Nancy L. Sheehan

An evaluation of pharmacists’ expectations towards pharmacogenomics

BACKGROUND Given their expertise in pharmacotherapy, pharmacists are well positioned to play a leading role in the implementation of pharmacogenomics in clinical practice. However, little is known about the opinions of pharmacists towards pharmacogenomics or their willingness to integrate this new field in their practice. METHODS We conducted a survey of 284 pharmacists practicing in the province of Québec (Canada) to describe the opinions, expectations and concerns of pharmacists toward pharmacogenomics. RESULTS Pharmacists were very hopeful regarding the potential role of pharmacogenomics. Moreover, more than 95% of responders would be willing to recommend pharmacogenomic testing. Nevertheless, only 7.7% of pharmacists currently felt comfortable advising patients based on pharmacogenomic test results. Accordingly, the majority of responders (96.6%) indicated that they would like to undertake continuing education related to pharmacogenomics. CONCLUSION Pharmacists are extremely hopeful towards pharmacogenomic testing. Furthermore, a vast majority is willing to integrate these tests as part of their clinical practice. Proper education will be required if the integration of pharmacogenomics in patient care is to be optimal.

Possible interaction between lopinavir/ritonavir and valproic acid exacerbates bipolar disorder

Objective: To describe a case of exacerbated mania potentially related to an interaction between lopinavir/ritonavir and valproic acid (VPA) and propose a mechanism of action for this interaction. Case Summary: A 30-year-old man with bipolar disorder and HIV initiated treatment with lopinavir/ritonavir, zidovudine, and lamivudine. Prior to beginning therapy with these antiretrovirals, he was receiving VPA 250 mg 3 times daily, with his most recent VPA concentration measured at 495 μmol/L. Twenty-one days after starting antiretroviral treatment, he became increasingly manic. His VPA concentration at admission was 238 μmol/L, a 48% decrease. The daily VPA dose was increased to 1500 mg, and olanzapine was introduced. The VPA concentration following this dose escalation was 392 μmol/L, and the patient improved clinically. Discussion: Fifty percent of VPA is metabolized by glucuronidation, 40% undergoes mitochondrial β-oxidation, and less than 10% is eliminated by the cytochrome P450 isoenzymes. Ritonavir can induce glucuronidation of several medications including ethinyl estradiol, levothyroxine, and lamotrigine. We believe that ritonavir-mediated induction of VPA glucuronidation resulted in a decrease in VPA concentrations and efficacy. An objective causality assessment suggested that the increased mania was probably related to the decrease in VPA concentration and that a possible interaction exists between lopinavir/ritonavir and VPA. Conclusions: A potential interaction exists between VPA and all ritonavir-boosted antiretroviral regimens. Clinicians should monitor patients closely for a decreased VPA effect when these medications are given concomitantly.

Understanding and preventing drug–drug and drug–gene interactions

Concomitant administration of multiple drugs can lead to unanticipated drug interactions and resultant adverse drug events with their associated costs. A more thorough understanding of the different cytochrome P450 isoenzymes and drug transporters has led to new methods to try to predict and prevent clinically relevant drug interactions. There is also an increased recognition of the need to identify the impact of pharmacogenetic polymorphisms on drug interactions. More stringent regulatory requirements have evolved for industry to classify cytochrome inhibitors and inducers, test the effect of drug interactions in the presence of polymorphic enzymes, and evaluate multiple potentially interacting drugs simultaneously. In clinical practice, drug alert software programs have been developed. This review discusses drug interaction mechanisms and strategies for screening and minimizing exposure to drug interactions. We also provide future perspectives for reducing the risk of clinically significant drug interactions.

Evaluation of HIV Drug Interaction Web Sites

BACKGROUND: Clinicians frequently consult HIV drug interaction Web sites of unknown quality. OBJECTIVE: To systematically review and identify HIV drug interaction Web sites of high quality and usefulness for healthcare professionals. METHODS: Relevant Web sites were identified through a structured search on commonly used search engines. An assessment tool containing 4 domains (content, reliability, access restrictions, ease of navigation) was developed. English and French Web sites were selected for review if they included HIV drug interaction information directed to healthcare professionals. Web sites were excluded if antiretroviral interaction data were not available or were out of date. Commercial online databases and sites that required payment were not included. Seventeen HIV pharmacists from across Canada participated in the review. The Web sites were ranked with total mean scores. Mean scores for each domain were then analyzed. Interrater agreement and ANOVA using the rater as a covariate were determined. RESULTS: Nine Web sites met the criteria for review. Web sites from Toronto General Hospital (Canada), HIVinSite (beta version) (US), and the University of Liverpool (UK) ranked highest for total mean scores and for content. Other Web sites were found to be reliable, accessible, and easy to navigate; however, they did not consistently include unpublished data or data on herbal preparations, recreational drugs, or multiple interactions. CONCLUSIONS: Three HIV interaction Web sites of high quality were identified that can be valuable tools for HIV and non-HIV healthcare professionals. Regular reviews are necessary in order to keep pace with the growing body of HIV interaction data and the constant evolution of Web sites.

Antiretroviral drug transporters and metabolic enzymes in human testicular tissue: potential contribution to HIV-1 sanctuary site

OBJECTIVES The testes are a potential viral sanctuary site for HIV-1 infection. Our study aims to provide insight into the expression and localization of key drug transporters and metabolic enzymes relevant to ART in this tissue compartment. METHODS We characterized gene and protein expression of 12 representative drug transporters and two metabolic enzymes in testicular tissue samples obtained from uninfected (n = 8) and virally suppressed HIV-1-infected subjects on ART (n = 5) and quantified antiretroviral drug concentrations in plasma and testicular tissues using LC/MS/MS from HIV-1-infected subjects. RESULTS Our data demonstrate that key ABC drug transporters (permeability glycoprotein, multidrug-resistance protein 1, 2 and 4, and breast cancer resistance protein), solute carrier transporters (organic anion transporting polypeptides 1B1 and 2B1, organic anion transporter 1, concentrative nucleoside transporter 1, equilibrative nucleoside transporter 2) and cytochrome P450 metabolic enzymes (CYP3A4 and CYP2D6) previously shown to interact with many commonly used antiretroviral drugs are expressed at the mRNA and protein level in the testes of both subject groups and localize primarily at the blood-testis barrier, with no significant differences between the two groups. Furthermore, we observed that PIs known to be substrates for ATP-binding cassette membrane transporters, displayed variable testicular tissue penetration, with darunavir concentrations falling below therapeutic values. In contrast, the NRTIs emtricitabine, lamivudine and tenofovir displayed favourable tissue penetration, reaching concentrations comparable to plasma levels. We also demonstrated that nuclear receptors, peroxisome proliferator-activated receptors α and γ exhibited higher gene expression in the testicular tissue compared with pregnane X receptor and constitutive androstane receptor, suggesting a potential regulatory pathway governing drug transporter and metabolic enzyme expression in this tissue compartment. CONCLUSIONS Our data suggest the testes are a complex pharmacological compartment that can restrict the distribution of certain antiretroviral drugs and potentially contribute to HIV-1 persistence.

CTN-194 (PICCO): Design of a trial of citalopram for the prevention of depression and its consequences in HIV-Hepatitis C co-infected individuals initiating pegylated interferon/ribavirin therapy

Hepatitis C (HCV)-related end stage liver disease is a primary cause of morbidity and mortality in people with HIV. Despite this, co-infected patients have low rates of HCV treatment initiation and completion. This is in large part due to the risk of pegylated-interferon alpha (PEG-IFN-alpha)-related neuropsychiatric complications. We describe the design of a multicentre randomized, placebo-controlled trial that evaluates whether antidepressant prophylaxis is superior to early detection and treatment of depression in increasing the successful completion of HCV therapy. Seventy-six HIV+ adults with chronic HCV infection requiring therapy and with no contraindications to PEG-IFN-alpha/ribavirin will be randomized in a 1:1 ratio to receive citalopram or placebo starting three weeks prior to HCV treatment. A novel aspect of the trial design is the built-in management of emergent depression while maintaining the blinded treatment assignment. This will permit the comparison of prophylactic versus therapeutic use of citalopram. The primary outcome is the average proportion of prescribed PEG-IFN-alpha and ribavirin doses taken per month at weeks 12 and 24, and will be compared between treatment arms. The study will also compare the development of moderate-to-severe depression between treatment arms. A unique feature of this trial will be the use of Telepsychiatry to standardize observer-administered neuropsychiatric evaluations. Assessments of anxiety, quality of life, and adherence to therapy, as well as pathogenetic studies of neuropsychiatric side effects, will be conducted. Intention-to-treat analyses using random regression modeling will be employed to analyze longitudinal data on prescribed PEG-IFN-alpha and ribavirin doses. Survival analyses will be used to compare the time to the development of depression between the two arms. Effective prevention of a broad range of neuropsychiatric symptoms by citalopram has the potential to diminish PEG-IFN-alpha associated morbidity and consequently, allow a greater number of patients to complete full therapy.

Negligible Effect of Tenofovir on Atazanavir Trough Concentrations and Genotypic Inhibitory Quotients in the Presence and Absence of Ritonavir

Background: It is recommended to boost atazanavir with ritonavir (ATV/r) when it is combined with tenofovir disoproxil fumarate (TDF) because of drug interactions. For tolerability, unboosted atazanavir (ATV) is sometimes coadministered with TDF. The objective of this study was to evaluate the impact of this interaction on the proportion of patients achieving target ATV Ctroughs and genotypic inhibitory quotients (GIQ). Materials and Methods: A therapeutic drug monitoring database was screened to evaluate ATV concentrations. Differences in Ctrough and GIQ values among 4 antiretroviral drug combinations were evaluated. Results: Three hundred eight Ctroughs, 91 GIQs, and 92 viral loads were evaluated for 238, 68, and 69 patients, respectively. Patients receiving ATV/r and TDF compared with ATV and TDF were more likely to have a therapeutic Ctrough (odds ratio, 2.27; 95% confidence interval: 1.46–3.52; P < 0.001). Among patients on unboosted ATV, the odds of having a therapeutic ATV Ctrough did not differ between groups with TDF versus without TDF. Although ritonavir increased the GIQ in patients receiving TDF (odds ratio, 3.38; 95% confidence interval: 1.30–8.81; P = 0.013), a similar proportion of patients on TDF and either ATV/r or ATV achieved a therapeutic GIQ. Conclusions: In patients receiving TDF, ritonavir increased the ATV Ctrough and GIQ and patients on ATV/r were more likely to have therapeutic Ctroughs. However, among subjects without ritonavir boosting, TDF compared with other nucleosides did not influence the odds of achieving a therapeutic ATV Ctrough. These data suggest that ritonavir boosting of ATV is prudent, particularly in patients with resistance mutations.

Citalopram for the prevention of depression and its consequences in HIV-hepatitis C coinfected individuals initiating pegylated interferon/ribavirin therapy: a multicenter randomized double-blind placebo-controlled trial.

Abstract Background: Depression related to interferon-alpha (IFN-α) is common, may reduce adherence, and can be treatment limiting. HIV-HCV coinfected persons experience lower sustained virologic response rates and commonly have psychiatric comorbidities, thus they may benefit from prevention of depression. Objective: The aim of the study was to determine whether prophylactic citalopram can increase HCV treatment adherence and reduce the incidence of moderate depression in HIV-HCV coinfected patients initiating PEG-IFN-α/ribavirin therapy. Methods: This was an investigator-initiated Canadian multicenter randomized, double-blind placebo-controlled trial. HIV-HCV coinfected patients were randomized in a 1:1 ratio to receive citalopram or placebo 3 weeks prior to starting PEG-IFN-α2b/ribavirin, stratified by study center and HCV genotype. The protocol design permitted the comparison of prophylaxis with the treatment of emergent depression. The primary outcomes were adherence (assessed through questionnaire and returned medication) and time to moderate depression measured by Beck Depression Inventory-II (BDI-II) score greater than 15, confirmed 2 weeks apart. Results: Seventy-six patients (36 citalopram/40 placebo) were randomized. Overall adherence was high, ranging from 95% (week 12) to 91% (week 48). There was no difference between arms with respect to mean or median adherence at any study time point. Cumulative incidence of moderate depression did not differ significantly by group (log rank P = .32). The hazard ratio for moderate depression was 0.81 (95% CI, 0.26 to 2.54) for citalopram compared with placebo when adjusted for baseline BDI-II score. Conclusions: A strategy of prophylactic citalopram compared to treatment of emergent depression was not associated with higher adherence or a reduction in treatment-limiting depression nor did it significantly reduce depressive symptoms among HIV-HCV coinfected persons during treatment for HCV.

Recognizing cognitive and psychiatric changes in the post-highly active antiretroviral therapy era.

Amid numerous complications that plague the health and quality of life of people living with HIV, neurocognitive and psychiatric illnesses pose unique challenges. While there remains uncertainty with respect to the pathophysiology surrounding these disorders, their adverse implications are increasingly recognized. Left undetected, they have the potential to significantly impact patient well being, adherence to antiretroviral treatment and overall health outcomes. As such, early identification of HIV-associated neurocognitive disorders (HAND) and psychiatric illnesses will be paramount in the proactive management of affected patients. The present review focuses on strategies to ensure optimal screening and detection of HAND, depression and substance abuse in routine practice. For each topic, currently available screening methods are discussed. These include identification of risk factors, recognition of relevant symptomatology and an update on validated screening tools that can be efficiently implemented in the clinical setting. Specifically addressed in the present review are the International HIV Dementia Scale, a novel screening equation and algorithm for HAND, as well as brief, validated, verbal questionnaires for detection of depression and substance abuse. Adequate understanding and usage of these screening mechanisms can ensure effective use of resources by distinguishing patients who require referral for more extensive diagnostic procedures from those who likely do not.

Exploring an alternative explanation for the second phase of viral decay: Infection of short-lived cells in a drug-limited compartment during HAART

Most HIV-infected patients who initiate combination antiretroviral therapy experience a viral load decline in several phases. These phases are characterized by different rates of viral load decay that decrease when transitioning from one phase to the next. There is no consensus as to the origin of these phases. One hypothesis put forward is that short- and long-lived infected cells are responsible for the first and second phases of decay, respectively. However, significant differences in drug concentrations are observed in monocytes from various tissues, suggesting the first two phases of decay in viral loads could instead be attributed to short-lived cells being differently exposed to drugs. Compared to a well-exposed compartment, new cell infection can be expected in a compartment with limited drug exposure, thus leading to a slower viral load decay with potential virologic failure and drug resistance. In the current study, the latter hypothesis was investigated using a model of viral kinetics. Empirical datasets were involved in model elaboration and parameter estimation. In particular, susceptibility assay data was used for an in vitro to in vivo extrapolation based on the expected drug concentrations inside physiological compartments. Results from numerical experiments of the short-term evolution of viral loads can reproduce the first two phases of viral decay when allowing new short-lived cell infections in an unidentified drug-limited compartment. Model long-term predictions are however less consistent with clinical observations. For the hypothesis to hold, efavirenz, tenofovir and emtricitabine drug exposure in the drug-limited compartment would have to be very low compared to exposure in peripheral blood. This would lead to significant long-term viral growth and the frequent development of resistant strains, a prediction not supported by clinical observations. This suggests that the existence of a drug-limited anatomical compartment is unlikely, by itself, to explain the second phase of viral load decay.