Pharmacokinetics of Nelfinavir in Subjects With Hepatic Impairment

The Potential of Long-Acting, Tissue-Targeted Synthetic Nanotherapy for Delivery of Antiviral Therapy Against HIV Infection

Oral administration of a combination of two or three antiretroviral drugs (cART) has transformed HIV from a life-threatening disease to a manageable infection. However, as the discontinuation of therapy leads to virus rebound in plasma within weeks, it is evident that, despite daily pill intake, the treatment is unable to clear the infection from the body. Furthermore, as cART drugs exhibit a much lower concentration in key HIV residual tissues, such as the brain and lymph nodes, there is a rationale for the development of drugs with enhanced tissue penetration. In addition, the treatment, with combinations of multiple different antiviral drugs that display different pharmacokinetic profiles, requires a strict dosing regimen to avoid the emergence of drug-resistant viral strains. An intriguing opportunity lies within the development of long-acting, synthetic scaffolds for delivering cART. These scaffolds can be designed with the goal to reduce the frequency of dosing and furthermore, hold the possibility of potential targeting to key HIV residual sites. Moreover, the synthesis of combinations of therapy as one molecule could unify the pharmacokinetic profiles of different antiviral drugs, thereby eliminating the consequences of sub-therapeutic concentrations. This review discusses the recent progress in the development of long-acting and tissue-targeted therapies against HIV for the delivery of direct antivirals, and examines how such developments fit in the context of exploring HIV cure strategies.

Recent developments of nanotherapeutics for targeted and long-acting, combination HIV chemotherapy

Combination antiretroviral therapy (cART) given orally has transformed HIV from a terminal illness to a manageable chronic disease. Yet despite the recent development of newer and more potent drugs for cART and suppression of virus in blood to undetectable levels, residual virus remains in tissues. Upon stopping cART, virus rebounds and progresses to AIDS. Current oral cART regimens have several drawbacks including (1) challenges in patient adherence due to pill fatigue or side-effects, (2) the requirement of life-long daily drug intake, and (3) limited penetration and retention in cells within lymph nodes. Appropriately designed injectable nano-drug combinations that are long-acting and retained in HIV susceptible cells within lymph nodes may address these challenges. While a number of nanomaterials have been investigated for delivery of HIV drugs and drug combinations, key challenges involve developing and scaling delivery systems that provide a drug combination targeted to HIV host cells and tissues where residual virus persists. With validation of the drug-insufficiency hypothesis in lymph nodes, progress has been made in the development of drug combination nanoparticles that are long-acting and targeted to lymph nodes and cells. Unique drug combination nanoparticles (DcNPs) composed of three HIV drugs-lopinavir, ritonavir, and tenofovir-have been shown to provide enhanced drug levels in lymph nodes; and elevated drug-combination levels in HIV-host cells in the blood and plasma for two weeks. This review summarizes the progress in the development of nanoparticle-based drug delivery systems for HIV therapy. It discusses how injectable nanocarriers may be designed to enable delivery of drug combinations that are long-lasting and target-selective in physiological contexts (in vivo) to provide safe and effective use. Consistent drug combination exposure in the sites of residual HIV in tissues and cells may overcome drug insufficiency observed in patients on oral cART.

[Consensus Statement by GeSIDA/National AIDS Plan Secretariat on antiretroviral treatment in adults infected by the human immunodeficiency virus (Updated January 2013)]

OBJECTIVE

This consensus document is an update of combined antiretroviral therapy (cART) guidelines for HIV-1 infected adult patients.

METHODS

To formulate these recommendations a panel composed of members of the GeSIDA/National AIDS Plan Secretariat (Grupo de Estudio de Sida and the Secretaría del Plan Nacional sobre el Sida) reviewed the efficacy and safety advances in clinical trials, cohort and pharmacokinetic studies published in medical journals (PubMed and Embase) or presented in medical scientific meetings. The strength of the recommendations and the evidence which support them are based on a modification of the criteria of Infectious Diseases Society of America.

RESULTS

cART is recommended in patients with symptoms of HIV infection, in pregnant women, in serodiscordant couples with high risk of transmission, in hepatitisB co-infection requiring treatment, and in HIV nephropathy. cART is recommended in asymptomatic patients if CD4 is <500cells/μl. If CD4 are >500cells/μl cART should be considered in the case of chronic hepatitisC, cirrhosis, high cardiovascular risk, plasma viral load >100.000 copies/ml, proportion of CD4 cells <14%, neurocognitive deficits, and in people aged >55years. The objective of cART is to achieve an undetectable viral load. The first cART should include 2 reverse transcriptase inhibitors (RTI) nucleoside analogs and a third drug (a non-analog RTI, a ritonavir boosted protease inhibitor, or an integrase inhibitor). The panel has consensually selected some drug combinations, for the first cART and specific criteria for cART in acute HIV infection, in tuberculosis and other HIV related opportunistic infections, for the women and in pregnancy, in hepatitisB or C co-infection, in HIV-2 infection, and in post-exposure prophylaxis.

CONCLUSIONS

These new guidelines update previous recommendations related to first cART (when to begin and what drugs should be used), how to monitor, and what to do in case of viral failure or adverse drug reactions. cART specific criteria in comorbid patients and special situations are similarly updated.

[Consensus document of Gesida and Spanish Secretariat for the National Plan on AIDS (SPNS) regarding combined antiretroviral treatment in adults infected by the human immunodeficiency virus (January 2012)]

This consensus document has been prepared by a panel consisting of members of the AIDS Study Group (Gesida) and the Spanish Secretariat for the National Plan on AIDS (SPNS) after reviewing the efficacy and safety results of clinical trials, cohort and pharmacokinetic studies published in medical journals, or presented in medical scientific meetings. Gesida has prepared an objective and structured method to prioritise combined antiretroviral treatment (cART) in naïve patients. Recommendations strength (A, B, C) and the evidence which supports them (I, II, III) are based on a modification of the Infectious Diseases Society of America criteria. The current antiretroviral treatment (ART) of choice for chronic HIV infection is the combination of three drugs. ART is recommended in patients with symptomatic HIV infection, in pregnancy, in serodiscordant couples with high transmission risk, hepatitis B fulfilling treatment criteria, and HIV nephropathy. Guidelines on ART treatment in patients with concurrent diagnosis of HIV infection and an opportunistic type C infection are included. In asymptomatic patients ART is recommended on the basis of CD4 lymphocyte counts, plasma viral load and patient co-morbidities, as follows: 1) therapy should be started in patients with CD4 counts <350 cells/μL; 2) when CD4 counts are between 350 and 500 cells/μL, therapy will be recommended and only delayed if patient is reluctant to take it, the CD4 are stabilised, and the plasma viral load is low; 3) therapy could be deferred when CD4 counts are above 500 cells/μL, but should be considered in cases of cirrhosis, chronic hepatitis C, high cardiovascular risk, plasma viral load >10(5) copies/mL, proportion of CD4 cells <14%, and in people aged >55 years. ART should include 2 reverse transcriptase inhibitors nucleoside analogues and a third drug (non-analogue reverse transcriptase inhibitor, ritonavir boosted protease inhibitor or integrase inhibitor). The panel has consensually selected and given priority to using the Gesida score for some drug combinations, some of them co-formulated. The objective of ART is to achieve an undetectable viral load. Adherence to therapy plays an essential role in maintaining antiviral response. Therapeutic options are limited after ART failures, but an undetectable viral load may be possible nowadays. Adverse events are a fading problem of ART. Guidelines in acute HIV infection, in women, in pregnancy, and to prevent mother-to-child transmission and pre- and post-exposition prophylaxis are commented upon. Management of hepatitis B or C co-infection, other co-morbidities, and the characteristics of ART in HIV-2 infection are included.

[AIDS Study Group/Spanish AIDS Plan consensus document on antiretroviral therapy in adults with human immunodeficiency virus infection (updated January 2010)]

OBJECTIVE

This consensus document is an update of antiretroviral therapy recommendations for adult patients with human immunodeficiency virus infection.

METHODS

To formulate these recommendations a panel made up of members of the Grupo de Estudio de Sida (Gesida, AIDS Study Group) and the Plan Nacional sobre el Sida (PNS, Spanish AIDS Plan) reviewed the advances in the current understanding of the pathophysiology of human immunodeficiency virus (HIV) infection, the efficacy and safety of clinical trials, and cohort and pharmacokinetic studies published in biomedical journals or presented at scientific meetings. Three levels of evidence were defined according to the data source: randomized studies (level A), cohort or case-control studies (level B), and expert opinion (level C). The decision to recommend, consider or not to recommend ART was established in each situation.

RESULTS

Currently, the treatment of choice for chronic HIV infection is the combination of three drugs of two different classes, including 2 nucleosides or nucleotide analogs (NRTI) plus 1 non-nucleoside (NNRTI) or 1 boosted protease inhibitor (PI/r), but other combinations are possible. Initiation of ART is recommended in patients with symptomatic HIV infection. In asymptomatic patients, initiation of ART is recommended on the basis of CD4 lymphocyte counts, plasma viral load and patient co-morbidities, as follows: 1) therapy should be started in patients with CD4 counts below 350 cells/microl; 2) When CD4 counts are between 350 and 500 cells/microl, therapy should be started in case of cirrhosis, chronic hepatitis C, high cardiovascular risk, HIV nephropathy, HIV viral load above 100,000 copies/ml, proportion of CD4 cells under 14%, and in people aged over 55; 3) Therapy should be deferred when CD4 are above 500 cells/microl, but could be considered if any of previous considerations concurs. Treatment should be initiated in case of hepatitis B requiring treatment and should be considered for reduce sexual transmission. The objective of ART is to achieve an undetectable viral load. Adherence to therapy plays an essential role in maintaining antiviral response. Therapeutic options are limited after ART failures but undetectable viral loads maybe possible with the new drugs even in highly drug experienced patients. Genotype studies are useful in these situations. Drug toxicity of ART therapy is losing importance as benefits exceed adverse effects. Criteria for antiretroviral treatment in acute infection, pregnancy and post-exposure prophylaxis are mentioned as well as the management of HIV co-infection with hepatitis B or C.

CONCLUSIONS

CD4 cells counts, viral load and patient co-morbidities are the most important reference factors to consider when initiating ART in asymptomatic patients. The large number of available drugs, the increased sensitivity of tests to monitor viral load, and the ability to determine viral resistance is leading to a more individualized therapy approach in order to achieve undetectable viral load under any circumstances.

Effects of hepatic impairment on the steady-state pharmacokinetics of etravirine 200 mg BID: an open-label, multiple-dose, controlled Phase I study in adults

BACKGROUND

Etravirine is a non-nucleoside reverse transcriptase inhibitor (NNRTI) with activity against both wild-type HIV and viruses harboring NNRTI resistance. Etravirine is mainly eliminated via the hepatobiliary route.

OBJECTIVES

This study in HIV- patients with mild or moderate hepatic impairment and healthy matched controls was conducted to explore the effects of mild and moderate hepatic impairment on the steady-state pharmacokinetics of etravirine and to provide guidance for the treatment of HIV+ patients with hepatic impairment.

METHODS

This open-label, multiple-dose study enrolled HIV- patients aged 18 to 65 years with mild or moderate hepatic impairment (Child-Pugh score, 5-6 or 7-9, respectively) and healthy volunteers matched for age, sex, race, and body mass index (BMI). All subjects received etravirine 200 mg BID with food for 7 days and a morning dose on day 8. Etravirine pharmacokinetics over a period of 12 hours on days 1 and 8 were determined using noncompartmental methods and analyzed using linear mixed-effects modeling. Tolerability of etravirine was assessed based on the reported adverse events, laboratory investigations, ECG, and physical examination.

RESULTS

Each group comprised 8 subjects (mild hepatic impairment patients: 5 men, 3 women; median age, 57 years [range, 41-65 years]; BMI, 26 kg/m(2) [range, 20-32 kg/m(2)]; moderate hepatic impairment patients: 6 men, 2 women; age, 54 years [range, 44-64 years]; BMI, 26 kg/m(2) [range, 22-32 kg/m(2)]). All patients were white and light smokers. On day 8, the least squares mean ratios (90% CIs) of the log transformed pharmacokinetic properties in patients with mild and moderate hepatic impairment were, respectively: C(min), 0.87 (0.65-1.17) and 0.98 (0.68-1.42) microg/mL; C(max), 0.79 (0.63-1.00) and 0.72 (0.54-0.96) ug/mL; and AUC(0-12), 0.87 (0.69-1.09) and 0.82 (0.60-1.11) microg/mL/h. All treatment-emergent adverse events were considered mild to moderate; the most common were headache (50% in healthy controls) and fatigue and nausea (both 25% in patients with mild hepatic impairment). No clinically significant changes in laboratory parameters, physical examination including vital signs, or ECG were observed. One serious adverse event was reported during the follow-up period in a patient with moderate hepatic impairment due to hepatic cirrhosis secondary to alcoholism. This patient presented at screening with dilated cardiomyopathy and cardiac arrhythmia.

CONCLUSIONS

In this Phase I pharmacokinetic study, no clinically relevant differences were observed between patients with mild or moderate hepatic impairment and healthy matched subjects with regard to the pharmacokinetics of etravirine. Based on these findings in these HIV- volunteers, no dose adjustment of etravirine appears to be necessary in patients with mild or moderate hepatic impairment. Etravirine was generally well tolerated.

Effects of standard and supratherapeutic doses of nelfinavir on cardiac repolarization: a thorough QT study

This was a randomized, 4-way crossover, third-party-blinded study in 68 healthy subjects to assess the effect of nelfinavir on QTc interval. Treatments included (A) nelfinavir 1250 mg every 12 hours on days 1-4, (B) nelfinavir 1250 mg every 12 hours on days 1-3 plus 3125 mg on day 4, (C) placebo, and (D) moxifloxacin 400 mg every 24 hours on days 1-4. Pharmacokinetics and triplicate 12-lead electrocardiograms were performed over 12 hours on days 1 and 4. Time-matched, placebo-subtracted, baseline-adjusted changes in QT intervals with Fridericia's (QTcF) correction were determined following nelfinavir and moxifloxacin administration. Neither dose of nelfinavir had a clinically relevant effect on the QTcF interval on day 4 (primary endpoint) and day 1 because at every time point the upper 90% confidence limit was below 10 milliseconds and, furthermore, the mean difference was below 5 milliseconds. Additionally, there was no clinically relevant effect on QTcB (Bazett's correction), uncorrected QT, or the RR interval on days 1 or 4. Pharmacokinetics confirmed adequate systemic exposure to nelfinavir and moxifloxacin. While nelfinavir exposure was higher in poor compared with extensive metabolizers of CYP2C19 isozyme, there were no corresponding significant differences in QTcF change from placebo. At clinically relevant, doses nelfinavir is unlikely to cause QTc prolongation.

A pilot study on the efficacy, pharmacokinetics and safety of atazanavir in patients with end-stage liver disease

OBJECTIVES

Antiretroviral combinations including atazanavir are currently not recommended in HIV-infected patients with end-stage liver disease (ESLD). The objective of our study was to evaluate efficacy, pharmacokinetics and safety of unboosted atazanavir in HIV-infected patients with ESLD screened for orthotopic liver transplantation (OLT(x)). Patients and methods Single-arm, 24 week pilot study. Atazanavir-naive patients undergoing highly active antiretroviral therapy were switched to atazanavir 400 mg/day plus two non-thymidine nucleoside reverse transcriptase inhibitors. Results Fifteen patients (10 males and 5 females) were included. In the study period, 2 patients were transplanted and 10 completed 24 weeks of atazanavir treatment. Median area under the concentration-time curve at week 4 was 19 211 ng.h/mL (IQR = 8959-27 500). At week 24, median atazanavir trough concentrations (C(trough)) per patient calculated across the study were above the minimum effective concentration (MEC = 100 ng/mL) in 8 of 10 subjects. Atazanavir C(trough) time-point values were always above the MEC in five patients. The other three subjects experienced only one determination below the MEC, with median atazanavir C(trough) levels across the study being above the MEC in two of them. At 8 of 11 time-points when atazanavir and proton pump inhibitors (PPIs) were co-administered and at 16 of 19 time-points in which patients had a concomitant tenofovir association, atazanavir C(trough) was above the MEC. Conclusions Unboosted atazanavir showed a favourable pharmacokinetic profile and was able to maintain or gain immuno-virological eligibility for OLT(x) in all patients. Limited biochemical toxicities (including unconjugated hyperbilirubinaemia) and allowance of concomitant administration of tenofovir and PPIs were observed.