Switch from ritonavir-boosted to unboosted atazanavir guided by therapeutic drug monitoring

Precision medicine for HIV: where are we?

To date, antiretroviral therapy is highly effective in HIV-affected patients, but the individualization of such a life-long therapy may be advised. This review briefly summarizes the main factors involved in the potential personalization of antiretroviral treatment. Relevant articles in English were identified by PubMed and recent congresses’ abstracts. Foremost influences concerning pharmacodynamics, therapeutic drug monitoring, pharmacogenetics, comorbidities, immune recovery and viral characteristics affecting the healthcare of HIV-positive patients are listed here. Furthermore, pharmacoeconomic aspects are mentioned. Applying pharmacokinetic and pharmacogenetic knowledge may be informative and guide the better choice of treatment in order to achieve long-term efficacy and avoid adverse events. Randomized investigations of the clinical relevance of tailored antiretroviral regimens are needed in order to obtain a better management of HIV/AIDS-affected patients.

Pharmaceutical characterization of novel tenofovir liposomal formulations for enhanced oral drug delivery: in vitro pharmaceutics and Caco-2 permeability investigations

Tenofovir, currently marketed as the prodrug tenofovir disoproxil fumarate, is used clinically to treat patients with HIV/AIDS. The oral bioavailability of tenofovir is relatively low, limiting its clinical effectiveness. Encapsulation of tenofovir within modified long-circulating liposomes would deliver this hydrophilic anti-HIV drug to the reticuloendothelial system for better therapeutic efficacy. The objectives of the current study were to prepare and pharmaceutically characterize model liposomal tenofovir formulations in an attempt to improve their bioavailability. The entrapment process was performed using film hydration method, and the formulations were characterized in terms of encapsulation efficiency and Caco-2 permeability. An efficient reverse-phase high-performance liquid chromatography method was developed and validated for tenofovir quantitation in both in vitro liposomal formulations and Caco-2 permeability samples. Separation was achieved isocratically on a Waters Symmetry C8 column using 10 mM Na₂PO₄/acetonitrile pH 7.4 (95:5 v/v). The flow rate was 1 mL/min with a 12 min elution time. Injection volume was 10 µL with ultraviolet detection at 270 nm. The method was validated according to United States Pharmacopeial Convention category I requirements. The obtained result showed that tenofovir encapsulation within the prepared liposomes was dependent on the employed amount of the positive charge-imparting agent. The obtained results indicated that calibration curves were linear with r² > 0.9995 over the analytical range of 1–10 µg/mL. Inter- and intraday accuracy and precision values ranged from 95% to 101% and 0.3% to 2.6%, respectively. The method was determined to be specific and robust. Regarding the potential of the prepared vectors to potentiate tenofovir permeability through the Caco-2 model, a 10-fold increase in tenofovir apparent permeability was observed compared to its oral solution. In conclusion, this novel and validated method was successfully applied to characterize both in vitro encapsulation efficiency and Caco-2 permeability transport for the pharmaceutical assessment of novel tenofovir formulations.

Efficacy and safety of "unboosting" atazanavir in a randomized controlled trial among HIV-infected patients receiving tenofovir DF

OBJECTIVES

To assess safety and efficacy of a switch to unboosted atazanavir (ATV) among HIV-infected adults receiving ATV/ritonavir (r) and tenofovir disoproxil fumarate (TDF).

METHODS

HIV-infected adults with viral load (VL) <40 copies/mL at screening and <150 copies/mL consistently for ≥3 months while receiving a regimen including ATV/r and TDF were randomized to continue ATV/r 300/100 mg daily (control) or change to ATV 400 mg daily (switch), while maintaining their TDF backbone. The primary outcome was proportion of subjects without treatment failure (regimen switch or VL > 200 copies/mL twice consecutively) at 48 weeks.

RESULTS

Fifty participants (46 male, median age 47 years) were randomized, 25 to each arm. At week 48, treatment success occurred in 76% in the control arm and 92% in the switch arm (ITT, p = 0.25). ATV trough levels at week 9 were higher in controls (median 438 ng/mL) than in the switch arm (median 124 ng/mL) (p = 0.003), as was total bilirubin at week 48 (median 38 μmol/L and 28 μmol/L, respectively; p = 0.02). Estimated glomerular filtration rate (eGFR) decreased in the control arm (p = 0.007), but did not change in the switch arm. At week 48, eGFR was higher in the switch arm (median 96 mL/min) than in the control arm (median 85 mL/min) (p = 0.035), but the arms were similar with respect to fasting glucose, C-reactive protein, and lipid parameters.

CONCLUSIONS

Switching from ATV/r to unboosted ATV appears to be safe and effective in selected virologically suppressed patients receiving TDF-containing regimens, and may have favorable effects on bilirubin and renal function.

Abacavir/lamivudine + unboosted atazanavir in routine clinical practice: Twelve years experience

OBJECTIVE

To describe the experience using the combination abacavir, lamivudine plus non-boosted atazanavir (ABC/3TC+ATV) in a group of pretreated patients.

PATIENTS AND METHODS

We performed a retrospective observational study to describe baseline characteristics and the evolution of patients who had received or were treating with ABC/3TC+ATV, from November 2004 and June 15th 2015, in the clinical setting.

RESULTS

Overall, 236 patients were included in the study. Median age (IQR) was 45 (42-50) years and 69% were male. The main reasons for using this combination were previous toxicity in 130 patients (56%), simplification in 60 (20%) and virologic failure in 29 (14%). Previous treatment was based in boosted protease inhibitor in 115 patients (48.7%), 3 analogs in 56 (28%) and non-analogous based in 19 (8.1%). Median treatment length was 2.2 years (IQR0.8-5.3). A total of 66 (28%) patients continue receiving ABC/3TC+ATV (median time 5.7, IQR2.2-8.3), treatment was changed in 170 patients (72%) (median time 1.6 years, IQR0.7-3.6), and 22 (9.3%) patients were lost. Virological failure was assessed in 30 patients.

CONCLUSION

In selected patients, ABC/3TC+ATV is a durable and attractive therapeutic alternative.

Long-term effectiveness of unboosted atazanavir plus abacavir/lamivudine in subjects with virological suppression: A prospective cohort study

Effectiveness data of an unboosted atazanavir (ATV) with abacavir/lamivudine (ABC/3TC) switch strategy in clinical routine are scant.We evaluated treatment outcomes of ATV + ABC/3TC in pretreated subjects in the EuroSIDA cohort when started with undetectable plasma HIV-1 viral load (pVL), performing a time to loss of virological response (TLOVR <50 copies/mL) and a snapshot analysis at 48, 96, and 144 weeks. Virological failure (VF) was defined as confirmed pVL >50 copies/mL.We included 285 subjects, 67% male, with median baseline CD4 530 cells, and 44 months with pVL ≤50 copies/mL. The third drug in the previous regimen was ritonavir-boosted atazanavir (ATV/r) in 79 (28%), and another ritonavir-boosted protease inhibitor (PI/r) in 29 (10%). Ninety (32%) had previously failed with a PI. Proportions of people with virological success at 48/96/144 weeks were 90%/87%/88% (TLOVR) and 74%/67%/59% (snapshot analysis), respectively. The rates of VF were 8%/8%/6%. Rates of adverse events leading to study discontinuation were 0.4%/1%/2%. The multivariable adjusted analysis showed an association between VF and nadir CD4+ (hazard ratio [HR] 0.63 [95% confidence interval [CI]: 0.42-0.93] per 100 cells higher), time with pVL ≤50 copies/mL (HR 0.87 [95% CI: 0.79-0.96] per 6 months longer), and previous failure with a PI (HR 2.78 [95% CI: 1.28-6.04]). Resistance selection at failure was uncommon.A switch to ATV + ABC/3TC in selected subjects with suppressed viremia was associated with low rates of VF and discontinuation due to adverse events, even in subjects not receiving ATV/r. The strategy might be considered in those with long-term suppression and no prior PI failure.

Treatment response to unboosted atazanavir in combination with tenofovir disoproxil fumarate and lamivudine in human immunodeficiency virus-1-infected patients who have achieved virological suppression: A therapeutic drug monitoring and pharmacogenetic study

BACKGROUND/PURPOSE

Treatment response to switch regimens containing unboosted atazanavir and tenofovir disoproxil fumarate (TDF)/lamivudine guided by therapeutic drug monitoring in human immunodeficiency virus-infected patients is rarely investigated.

METHODS

Consecutive patients with plasma human immunodeficiency virus RNA load < 200 copies/mL switching to unboosted atazanavir plus zidovudine-lamivudine (coformulated), abacavir-lamivudine (coformulated), or TDF/lamivudine > 3 months were included for determinations of treatment response, plasma atazanavir concentrations, and single-nucleotide polymorphisms of MDR1, PXR, and UGT1A1 genes from 2010 to 2014. Treatment failure was defined as either discontinuation of atazanavir for any reason or plasma viral load ≥ 200 copies/mL within 96 weeks.

RESULTS

During the study period, 128 patients switched to unboosted atazanavir with TDF/lamivudine (TDF group) and 186 patients switched to unboosted atazanavir with two other nucleoside reverse-transcriptase inhibitors (non-TDF group). There were no statistically significant differences in the distributions of single-nucleotide polymorphisms of MDR1 (2677 and 3435), PXR genotypes (63396), and UGT1A1*28 between the two groups. Recommended plasma atazanavir concentrations were achieved in 83.5% and 64.9% of the TDF group and non-TDF group, respectively (p < 0.01). After a median follow-up duration of 96.0 weeks, treatment failure occurred in 19 (14.9%) and 34 (18.3%) patients in the TDF group and non-TDF group, respectively (p = 0.60). Low-level viremia (40-200 copies/mL) before switch (adjusted hazard ratio, 2.12; 95% confidence interval, 1.12-4.01) and without therapeutic drug monitoring (adjusted hazard ratio, 2.08; 95% confidence interval, 1.16-3.73) were risk factors for treatment failure.

CONCLUSION

Switch to unboosted atazanavir with TDF/lamivudine achieves a similar treatment response to that with two other nucleoside reverse-transcriptase inhibitors in patients achieving virological suppression with the guidance of therapeutic drug monitoring.

Long term effectiveness of once-daily unboosted atazanavir plus abacavir/lamivudine as a switch strategy in subjects with virological suppression

Background

Use of unboosted atazanavir (ATV₄₀₀) is approved in the US but not in Europe [1]. Due to pharmacokinetic interactions it should not be used with tenofovir but can be used with abacavir/lamivudine (ABC/3TC) [1, 2,3]. Effectiveness data of ATV₄₀₀+ABC/3TC as a switch strategy in clinical routine however are scant.

Methods

We evaluated treatment outcomes of ATV₄₀₀+ABC/3TC in pre-treated subjects in the EuroSIDA cohort with undetectable HIV-1 RNA, and previous ABC experience or assumed previous HLA B57*01 testing. We performed a time to loss of virologic response (TLOVR below 50 c/mL) and a snapshot analysis at 48, 96 and 144 weeks. Virological failure (VF) was defined as a confirmed plasma HIV-1 RNA >50 c/mL.

Results

We included 258 subjects: 176 (68%) male, median age 46 (IQR 41, 53) y, 225 (87.2%) white, hepatitis virus co-infection 36%, median baseline CD4 at switch 540 cells (360, 700), time with VL≤ 50 c/mL 45 (24, 69) months. The median calendar year of switching was 2008 (2006, 2010). The 3rd drug in previous regimen was ATV/r in 70 (27.1%), other PI/r in 25 (9.7%), and other 163 (63.2%); 85 (32.9%) had previously failed with a PI. The virological response at 48/96/144 weeks was, respectively, 89.5 [95% CI 85.1, 92.9]/88 [83.4, 91.7]/86.3% [81.6, 90.4] (TLOVR, composite endpoint failure or stop for any reason) and the risk of VF was 8.3/7.6/7.6%. In the snapshot analysis HIV-RNA was below 50 c/mL in 72.5/65.9/51.6%, respectively, and >50 c/mL in 6.6/5.4/4.3%. Only 0.8/1.9/3.5% discontinued due to adverse events. There was a high rate of discontinuations due to other reasons or with VL missing in window. In a multivariate adjusted analysis, we observed an association between VF and nadir CD4 count (RH 0.60 [0.39, 0.93] per 100 cells higher), time with VL≤50 c/mL (RH 0.89 [0.81, 0.98] per 6 months longer) and previous failure with a PI (3.04 [1.36, 6.80]). There was no association with gender, age, hepatitis virus co-infection, CD4 count at time of switching or third drug used in the previous regimen.

Conclusions

A switch to ATV₄₀₀+ABC/3TC in selected subjects with HIV-RNA below 50 c/mL is associated with relatively low rates of VF and discontinuation due to adverse events. Use might be considered in those with long-term suppression and without prior PI failure. Larger cohorts are required to further define the appropriate selection criteria.

Atazanavir and other determinants of hyperbilirubinemia in a cohort of 1150 HIV-positive patients: results from 9 years of follow-up

Hyperbilirubinemia is common among patients exposed to atazanavir (ATV), but its long-term significance is not well documented. The objective was to analyze hyperbilirubinemia (incidence, regression, determinants, and outcome) among 1150 HIV-positive patients followed-up in a prospective cohort between 2003 and 2012. Cumulative incidence of hyperbilirubinemia grades 3-4 and its probability of regression were estimated using Kaplan-Meier method. Cox proportional hazards model was used to study the determinants. Generalized estimating equation (GEE) regression was used to evaluate the association between hyperbilirubinemia grades 3-4 and adverse health outcome. Eight years cumulative incidence of hyperbilirubinemia was 83.6% (95% CI:79.0-87.7) and 6.6% (95% CI:4.7-9.2) among ATV users and non-users, respectively. This clinical outcome fluctuated considerably, as most patients exposed to ATV (91%) regressed, transiently, to lower grade at some point during follow-up. Determinants were atazanavir (HR=147.90, 95% CI: 33.64-604.18), ritonavir (HR=5.18, 95% CI:2.33-11.48), zidovudine (HR=2.62, 95% CI:1.07-6.46), and age (HR=1.04 95% CI:1.01-1.08). Alcohol consumption and others non-antiretroviral medications including hepatotoxic and recreational drugs were not available for analyses. Incidence of hyperbilirubinemia was very high among ATV users and, although regression to lower grade was frequent in the clinical follow-up of these patients, this was usually transient as the mean level of bilirubin stayed at a relatively high level. Importantly, long-term hyperbilirubinemia was not associated with adverse health outcome.

Unboosted atazanavir for treatment of HIV infection: rationale and recommendations for use

Atazanavir (Reyataz®) is a protease inhibitor (PI) for the treatment of HIV infection. Several trials have demonstrated the good efficacy and toxicity profile of atazanavir boosted by ritonavir (atazanavir/r). However, several toxicity events and pharmacokinetic issues due to drug-to-drug interactions (partly related to ritonavir) may complicate atazanavir/r therapy. This is why regimens with unboosted atazanavir have been experimented with and are used in clinical practice. The aim of this article is to identify the clinical settings in which unboosted atazanavir may be a safe and effective option for the long-term control of HIV replication. Despite the fact that a favourable lipid profile and good gastrointestinal tolerability have been reported in comparative trials, unboosted atazanavir should not be considered an optimal choice for treatment-naive patients. In fact, boosting with ritonavir produces higher atazanavir plasma levels, which are beneficial in terms of efficacy, especially in untreated patients with high plasma HIV RNA. Clinical data indicate that, in patients with sustained undetectable HIV RNA and without previous virological failure or HIV drug resistance-associated mutations, a switch to unboosted atazanavir-based regimens is a feasible option to control and prevent toxicity events, especially in patients who cannot tolerate ritonavir and in those with severe hyperbilirubinaemia on atazanavir/r. Moreover, while unboosted atazanavir must not be used in pregnant women, it is a recommended option in special populations, such as patients with moderate liver insufficiency. Lastly, unboosted atazanavir in combination with raltegravir may allow the construction of a well tolerated and effective regimen without nucleoside reverse transcriptase inhibitors in patients for whom these drugs are contraindicated. In conclusion, there is a good rationale, significant clinical interest and accumulating clinical experience with unboosted atazanavir-based regimens, although this formulation should be used only in specific situations and as a maintenance strategy. Moreover, therapeutic drug monitoring could be useful in specific circumstances (such as in patients with liver impairment or in case of potential drug-drug interactions).

Lamivudine or emtricitabine (XTC)/protease inhibitor dual therapy as a harm-reduction strategy in patients with tenofovir-related renal toxicity: a case-control study

Tenofovir disoproxil fumarate (TDF) is widely used in HIV-infected patients. It is associated with tubular toxicity, but its management is controversial. A possible strategy is to switch to a dual therapy based on lamivudine or emtricitabine (XTC) and protease inhibitors (PIs). A case-control study was designed to evaluate the switch to XTC + PI therapy in patients with TDF-related renal toxicity. A case was defined as a patient who was on TDF/XTC + PI and who switched to XTC + PI. A control was defined as a patient with the same clinical features who remained on TDF/XTC + PI. Twenty-one cases and 21 controls were included. After 48 weeks, no differences in efficacy were observed. No improvement in the glomerular filtration rate as estimated with the Cockroft-Gault formula (eGFR) was seen, but the number of times that patients had values below 60 ml/min was higher with standard TDF/XTC 1 PI treatment than with dual XTC + PI treatment. A switch to dual therapy could be an option for patients at risk of TDF-related renal damage with no relevant risk of virological or immunological failure.

Ritonavir boosting dose reduction from 100 to 50 mg does not change the atazanavir steady-state exposure in healthy volunteers

OBJECTIVES

To evaluate the pharmacokinetics, tolerability and safety of 300 mg of atazanavir boosted with 100 or 50 mg of ritonavir, both once daily, at steady state.

METHODS

This was a single-blind, multiple-dose, crossover, sequence-randomized trial. Thirteen healthy HIV-1-negative men received witnessed once-daily doses of atazanavir (300 mg) and 100 or 50 mg of ritonavir for 10 days (15 day washout). Atazanavir and ritonavir plasma concentrations were determined for 24 h on day 10. Log-transformed individual pharmacokinetic parameters were compared between treatments (analysis of variance); the difference between treatments on the log scale and 95% CIs were calculated. Fasting cholesterol, triglycerides, glucose and bilirubin plasma levels were measured at the beginning and end of each period and compared (Wilcoxon signed rank test). Gastrointestinal symptoms and other events were recorded.

RESULTS

Ritonavir C(max) and the AUC₀₋₂₄ were lower after the 50 mg booster dose than after 100 mg [geometric mean ratio (GMR) (95% CI), 0.40 (0.31-0.51) and 0.35 (0.29-0.42), respectively]. No differences were observed in atazanavir exposure with 50 or 100 mg of ritonavir [GMR C(max) (95% CI), 1.00 (0.79-1.28); GMR AUC₀₋₂₄ (95% CI), 0.98 (0.79-1.21)]. Atazanavir trough concentration was >0.15 mg/L in all volunteers. Total and low-density lipoprotein cholesterol increased 0.40 mM (P = 0.01) and 0.37 mM (P = 0.003) from their corresponding baseline value during the 100 mg dosing period; there were no significant changes on 50 mg. Mild increases in bilirubin were detected on day 10 after both treatments without differences between treatments.

CONCLUSIONS

In spite of higher exposure to ritonavir with 100 mg, atazanavir exposure was equivalent; the lipid profile was better under the lower booster dose (50 mg).

Therapeutic monitoring and variability of atazanavir in HIV-infected patients, with and without HCV coinfection, receiving boosted or unboosted regimens

BACKGROUND

Adequate plasma trough concentrations (Ctrough) of protease inhibitors are required to maintain antiviral activity throughout the dosing interval. Therapeutic drug monitoring is used in clinical practice to optimize dosage and avoid toxic or subtherapeutic drug exposure. The pharmacokinetic variability of Atazanavir (ATV) can be relatively large, as a result of several factors. One of the affecting factors may be hepatic impairment due to hepatitis C virus (HCV) coinfection.

METHODS

We collected trough plasma samples from human immunodeficiency virus (HIV)-1-infected outpatients, with and without HCV coinfection and/or cirrhosis, receiving stable highly active antiretroviral therapy containing ATV. In the total population, we mainly compared the 2 regimens: 300ATV + 100RTV OD [ritonavir (RTV), once daily (OD)] versus 400ATV OD. We used a threshold value of 0.15 μg/mL, based on the proposed therapeutic range (0.15-0.85 μg/mL). Plasma concentrations of ATV were determined by a validated assay using high-performance liquid chromatography with ultraviolet detection. A total of 214 HIV-infected outpatients were included. For each regimen, we compared 3 groups of subjects: HIV+/HCV-, HIV+/HCV+, and HIV+/HCV+ with cirrhosis.

RESULTS

In the whole study population, we observed a large variability and found suboptimal Ctrough levels (<0.15 μg/mL) in 23 subjects (2 belonging to the 300/100 OD group and 21 to the 400 OD group). For the standard dosage regimen of 300ATV + 100RTV OD, we did not find a statistical difference between HIV-infected patients without HCV coinfection versus HIV-infected patients with HCV coinfection: median 0.85 (interquartile range 0.53-1.34) and 0.95 (0.70-1.36) μg/mL, respectively. In HIV+/HCV+-infected patients with cirrhosis, we found a median Ctrough of 0.70 (0.43-1.0) μg/mL, with no statistical difference when compared with HIV+/HCV- infected patients. For the 400ATV OD (n=90) dosage regimen, the total median ATV Ctrough was 0.40 (0.23-1.0) μg/mL. In this group, we found a statistically significant difference between HIV+/HCV- and HIV+/HCV+-infected patients: median Ctrough was 0.23 (0.11-0.42) and 0.52 (0.20-1.0) μg/mL, respectively. In HIV+/HCV+ subjects with cirrhosis, the Ctrough median value was 0.42 (0.13-0.75) μg/mL, and there was a significant difference when compared with HIV patients without coinfection.

CONCLUSIONS

Therapeutic drug monitoring of ATV in patients receiving unboosted regimen may be useful to identify those HIV-infected subjects, with or without HCV coinfection, who may benefit from adding low RTV doses, or the subset of patients in whom removal of RTV could be attempted without the risk of suboptimal plasma ATV exposure.

Atazanavir/ritonavir-based combination antiretroviral therapy for treatment of HIV-1 infection in adults

In the past 15 years, improvements in the management of HIV infection have dramatically reduced morbidity and mortality. Similarly, rapid advances in antiretroviral medications have resulted in the possibility of life-long therapy with simple and tolerable regimens. Protease inhibitors have been important medications in regimens of combination antiretroviral therapy for the treatment of HIV. One of the recommended and commonly used therapies in this class is once-daily-administered atazanavir, pharmacologically boosted with ritonavir (atazanavir/r). Clinical studies and practice have shown these drugs, in combination with other antiretroviral agents, to be potent, safe and easy to use in a variety of settings. Atazanavir/r has minimal short-term toxicity, including benign bilirubin elevation, and has less potential for long-term complications of hyperlipidemia and insulin resistance compared with other protease inhibitors. A high genetic barrier to resistance and a favorable resistance profile make it an excellent option for initial HIV treatment or as the first drug utilized in the protease inhibitors class. Atazanavir/r is also currently being studied in novel treatment strategies, including combinations with new classes of antiretrovirals to assess nucleoside reverse transcriptase inhibitor-sparing regimens. In this article we review atazanavir/r as a treatment for HIV infection and discuss the latest information on its pharmacology, efficacy and toxicity.

Therapeutic drug monitoring in highly active antiretroviral therapy

IMPORTANCE OF THE FIELD

Despite the efficacy of combination antiretroviral therapy (ART), a large proportion of patients living with HIV/AIDS on ART does not achieve or maintain adequate virological suppression. Therapeutic drug monitoring (TDM) has been utilised to improve treatment outcomes of ART.

AREAS COVERED IN THE REVIEW

The potential incorporation of TDM into the clinical HIV management is supported by the existing relationship between drug exposure and efficacy/toxicity, the high inter-patient variability pharmacokinetics, and the accurate, specific and rapid method for drug level determination. The current status of TDM in ART is reviewed in this article with discussions on its feasibility, potential use and limitations.

WHAT THE READER WILL GAIN

Mounting evidence from clinical trials has indicated the potential use of TDM in reducing the rates of treatment failure and adverse effect, avoiding the drug interactions, and special populations, such as children, pregnant women and patients with co-infections. TDM may play an important role even in resource-limited settings, to safeguard expanded use of bioequivalent generic antiretroviral drugs and avoid drug interactions with traditional Chinese medicines.

TAKE HOME MESSAGE

TDM is still in the centre of controversy in that several critical issues need to be addressed, such as limited adherence assessment, inappropriate response predictors, insufficient validation of target concentration windows and lack of the quality control of assay. The utility of TDM will remain experimental until more data are obtained from large clinical trials showing the benefit of TDM.

[The role of the hospital pharmacist in the prevention, treatment and management of the side effects associated with antiretroviral treatment]

At present, the side effects associated with antiretroviral treatment are the main reasons for discontinuation of this kind of therapy, both in clinical trials and in regular clinical practise. On the other hand, due to the change of direction that our profession has suffered in recent years, we face the need to establish a different relationship with the patient, achieving direct and effective Pharmaceutical Care within a framework of shared responsibility for therapeutic results. Pharmacist interventions should be aimed at improving the quality of life of patients, which can only be achieved with a multidisciplinary approach and individualised and adjusted to new patterns of toxicity of the drugs currently used. The pharmacist who does this work must know how to interpret these side effects, giving accurate information to the patient about both pharmacological and non-pharmacological treatment and correct pharmaceutical follow-up which clearly sets forth the criteria for referral to medical appointments. The aim of this paper is to establish baselines so that the hospital pharmacist can perform clearly and uniformly in the prevention, identification and management of major side effects: gastrointestinal, cardiovascular, dermatological, at the central nervous system and kidney level, associated with antiretroviral therapy.

Efficacy and safety of unboosted atazanavir in combination with lamivudine and didanosine in naive HIV type 1 patients in Senegal

The use of ritonavir as a protease inhibitor boost is rare in sub-Saharan Africa because a heat-stable formula is not available. We report the results of an open-label pilot trial with unboosted atazanavir in combination with lamivudine and didanosine as first-line therapy conducted in Senegal. Treatment-naive HIV-1 infected adult patients without active opportunistic disease were included. The primary endpoint was the proportion of patients with plasma HIV-1 RNA <400 copies/ml at week 48. Forty patients (12 men and 28 women; mean age +/- SD: 40 +/- 9 years) were included. Treatment was changed during the study for two patients (pregnancy, tuberculosis); one patient was lost to follow-up and one patient died (gastroenteritis with cachexia). At week 48, 78% [95% confidence interval (CI): 65-90%] and 68% (95% CI: 53-82%) of the patients had HIV-1 RNA <400 and <50 copies/ml, respectively (intent-to-treat analysis; not completer = failure). Among the seven patients with HIV-1 RNA >or=400 copies/ml at week 48, five were not compliant; genotyping analysis (n = 4) did not reveal a major mutation for protease inhibitors. The mean CD4 cell count change from baseline to week 48 was +238 +/- 79 cells/mm(3). The combination of unboosted atazanavir with lamivudine and didanosine was efficient and well tolerated in HIV-1-infected patients with results similar to those observed in Northern countries. These results suggest that unboosted atazanavir with its high genetic barrier could be a valuable alternative to NNRTIs in resource-limited countries in some HIV-1-infected patients in case of compliance issues with NNRTIs, intolerance to NNRTIs, resistance mutations to NNRTIs, in women with childbearing potential, or as a maintenance therapy in patients with virological suppression.

The benefit of simplification from tipranavir/ritonavir 500/200 bid to 500/100 bid guided by therapeutic drug monitoring

Despite being among the most potent protease inhibitors, the use of tipranavir (TPV) is hampered by a high pill burden and frequent side effects compared with other boosted protease inhibitors. A total of 10 patients receiving TPV/ritonavir (TPV/RTV) 500/200 for longer than 6 months were randomized to stay on the same dosing schedule or switch to TPV/RTV 500/100. Although all patients on TVP/RTV 500/200 remained stable for the next 12 weeks, 3 out of 5 patients who switched doses experienced benefits in terms of reducing aminotransferases and total cholesterol. Fasting triglycerides were also reduced in 2 of them. Plasma HIV-RNA remained undetectable in all patients, despite the observed decline in TPV trough concentrations.

[Viral resistance and genetic barrier of atazanavir]

Resistance to protease inhibitors (PI) is generally due to a mutation in the protease gene. Different changes have been described for each PI. The I 50L mutation is characteristic of resistance to atazanavir (ATV). It does not produce cross resistance to other PI; but it does increase susceptibility to all of them (hypersusceptibility). When PI are given concomitantly with low doses of ritonavir, the exposure to higher levels of PI requires that multiple resistance mutations have to be selected in the protease so that there is a significant loss of susceptibility. For the majority of PI/r, including ATV/r, >or=5 mutations in the protease are required to produce a compromise in the virological response. Despite having a moderate genetic barrier when not boosted with ritonavir, the prolonged half life of ATV minimises the risk of resistance in clinical practice.

[Clinical utility of atazanavir]

Atazanavir (ATV) is a protease inhibitor (PI) in which its main qualities, compared to other PI are dosing convenience, good tolerability and excellent metabolic profile. These characteristics makes it more like a nonnucleoside than a PI, but with the increased genetic barrier common to PI. It is indicated in initial treatment, simplification treatment or a change due to toxicity and in first line rescue treatment. The administering of ATV boosted with ritonavir (300/100 mg/d) has been approved in Europe in all clinical situations. In naïve patients it has been combined with practically all the nucleoside analogue pairs and has shown to be as effective as lopinavir/ritonavir and even efavirenz. In the USA, this indication has been approved for almost 5 years and ATV has become the most prescribed PI, while the EMEA has approved it this year. ATV is an optimal drug to replace other antiretrovirals in simplification strategies or changes due to toxicity. In several studies it has been shown that, in patients with good virological control, it can LPV/r or another PI, the therapeutic efficacy being maintained, with excellent tolerance and an improved lipid profile, and decreasing the cardiovascular risk. This strategy is widely used in Spain. In this scenario some patients could benefit from non-boosted ATV treatment (400 mg/d). ATV is an effective and very attractive option in first line rescue treatments in which the virus shows little or no resistance to PI, as its simplicity and tolerability can improve problems with compliance, the main cause of therapeutic failure. In patients with moderate resistance to PI, ATV is as effective as LPV/r. The survival of patients with HIV infection is increasingly longer and factors such as tolerability, cardiovascular risk and the adaptability of the treatment to the lifestyle of the patient, become more important, therefore ATV must play an important role in the treatment of HIV-infection.