Long-term safety and tolerability of the lamivudine/abacavir combination as components of highly active antiretroviral therapy

Abacavir (Ziagen(®)) use between 2003 and 2008 in France according to the electronic medical record NADIS(®)

OBJECTIVE

The authors had for objective to describe HIV-infected patients treated with ABC (Ziagen(®), ABC), and the immune, virological, and clinical treatment outcome between 2003 and 2008.

PATIENTS AND METHODS

We performed a retrospective analysis of the Dat'AIDS database on patients who were treated with ABC for the first time between 2003 and 2008.

RESULTS

Eight hundred and thirty-six patients were included. Before initiation of ABC, 26.3% has stopped the previous treatment because of immuno-virological failure, 30.5% because of adverse events, and 29.8% for other reasons. Thirteen percent were antiretroviral naive. One third of patients were ranked as CDC class C, and more than 2/3 had a viral load<5 log copies/mL or a CD4 count≥200mm(3). ABC was mainly included in a combination containing 2 NRTI and 1 PI (63%), or 1 non-NRTI (16%). Thirty-two percent of patients were still treated with ABC after 2years of treatment and the median of ABC treatment was 11months (IQ 84days-2years). The main causes for stopping ABC were therapeutic simplification (47.4% of patients), intolerance (19.0%), and immuno-virological failure (9.8%). Suspected hypersensitivity reactions were the main cause of discontinuation due to intolerance (27.6%); the rate was 3.8% when ABC had been introduced before the routine use of the screening test HLA-B*5701. The incidence of myocardial infarction was 3.8 per 1000 patient-years; 70.6% of patients received a fixed combination including ABC after discontinuation of ABC as a single agent (Ziagen(®)).

CONCLUSION

This retrospective analysis confirmed the effectiveness and the good tolerance of ABC in the therapeutic strategy, between 2003 and 2008.

Organic cation transporters OCT1 and OCT2 determine the accumulation of lamivudine in CD4 cells of HIV-infected patients

PURPOSE

Identifying factors that determine concentrations of antiretroviral drugs in CD4 cells are important for improving therapeutic efficacy. Experimental models indicate that the nucleoside reverse transcriptase inhibitor lamivudine is transported by the organic cation transporters 1 and 2 (OCT1 and OCT2, respectively). Here, we tested whether OCT1 and OCT2 contribute to the uptake of lamivudine into native CD4 cells of human immunodeficiency virus (HIV)-infected individuals.

METHODS

CD4 cells obtained by non-activated cell sorting from 35 individuals with HIV-1 infection were incubated with lamivudine (10 μM, 30 min), and intracellular concentrations of lamivudine and its active metabolite lamivudine triphosphate were determined by liquid chromatography tandem mass spectrometry. The expression of OCT1 and OCT2 mRNA was measured by quantitative real-time polymerase chain reaction (PCR). A model of OCT2-transfected CD4 cells was established for mechanistic investigations.

RESULTS

Intracellular concentrations of lamivudine and its active metabolite lamivudine triphosphate showed strong linear correlations with each other and with the CD4 mRNA expression of OCT1 and OCT2 (r > 0.80). Coincubation with protease inhibitors (ritonavir, nelfinavir) that inhibit OCT1 and OCT2 yielded decreased intracellular concentrations of lamivudine and lamivudine triphosphate. Incubation of CD4 cells from healthy donors transfected with an OCT2 expression vector yielded increased concentrations of lamivudine and lamivudine triphosphate.

CONCLUSION

Our studies indicate a role of OCT1 and OCT2 for the cellular accumulation of lamivudine in HIV-infected individuals.

Vestibular evoked myogenic potential in unilateral vestibular hypofunction

CONCLUSION

The patients with unilateral chronic vestibular hypofunction detected by caloric test demonstrated at least some sort of altered vestibular evoked myogenic potential (VEMP) in 63.63% of the cases. The VEMP altered side was the same as the unilateral vestibular hypofunction side in 54.54% of the cases and was the opposite side in 24.24%. The VEMP test improved functional vestibular assessment in patients with unilateral caloric hypofunction.

OBJECTIVES

To analyze VEMP in patients with chronic dizziness and unilateral vestibular hypofunction and verify findings according to the side and structures involved.

METHODS

This was an observational study. In all, 66 subjects were evaluated by VEMP (tone bursts/1000 Hz/100 dBnHL/bandpass filtered 10-1500 Hz/4.3 Hz rate), 33 with unilateral vestibular hypofunction, detected by caloric test and clinical data, and 33 control subjects, matched by gender and age. Amplitude of the p13-n23, asymmetry index of the amplitude, p13 and n23 latencies, p13 and n23 interaural difference and threshold were analyzed. Simple descriptive analysis was carried out using the t test, Shapiro-Wilks test, and Mann-Whitney test, p < 0.05.

RESULTS

VEMP was altered in patients with unilateral vestibular hypofunction in 63.63% of cases. Thirteen of them were ipsilateral to the vestibular hypofunction and three were contralateral to the vestibular hypofunction. In five cases, VEMP were bilaterally altered.

Headache attributed to infections nosography and differential diagnosis

Headache is a very frequent symptom of infection. It has many possible underlying mechanisms, of which two or more can coexist in a single patient. It can be caused by direct stimulation of intracranial pain-producing structures, as in the case of brain abscesses, by irritation of the pachy- and leptomeninges, as in cases of bacterial or viral meningitis, or by a state of intracranial hypertension, as seen in obstructive hydrocephalus. There is no doubt that headache is often the first or the predominant symptom of serious, sometimes life-threatening, infectious diseases; certainly, it is a condition frequently encountered in all epidemiological studies. Indeed, it is estimated that over 60% of people have, at some point in their lives, experienced headache during an infection. This evidence leads to the need for a systematic approach to headache secondary to infection. This chapter provides some elements on pain mechanisms in systemic and intracranial infections and on the possible role of antimicrobial agents in the genesis of headache. The first section provides a detailed "etiology-based" description of the International Classification of Headache Disorders, 2nd edition (ICHD-II: Headache Classification Subcommittee of the International Headache Society, 2004), while the second section presents a "symptom-based" algorithm applicable in the first diagnostic assessment, according to the headache features and to the most frequently associated clinical manifestations during infections of the central nervous system (CNS).

Fatigue in HIV/AIDS patients with comorbidities

Fatigue has been identified as a key complaint among patients with HIV/AIDS. Although having more than one disease is expected to increase symptom severity, this relationship has not been explored extensively. We investigated differences in fatigue severity together with the impact of demographic factors and the number of comorbidities and symptoms among patients with and those without comorbidities at 18 international clinical and community sites. Specific comorbidities and the number of symptoms associated with increased fatigue severity. Only by distinguishing fatigue as to its causes and patterns will health care providers be able to intervene specifically and thus more effectively.

The cost-effectiveness of HLA-B*5701 genetic screening to guide initial antiretroviral therapy for HIV

OBJECTIVE

To evaluate the clinical impact and cost-effectiveness of HLA-B*5701 testing to guide selection of first-line HIV regimens in the United States.

DESIGN

Cost-effectiveness analysis using a simulation model of HIV disease. The prevalence of HLA-B*5701 and the probabilities of confirmed and unconfirmed severe systemic hypersensitivity reaction among patients taking abacavir testing HLA-B*5701 positive and negative were from the Prospective Randomized Evaluation of DNA Screening in a Clinical Trial study. The monthly costs of abacavir-based and tenofovir-based regimens were $1135 and $1139, respectively; similar virologic efficacy was assumed and this assumption was varied in sensitivity analysis.

PATIENTS

Simulated cohort of patients initiating HIV therapy.

INTERVENTIONS

The interventions are first-line abacavir, lamivudine, and efavirenz without pretreatment HLA-B*5701 testing; the same regimen with HLA-B*5701 testing; and first-line tenofovir, emtricitabine, and efavirenz.

MAIN OUTCOME MEASURES

Quality-adjusted life years and lifetime medical costs discounted at 3% per annum, cost-effectiveness ratios ($/QALY).

RESULTS

Abacavir-based treatment without HLA-B*5701 testing resulted in a projected 30.93 years life expectancy, 16.23 discounted quality-adjusted life years, and $472,200 discounted lifetime cost per person. HLA-B*5701 testing added 0.04 quality-adjusted months at an incremental cost of $110, resulting in a cost-effectiveness ratio of $36,700/QALY compared with no testing. Initiating treatment with a tenofovir-based regimen increased costs without improving quality-adjusted life expectancy. HLA-B*5701 testing remained the preferred strategy only if abacavir-based treatment had equal efficacy and cost less per month than tenofovir-based treatment. Results were also sensitive to the cost of HLA-B*5701 testing and the prevalence of HLA-B*5701.

CONCLUSION

Pharmacogenetic testing for HLA-B*5701 is cost-effective only if abacavir-based treatment is as effective and costs less than tenofovir-based treatment.

Design and study of lamivudine oral controlled release tablets

The objective of this study was to design oral controlled release matrix tablets of lamivudine using hydroxypropyl methylcellulose (HPMC) as the retardant polymer and to study the effect of various formulation factors such as polymer proportion, polymer viscosity, and compression force on the in vitro release of drug. In vitro release studies were performed using US Pharmacopeia type 1 apparatus (basket method) in 900 mL of pH 6.8 phosphate buffer at 100 rpm. The release kinetics were analyzed using the zero-order model equation, Higuchi's square-root equation, and the Ritger-Peppas empirical equation. Compatibility of the drug with various excipients was studied. In vitro release studies revealed that the release rate decreased with increase in polymer proportion and viscosity grade. Increase in compression force was found to decrease the rate of drug release. Matrix tablets containing 60% HPMC 4000 cps were found to show good initial release (26% in first hour) and extended the release up to 16 hours. Matrix tablets containing 80% HPMC 4000 cps and 60% HPMC 15,000 cps showed a first-hour release of 22% but extended the release up to 20 hours. Mathematical analysis of the release kinetics indicated that the nature of drug release from the matrix tablets was dependent on drug diffusion and polymer relaxation and therefore followed non-Fickian or anomalous release. No incompatibility was observed between the drug and excipients used in the formulation of matrix tablets. The developed controlled release matrix tablets of lamivudine, with good initial release (20%-25% in first hour) and extension of release up to 16 to 20 hours, can overcome the disadvantages of conventional tablets of lamivudine.