives

With the current national opioid crisis, it is critical to examine the mechanisms underlying pathophysiologic interactions between human immunodeficiency virus (HIV) and opioids in the central nervous system (CNS). Recent advances in experimental models, methodology, and our understanding of disease processes at the molecular and cellular levels reveal opioid-HIV interactions with increasing clarity. However, despite the substantial new insight, the unique impact of opioids on the severity, progression, and prognosis of neuroHIV and HIV-associated neurocognitive disorders (HAND) are not fully understood. In this review, we explore, in detail, what is currently known about mechanisms underlying opioid interactions with HIV, with emphasis on individual HIV-1-expressed gene products at the molecular, cellular and systems levels. Furthermore, we review preclinical and clinical studies with a focus on key considerations when addressing questions of whether opioid-HIV interactive pathogenesis results in unique structural or functional deficits not seen with either disease alone. These considerations include, understanding the combined consequences of HIV-1 genetic variants, host variants, and μ-opioid receptor (MOR) and HIV chemokine co-receptor interactions on the comorbidity. Lastly, we present topics that need to be considered in the future to better understand the unique contributions of opioids to the pathophysiology of neuroHIV. Graphical Abstract Blood-brain barrier and the neurovascular unit. With HIV and opiate co-exposure (represented below the dotted line), there is breakdown of tight junction proteins and increased leakage of paracellular compounds into the brain. Despite this, opiate exposure selectively increases the expression of some efflux transporters, thereby restricting brain penetration of specific drugs.

Early Discontinuation of Buprenorphine Therapy for Opioid Use Disorder Among Privately Insured Adults

OBJECTIVE

This study examined the temporal relationship between early discontinuation of buprenorphine treatment and health care expenditures before and after treatment initiation.

METHODS

MarketScan commercial claims for patients who initiated buprenorphine for opioid use disorder in 2013 and had continuous insurance for the subsequent 12 months (N=6,444) were used to examine the relationship between treatment retention and health care expenditures before and after buprenorphine initiation. Analysis of covariance and generalized linear models (with gamma distribution/log link) were used to compare expenditures across four buprenorphine-retention groups (0-3, 3-6, 6-12, and 12 or more months).

RESULTS

Average total health care expenditures in the 3 months prior to buprenorphine initiation ranged from a high of $7,588 among those with the shortest retention to $4,929 among those with the longest retention (p<0.001). In the 12 months after buprenorphine initiation, total health care expenditures averaged $26,332 per year, with $2,916 (11.1%) in out-of-pocket expenditures. Average annual expenditures for medication were highest among patients with the longest buprenorphine retention, and total health care expenditures were highest among those with the shortest retention. Expenditures for health care services other than medication were highest among those with early discontinuation both before the initiation of buprenorphine and during the initial period after initiation but not in subsequent quarters.

CONCLUSIONS

Poorer treatment retention among privately insured adults was associated with greater clinical and financial burdens that preceded and continued during the period shortly following treatment initiation, suggesting that cost burdens may contribute to poor retention among privately insured adults.

Adherence among HIV-positive injection drug users undergoing methadone treatment in Taiwan

AIMS

The study aims were to investigate adherence to methadone maintenance treatment (MMT) and to identify associated clinical factors in patients who inject drugs diagnosed with human immunodeficiency virus (HIV) infection in Taiwan.

METHODS

Data were from the National Health Surveillance System on HIV and the National Drug Treatment System on MMT. HIV-positive people who inject drugs (HIVPWID) were defined as the study population. Information obtained included age, sex, education, marital status, employment, methadone dose, and date of diagnosis of HIV infection. Adherence was defined as taking methadone for the past 90, 180 and 365 days, then categorized as high (> 90%), moderate (51 to 90%), or low (<=50%) adherent respectively.

RESULTS

Of 1641 HIVPWID registered in the datasets from 2007 to 2012, 961 (58.56%) had received MMT. For HIVPWID evaluated at 90 days (n = 951), 271 (28.5%), 382 (40.2%), and 298 (31.3%) were classified as high, moderate, and low adherent respectively. For HIVPWID evaluated at 180 days (n = 936), 190 (20.3%), 349 (37.3%), and 397 (42.4%) were classified as high, moderate, and low adherent respectively. For HIVPWID evaluated at 365 days (n = 919), 133 (14.5%), 271 (29.5%), and 515 (56.0%) were classified as high, moderate, and low adherent respectively. After controlling for sociodemographics, results showed that methadone dose, location of MMT clinic, and date of HIV diagnosis were significantly associated with MMT adherence.

CONCLUSIONS

Study findings underscore the importance to MMT adherence of methadone dosage, early diagnosis of patient's HIV infection, and area of patient residence.

Methadone serum concentrations and influencing factors: A naturalistic observational study

RATIONALE

Although methadone maintenance treatment (MMT) has long been used for opioid addiction, our knowledge on its pharmacokinetics is still limited.

OBJECTIVES

We aimed to investigate effects of age, gender, and various co-medications on methadone serum concentration-to-dose ratio (CDR) in a naturalistic setting.

METHODS

In total, 4425 routine serum methadone concentrations obtained from 1691 MMT patients in the period October 1999 to July 2017 were included. Information about doses, age, gender, and concurrent medications was available in the laboratory database at the Department of Clinical Pharmacology at St. Olav University Hospital in Trondheim, Norway. A log-linear mixed model was used when analyzing the data.

RESULTS

Mean age was 38.4 (range, 21-78) years and 70% were men. Mean CDR was 332 (range, 7-1776) (ng/mL)/(100 mg/d). Concomitant medication with at least one out of totally 170 drugs was recorded in 26% of the samples. CDRs were significantly lower in women (- 9%; confidence interval (CI), - 13%, - 4%; p = 0.001) and with concurrent use of CYP inducers (- 36%; CI, - 44%, - 28%; p < 0.001), but higher using CYP3A4 inhibitors as co-medications (+ 36%; CI, + 10%, + 68%; p = 0.005).

CONCLUSIONS

Our results warrant taking into consideration gender differences in methadone metabolism as well as the impact of potential drug-drug interactions to obtain an optimal therapeutic effect and avoid adverse effects in MMT. Although the clinical implications of the altered drug levels require further study, our results call for close clinical monitoring of all patients undergoing MMT, preferably along with laboratory measurements of methadone serum concentrations.

Opioid-Related Diagnoses and Concurrent Claims for HIV, HBV, or HCV among Medicare Beneficiaries, United States, 2015

Unsterile opioid injection increases risk for infection transmission, including HIV, hepatitis B virus (HBV), or hepatitis C virus (HCV). We assess prevalence of and risk factors associated with opioid overdose and infections with HIV, HBV, or HCV among Medicare beneficiaries with opioid-related fee-for-service claims during 2015. We conducted a cross-sectional analysis to estimate claims for opioid use and overdose and HIV, HBV, or HCV infections, using data from US Medicare fee-for-service claims. Beneficiaries with opioid-related claims had increased odds for HIV (2.3; 95% confidence interval (CI), 2.3–2.4), acute HBV (6.7; 95% CI, 6.3–7.1), chronic HBV (5.0; 95% CI, 4.7–5.4), acute HCV (9.6; 95% CI, 9.2–10.0), and chronic HCV (8.9; 95% CI, 8.7–9.1). Beneficiaries with opioid-related claims and for HIV, HBV, or HCV infection, respectively, had a 1.1–1.9-fold odds for having a claim for opioid overdose. Independent risk factors for opioid overdose and each selected infection outcome included age, sex, race/ethnicity, region, and residence in a high-vulnerability county. Having opioid-related claims and selected demographic attributes were independent, significant risk factors for having HIV, HBV, or HCV claims among US Medicare beneficiaries. These results might help guide interventions intended to reduce incidences of HIV, HCV, and HBV infections among beneficiaries with opioid-related claims.

Understanding and treating opioid use disorders in lesbian, gay, bisexual, transgender, and queer populations

Although little is known about the specific burden of the opioid epidemic on lesbian, gay, bisexual, transgender, and queer (LGBTQ) populations, there is evidence to suggest that opioid use disorders are disproportionately prevalent in the LGBTQ community. In this commentary, we present an overview of the current state of evidence on opioid use and misuse among LGBTQ-identified people in the United States and suggest ways to adapt behavioral health interventions to the specific needs of this population. Programs that integrate behavioral health with primary care, address minority stress, and use a trauma-informed approach have the most potential to produce effective, long-term benefits for LGBTQ-identified people with opioid use disorders.

Medications for Treatment of Opioid Use Disorder among Persons Living with HIV

PURPOSE OF REVIEW

Recent HIV outbreaks have occurred as a result of the current US opioid epidemic. Providing medications for opioid use disorder (MOUD) with methadone, buprenorphine, and extended-release naltrexone is essential to achieving optimal HIV treatment outcomes including viral suppression and retention in treatment. This review describes the pharmacology of MOUD with specific attention to interactions with antiretroviral therapy, and to the effect of MOUD on HIV treatment outcomes.

RECENT FINDINGS

Methadone and buprenorphine both improve HIV viral suppression, adherence to antiretroviral therapy, and overall mortality for persons with opioid use disorder (OUD). Extended-release naltrexone has been most extensively studied in persons with HIV leaving incarcerated settings, and improves HIV viral suppression in that context. Strategies that integrate MOUD and HIV treatment are crucial to optimize viral suppression. The differing pharmacokinetic and delivery characteristics of these MOUD offer diverse options. Given the chronic and relapsing nature of both HIV and OUD, long-term approaches are required.

Pharmacokinetic Considerations for Combining Antiretroviral Therapy, Direct-Acting Antiviral Agents for Hepatitis C Virus, and Addiction Treatment Medications

There are many factors that can affect the pharmacokinetics (PK) of drugs. Pathophysiological changes from disease states can alter the mechanisms that control the PK of antiretrovirals (ARVs), direct-acting antivirals (DAAs), and addiction treatment medications. Drug-drug interaction pathways of certain ARVs and DAAs can be very complex, with agents being substrates, inhibitors, or inducers of multiple metabolic and transporter pathways. Buprenorphine and methadone may be used in HIV- and hepatitis C virus (HCV)-infected patients and may also be affected by drug interactions. Current research is focused on novel PK analyses, which aim to describe the PK of agents within organs that host the infection of interest, such as within hepatocytes during treatment for HCV. Modeling techniques allow for the prediction of drug PK in specific organs and the plasma compartment. This review will provide a summary of these areas while exploring PK considerations for ARVs, DAAs, and addiction treatment medications.

Combined Effect of CYP2B6 Genotype and Other Candidate Genes on a Steady-State Serum Concentration of Methadone in Opioid Maintenance Treatment

BACKGROUND

A considerable interindividual variability in methadone pharmacokinetics is seen in patients on methadone maintenance treatment. The aim of this study was to clarify the impact of the reduced function CYP2B6*6 variant allele together with variants in other candidate genes on a steady-state methadone concentration in a naturalistic setting.

METHODS

Information of methadone serum concentration, dose, age, sex, and CYP2C9, CYP2C19, and CYP2D6 genotypes were collected from a routine therapeutic drug monitoring database, whereas variant alleles in CYP2B6 and CYP3A5 were retrospectively genotyped. Linear mixed model analyses were used to study the impact of gene variants on methadone serum concentration/dose (C/D) ratios, including age, sex, and time since the last dose intake as covariates.

RESULTS

Overall, 155 serum samples from 62 patients were included in this study. The estimated mean methadone C/D ratios was 17.8 nmol·L·mg for homozygous carriers of CYP2B6*6, which was significantly (P < 0.001) higher than noncarriers (9.2 nmol·L·mg). There was no difference in C/D ratios between heterozygous carriers of CYP2B6*6 (9.1 nmol·L·mg) and noncarriers. An increase in mean methadone C/D ratios was also seen for homozygous carriers of CYP3A5*3 and heterozygous carriers of CYP2C9*2 or *3 and CYP2C19*2 or *3.

CONCLUSIONS

Patients homozygous for CYP2B6*6 had a >90% higher methadone C/D ratio. Genotyping of CYP2B6 may therefore be of value when assessing dose requirements in methadone maintenance treatment.

Methadone treatment, severe food insecurity, and HIV-HCV co-infection: A propensity score matching analysis

BACKGROUND

Severe food insecurity (FI) is common among individuals living with HIV-hepatitis C virus (HCV) co-infection. We hypothesize that the injection of opioids is partly responsible for the association between injection drug use and severe FI. Therefore, this analysis examines whether methadone maintenance treatment for opioid dependence is associated with a lower risk of severe FI.

METHODS

We used biannual data from the Canadian Co-infection Cohort (N = 608, 2012-2015). Methadone treatment (exposure) was self-reported and severe FI (outcome) was measured using the Household Food Security Survey Module. To quantify the association between methadone treatment and severe FI, we estimated an average treatment effect on the treated (marginal risk difference [RD]) using propensity score matching.

RESULTS

Among participants, 25% experienced severe FI in the six months preceding the first time-point in the analytical sample and 5% concurrently reported receiving methadone treatment. Injection of opioids in the six months preceding the treatment and outcome measurements was much higher among those who received methadone treatment (39% vs. 12%). Among the treated participants, 97% had injected opioids in their lifetimes. After propensity score matching, the average risk of experiencing severe FI is 12.3 percentage-points lower among those receiving methadone treatment, compared to those who are not receiving treatment (marginal RD = -0.123, 95% CI = -0.230, -0.015).

CONCLUSIONS

After adjustment for socioeconomic, sociodemographic, behavioural, and clinical confounders, methadone treatment is associated with a lower risk of severe FI. This finding suggests that methadone treatment may mitigate severe FI in this vulnerable subset of the HIV-positive population.

Patterns of drug use and HIV infection among adults in a nationally representative sample

BACKGROUND

Little is known about drug use patterns among people living with HIV in comparison to an uninfected group in the general population. The aim of this study was to investigate the association between legal and illegal drug use and HIV infection in a nationally representative sample of adults in the United States.

METHODS

Public use data files (2005-2014) from the National Survey on Drug Use and Health (NSDUH) were used. Respondents were asked whether a medical professional had ever told them that they had HIV/AIDS. Ever (lifetime), past-year, and past month use of cigarettes, alcohol, marijuana, cocaine, heroin, hallucinogens, inhalants, and nonmedical use of psychotherapeutics was assessed. Logistic regression was used to estimate adjusted odds ratios (aOR) of the relationship between drug use and HIV infection, adjusting for demographics.

RESULTS

Of 377,787 respondents age 18 and older, 548 (0.19%) were categorized as HIV-infected. Ever use of cigarettes, tobacco, marijuana, cocaine, heroin, hallucinogens, inhalants, and psychotherapeutics was higher in HIV-infected individuals compared to HIV-uninfected individuals after adjustment for sex, age, race/ethnicity, education, total family income, and marital status. Past year and past month use was also higher for HIV-infected individuals for all substances aside from alcohol.

CONCLUSIONS

In a nationally representative sample, there are higher levels of drug use and DSM-IV dependence among the HIV-infected population compared to the HIV-uninfected population. This is of concern because drug use and dependence can impede engagement in HIV care and adherence to antiretroviral therapy.

HCV/HIV coinfection among people who inject drugs and enter opioid substitution treatment in Greece: prevalence and correlates

Background

HCV/HIV coinfection in people who inject drugs is a public health issue, which presents a variety of challenges to healthcare providers. The determinants of HCV/HIV coinfection in this population are nonetheless not well known. The aim of the present study is to identify the factors associated with HCV/HIV coinfection in people who inject drugs and enter drug-related treatment.

Methods

Linked serological and behavioral data were collected from people who entered 38 opioid substitution treatment clinics in central and southern Greece between January and December 2013. Three mutually exclusive groups were defined based on the presence of HCV and HIV antibodies. Group 1 clients had neither infection, Group 2 had HCV but not HIV, and Group 3 had HCV/HIV coinfection. Multinomial logistic regression analyses identified differences between groups according to socio-demographic, drug use and higher-risk behavioral characteristics.

Results

Our study population consisted of 580 people who injected drugs in the past 12 months (79.8 % males, with median age 36 years).79.4 % were HCV and 15.7 % HIV infected. Of those with complete serological data in both HCV and HIV indicators, 20.4 % were uninfected, 64.0 % HCV monoinfected, and 14.9 % HCV/HIV coinfected. HCV infection with or without HIV coinfection was positively associated with living alone or with a spouse/partner without children, prior incarceration, drug injecting histories of ≥10 years, and syringe sharing in the past 12 months, and negatively associated with never having previously been tested for HCV. HCV/HIV coinfection, but not HCV infection alone, was positively associated with residence in urban areas (relative risk ratio [RRR] = 4.8, 95 % confidence interval [CI]: 1.7–13.7, p = 0.004) and averaging >3 injections a day in the past 30 days (RRR = 4.5, 95 % CI: 1.6–12.8, p = 0.005), and negatively associated with using a condom in the last sexual intercourse.

Conclusions

People who inject drugs and live in urban areas and inject frequently have higher risk of coinfection. Findings highlight the need for scaling-up needle and syringe programs in inner city areas and promoting access of this population to screening and treatment, especially in prisons. The protective role of living with parents and children could inform the implementation of indicated interventions.

Determination and Validation of a Solid-phase Extraction Gas Chromatography-mass Spectrometry for the Quantification of Methadone and Its Principal Metabolite in Human Plasma

This study aimed to develop a solid-phase extraction gas chromatography-selected ion monitoring-mass spectrometry method for the determination of methadone (MDN) and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in human plasma. The linear response was obtained over the concentration range from 10 to 2000 ng/mL for MDN and EDDP. The absolute recoveries of MDN and EDDP were 95.9%–98.9% and 94.8%–102.4%, with relative standard deviation (RSD) ranging from 1.8% to 2.7% and 1.8% to 3.9%, respectively. The intra- and interday precisions were found to be less than 5% for both analytes. The limits of detection of MDN and EDDP were 4 and 5 ng/mL, respectively. The presented method was convenient for therapeutic drug monitoring and pharmacokinetic studies in patients on heroin-assisted MDN therapy.

Association between hepatitis C virus and opioid use while in buprenorphine treatment: preliminary findings

BACKGROUND

The prevalence of hepatitis-C-virus (HCV) infections is high among opioid-dependent individuals. Prior research on the simultaneous treatment of both conditions has primarily assessed success as it pertains to HCV. However, it has been noted that favorable substance use therapy outcomes may improve the likelihood of HCV-treatment initiation and success. Therefore, current guidelines for the treatment of HCV among illicit drug users suggest that treatment for addiction be given the highest priority.

OBJECTIVES

To determine whether opioid-dependent participants in a clinical trial of buprenorphine-treatment tapering regimens, who tested positive for the HCV antibody, experienced significantly different levels of opioid abstinence than those not infected.

METHODS

Data came from the National Drug Abuse Treatment Clinical Trial Network study 0003. 516 eligible opioid-dependent participants were randomized to either a 7-day or 28-day buprenorphine tapering schedule following a 4-week buprenorphine stabilization period. Generalized estimating equations were used to test the research question.

RESULTS

Participants with the HCV antibody were significantly less likely to submit opioid-negative urine analyses during and/or immediately following active treatment [OR = 0.69; CI = 0.51-0.93], indicating a higher rate of opioid use among this group.

CONCLUSION

Individualized opioid-dependence treatment strategies may be required for opioid-dependent individuals who test positive for the HCV antibody in order to ensure resources for both opioid-dependence and HCV therapies are used efficiently.

HIV-gp120 and physical dependence to buprenorphine

BACKGROUND

Opioids are among the most effective and commonly used analgesics in clinical practice for severe pain. However, the use of opioid medications is clinically limited by several adverse properties including dependence. While opioid dependence is a complex health condition, the treatment of HIV-infected individuals with opioid dependence presents additional challenges. The goal of this study was to examine the physical dependence to buprenorphine in the context of HIV.

METHODS

Young adult male rats (Sprague-Dawley) were pretreated with HIV-1 envelope glycoprotein 120 (gp120) injected into the periaqueductal gray area (PAG) and we examined the impact on physical dependence to opioid.

RESULTS

It was found that the physical dependence to methadone occurred earlier than that to buprenorphine, and that gp120 did not enhance or precipitate the buprenorphine withdrawal.

CONCLUSION

The results suggest that buprenorphine could be the better therapeutic option to manage opioid dependence in HIV.

Considerations on the role of buprenorphine in recovery from heroin addiction from a UK perspective

The United Kingdom Drug Strategy emphasises recovery as a key focus in the treatment of drug dependence. A framework for recovery is defined in the Recovery-Orientated Drug Treatment report, written by an expert working group, and comprises four key phases: engagement and stabilisation, including the establishment of treatment goals; preparation for change, involving engagement in psychosocial and pharmacological interventions; active change, including detoxification and medical withdrawal; and completion, including interventions that strengthen community integration. A body of evidence supports the benefits of buprenorphine, a partial agonist at mu opioid receptors, in supporting individualised recovery based on this framework, specifically in relation to the potential for rapid stabilisation, flexibility to transition to other treatment options or achieve abstinence, effective blocking of on-top use of illicit drugs, the treatment of comorbidities through the minimisation of drug-drug interactions, and a good safety profile. In addition, the newer abuse-deterrent formulation of buprenorphine combined with the opioid antagonist naloxone is likely to strengthen recovery-orientated systems of care due to its potential to reduce misuse and diversion. Progress through the recovery journey and the ability to sustain recovery will depend on individual needs and goals and on the amount of recovery capital that individuals have developed.

Statement of the American Society Of Addiction Medicine Consensus Panel on the use of buprenorphine in office-based treatment of opioid addiction

OBJECTIVES

Opioid addiction affects over 2 million patients in the United States. The advent of buprenorphine and the passage of the Drug Addiction Treatment Act in 2000 have revolutionized the opioid treatment delivery system by granting physicians the ability to administer office-based opioid treatment (OBOT), thereby giving patients greater access to treatment. The purpose of this consensus panel was to synthesize the most current evidence on the use of buprenorphine in the office-based setting and to make recommendations that will enable and allow additional physicians to begin to treat opioid-addicted individuals.

METHODS

Literature published from 2000 to 2009 was searched using the PubMed search engine and yielded over 375 articles published in peer-reviewed journals, including some that were published guidelines. These articles were submitted to a consensus panel composed of researchers, educators, and clinicians who are leaders in the field of addiction medicine with specific expertise in the use of OBOT. The panel discussed results and agreed upon consensus recommendations for several facets of OBOT.

RESULTS

: On the basis of the literature review and consensus discussions, the panel developed a series of findings, conclusions, and recommendations regarding the use of buprenorphine in office-based treatment of opioid addiction.

CONCLUSIONS

Therapeutic outcomes for patients who self-select office-based treatment with buprenorphine are essentially comparable to those seen in patients treated with methadone programs. There are few absolute contraindications to the use of buprenorphine, although the experience and skill levels of treating physicians can vary considerably, as can access to the resources needed to treat comorbid medical or psychiatric conditions--all of which affect outcomes. It is important to conduct a targeted assessment of every patient to confirm that the provider has resources available to meet the patient's needs. Patients should be assessed for a broad array of biopsychosocial needs in addition to opioid use and addiction, and should be treated, referred, or both for help in meeting all their care needs, including medical care, psychiatric care, and social assistance. Current literature demonstrates promising efficacy of buprenorphine, though further research will continue to demonstrate its effectiveness for special populations, such as adolescents, pregnant women, and other vulnerable populations. Since the time of this review, several new studies have provided new data to continue to improve our understanding of the safety and efficacy of buprenorphine for special patient populations.

Treatment of opioid dependence in the setting of pregnancy

Opioid dependence in the setting of pregnancy provides a distinct set of challenges for providers. Treatment plans must take into consideration psychiatric and medical comorbidities while balancing risks and benefits for the maternal-fetal dyad. Treatment is best offered through a comprehensive treatment program designed to effectively deliver opioid agonist maintenance treatment along with psychosocial and obstetric care. As misuse of prescription analgesics increases in the United States, identification of the problem in pregnancy will become more important because this misuse is expected to lead to an increased prevalence of opioid dependence in pregnancy. Buprenorphine as maintenance treatment of opioid dependence during pregnancy has promise and may offer some benefits, but more research is needed, especially regarding induction of actively addicted women during pregnancy. For the present, methadone maintenance remains the standard of care for agonist treatment of opioid dependence in pregnancy against which other treatments must be compared.

Design and synthesis of a bivalent ligand to explore the putative heterodimerization of the mu opioid receptor and the chemokine receptor CCR5

The bivalent ligand approach has been utilized not only to study the underlying mechanism of G protein-coupled receptors dimerization and/or oligomerization, but also to enhance ligand affinity and/or selectivity for potential treatment of a variety of diseases by targeting this process. Substance abuse and addiction have made both the prevention and the treatment of human immunodeficiency virus (HIV) infection more difficult to tackle. Morphine, a mu opioid receptor (MOR) agonist, can accelerate HIV infection through up-regulating the expression of the chemokine receptor CCR5, a well-known co-receptor for HIV invasion to the host cells and this has been extensively studied. Meanwhile, two research groups have described the putative MOR-CCR5 heterodimers in their independent studies. The purpose of this paper is to report the design and synthesis of a bivalent ligand to explore the biological and pharmacological process of the putative MOR-CCR5 dimerization phenomenon. The developed bivalent ligand thus contains two distinct pharmacophores linked through a spacer; ideally one of which will interact with the MOR and the other with the CCR5. Naltrexone and Maraviroc were selected as the pharmacophores to generate such a bivalent probe. The overall reaction route to prepare this bivalent ligand was convergent and efficient, and involved sixteen steps with moderate to good yields. The preliminary biological characterization showed that the bivalent compound 1 retained the pharmacological characteristics of both pharmacophores towards the MOR and the CCR5 respectively with relatively lower binding affinity, which tentatively validated our original molecular design.

Rifampin, but not rifabutin, may produce opiate withdrawal in buprenorphine-maintained patients

BACKGROUND

This series of studies examines the pharmacokinetic/pharmacodynamic interactions between buprenorphine, an opioid partial agonist increasingly used in treatment of opioid dependence, and rifampin, a medication used as a first line treatment for tuberculosis; or rifabutin, an alternative antituberculosis medication.

METHODS

Opioid-dependent individuals on stable doses of buprenorphine/naloxone underwent two, 24-h blood sampling studies: (1) for buprenorphine pharmacokinetics and (2) following 15 days of rifampin 600 mg daily or rifabutin 300 mg daily for buprenorphine and rifampin or rifabutin pharmacokinetics.

RESULTS

Rifampin administration produced significant reduction in plasma buprenorphine concentrations (70% reduction in mean area under the curve (AUC); p=<0.001) and onset of opiate withdrawal symptoms in 50% of participants (p=0.02). While rifabutin administration to buprenorphine-maintained subjects resulted in a significant decrease in buprenorphine plasma concentrations (35% decrease in AUC; p<0.001) no opiate withdrawal was seen. Compared with historical control data, buprenorphine had no significant effect on rifampin pharmacokinetics, but was associated with 22% lower rifabutin mean AUC (p=0.009), although rifabutin and its active metabolite concentrations remained in the therapeutic range.

CONCLUSIONS

Rifampin is a more potent inducer of buprenorphine metabolism than rifabutin with pharmacokinetic and pharmacodynamic adverse consequences. Those patients requiring rifampin treatment for tuberculosis and receiving buprenorphine therapy are likely to require an increase in buprenorphine dose to prevent withdrawal symptoms. Rifabutin administration was associated with decreases in buprenorphine plasma concentrations, but no clinically significant adverse events were observed.

Therapeutic drug monitoring of protease inhibitors and efavirenz in HIV-infected individuals with active substance-related disorders

BACKGROUND

Achieving targeted antiretroviral (ARV) plasma concentrations during long-term treatment in human immunodeficiency virus (HIV)-infected patients with substance-related disorders (SRDs) may be challenging due to a number of factors, including medication adherence, coinfection with hepatitis B or C virus, medication intolerance, and drug interactions. One approach to investigate these factors is to conduct therapeutic drug monitoring to measure ARV exposure during treatment. The objective of this study was to utilize therapeutic drug monitoring to compare efavirenz (EFV) and protease inhibitor pharmacokinetics in patients with and without SRDs.

METHODS

This was a multicenter, cross-sectional open-label study in patients with HIV-1 infection receiving antiretroviral therapy (ART), with active (n=129) or without (n=146) SRD according to National Institute on Drug Abuse criteria. Two hundred seventy-five subjects who were receiving either protease inhibitor-based or EFV-based ART regimens for >6 months were enrolled at 4 HIV treatment centers with an equal distribution of SRD and non-SRD at each site. The patients were instructed during enrollment visits with regard to the importance of adherence before and after study visits. Demographics and routine clinical laboratory tests were recorded.

RESULTS

Among the 275 patients, 47% had SRD with at least 1 substance. There were no significant differences between SRD and non-SRD groups for race, gender, age, or CD4 count at entry. A significantly higher proportion of patients with SRD had an entry HIV RNA plasma concentration>75 copies per milliliter compared with patients without SRD (40% vs 28%, P=0.044). Logistic regression modeling revealed an association between HIV RNA plasma concentration and African American race (P=0.017). A significantly higher proportion of SRDs also had an EFV or protease inhibitor trough concentration below the desired range (23% vs 9%, P=0.048). Significantly lower trough concentrations were noted in patients with SRDs receiving atazanavir (0.290 vs 0.976 μg/mL) or lopinavir (3.75 vs 5.30 μg/mL).

CONCLUSIONS

The pharmacokinetic data indicate differences between HIV-infected patients with and without SRDs that may influence viral load suppression during long-term ART. These findings require additional investigation in a randomized design with more intensive pharmacokinetic assessment to identify individual factors that are contributing to suboptimal ARV exposure in patients with SRDs.

Interactions between buprenorphine and antiretrovirals: nucleos(t)ide reverse transcriptase inhibitors (NRTI) didanosine, lamivudine, and tenofovir

To improve outcomes among injection drug users with HIV and/or chronic hepatitis B, it is important to identify drug interactions between antiretroviral and opiate therapies. We report the results of a study designed to examine the interaction between buprenorphine and the nucleos(t)ide reverse transcriptase inhibitors (NRTI) didanosine (ddI), lamivudine (3TC), and tenofovir (TDF). Opioid-dependent, buprenorphine/naloxone-maintained, HIV-negative volunteers (n = 27) participated in two 24-hour sessions to determine (1) pharmacokinetics of buprenorphine alone and (2) pharmacokinetics of both buprenorphine and either ddI, 3TC, or TDF. Among buprenorphine/naloxone-maintained study participants, no significant changes in buprenorphine pharmacokinetics were observed following ddI, 3TC, or TDF administration. Buprenorphine had no significant effect on NRTI concentrations. Concomitant use of buprenorphine with ddI, 3TC, or TDF results in neither a significant pharmacokinetic nor pharmacodynamic interaction.

Lack of clinically significant drug interactions between nevirapine and buprenorphine

This study was conducted to determine whether drug interactions of clinical importance occur between buprenorphine, an opioid partial agonist medication used in treatment of opioid dependence, and the nonnucleoside reverse transcriptase inhibitor (NNRTI) nevirapine. Opioid-dependent, buprenorphine/naloxone-maintained, HIV-negative volunteers (n = 7) participated in 24-hour sessions to determine the pharmacokinetics of buprenorphine alone and of buprenorphine and nevirapine following administration of 200 mg nevirapine daily for 15 days. Opiate withdrawal symptoms, cognitive effects, and adverse events were determined prior to and following nevirapine administration. Modest decreases were observed for AUC for buprenorphine and its metabolites. There was a trend for more rapid clearance of both buprenorphine (p = .08) and buprenorphine-3-glucuronide (p = .08). While no single effect reached statistical significance, the joint probability that the consistent declines in all measures of exposure were due to chance was extremely low, indicating that nevirapine significantly reduces overall exposure to buprenorphine and buprenorphine metabolites. Clinically significant consequences of the interaction were not observed. Buprenorphine did not alter nevirapine pharmacokinetics. Dose adjustments of either buprenorphine or nevirapine are not likely to be necessary when these drugs are coadministered for the treatment of opiate dependence and HIV disease.

Drug interactions between antiretroviral medications and medications used in the treatment of drug addiction: research needs

Today substance dependence is one of the major public health problems in the world with millions of people abusing legal and illegal drugs. In addition, almost one-third of the world's population suffers with one or more infections. Both drugs of abuse and infections are associated with serious medical and health consequences, some of which may be exacerbated by the occurrence of pharmacokinetic and/or pharmacodynamic interactions between medications used in the treatment of these conditions when they co-occur. This review briefly discusses issues surrounding clinical management related to drug interactions experienced by substance abusing patients. The emphasis of this paper is on the research needed to further study the extent, nature, and underlying molecular/genetic mechanism(s) of interactions between drugs of abuse, medications used in the treatment of drug addiction, and co-occurring infections.

Pharmacogenomics of CYP3A: considerations for HIV treatment

The understanding of the cytochrome P450 3A SNP in antiretroviral therapy is important, because it is highly inducible, extremely polymorphic and metabolizes many of the drugs that are key components of highly active antiretroviral therapy regimens. This enzyme is prolific and promiscuous towards drug and xenobiotic substrate selection and it is also unpredictable among individuals, having a 5- to 20-fold variability in its ability to contribute to drug clearance. The importance of human CYP3A pharmacogenetics is also gaining attention in other established areas of pharmacotherapy as it may contribute to the goal of predicting efficacy and/or toxicity, specifically with the discovery of null allele CYP3A4*20. This review summarizes the current understanding, implications of genetic variation in the CYP3A enzymes, the central role of CYP3A in linking human genetics, the pharmacokinetics and resulting pharmacodynamic responses to certain antiretroviral drugs, and their eventual place in applied clinical pharmacotherapy.

Drug interactions of clinical importance among the opioids, methadone and buprenorphine, and other frequently prescribed medications: a review

Drug interactions are a leading cause of morbidity and mortality. Methadone and buprenorphine are frequently prescribed for the treatment of opioid addiction. Patients needing treatment with these medications often have co-occurring medical and mental illnesses that require medication treatment. The abuse of illicit substances is also common in opioid-addicted individuals. These clinical realities place patients being treated with methadone and buprenorphine at risk for potentially toxic drug interactions. A substantial literature has accumulated on drug interactions between either methadone or buprenorphine with other medications when ingested concomitantly by humans. This review summarizes current literature in this area.

Effect of rifampin and nelfinavir on the metabolism of methadone and buprenorphine in primary cultures of human hepatocytes

We tested the hypothesis that primary cultures of human hepatocytes could predict potential drug interactions with methadone and buprenorphine. Hepatocytes (five donors) were preincubated with dimethyl sulfoxide (DMSO) (vehicle), rifampin, or nelfinavir before incubation with methadone or buprenorphine. Culture media (0-60 min) was analyzed by liquid chromatography-tandem mass spectrometry for R- and S-methadone and R- and S-2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) or for buprenorphine, norbuprenorphine, and their glucuronides [buprenorphine-3-glucuronide (B-3-G) and norbuprenorphine-3-glucuronide (N-3-G)]. R- and S-EDDP were detected in three of five, four of five, and five of five media from cells pretreated with DMSO, nelfinavir, and rifampin. R-EDDP increased 3.1- and 26.5-fold, and S-EDDP increased 2.5- and 21.3-fold after nelfinavir and rifampin. The rifampin effect was significant. B-3-G production was detected in media of all cells incubated with buprenorphine and accounted for most of the buprenorphine loss from culture media; it was not significantly affected by either pretreatment. Norbuprenorphine and N-3-G together were detected in three of five, four of five, and five of five donors pretreated with DMSO, nelfinavir and rifampin, and norbuprenorphine in one of five, one of five, and two of five donors. Although there was a trend for norbuprenorphine (2.8- and 4.9-fold) and N-3-G (1.7- and 1.9-fold) to increase after nelfinavir and rifampin, none of the changes were significant. To investigate low norbuprenorphine production, buprenorphine was incubated with human liver and small intestine microsomes fortified to support both N-dealkylation and glucuronidation; N-dealkylation predominated in small intestine and glucuronidation in liver microsomes. These studies support the hypothesis that methadone metabolism and its potential for drug interactions can be predicted with cultured human hepatocytes, but for buprenorphine the combined effects of hepatic and small intestinal metabolism are probably involved.

Efavirenz: a decade of clinical experience in the treatment of HIV

Efavirenz, a non-nucleoside reverse transcriptase inhibitor, has been an important component of the treatment of HIV infection for 10 years and has contributed significantly to the evolution of highly active antiretroviral therapy (HAART). The efficacy of efavirenz has been established in numerous randomized trials and observational studies in HAART-naive patients, including those with advanced infection. In the ACTG A5142 study, efavirenz showed greater virological efficacy than the boosted protease inhibitor (PI), lopinavir. Efavirenz is more effective as a third agent than unboosted PIs or the nucleoside analogue abacavir. Some, but not all, studies have suggested that efavirenz (added to two nucleoside reverse transcriptase inhibitors) is more effective than nevirapine. Virological and immunological responses achieved with efavirenz-based HAART have been maintained for 7 years. Dosing convenience predicts adherence, and studies have demonstrated that patients can be switched from PI-based therapy to simplified, once-daily efavirenz-based regimens without losing virological control. The one-pill, once-daily formulation of efavirenz plus tenofovir and emtricitabine offers a particular advantage in this regard. Efavirenz also retains a role after failure of a first PI-based regimen. Efavirenz is generally well tolerated: rash and neuropsychiatric disturbances are the most notable adverse events. Neuropsychiatric disturbances generally develop early in treatment and they tend to resolve with continued administration, but they are persistent and troubling in a minority of patients. Efavirenz has less effect on plasma lipid profiles than some boosted PIs. Lipodystrophy can occur under treatment with efavirenz but it may be reduced if the concurrent use of thymidine analogues is avoided. Efavirenz resistance mutations (especially K103N) can be selected during long-term treatment, underscoring the importance of good adherence. Recent data have confirmed that efavirenz is a cost-effective option for first-line HAART. In light of these features, efavirenz retains a key role in HIV treatment strategies and is the first-line agent recommended in some guidelines.

Are opioid dependence and methadone maintenance treatment (MMT) documented in the medical record? A patient safety issue

BACKGROUND

Opioid-dependent patients often have co-occurring chronic illnesses requiring medications that interact with methadone. Methadone maintenance treatment (MMT) is typically provided separately from medical care. Hence, coordination of medical care and substance use treatment is important to preserve patient safety.

OBJECTIVE

To identify potential safety risks among MMT patients engaged in medical care by evaluating the frequency that opioid dependence and MMT documentation are missing in medical records and characterizing potential medication-methadone interactions.

METHODS

Among patients from a methadone clinic who received primary care from an affiliated, but separate, medical center, we reviewed electronic medical records for documentation of methadone, opioid dependence, and potential drug-methadone interactions. The proportions of medical records without opioid dependence and methadone documentation were estimated and potential medication-methadone interactions were identified.

RESULTS

Among the study subjects (n = 84), opioid dependence documentation was missing from the medical record in 30% (95% CI, 20%-41%) and MMT documentation was missing from either the last primary care note or the last hospital discharge summary in 11% (95% CI, 5%-19%). Sixty-nine percent of the study subjects had at least 1 medication that potentially interacted with methadone; 19% had 3 or more potentially interacting medications.

CONCLUSION

Among patients receiving MMT and medical care at different sites, documentation of opioid dependence and MMT in the medical record occurs for the majority, but is missing in a substantial number of patients. Most of these patients are prescribed medications that potentially interact with methadone. This study highlights opportunities for improved coordination between medical care and MMT.

Methadone metabolism and clearance are induced by nelfinavir despite inhibition of cytochrome P4503A (CYP3A) activity

BACKGROUND

Methadone plasma concentrations are decreased by nelfinavir. Methadone clearance and the drug interactions have been attributed to CYP3A4, but actual mechanisms of methadone clearance and the nelfinavir interaction are unknown. We assessed nelfinavir effects on methadone pharmacokinetics and pharmacodynamics, intestinal and hepatic CYP3A4/5 activity, and intestinal P-glycoprotein transport activity. CYP3A4/5 and transporters were assessed using alfentanil and fexofenadine, respectively.

METHODS

Twelve healthy HIV-negative volunteers underwent a sequential crossover. On three consecutive days they received oral alfentanil plus fexofenadine, intravenous alfentanil, and intravenous plus oral methadone. This was repeated after nelfinavir. Plasma and urine analytes were measured by mass spectrometry. Opioid effects were measured by pupil diameter change (miosis).

RESULTS

Nelfinavir decreased intravenous and oral methadone plasma concentrations 40-50%. Systemic clearance, hepatic clearance, and hepatic extraction all increased 1.6- and 2-fold, respectively, for R- and S-methadone; apparent oral clearance increased 1.7- and 1.9-fold. Nelfinavir stereoselectively increased (S>R) methadone metabolism and metabolite formation clearance, and methadone renal clearance. Methadone bioavailability and P-glycoprotein activity were minimally affected. Nelfinavir decreased alfentanil systemic and apparent oral clearances 50 and 76%, respectively. Nelfinavir appeared to shift the methadone plasma concentration-effect (miosis) curve leftward and upward.

CONCLUSIONS

Nelfinavir induced methadone clearance by increasing renal clearance, and more so by stereoselectively increasing hepatic metabolism, extraction and clearance. Induction occurred despite 50% inhibition of hepatic CYP3A4/5 activity and more than 75% inhibition of first-pass CYP3A4/5 activity, suggesting little or no role for CYP3A in clinical methadone disposition. Nelfinavir may alter methadone pharmacodynamics, increasing clinical effects.

The impact of integrated HIV care on patient health outcomes

BACKGROUND

Control of viral replication through combination antiretroviral therapy (cART) improves patient health outcomes. Yet many HIV-infected patients have comorbidities that pose social and clinical barriers to achieving viral suppression. Integration of subspecialty services into HIV primary care may overcome such barriers.

OBJECTIVE

To evaluate effect of integrated HIV care (IHC) on suppression of HIV replication.

RESEARCH DESIGN

A retrospective cohort study of HIV patients from 5 Veterans Affairs healthcare facilities 2000 to 2006.

SUBJECTS

Patients with >3 months of follow-up, sufficient baseline HIV severity, on cART.

MEASURES

We measured and ranked Integrated Care at the facilities. These rankings were applied to patient visits to form an index of IHC utilization. We evaluated effect of IHC utilization on likelihood of achieving viral suppression while on cART, controlling for demographic and clinical factors using survival analysis.

RESULTS

: The 1018 HIV-infected patients eligible for analysis had substantial barriers to responding to cART: 93% had comorbidities with mean 3.2 comorbidities per patient (SD = 2.0); 52% achieved viral suppression in median 231 days (SD = 411.6). Patients visiting clinics that offered hepatitis, psychiatric, psychologic, and social services in addition to HIV primary care were 3.1 times more likely to achieve viral suppression than patients visiting clinics which offered only HIV primary care (hazard ratio = 3.1, P < 0.001).

CONCLUSIONS

Patients who visited IHC clinics were more likely to achieve viral suppression while on cART. Future research should investigate which elements of Integrated Care are most associated with viral control and what role provider experience plays in this association.

Mechanism of ritonavir changes in methadone pharmacokinetics and pharmacodynamics: II. Ritonavir effects on CYP3A and P-glycoprotein activities

Ritonavir diminishes methadone plasma concentrations, an effect attributed to CYP3A induction, but the actual mechanisms are unknown. We determined short-term (2-day) and steady-state (2-week) ritonavir effects on intestinal and hepatic CYP3A4/5 (probed with intravenous (IV) and oral alfentanil (ALF) and with miosis) and P-glycoprotein (P-gp) (fexofenadine), and on methadone pharmacokinetics and pharmacodynamics in healthy volunteers. Acute ritonavir increased the area under the concentration-time curve (AUC)(0-infinity)/dose ratio (ritonavir/control) for oral ALF 25-fold. Steady-state ritonavir increased the AUC(0-Infinity)/dose ratio for IV and oral ALF 4- and 10-fold, respectively; reduced hepatic extraction (from 0.26 to 0.07) and intestinal extraction (from 0.51 to 0); and increased bioavailability (from 37 to 95%). Acute ritonavir inhibits first-pass CYP3A > 96%. Chronic ritonavir inhibits hepatic CYP3A (> 70%) and first-pass CYP3A (> 90%). Acute and steady-state ritonavir increased the fexofenadine AUC(0-infinity) 2.8- and 1.4-fold, respectively, suggesting P-gp inhibition. Steady-state compared with acute ritonavir caused mild apparent induction of P-gp and hepatic CYP3A, but net inhibition still predominated. Ritonavir inhibited both intestinal and hepatic CYP3A and drug transport. ALF miosis noninvasively determined CYP3A inhibition by ritonavir.

Methadone pharmacokinetics are independent of cytochrome P4503A (CYP3A) activity and gastrointestinal drug transport: insights from methadone interactions with ritonavir/indinavir

BACKGROUND

Methadone clearance is highly variable, and drug interactions are problematic. Both have been attributed to CYP3A, but actual mechanisms are unknown. Drug interactions can provide such mechanistic information. Ritonavir/indinavir, one of the earliest protease inhibitor combinations, may inhibit CYP3A. We assessed ritonavir/indinavir effects on methadone pharmacokinetics and pharmacodynamics, intestinal and hepatic CYP3A activity, and intestinal transporters (P-glycoprotein) activity. CYP3A and transporters were assessed with alfentanil and fexofenadine, respectively.

METHODS

Twelve healthy human immunodeficiency virus-negative volunteers underwent a sequential three-part crossover. On three consecutive days, they received oral alfentanil/fexofenadine, intravenous alfentanil, and intravenous plus oral (deuterium-labeled) methadone, repeated after acute (3 days) and steady-state (2 weeks) ritonavir/indinavir. Plasma and urine analytes were measured by mass spectrometry. Opioid effects were assessed by miosis.

RESULTS

Alfentanil apparent oral clearance was inhibited more than 97% by both acute and steady-state ritonavir/indinavir, and systemic clearance was inhibited more than 90% due to diminished hepatic and intestinal extraction. Ritonavir/indinavir increased fexofenadine area under the plasma concentration-time curve four- to five-fold, suggesting significant inhibition of gastrointestinal P-glycoprotein. Ritonavir/indinavir slightly increased methadone N-demethylation, but it had no significant effects on methadone plasma concentrations or on systemic or apparent oral clearance, renal clearance, hepatic extraction or clearance, or bioavailability. Ritonavir/indinavir had no significant effects on methadone plasma concentration-effect relationships.

CONCLUSIONS

Inhibition of both hepatic and intestinal CYP3A activity is responsible for ritonavir/indinavir drug interactions. Methadone disposition was unchanged, despite profound inhibition of CYP3A activity, suggesting little or no role for CYP3A in clinical methadone metabolism and clearance. Methadone bioavailability was unchanged, despite inhibition of gastrointestinal P-glycoprotein activity, suggesting that this transporter does not limit methadone intestinal absorption.

Medical consequences of drug abuse and co-occurring infections: research at the National Institute on Drug Abuse

Substance abuse still remains one of the major problems in the world today, with millions of people abusing legal and illegal drugs. In addition, a billion people may also be infected with one or more infections. Both drugs of abuse and infections are associated with enormous burden of social, economic, and health consequences. This article briefly discusses a few medical consequences of drugs of abuse and infections such as human immunodeficiency virus, hepatitis C virus, psychiatric complications in hepatitis C infection, pharmacokinetic drug-drug interactions among medications used in the treatment of addiction and infections, and new drugs in development for the treatment of infections. Research is encouraged to study interactions between infections, drugs of abuse, and underlying pathophysiologic and molecular/genetic mechanisms of these interactions.

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.

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.

Multi-centre observational study of buprenorphine use in 32 Italian drug addiction centres

AIM

To examine how buprenorphine is currently being used across Italy, and to identify simultaneously best practice protocols to guide physicians in optimising the safety and efficacy of this treatment option.

DESIGN

Retrospective, observational, multi-centre study.

PARTICIPANTS

A total of 979 opioid-dependent patients were included from 32 centres involving the initiation of 1122 treatments.

FINDINGS

During the study period 33.4% of patients relapsed during the induction phase. Lower induction doses resulted in markedly higher relapse rates (51.2% of those who received 2 mg versus 20.6% of those who received 10mg of buprenorphine relapsed). Over 89% of patients who received 16 mg of buprenorphine during the induction phase successfully went on to maintenance treatment. The percentage of drug-positive urines also decreased over time on buprenorphine treatment (cocaine-positive urines decreased from 25.8% at study entrance to 0% at 24 months). Psychosocial support in addition to buprenorphine pharmacotherapy further decreased the risk of relapse and was associated with lower levels of heroin craving. Retention in treatment was increased by less-than-daily dosing of buprenorphine.

CONCLUSIONS

Higher induction doses of buprenorphine significantly decreased relapse rates and increased the percentage of patients achieving maintenance treatment. Psychosocial support and/or less-than-daily dosing also appeared to promote positive treatment outcomes.

Factors associated with antiretroviral therapy adherence and medication errors among HIV-infected injection drug users

BACKGROUND

Active drug use is often associated with poor adherence, but few studies have determined psychosocial correlates of adherence in injection drug users (IDUs).

METHODS

Of 1161 Intervention for Seropositive Injectors-Research and Evaluation study enrollees, 636 were taking antiretrovirals. We assessed self-reported adherence to self-reported antiretroviral regimens and medication errors, which we defined as daily doses that were inconsistent with standard or alternative antiretroviral prescriptions.

RESULTS

Most subjects (75%, n=477) self-reported good (>or=90%) adherence, which was strongly associated with an undetectable viral load. Good adherence was independently associated with being a high school graduate, not sharing injection equipment, fewer depressive symptoms, positive attitudes toward antiretrovirals, higher self-efficacy for taking antiretrovirals as prescribed, and greater sense of responsibility to protect others from HIV. Medication errors were made by 54% (n=346) and were strongly associated with a detectable viral load and fewer CD4 cells. Errors were independently associated with nonwhite race and with depressive symptoms, poorer self-efficacy for safer drug use, and worse attitudes toward HIV medications.

CONCLUSIONS

Modifiable factors associated with poor adherence, including depressive symptoms and poor self-efficacy, should be targeted for intervention. Because medication errors are prevalent and associated with a detectable viral load and fewer CD4 cells, interventions should include particular efforts to identify medication taking inconsistent with antiretroviral prescriptions.

Underlying pathophysiology of HCV infection in HIV-positive drug users

HCV and HIV infections are very common among injection drug users (IDUs). It is well known that 80-90% of HIV-infected IDUs are also infected with HCV. Furthermore, patients with HCV/HIV co-infection are at a higher risk of progressing to end-stage liver disease, namely cirrhosis. Even though there is increasing global awareness of HCV/HIV co-infection and extended therapeutic programs for this infected population, little is known about the HCV/HIV pathophysiology that mediates the rapid progression to hepatic disease. Liver disease caused by HCV/HIV co-infection is characterized by inflammation and cell-death. Recent reports suggest that the HIV and HCV envelope proteins may induce apoptosis and inflammation in hepatocytes via a novel pathway involving collaborative signaling. Moreover, HCV/HIV co-infection may also alter the cytokine production in vivo. Further studies to elucidate the molecular mechanisms of HCV and HIV-mediated pathogenesis will help in the development of therapeutic strategies against HCV/HIV co-infection in these patients.

Interaction between buprenorphine and atazanavir or atazanavir/ritonavir

Opioid addiction and HIV disease frequently co-occur. Adverse drug interactions have been reported between methadone and some HIV medications, but less is known about interactions between buprenorphine, an opioid partial agonist used to treat opioid dependence, and HIV therapeutics. This study examined drug interactions between buprenorphine and the protease inhibitors atazanavir and atazanavir/ritonavir. Opioid-dependent, buprenorphine/naloxone-maintained, HIV-negative volunteers (n=10 per protease inhibitor) participated in two 24-h sessions to determine pharmacokinetics of (1) buprenorphine and (2) buprenorphine and atazanavir (400mg daily) or atazanavir/ritonavir (300/100mg daily) following administration for 5 days. Objective opiate withdrawal scale scores and mini-mental state examination were determined prior to and following antiretroviral administration to examine pharmacodynamic effects. Pharmacokinetics of atazanavir and atazanavir/ritonavir were compared in subjects and matched, healthy controls (n=10 per protease inhibitor) to determine effects of buprenorphine. With atazanavir and atazanavir/ritonavir, respectively concentrations of buprenorphine (p<0.001, p<0.001), norbuprenorphine (p=0.026, p=0.006), buprenorphine glucuronide (p=0.002, p<0.001), and norbuprenorphine glucuronide (NS, p=0.037) increased. Buprenorphine treatment did not significantly alter atazanavir or ritonavir concentrations. Three buprenorphine/naloxone-maintained participants reported increased sedation with atazanavir/ritonavir. Atazanavir or atazanavir/ritonavir may increase buprenorphine and buprenorphine metabolite concentrations and might require a decreased buprenorphine dose.

Antiretroviral HIV treatment and care for injecting drug users: an evidence-based overview

AIDS-related mortality and the rate of progression to AIDS have dramatically decreased since the advent of highly active antiretroviral treatment (HAART). The overall benefit from antiretroviral HIV treatment has, however, been lesser in HIV-infected injecting drug users (IDUs) than in other patient groups (e.g. men who have sex with men). Poorer outcomes in HIV-infected IDUs are related to a variety of factors, including increased rates of non-HIV-related deaths, hepatitis C, delayed access to effective treatment, lower adherence to care and treatment regimens, continuation of illicit drug use, depression and negative life events. The available evidence strongly suggests the need for the large-scale implementation of comprehensive treatment and care strategies for IDUs that include both treatment of drug dependence and HAART.

Interactions between buprenorphine and antiretrovirals. I. The nonnucleoside reverse-transcriptase inhibitors efavirenz and delavirdine

This study examined drug interactions between buprenorphine, an opioid partial agonist medication used in the treatment of opioid dependence, and the nonnucleoside reverse-transcriptase inhibitors (NNRTIs) efavirenz (EFV) and delavirdine (DLV). Opioid-dependent, buprenorphine/naloxone-maintained, human immunodeficiency virus (HIV)-negative volunteers (n=10 per NNRTI) participated in 24-h sessions to determine pharmacokinetics of buprenorphine and of buprenorphine with either EFV or DLV after administration of standard doses of either antiretroviral for 15 or 7 days, respectively. Opiate withdrawal symptoms, cognitive effects, and adverse events were determined before and after antiretroviral administration in opioid-dependent participants. The pharmacokinetics of NNRTIs in healthy control participants were used to determine the effect of buprenorphine on NNRTIs. EFV decreased the buprenorphine area under the concentration-time curve (P<.001). DLV increased buprenorphine concentrations (P<.001). Clinically significant consequences of these interactions were not observed. Buprenorphine did not alter antiretroviral pharmacokinetics. Adjustments of doses of either buprenorphine or EFV or DLV are not likely to be necessary when these drugs are administered for the treatment of opiate dependence and HIV disease.

Interactions between buprenorphine and antiretrovirals. II. The protease inhibitors nelfinavir, lopinavir/ritonavir, and ritonavir

We examined drug interactions between buprenorphine, an opioid partial agonist available by prescription for treatment of opioid dependence, and the protease inhibitors (PIs) nelfinavir (NFV), ritonavir (RTV), and lopinavir/ritonavir (LPV/R). Opioid-dependent, buprenorphine/naloxone-maintained, human immunodeficiency virus (HIV)-negative volunteers (n=10 per PI) participated in 24-h pharmacokinetic studies, before and after administration of each PI. Symptoms of opiate withdrawal and excess were determined before and after PI administration. PI pharmacokinetics were determined and compared between opiate-dependent participants and healthy control participants (n=15 per PI). Administration of RTV, but not of NFV or LPV/R, resulted in a significant increase in the buprenorphine area under the concentration-time curve (AUC). Symptoms of opiate excess, however, were not observed. Buprenorphine had no significant effects on PI AUC. Adjustments of doses of either buprenorphine or NFV, LPV/R, or RTV are not likely to be necessary when these drugs are administered for the treatment of opioid dependence and HIV disease.