Ritonavir and saquinavir combination therapy for the treatment of HIV infection

A robust fluorogenic substrate for chikungunya virus protease (nsP2) activity

Chikungunya virus (CHIKV) is an emerging pathogen with pandemic potential. CHIKV infection in humans is transmitted by mosquitoes and induces common symptoms of high fever, arthralgia and myalgia. Because no specific antiviral drugs for treatment of CHIKV infection are available, drug development remains a central goal. The chikungunya virus protease from nsP2 (CHIKVP) has emerged as a key drug target due to its indispensable role in viral replication via cleavage of the viral polyprotein. To date, effective tools for screening for CHIKVP inhibitors that reflect the most critical polyprotein cleavage sites have been lacking, hampering drug-development efforts. We found that the recognition ability of CHIKVP is sensitive to the length of peptide substrates. In this study, we report a robust fluorogenic substrate comprising a 15-mer peptide derived from the nsP3/4 junction from the CHIKV polyprotein. This peptide is flanked by an ACC-Lys(dnp) donor-quencher pair. Our new substrate acc-CHIK15-dnp shows a 30-fold improved signal-to-noise ratio as compared to the previously reported edab8 substrate, which is also based on the nsP3/4 junction. We found acc-CHIK15-dnp is recognized only by CHIKVP but not by other alphavirus proteases. This is surprising due to the high level of sequence conservation in the alpha virus polyprotein junctions and indicates that the P-side residues are more important than the P'-side sequence for effective CHIKVP cleavage. The robust signal-to-noise ratio obtained using acc-CHIK15-dnp derived from the nsP3/4 cleavage site enabled much improved small molecule HTS on CHIKV relative to other fluorogenic reporters.

Saquinavir potentiates itraconazole's antifungal activity against multidrug-resistant Candida auris in vitro andin vivo

Candida species are highly opportunistic yeasts that are responsible for serious invasive fungal infections among immunocompromised patients worldwide. Due to the increase in drug resistance and incidence of infections, there is an urgent need to develop new antifungals and to identify co-drugs that can sensitize drug-resistant Candida to antifungals. The objective of this study was to assess the effect of saquinavir on the activity of azole antifungals against C. auris. The in vitro interaction of saquinavir and three azole antifungals (itraconazole, voriconazole, and fluconazole) was evaluated against a panel of C. auris isolates. The itraconazole/saquinavir combination exhibited a synergistic (SYN) relationship against all C. auris isolates tested with the fractional inhibitory concentration index ranging from 0.03 to 0.27. Moreover, a time-kill kinetics assay revealed that saquinavir restored the itraconazole's fungistatic activity against C. auris. Furthermore, saquinavir restored itraconazole's antifungal activity against other clinically important Candida species. The mechanistic investigation indicated that saquinavir significantly inhibited efflux pumps, glucose utilization, and ATP synthesis in Candida. Finally, a murine model of C. auris infection was used to evaluate the efficacy of the itraconazole/saquinavir combination in the presence of ritonavir (as a pharmacokinetic enhancer). The combination significantly reduced the fungal burden in the kidneys by 0.93-log10 colony-forming units (88%) compared to itraconazole alone. This study identified that saquinavir exhibits a potent SYN relationship in combination with itraconazole against Candida species, which warrants further consideration.

Ponatinib Represses Latent HIV-1 by Inhibiting AKT-mTOR

Although antiretroviral therapy (ART) is effective in suppressing viral replication, it does not cure HIV-1 infection due to the presence of the viral latent reservoir. Rather than reactivating the latent viruses, the "block and lock" strategy aims to shift the viral reservoir to a deeper state of transcriptional silencing, thus preventing viral rebound after ART interruption. Although some latency-promoting agents (LPAs) have been reported, none of them have been approved for clinical application due to cytotoxicity and limited efficacy; therefore, it is important to search for novel and effective LPAs. Here, we report an FDA-approved drug, ponatinib, that can broadly repress latent HIV-1 reactivation in different cell models of HIV-1 latency and in primary CD4+ T cells from ART-suppressed individuals ex vivo. Ponatinib does not change the expression of activation or exhaustion markers on primary CD4+ T cells and does not induce severe cytotoxicity and cell dysfunction. Mechanistically, ponatinib suppresses proviral HIV-1 transcription by inhibiting the activation of the AKT-mTOR pathway, which subsequently blocks the interaction between key transcriptional factors and the HIV-1 long terminal repeat (LTR). In summary, we discovered a novel latency-promoting agent, ponatinib, which could have promising significance for future applications of HIV-1 functional cure.

Current evidence for the risk of PR prolongation, QRS widening, QT prolongation, from lopinavir, ritonavir, atazanavir, and saquinavir: A systematic review

BACKGROUND

Lopinavir, ritonavir, atazanavir, and saquinavir had been reportedly used or suggested for coronavirus disease 2019 (COVID-19) treatment. They may cause electrocardiography changes. We aim to evaluate risk of PR prolongation, QRS widening, and QT prolongation from lopinavir, ritonavir, atazanavir, and saquinavir.

METHODS

In accordance with preferred reporting items for systematic reviews and meta-analyses guidelines, our search was conducted in PubMed Central, PubMed, EBSCOhost, and ProQuest from inception to June 25, 2020. Titles and abstracts were reviewed for relevance. Cochrane Risk of Bias Tool 2.0 and Downs and Black criteria was used to evaluate quality of studies.

RESULTS

We retrieved 9 articles. Most randomized controlled trials have low risk of biases while all quasi-experimental studies have a positive rating. Four studies reporting PR prolongation however only 2 studies with PR interval >200 ms. One of which, reported its association after treatment with ritonavir-boosted saquinavir treatment while another, during treatment with ritonavir-boosted atazanavir. No study reported QRS widening >120 ms with treatment. Four studies reporting QT prolongation, with only one study reaching QT interval >450 ms after ritonavir-boosted saquinavir treatment on healthy patients. There is only one study on COVID-19 patients reporting QT prolongation in 1 out of 95 patients after ritonavir-boosted lopinavir treatment.

CONCLUSION

Limited evidence suggests that lopinavir, ritonavir, atazanavir, and saquinavir could cause PR prolongation, QRS widening, and QT prolongation. Further trials with closer monitoring and assessment of electrocardiography are needed to ascertain usage safety of antivirals in COVID-19 era.

Protease Inhibitors for the Treatment of HIV/AIDS: Recent Advances and Future Challenges

Acquired Immunodeficiency Syndrome (AIDS) is a chronic disease characterized by multiple life-threatening illnesses caused by a retro-virus, Human Immunodeficiency Virus (HIV). HIV infection slowly destroys the immune system and increases the risk of various other infections and diseases. Although, there is no immediate cure for HIV infection/AIDS, several drugs targeting various cruxes of HIV infection are used to slow down the progress of the disease and to boost the immune system. One of the key therapeutic strategies is Highly Active Antiretroviral Therapy (HAART) or ' AIDS cocktail' in a general sense, which is a customized combination of anti-retroviral drugs designed to combat the HIV infection. Since HAART's inception in 1995, this treatment was found to be effective in improving the life expectancy of HIV patients over two decades. Among various classes of HAART treatment regimen, Protease Inhibitors (PIs) are known to be widely used as a major component and found to be effective in treating HIV infection/AIDS. For the past several years, a variety of protease inhibitors have been reported. This review outlines the drug design strategies of PIs, chemical and pharmacological characteristics of some mechanism-based inhibitors, summarizes the recent developments in small molecule based drug discovery with HIV protease as a drug target. Further discussed are the pharmacology, PI drug resistance on HIV PR, adverse effects of HIV PIs and challenges/impediments in the successful application of HIV PIs as an important class of drugs in HAART regimen for the effective treatment of AIDS.

Proteases and protease inhibitors in infectious diseases

There are numerous proteases of pathogenic organisms that are currently targeted for therapeutic intervention along with many that are seen as potential drug targets. This review discusses the chemical and biological makeup of some key druggable proteases expressed by the five major classes of disease causing agents, namely bacteria, viruses, fungi, eukaryotes, and prions. While a few of these enzymes including HIV protease and HCV NS3-4A protease have been targeted to a clinically useful level, a number are yet to yield any clinical outcomes in terms of antimicrobial therapy. A significant aspect of this review discusses the chemical and pharmacological characteristics of inhibitors of the various proteases discussed. A total of 25 inhibitors have been considered potent and safe enough to be trialed in humans and are at different levels of clinical application. We assess the mechanism of action and clinical performance of the protease inhibitors against infectious agents with their developmental strategies and look to the next frontiers in the use of protease inhibitors as anti-infective agents.

World Workshop on Oral Medicine VI: a systematic review of medication-induced salivary gland dysfunction

The aim of this paper was to perform a systematic review of the pathogenesis of medication-induced salivary gland dysfunction (MISGD). Review of the identified papers was based on the standards regarding the methodology for systematic reviews set forth by the World Workshop on Oral Medicine IV and the PRISMA statement. Eligible papers were assessed for both the degree and strength of relevance to the pathogenesis of MISGD as well as on the appropriateness of the study design and sample size. A total of 99 papers were retained for the final analysis. MISGD in human studies was generally reported as xerostomia (the sensation of oral dryness) without measurements of salivary secretion rate. Medications may act on the central nervous system (CNS) and/or at the neuroglandular junction on muscarinic, α-and β-adrenergic receptors and certain peptidergic receptors. The types of medications that were most commonly implicated for inducing salivary gland dysfunction were those acting on the nervous, cardiovascular, genitourinary, musculoskeletal, respiratory, and alimentary systems. Although many medications may affect the salivary flow rate and composition, most of the studies considered only xerostomia. Thus, further human studies are necessary to improve our understanding of the association between MISGD and the underlying pathophysiology.

HIV protease inhibitors: a review of molecular selectivity and toxicity

Highly active antiretroviral therapy (HAART) is recognized as the most effective treatment method for AIDS, and protease inhibitors play a very important role in HAART. However, poor bioavailability and unbearable toxicity are their common disadvantages. Thus, the development of safer and potentially promising protease inhibitors is eagerly needed. In this review, we introduced the chemical characteristics and associated side effects of HIV protease inhibitors, as well as the possible off-target mechanisms causing the side effects. From the chemical structures of HIV protease inhibitors and their possible off-target molecules, we could obtain hints for optimizing the molecular selectivity of the inhibitors, to provide help in the design of new compounds with enhanced bioavailability and reduced side effects.

Pilot Study of Saquinavir and Lopinavir/Ritonavir Twice Daily in Protease Inhibitor-Naive HIV-Positive Patients

PURPOSE

Protease inhibitor (PI)-naive patients may have limited reverse transcriptase inhibitor (RTI) options due to resistance and/or toxicity. Effective, well-tolerated nucleoside reverse transcriptase inhibitor (NRTI)-sparing regimens are therefore needed.

METHOD

This prospective study evaluated the efficacy and safety of saquinavir/lopinavir/ritonavir (1000/400/100 mg bid) in PI-naive patients over 48 weeks. The regimen could be intensified with NRTIs if patients did not achieve virologic suppression by 12 weeks. The primary study endpoint was virologic suppression at 48 weeks. Additional study objectives included assessment of safety, CD4 cell counts, blood lipids, PI trough levels, and anthropometrics.

RESULTS

Of the 20 PI-naive study participants, 16 completed 48 weeks of study treatment, with no discontinuations attributed to virologic failure. Fourteen of 16 patients achieved virologic suppression with only the PIs; 2 patients required tenofovir intensification to achieve complete suppression. Median CD4 counts increased significantly over 48 weeks. Adverse events were generally mild and manageable. Extreme lipid elevations were uncommon, although moderate lipid elevations occurred in the majority of patients. Most patients reported some degree of central fat accumulation.

CONCLUSION

Our study demonstrates that saquinavir/lopinavir/ritonavir 1000/400/100 mg bid with tenofovir intensification is a potent nucleoside-sparing regimen for PI-naive patients, associated with durable HIV suppression and improved CD4 cell counts. Fat accumulation and metabolic changes observed in this study warrant confirmation from ongoing trials.

The Effects of Once-Daily Saquinavir/Minidose Ritonavir on the Pharmacokinetics of Methadone

Twelve methadone-maintained HIV-negative subjects were given saquinavir/ritonavir (SQV/rtv) 1600 mg/100 mg once daily for 14 days. Pharmacokinetic evaluations of total and unbound methadone enantiomers (R and S) were conducted before and after SQV/rtv. SQV/rtv was well tolerated, with no ACTG Grade 3-4 adverse events, no evidence of sedation, and no changes in methadone dose. For R-methadone (active isomer), C(max), AUC(0-24 h), and C(min) were unchanged, but percent unbound 4 hours after dosing was reduced by 12%. For S-methadone, no differences in pharmacokinetic parameters of total drug were seen, but unbound concentrations were reduced by 15% and 21% at 4 and 24 hours after dosing, respectively. SQV trough concentrations exceeded the anticipated EC(50) (50 ng/mL) in 10/12 subjects, persisting for at least 6 hours after the final dose in 4/6 subjects. Once-daily SQV/rtv in methadone-maintained subjects is safe and not associated with any clinically significant interaction with methadone during 14 days of concomitant administration.

CSF penetration by antiretroviral drugs

Severe HIV-associated neurocognitive disorders (HAND), such as HIV-associated dementia, and opportunistic CNS infections are now rare complications of HIV infection due to comprehensive highly active antiretroviral therapy (HAART). By contrast, mild to moderate neurocognitive disorders remain prevalent, despite good viral control in peripheral compartments. HIV infection seems to provoke chronic CNS injury that may evade systemic HAART. Penetration of antiretroviral drugs across the blood-brain barrier might be crucial for the treatment of HAND. This review identifies and evaluates the available clinical evidence on CSF penetration properties of antiretroviral drugs, addressing methodological issues and discussing the clinical relevance of drug concentration assessment. Although a substantial number of studies examined CSF concentrations of antiretroviral drugs, there is a need for adequate, well designed trials to provide more valid drug distribution profiles. Neuropsychological benefits and neurotoxicity of potentially CNS-active drugs require further investigation before penetration characteristics will regularly influence therapeutic strategies and outcome.

Cost-Effectiveness of Antiretroviral Therapy for Multidrug-Resistant HIV: Past, Present, and Future

In the early years of the highly active antiretroviral therapy (HAART) era, HIV with resistance to two or more agents in different antiretroviral classes posed a significant clinical challenge. Multidrug-resistant (MDR) HIV was an important cause of treatment failure, morbidity, and mortality. Treatment options at the time were limited; multiple drug regimens with or without enfuvirtide were used with some success but proved to be difficult to sustain for reasons of tolerability, toxicity, and cost. Starting in 2006, data began to emerge supporting the use of new drugs from the original antiretroviral classes (tipranavir, darunavir, and etravirine) and drugs from new classes (raltegravir and maraviroc) for the treatment of MDR HIV. Their availability has enabled patients with MDR HIV to achieve full and durable viral suppression with more compact and cost-effective regimens including at least two and often three fully active agents. The emergence of drug-resistant HIV is expected to continue to become less frequent in the future, driven by improvements in the convenience, tolerability, efficacy, and durability of first-line HAART regimens. To continue this trend, the optimal rollout of HAART in both rich and resource-limited settings will require careful planning and strategic use of antiretroviral drugs and monitoring technologies.

Tools for eradicating HIV in the brain: prodrug dimeric inhibitors of P-gp

Despite positive developments with the use of combination antiretroviral therapy, a major impediment to limiting the neurocognitive effects of HIV and eradicating HIV brain reservoirs is the penetration of these therapies across the blood-brain barrier (BBB). The focus of our work, therefore, has been to develop tools to significantly improve the penetration of antiretroviral agents to sites of HIV reservoirs, with an emphasis on the CNS. To this end, we have developed an innovative chemical approach--dimeric prodrugs of the antiretroviral agents themselves with a traceless tether. These dimeric prodrugs were designed to serve two purposes: inhibition of P-gp, the major drug efflux protein at the BBB, by occupying two substrate binding sites in the transporter; and prodrug dimers that gain entry into the endothelial cells at the BBB would revert to their monomeric forms in the reducing environment of the cytosol due to breakdown of the traceless tether, thus delivering the therapy. We have demonstrated the feasibility of this design by dimerizing the P-gp substrate and antiviral agent abacavir with a traceless tether. Abacavir dimers displayed potent inhibition of P-gp in two different cellular settings and reverted to active abacavir in the reducing environment of HIV-infected T cells, also leading to antiviral activity. Overall, these experiments point to the excellent promise for future use of dimeric prodrug inhibitors of P-gp for brain penetration of a wide range of CNS-active agents that are substrates of P-gp.

The history of antiretroviral therapy and of its implementation in resource-limited areas of the world

HIV/AIDS not only represents the most severe epidemic in modern times, but also the greatest public health challenge in history. The response of the scientific community has been impressive and in just a few years, turned an inevitably fatal disease into a chronic manageable although not yet curable condition. The development of antiretroviral therapy is not only the history of scientific advancements: it is the result of the passionate 'alliance' towards a common goal between researchers, doctors and nurses, pharmaceutical industries, regulators, public health officials and the community of HIV-infected patients, which is rather unique in the history of medicine. In addition, the rapid and progressive development of antiretroviral therapy has not only proven to be life-saving for many millions but has been instrumental in unveiling the inequities in access to health between rich and poor countries of the world. Optimal benefits indeed, are not accessible to all people living with HIV, with challenges to coverage and sustainability in low and middle income countries. This paper will review the progress made, starting from the initial despairing times, till the current battle towards universal access to treatment and care for all people living with HIV.

Population pharmacokinetics of lopinavir/ritonavir (Kaletra) in HIV-infected patients

BACKGROUND

A relationship between plasma concentrations and viral suppression in patients receiving lopinavir (LPV)/ritonavir (RTV) has been observed. Therefore, it is important to increase our knowledge about factors that determine interpatient variability in LPV pharmacokinetics (PK).

METHODS

The study, designed to develop and validate population PK models for LPV and RTV, involved 263 ambulatory patients treated with 400/100 mg of LPV/RTV twice daily. A database of 1110 concentrations of LPV and RTV (647 from a single time-point and 463 from 73 full PK profiles) was available. Concentrations were determined at steady state using high-performance liquid chromatography with ultraviolet detection. PK analysis was performed with NONMEM software. Age, gender, height, total body weight, body mass index, RTV trough concentration (RTC), hepatitis C virus coinfection, total bilirubin, hospital of origin, formulation and concomitant administration of efavirenz (EFV), saquinavir (SQV), atazanavir (ATV), and tenofovir were analyzed as possible covariates influencing LPV/RTV kinetic behavior.

RESULTS

Population models were developed with 954 drug plasma concentrations from 201 patients, and the validation was conducted in the remaining 62 patients (156 concentrations). A 1-compartment model with first-order absorption (including lag-time) and elimination best described the PK. Proportional error models for interindividual and residual variability were used. The final models for the drugs oral clearance (CL/F) were as follows: CL/F(LPV)(L/h)=0.216·BMI·0.81(RTC)·1.25(EFV)·0.84(ATV); CL/F(RTV)(L/h) = 8.00·1.34(SQV)·1.77(EFV)·1.35(ATV). The predictive performance of the final population PK models was tested using standardized mean prediction errors, showing values of 0.03 ± 0.74 and 0.05 ± 0.91 for LPV and RTV, and normalized prediction distribution error, confirming the suitability of both models.

CONCLUSIONS

These validated models could be implemented in clinical PK software and applied to dose individualization using a Bayesian approach for both drugs.

Drug-drug interactions in the treatment of HIV infection: focus on pharmacokinetic enhancement through CYP3A inhibition

The aim of this review is to discuss the effect of pharmacokinetic drug-drug interactions (DDIs) in the antiretroviral treatment of HIV infection. In particular, but not exclusively, DDIs due to the cytochrome P450 3A (CYP3A) inhibitor ritonavir, which is used to increase antiretroviral drug exposure - a technique known as pharmacokinetic enhancement or 'ritonavir boosting'- will be reviewed. The emphasis here will be on the treatment of important co-morbidities common in patients with HIV, including dyslipidaemia, hypertension, tuberculosis and opiate dependence, as well as on the potentially life-threatening interaction between ritonavir and inhalational steroids, and on the effect of acid-reducing agents on some antiretroviral drugs. Finally, further developments with regard to the use of CYP3A-blocking agents to augment the efficacy of antiviral therapy will be discussed.

Cutaneous toxicities of antiretroviral therapy for HIV: part I. Lipodystrophy syndrome, nucleoside reverse transcriptase inhibitors, and protease inhibitors

Antiretroviral medications for the treatment of HIV are common drugs with diverse and frequent skin manifestations. Multiple new cutaneous effects have been recognized in the past decade. Dermatologists play an important role in accurately diagnosing and managing the cutaneous toxicities of these medications, thereby ensuring that a patient has as many therapeutic options as possible for life-long viral suppression. Part I of this two-part series on the cutaneous adverse effects of antiretroviral medications will discuss HIV-associated lipodystrophy syndrome, which can be seen as a result of many antiretroviral medications for HIV, and the specific cutaneous effects of the nucleoside reverse transcriptase inhibitors and protease inhibitors.

How much ritonavir is needed to boost protease inhibitors? Systematic review of 17 dose-ranging pharmacokinetic trials

BACKGROUND

Ritonavir has been evaluated at boosting doses of 50–800 mg daily with seven protease inhibitors: amprenavir, atazanavir, darunavir, indinavir, lopinavir,saquinavir and tipranavir. Minimizing the boosting dose of ritonavir could improve tolerability and lower costs.

METHODS

A MEDLINE search identified 17 phamacokinetic trials using different ritonavir doses with protease inhibitors. The dose of ritonavir used was correlated with plasma levels of each boosted protease inhibitor. For the five pharmacokinetic trials of lopinavir/ritonavir, a meta-analysis was used to estimate the effects of lopinavir dose versus ritonavir dose on lopinavir pharmacokinetics.

RESULTS

Saquinavir, fosamprenavir and darunavir were boosted equally well by lower(50–100 mg) versus higher doses of ritonavir. Indinavir, tipranavir and lopinavir were boosted more by higher ritonavir doses. Data on atazanavir were inconclusive. The ritonavir dose-dependence of boosting effects did not correlate with their bioavailability or their effects on ritonavir plasma levels. Atazanavir and indinavir raised plasma ritonavir levels by 69–72%, whereas saquinavir had no effects on ritonavir. Darunavir,lopinavir, tipranavir and fosamprenavir all lowered ritonavir plasma levels. For the meta-analysis of lopinavir/ritonavir trials, the 200/150 mg twice daily (b.i.d.) dose of lopinavir/ritonavir (one Meltrex 200/50mg tablet and one ritonavir 100mg b.i.d.)showed lopinavir area under the curve and minimum concentration similar to the standard 400/100mg b.i.d. dose.

CONCLUSION

It may be possible to use three protease inhibitors (saquinavir, amprenavir and darunavir) with lower doses of ritonavir. A 200/150 mg b.i.d. dose of lopinavir/ritonavir could lower costs while maintaining very similar lopinavir plasma levels to the standard dose. New pharmaco enhancer drugs may need to be used at different doses to boost different antiretrovirals.

Cytochrome P450 3A inhibition by atazanavir and ritonavir, but not demography or drug formulation, influences saquinavir population pharmacokinetics in human immunodeficiency virus type 1-infected adults

Inadequate concentrations of the human immunodeficiency virus (HIV) protease inhibitor saquinavir jeopardize individual therapy success or produce side effects despite treatment according to the current guidelines. We performed a population pharmacokinetic analysis with NONMEM and determined that the steady-state pharmacokinetics of saquinavir in 136 HIV type 1-infected adults was modulated by a decrease in saquinavir CL following coadministration of the cytochrome P450 3A inhibitors ritonavir and atazanavir. In contrast, age, sex, weight, pregnancy, and the pharmaceutical formulation exerted only minor, nonsignificant effects.

[Hypertension, HIV infection, and highly active antiretroviral therapy]

The decline in mortality resulting from the use of highly active antiretroviral therapy (HAART) has been accompanied by an increase in metabolic complications that produce accelerated atherosclerosis. Hypertension is one of the most important cardiovascular risk factors. Little is known about the impact of HAART on blood pressure, and it is uncertain whether chronic HIV infection or HAART have a role in the development of hypertension. In this study, the research on the relationships between hypertension and HIV infection published to date is reviewed. Antiretroviral therapy appears to have a modest impact on blood pressure and to be partially mediated by the metabolic changes occurring with this treatment.

Cardiovascular manifestations in human immunodeficiency virus-infected patients

Human immunodeficiency virus (HIV) is now a pandemic. It afflicts multiple organs, including the cardiovascular system. This occurs by direct invasion as well as opportunistic infections complicating acquired immunodeficiency syndrome. The presence of newer highly active antiretroviral therapy has led to longer survival of patients infected with HIV, but the cardiac abnormalities related to HIV have remained less well characterized. It is now evident that cardiac involvement in patients with acquired immunodeficiency syndrome is relatively common. This includes coronary artery disease, dilated cardiomyopathy, pericardial effusion, pulmonary hypertension, and ill effects of highly active antiretroviral therapy in the form of lipodystrophy, lipoatrophy, and dyslipidemia. In fact, HIV can now be viewed as a potential risk factor for coronary artery disease, and the dilemma facing clinicians is how to quantify this risk. Awareness of accelerated coronary artery disease and dilated cardiomyopathy is critical to implement preventive measures early in the course of HIV. However, better guidelines are still needed on the basis of prospective randomized controlled studies involving large populations. In conclusion, this review describes cardiac abnormalities associated with HIV, including possible molecular mechanisms. The co-morbid sequelae, their presentation, and pharmacologic management are also discussed.

The cost-effectiveness of counseling strategies to improve adherence to highly active antiretroviral therapy among men who have sex with men

OBJECTIVE

Inadequate adherence to highly active antiretroviral therapy (HAART) may lead to poor health outcomes and the development of HIV strains that are resistant to HAART. The authors developed a model to evaluate the cost-effectiveness of counseling interventions to improve adherence to HAART among men who have sex with men (MSM).

METHODS

The authors developed a dynamic compartmental model that incorporates HIV treatment, adherence to treatment, and infection transmission and progression. All data estimates were obtained from secondary sources. The authors evaluated a counseling intervention given prior to initiation of HAART and before all changes in drug regimens, combined with phone-in support while on HAART. They considered a moderate-prevalence and a high-prevalence population of MSM.

RESULTS

If the impact of HIV transmission is ignored, the counseling intervention has a cost-effectiveness ratio of $25,500 per quality-adjusted life year (QALY) gained. When HIV transmission is included, the cost-effectiveness ratio is much lower: $7400 and $8700 per QALY gained in the moderate- and high-prevalence populations, respectively. When the intervention is twice as costly per counseling session and half as effective as estimated in the base case (in terms of the number of individuals who become highly adherent, and who remain highly adherent), then the intervention costs $17,100 and $19,600 per QALY gained in the 2 populations, respectively.

CONCLUSIONS

Counseling to improve adherence to HAART increased length of life, modestly reduced HIV transmission, and cost substantially less than $50,000 per QALY gained over a wide range of assumptions but did not reduce the proportion of drug-resistant strains. Such counseling provides only modest benefit as a tool for HIV prevention but can provide significant benefit for individual patients at an affordable cost.

Association of saquinavir plasma concentrations with side effects but not with antiretroviral outcome in patients infected with protease inhibitor-susceptible human immunodeficiency virus type 1

The objective of this study was to identify parameters among saquinavir pharmacokinetics, patients' demographics or comedications, to be addressed for improved personalized therapy. The presence of human immunodeficiency virus type 1 (HIV-1) RNA at therapy week 48 (principal target parameter), CD4 cell count at week 48, infections and side effects during 48 weeks, indicators of liver toxicity and lipid abnormalities at week 48, and a 12-h saquinavir plasma concentration-versus-time profile were assessed in 56 patients receiving saquinavir-ritonavir (1,000 and 100 mg, respectively) twice daily (44 therapy-naïve and 12 antiretrovirally pretreated patients) for association with saquinavir plasma concentrations, demographics, baseline values of target parameters, and coadministered antiretrovirals. Antiretroviral failure was observed in 8 of the 56 patients in whom HIV-1 RNA was detectable at week 48. This therapeutic failure was not associated with individual saquinavir pharmacokinetics. More likely, therapeutic failure was related to incidences interfering with antiretroviral therapy, causing therapy interruptions or incompliance. Weak associations were, however, seen between high maximum saquinavir plasma concentrations and both CD4 counts of > or =200 cells microl(-1) at week 48 (P = 0.014) and constitutional side effects during 48 weeks (P = 0.002). However, patients with high CD4 counts and constitutional side effects were not identical (P = 0.53). Saquinavir therapeutic drug monitoring in patients infected with protease inhibitor-susceptible HIV-1 taking saquinavir-ritonavir (1,000 and 100 mg, respectively) is not demanded for improving the antiretroviral effect. It may be contemplated in cases with constitutional side effects or low CD4 counts with weak immune responses.

Exploratory study comparing the metabolic toxicities of a lopinavir/ritonavir plus saquinavir dual protease inhibitor regimen versus a lopinavir/ritonavir plus zidovudine/lamivudine nucleoside regimen

OBJECTIVES

To assess the safety, efficacy and metabolic toxicity of lopinavir/ritonavir + saquinavir or zidovudine/lamivudine and evaluate the pharmacokinetics of lopinavir/ritonavir + saquinavir.

METHODS

HIV-1-infected, antiretroviral-naive subjects were randomized to lopinavir/ritonavir (400/100 mg) twice daily + saquinavir (800 mg) or zidovudine/lamivudine (150/300 mg) in a Phase II, 48 week study. Subjects receiving lopinavir/ritonavir + zidovudine/lamivudine initiated escalating doses of saquinavir (400, 600 and 800 mg) weekly for 3 weeks.

RESULTS

By intent-to-treat (non-completer = failure) analysis, 10/16 (63%) lopinavir/ritonavir + saquinavir-treated and 7/14 (50%) lopinavir/ritonavir + zidovudine/lamivudine-treated subjects achieved plasma HIV-1 RNA <50 copies/mL (P=0.713) at week 48. Safety, tolerability, metabolic changes and truncal fat increases were similar between groups. Small decreases in the lower extremity fat in the zidovudine/lamivudine group (-6%) and a statistically significant increase in the lower extremity fat in the saquinavir group (+19%) were observed. Lopinavir/ritonavir co-administered with saquinavir 600 or 800 mg twice daily produced saquinavir concentrations similar to those previously reported for saquinavir/ritonavir 1000/100 mg twice daily.

CONCLUSIONS

Treatment regimens had similar efficacy and tolerability. Metabolic parameters suggested lipoatrophy in the zidovudine/lamivudine treatment group. Saquinavir 600 and 800 mg twice daily produced concentrations similar to those previously reported for saquinavir/ritonavir 1000/100 mg twice daily.

Clinical Validation of Saquinavir/Ritonavir Genotypic Resistance Score in Protease-Inhibitor-Experienced Patients

Objective

To identify a genotypic score for resistance to saquinavir boosted with ritonavir (SQV/r; 1,000/100 mg twice daily)-based regimens in protease inhibitor (PI)-experienced patients.

Methods

One-hundred and fifty-one PI-experienced patients receiving a SQV/r-containing regimen were enrolled retrospectively. The virological response (VR) was defined as the decrease in HIV RNA at months 3–5. The effect of each mutation in the protease gene on the VR to SQV/r regimen was assessed using non-parametric univariate analyses and then a step-by-step analysis was carried out using a Jonckheere-Tepstra (JT) non-parametric test to retain the group of mutations most strongly associated with VR.

Results

Among the 138 patients with detectable plasma SQV, the median VR was -1.48 [range: -4 to +1.2] log10 copies/ml. Changes at 12 codons were associated with a reduced VR to SQV/r: codons 10, 15, 20, 24, 46, 54, 62, 71, 73, 82, 84 and 90. The JT procedure led to selection of the following genotypic score, 10+15+20+ 24+62+73+82+84+90, as providing the strongest association with VR. In the 35 patients with none of the mutations in this score, the median decrease in HIV RNA was -2.24 log10 copies/ml and it was -1.88 ( n=29), -1.43 ( n=24), -0.52 ( n=30), -0.18 ( n=9), -0.11 ( n=6) and -0.30 ( n=5) log10 copies/ml in those with 1, 2, 3, 4, 5 and 6 mutations, respectively.

Conclusion

With this resistance score to SQV/r, the isolates were classified as having no evidence of resistance (0–2), possible resistance (3) or resistance (≥4) by grouping the number of mutations in samples for which the viral load reduction was similar.

Ritonavir-Boosted Protease Inhibitors: Impact of Ritonavir on Toxicities in Treatment-Experienced Patients

The purpose of this review is to discuss the basis for ritonavir boosting of protease inhibitors as well as the complications and benefits associated with ritonavir boosting when designing an antiretroviral regimen for treatment-experienced patients. Such patients have fewer viable options because of cross-resistance arising from previous regimen failures. Ritonavir administered at a low dose to boost another protease inhibitor may be a useful strategy for achieving virological efficacy while minimizing the toxicities associated with full-dose ritonavir. There may be an increased risk of adverse events associated with increased plasma concentration of the concurrent protease inhibitor. Still, the incidence of these adverse events is generally low, and clinical trials have suggested that they rarely result in discontinuation or alteration of the regimen. In highly treatment-experienced patients in particular, the potential benefits associated with ritonavir boosting usually outweigh the risks.

Theoretical basis, experimental design, and computerized simulation of synergism and antagonism in drug combination studies

The median-effect equation derived from the mass-action law principle at equilibrium-steady state via mathematical induction and deduction for different reaction sequences and mechanisms and different types of inhibition has been shown to be the unified theory for the Michaelis-Menten equation, Hill equation, Henderson-Hasselbalch equation, and Scatchard equation. It is shown that dose and effect are interchangeable via defined parameters. This general equation for the single drug effect has been extended to the multiple drug effect equation for n drugs. These equations provide the theoretical basis for the combination index (CI)-isobologram equation that allows quantitative determination of drug interactions, where CI < 1, = 1, and > 1 indicate synergism, additive effect, and antagonism, respectively. Based on these algorithms, computer software has been developed to allow automated simulation of synergism and antagonism at all dose or effect levels. It displays the dose-effect curve, median-effect plot, combination index plot, isobologram, dose-reduction index plot, and polygonogram for in vitro or in vivo studies. This theoretical development, experimental design, and computerized data analysis have facilitated dose-effect analysis for single drug evaluation or carcinogen and radiation risk assessment, as well as for drug or other entity combinations in a vast field of disciplines of biomedical sciences. In this review, selected examples of applications are given, and step-by-step examples of experimental designs and real data analysis are also illustrated. The merging of the mass-action law principle with mathematical induction-deduction has been proven to be a unique and effective scientific method for general theory development. The median-effect principle and its mass-action law based computer software are gaining increased applications in biomedical sciences, from how to effectively evaluate a single compound or entity to how to beneficially use multiple drugs or modalities in combination therapies.

Antiretroviral therapy 2006: Pharmacology, applications, and special situations

As we approach the completion of the first 25 years of the human immunodeficiency virus (HIV) epidemic, there have been dramatic improvements in the care of patients with HIV infection. These have prolonged life and decreased morbidity. There are twenty currently available antiretrovirals approved in the United States for the treatment of this infection. The medications, including their pharmacokinetic properties, side effects, and dosing are reviewed. In addition, the current approach to the use of these medicines is discussed. We have included a section addressing common comorbid conditions including hepatitis B and C along with tuberculosis.

Analysis of genotypic and phenotypic clinical cut-off levels for ritonavir-boosted saquinavir

There is a need for new, clinically relevant interpretation algorithms for genotypic and phenotypic resistance for ritonavir-boosted saquinavir (SQV/r) at the current approved dosage [1000/100 mg twice a day (bid)]. Clinical cut-off levels, which correlate baseline measures of resistance with HIV RNA responses in large cohorts or clinical trials, are the ideal reference for developing such algorithms. Cut-off levels previously developed for unboosted saquinavir may no longer apply, as the plasma drug levels with SQV/r are significantly higher and may be able partially to overcome protease inhibitor-resistant HIV. Clinical cut-off levels for SQV/r, assessed in several cohort studies and clinical trials, also suggest that multiple genotypic mutations are required for complete loss of virological response. For phenotypic analysis of resistance, saquinavir cut-off levels 10-11-fold higher than the wild-type IC50 have best distinguished responders from non-responders in cohort studies. Using Virtual Phenotype, a 12.3-fold upper cut-off level was determined from analysis of large cohort databases. These genotypic and phenotypic algorithms need to be validated in larger prospective studies.

Pharmacoenhancement of Protease Inhibitors

Toxicity, adherence problems, and virological failure may limit treatment by protease inhibitor-containing regimens at standard doses. Addition of low-dose ritonavir results in a high plasma concentration of coadministered protease inhibitor resulting in decreased pill burden, a reduction in the number of doses, fewer food and/or fluid restrictions, and a higher rate of virological suppression. These effects are due to improved pharmacokinetics of coadministered protease inhibitors.

Virologic and immunologic response to a boosted double-protease inhibitor-based therapy in highly pretreated HIV-1-infected patients

PURPOSE

To assess the virologic and immunologic response to a boosted double-protease inhibitor (PI) regimen of highly pretreated patients infected with HIV-1 and to examine the role of PI resistance and concentration of serum saquinavir.

METHOD

In an open-label prospective study, lopinavir/ritonavir, saquinavir-sgc, lamivudine, and other nucleoside analogues were offered to highly pretreated patients who had advanced HIV-1 infection and who had failed at least 2 previous highly active antiretroviral therapy regimens including at least 1 nonnucleoside reverse transcriptase inhibitor. The relationship between baseline drug resistance and steady-state saquinavir serum levels and early (week 4) and sustained (week 48) virologic response was documented.

RESULTS

35 advanced HIV-1 patients were enrolled. The boosted double-PI regimen was well tolerated. Twenty-two (63%) of the 35 patients had a > 0.8 log(10) decrease in HIV viral load at week 4. After 48 weeks of follow-up, the 22 patients who remained on the study therapy had an average decrease in viral load of 1 log(10) and had a median increase in CD4 cells of 60 cell/microL. Multiple logistic regression analysis indicated that genotypic resistance to both PIs and the week-3 trough concentrations of saquinavir were associated with virologic outcome at week 4. The presence of > or = 6 lopinavir mutations [odds ratio (OR) 0.03; 95% CI 0.01 to 0.79] and the 48V mutation (OR 0.01; 95%CI <0.01 to 0.88) was independently associated with lower odds of achieving an early response, whereas a higher saquinavir concentration at week 3 (OR 8.36; 95% CI 1.28 to 54.70) was associated with greater odds of an early response.

CONCLUSION

These findings suggest that baseline PI resistance and saquinavir concentration were associated with virologic response and should be considered when planning salvage therapy.

Efficacy and tolerability of a nucleoside reverse transcriptase inhibitor-sparing combination of lopinavir/ritonavir and efavirenz in HIV-1-infected patients

BACKGROUND

Recommended antiretroviral regimens include a nucleoside reverse transcriptase inhibitor (NRTI) component. Class cross-resistance and mitochondrial toxicity are recognized as problems with this class of antiretrovirals.

METHODS

In a pilot open-label study, 65 antiretroviral-naive and 21 experienced but nonnucleoside reverse transcriptase inhibitor-naive HIV-1-infected adults were given a combination of lopinavir/ritonavir (533.3/133.3 mg twice daily) and efavirenz (600 mg once daily) for 48 weeks.

RESULTS

At baseline, the mean viral load was 4.84 log10 copies/mL and the mean CD4 count was 311 cells/mm. At week 24, the proportions of patients with a viral load <400 copies/mL were 78% and 93% using an intent-to-treat and on-treatment analysis, respectively. At week 48, proportions were 73% and 97%, respectively. Treatment discontinuation occurred in 21 patients during the 48-week period, with 33% of those attributable to drug-related adverse effects. A viral load >400 copies/mL at week 24 or 48 was associated with nonadherence in 3 patients and virologic failure in 1 patient. After an increase during the first 8 weeks, fasting lipid levels remained stable up to 48 weeks.

CONCLUSION

The lopinavir/ritonavir-efavirenz combination is associated with a high rate of virologic response and should be compared with more classic NRTI-containing regimens in randomized and controlled clinical trials.

[Treatment strategies for human immunodeficiency virus infection or "return to the future"]

New therapeutic strategies aiming at an improved management of patients infected by the human immunodeficiency virus are actually based, at least partly, on older concepts and molecules developed since the discovery of the acquired immunodeficiency syndrome. Accordingly, the first antiretroviral drug available zidovudine, after being left over for some time, now is an active component of tritherapies because of its ability to reduce the emergence of the K65R resistance mutation induced by some nucleosidic reverse transcriptase inhibitors. Similarly, the old concept of inhibiting the virus entry in its target cells, that was once developed with soluble recombined CD4, has been revived in the form of fusion inhibitors, such as the already marketed enfuvirtide, and the currently under phase I development BMS-488043 and SCH-D. Finally, monotherapy, which was abandoned since the advent of the more powerful tritherapies, has now regained interest with the boosted protease inhibitor lopinavir/ritonavir.

Cost-effectiveness of screening for HIV in the era of highly active antiretroviral therapy

BACKGROUND

The costs, benefits, and cost-effectiveness of screening for human immunodeficiency virus (HIV) in health care settings during the era of highly active antiretroviral therapy (HAART) have not been determined.

METHODS

We developed a Markov model of costs, quality of life, and survival associated with an HIV-screening program as compared with current practice. In both strategies, symptomatic patients were identified through symptom-based case finding. Identified patients started treatment when their CD4 count dropped to 350 cells per cubic millimeter. Disease progression was defined on the basis of CD4 levels and viral load. The likelihood of sexual transmission was based on viral load, knowledge of HIV status, and efficacy of counseling.

RESULTS

Given a 1 percent prevalence of unidentified HIV infection, screening increased life expectancy by 5.48 days, or 4.70 quality-adjusted days, at an estimated cost of 194 dollars per screened patient, for a cost-effectiveness ratio of 15,078 dollars per quality-adjusted life-year. Screening cost less than 50,000 dollars per quality-adjusted life-year if the prevalence of unidentified HIV infection exceeded 0.05 percent. Excluding HIV transmission, the cost-effectiveness of screening was 41,736 dollars per quality-adjusted life-year. Screening every five years, as compared with a one-time screening program, cost 57,138 dollars per quality-adjusted life-year, but was more attractive in settings with a high incidence of infection. Our results were sensitive to the efficacy of behavior modification, the benefit of early identification and therapy, and the prevalence and incidence of HIV infection.

CONCLUSIONS

The cost-effectiveness of routine HIV screening in health care settings, even in relatively low-prevalence populations, is similar to that of commonly accepted interventions, and such programs should be expanded.

Actual medication pill burden and dosing frequency in HIV-infected patients with undetectable viral loads

Studies have shown equivalent or improved outcomes with once-daily antiretroviral (ARV) regimens, but have failed to quantify the true daily dosing frequency and pill burden of HIV-infected patients, by not considering concomitant medications. This study was conducted to describe the total daily number (pill burden) and dosing frequency for all oral medicines, and not just ARV medications in HIV-infected patients with undetectable viral loads. A retrospective chart review of patients with undetectable viral loads in an HIV primary care clinic identified dosing frequency and pill burden for all prescribed medications. These patients were divided into those with concomitant medications (WITH) and those only on ARV medications (WITHOUT). One hundred and seventeen patients qualified for the evaluation. Ninety-three were in the WITH group and 24 were in the WITHOUT group. WITH patients were older (p < 0.05), and had advanced US Centers for Disease Control and Prevention (CDC)-defined HIV disease stage (p< 0.05), a longer duration of HIV infection (p= 0.03), and a longer duration of AIDS (p= 0.02). WITH patients had a significantly greater total pill burden (p<0.01) and dosing frequency (p<0.001) when considering all medications. Assessing only ARV medications, a significant difference existed only in pill burden (mean +/- SD) (WITH = 9.91 +/- 2.1 versus WITHOUT = 6.6 +/- 1; p < 0.01), and no difference existed in ARV dosing frequency of 2.09 +/- 1.9 and 1.83 +/- 1.7, respectively (p = 0.07). Higher dosing frequencies and pill burdens were present in patients with co-morbid conditions. All patients were on more than once-daily therapies. Dosing requirements for non-ARV medications should also be considered when optimizing or simplifying ARV regimens.

Clinically relevant interpretation of genotype and relationship to plasma drug concentrations for resistance to saquinavir-ritonavir in human immunodeficiency virus type 1 protease inhibitor-experienced patients

It has been shown that virological protease inhibitor (PI) resistance mutations present at the initiation of saquinavir (SQV) plus ritonavir (RTV) therapy in PI-experienced patients are the strongest predictors of virological response. But most of the current resistance algorithms are adapted for unboosted SQV regimens. We applied a stepwise methodology for the development and validation of a clinically relevant genotypic resistance score for an SQV (800 mg twice per day [b.i.d.]) plus RTV (100 mg b.i.d.)-containing regimen. PI-experienced patients treated by this regimen achieved a human immunodeficiency virus plasma viral load (VL) of <200 copies/ml at months 3 to 5 for 41.7% of subjects. Adjusted in a multivariate analysis, taking into account all the confounding factors, such as the nucleoside used, five mutations were combined in a resistance score associated with a reduced virological response to an SQV-plus-RTV regimen: L24I, I62V, V82A/F/T/S, I84V, and L90IM. Patients with isolates harboring 0 to 1 mutation among the score achieved -2.20 log10 and -1.23 log10 copies/ml of VL reduction, respectively, while it was -0.27 log10 copies/ml for those with at least two mutations, classifying the isolates as "no evidence of resistance" (0 or 1 mutation) or "resistance " (> or =2 mutations). The minimum concentration in plasma (Cmin) of SQV alone was not associated with the virological response. However, the combination of the SQV Cmin and the genotypic score, expressed as the genotypic inhibitory quotient, was predictive of the virological response, suggesting that the interpretation of SQV concentrations in plasma should be done only in the context of the resistance index provided by viral genotype for PI-experienced patients.