High-Dose Lopinavir/Ritonavir in Highly Treatment-Experienced HIV-1 Patients: Efficacy, Safety, and Predictors of Response

Clinical Efficacy and Safety of Antiviral Drugs in the Extended Use against COVID-19: What We Know So Far

Human beings around the globe have been suffering from a devastating novel pandemic and public health emergency, coronavirus disease 2019 (COVID-19), for more than one and a half years due to the deadly and highly pathogenic severe acute respiratory coronavirus 2 (SARS-CoV-2) infection worldwide. Notably, no effective treatment strategy has been approved for the complete recovery of COVID-19 patients, though several vaccines have been rolled out around the world upon emergency use authorization. After the emergence of the COVID-19 outbreak globally, plenty of clinical investigations commenced to screen the safety and efficacy of several previously approved drugs to be repurposed against the SARS-CoV-2 pathogen. This concise review aims at exploring the current status of the clinical efficacy and safety profile of several antiviral medications for the treatment of patients with COVID-19 and other respiratory complications caused by SARS-CoV-2 infection. The paper covers all kinds of human studies (January 2020 to June 2021) except case reports/series to highlight the clear conclusion based on the current clinical evidence. Among the promising repositioned antivirals, remdesivir has been recommended in critical conditions to mitigate the fatality rate and improve clinical conditions. In addition, boosting the immune system is believed to be beneficial in treating COVID-19 patients, so interferon type I might exert immunomodulation through its antiviral effects by stimulating interferon-stimulated gene (ISG). However, more extensive clinical studies covering all ethnic groups globally are warranted based on current data to better understand the clinical efficacy of the currently proposed repurposed drugs against COVID-19.

Repurposing therapeutic agents against SARS-CoV-2 infection: most promising and neoteric progress

INTRODUCTION

The pathogenic and highly transmissible etiological agent, SARS-CoV-2, has caused a serious threat COVID-19 pandemic. WHO has declared the epidemic a public health emergency of international concern owing to its high contagiosity, mortality rate, and morbidity. Till now, there is no approved vaccine or drug to combat the COVID-19 and avert this global crisis.

AREAS COVERED

In this narrative review, we summarized the updated results (January to August 2020) of the most promising repurposing therapeutic candidates to treat the SARS-CoV-2 viral infection. The repurposed drugs classified under four headlines like antivirals, anti-parasitic, immune-modulating, and miscellaneous drugs were discussed with their in vitro efficacy to recent clinical advancements against COVID-19.

EXPERT OPINION

Currently, palliative care, ranging from outpatient management to intensive care, including oxygen administration, ventilator support, intravenous fluids therapy, with some repurposed drugs, are the primary weapons to fight against COVID-19. Until a safe and effective vaccine is developed, an evidence-based drug repurposing strategy might be the wisest option to save people from this catastrophe. Several existing drugs are now under clinical trials, and some of them are approved in different places of the world for emergency use or as adjuvant therapy in COVID-19 with standard of care.

Physiologically-Based Pharmacokinetic Modeling to Predict the Clinical Efficacy of the Coadministration of Lopinavir and Ritonavir against SARS-CoV-2

Lopinavir/ritonavir, originally developed for treating HIV, is currently undergoing clinical studies for treating the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). Although recent reports suggest that lopinavir exhibits in vitro efficacy against SARS‐CoV‐2, it is a highly protein‐bound drug and it remains unknown if it reaches adequate in vivo unbound (free) concentrations in lung tissue. We built a physiologically‐based pharmacokinetic model of lopinavir/ritonavir in white and Chinese populations. Our aim was to perform pharmacokinetic/pharmacodynamic correlations by comparing simulated free plasma and lung concentration values achieved using different dosing regimens of lopinavir/ritonavir with unbound half‐maximal effective concentration (EC_50,unbound) and unbound effective concentration 90% values of lopinavir against SARS‐CoV‐2. The model was validated against multiple observed clinical datasets for single and repeated dosing of lopinavir/ritonavir. Predicted pharmacokinetic parameters, such as the maximum plasma concentration, area under the plasma concentration‐time profile, oral clearance, half‐life, and minimum plasma concentration at steady‐state were within two‐fold of clinical values for both populations. Using the current lopinavir/ritonavir regimen of 400/100 mg twice daily, lopinavir does not achieve sufficient free lung concentrations for efficacy against SARS‐CoV‐2. Although the Chinese population reaches greater plasma and lung concentrations as compared with whites, our simulations suggest that a significant dose increase from the current clinically used dosing regimen is necessary to reach the EC_50,unbound value for both populations. Based on safety data, higher doses would likely lead to QT prolongation and gastrointestinal disorders (nausea, vomiting, and diarrhea), thus, any dose adjustment must be carefully weighed alongside these safety concerns.

Pharmacokinetics of lopinavir determined with an ELISA test in youths with perinatally acquired HIV

OBJECTIVE

To investigate the plasma levels of lopinavir by enzyme-linked immunosorbent assay (ELISA) in a cohort of patients who were vertically infected with human immunodeficiency virus 1 (HIV).

METHODS

Plasma levels of lopinavir (Cmin) were determined by ELISA test in patients treated with lopinavir/ritonavir-based combined antiretroviral therapy who had achieved virological response after 4 wk of therapy. Reference lopinavir concentrations were Cmin 1-8 μg/mL. Correlation between lopinavir plasma concentration and continuous variables was evaluated by mean of Pearson correlation coefficient. Differences in lopinavir (LPV) concentration for binary categorical variables were assessed by Mann-Whitney test, while for variables with more than two categories Kruskal-Wallis test was used.

RESULTS

Thirty-four patients were enrolled; median age was 133 mo (15-265). The median lopinavir dose tested was 383.5 mg/kg (IQR: 266.6-400 mg/kg), with a median plasma concentration of 8.8 μg/mL (IQR: 5-14 μg/mL). Lopinavir Cmin was <1 μg/mL in only one sample (2.9 %), while 14 samples had Cmin between 1 and 8 μg/mL (41.2 %) and 19 (55.9 %) > 8 μg/mL. No significant correlations were found between plasma concentrations of lopinavir and the continuous variables considered in the study. A negative but, not completely significant, correlation was found between plasma drug concentration and body mass index (r = -0.29; p = 0.09).

CONCLUSIONS

The use of a simple and relatively cost-effective methodology might render therapeutic drug monitoring (TDM) appeal in the daily clinical practice.

Pharmacokinetics and virological efficacy after switch to once-daily lopinavir-ritonavir in treatment-experienced HIV-1-infected children

Lopinavir-ritonavir (LPV/r) is a protease inhibitor that is used twice daily (BID) in the treatment of HIV infection in children. In the context of a single-center observational study, a switch to a once-a-day (QD) LPV/r regimen was proposed for considerations of convenience and to support adherence. The aims of this study were to compare the pharmacokinetics, viral loads, percentages of CD4(+) T cells, and lipid profiles after switching from a twice-daily to a once-daily regimen of LPV/r in experienced children. For this purpose, LPV concentrations, viral loads, CD4(+) T cells, and biochemistry data were measured in routine therapeutic drug monitoring procedures in 45 children and adolescents. Thirty-six children were switched to the QD regimen. Nine children on the BID or QD regimen were added for pharmacokinetic-study purposes only. The QD trough concentrations (C(trough)) of lopinavir in plasma were significantly lower than those observed with the BID regimen (P < 0.0001), but the 24-h exposure levels were not significantly lower with the QD than with the BID regimen (P = 0.09). Among 34 evaluable patients who switched from the BID to the QD regimen, the virological efficacy of LPV/r appeared to differ (P < 0.001), with 74% and 57% of viral loads, respectively, being <50 copies/ml (mean follow-up times, 33 and 20 months). Among 22 patients with stable virological control before the switch, 12 experienced either failure or blip (one observation of detectable viral load between two observations of undetectable viral load) after the switch. The change from the BID to the QD regimen did not result in significant differences in CD4(+) T cell percentages or total cholesterol, high-density lipoprotein (HDL) cholesterol, or triglyceride levels. The switch from the BID to the QD LPV/r regimen led to equivalent exposure and lower C(trough) values and resulted in lower levels of virological control in these antiretroviral-experienced children.

Lopinavir/Ritonavir: a review of its use in the management of HIV-1 infection

Lopinavir/ritonavir (Kaletra®) is an orally administered coformulated ritonavir-boosted protease inhibitor (PI) comprising lopinavir and low-dose ritonavir. It is indicated, in combination with other antiretroviral agents, for the treatment of HIV-1 infection in adults, adolescents and children. Lopinavir/ritonavir is available as a tablet, soft-gel capsule and an oral solution for patients with difficulty swallowing. In well designed, randomized clinical trials, lopinavir/ritonavir, in combination with other antiretroviral therapies (ART), provided durable virological suppression and improved immunological outcomes in both ART-naive and -experienced adult patients with virological failure. Furthermore, lopinavir/ritonavir demonstrated a high barrier to the development of resistance in ART-naive patients. More limited data indicate that it is effective in reducing plasma HIV-1 RNA levels in paediatric patients. Lopinavir/ritonavir has served as a well established benchmark comparator for the noninferiority of other ritonavir-boosted PI regimens. Although generally well tolerated, lopinavir/ritonavir is associated with generally manageable adverse gastrointestinal side effects and hypertriglyceridaemia and hypercholesterolaemia, which may require coadministration of lipid-lowering agents to reduce the risk of coronary heart disease. Lopinavir/ritonavir, in combination with other ART agents, is a well established and cost-effective treatment for both ART-naive and -experienced patients with HIV-1 infection and, with successful management of adverse events, continues to have a role as an effective component of ART regimens for the control of HIV-1 infection.

A once-daily lopinavir/ritonavir-based regimen is noninferior to twice-daily dosing and results in similar safety and tolerability in antiretroviral-naive subjects through 48 weeks

BACKGROUND

Lopinavir/ritonavir (LPV/r)-dosed twice daily has demonstrated durable efficacy in antiretroviral-naive and protease inhibitor (PI) -experienced patients. Study M05-730 compared LPV/r tablets dosed once daily vs. twice daily in antiretroviral-naive subjects.

METHODS

Six hundred sixty-four subjects were randomized to LPV/r soft gel capsules (SGCs) once daily, SGC twice daily, tablets once daily, and tablets twice daily, all with tenofovir and emtricitabine once daily. At week 8, all SGC-treated subjects were switched to tablets, maintaining randomized dose frequency. The primary efficacy analysis used an intent-to-treat, noncompleter = failure approach to assess noninferiority of the LPV/r once-daily group compared with the twice-daily group.

RESULTS

At week 48, 77% of once-daily-dosed subjects vs. 76% of twice-daily-dosed subjects had HIV-1 RNA <50 copies per milliliter (P = 0.715; 95% confidence interval for difference: 5% to 8%). Response rates were numerically similar between the once-daily and twice-daily groups among subjects with baseline HIV-1 RNA > or = 100,000 copies per milliliter (75% once daily vs. 74.6% twice daily; P > 0.999) or when analyzed by baseline CD4+ T-cell count (<50, 50 to <200, and > or = 200 cells/mm3). Rates of discontinuation and adverse events, including diarrhea, were similar between arms. Among subjects with protocol-defined virologic rebound through week 48, no new PI resistance mutations were detected.

CONCLUSIONS

At 48 weeks, the antiviral response in the LPV/r once-daily group was noninferior to the twice-daily group when coadministered with tenofovir and emtricitabine in antiretroviral-naive subjects. Efficacy was comparable between the once-daily and twice-daily groups regardless of baseline HIV-1 RNA or CD4+ T-cell count. Safety and tolerability of once-daily and twice-daily dosing was also comparable. No new PI resistance mutations were detected upon virologic rebound.

Population pharmacokinetics of lopinavir predict suboptimal therapeutic concentrations in treatment-experienced human immunodeficiency virus-infected children

In adult protease inhibitor (PI)-experienced patients, a lopinavir (LPV) phenotypic inhibitory quotient (PIQ) of >15 has been associated with a higher likelihood of viral suppression. The aims of this study were to develop a population pharmacokinetic (PK) model of LPV in children and to estimate the probability of achieving a PIQ of >15. HIV-infected, PI-experienced children receiving LPV were intensively sampled for 12 h to measure plasma LPV. The data were fitted to candidate PK models (using MM-USCPACK software), and the final model was used to simulate 1,000 children to determine the probability of achieving an LPV PIQ of >15. In 50 patients (4 to 18 years old), the median LPV plasma 12-hour-postdose concentration was 5.9 mg/liter (range, 0.03 to 16.2 mg/liter) lower than that reported in adults. After a delay, LPV was absorbed linearly into a central compartment whose size was dependent on the weight and age of the patient. Elimination was dependent on weight. The regression line of observed versus predicted LPV had an R(2) of 0.99 and a slope of 1.0. Visual predictive checks against all available measured concentrations showed good predictive ability of the model. The probability of achieving an LPV PIQ of >15 was >90% for wild-type virus but <10% for even moderately resistant virus. The currently recommended dose of LPV/ritonavir appears to be adequate for children infected with wild-type virus but is unlikely to provide adequate inhibitory concentrations for even moderately resistant human immunodeficiency virus (HIV). PI-experienced HIV-infected children will likely benefit from longitudinal, repeated LPV measurement in plasma to ensure that drug exposure is most often near the maximal end of the observed safe range.

Antiretroviral-related adipocyte dysfunction and lipodystrophy in HIV-infected patients: Alteration of the PPARγ-dependent pathways

Lipodystrophy and metabolic alterations are major complications of antiretroviral therapy in HIV-infected patients. In vitro studies using cultured murine and human adipocytes revealed that some protease inhibitors (PIs) and nucleoside reverse transcriptase inhibitors (NRTIs) were implicated to a different extent in adipose cell dysfunction and that a chronic incubation with some PIs decreased mRNA and protein expression of PPARγ. Defective lamin A maturation linked to PI inhibitory activity could impede the nuclear translocation of SREBP1c, therefore, reducing PPARγ expression. Adipose cell function was partially restored by the PPARγ agonists, thiazolidinediones. Adverse effects of PIs and NRTIs have also been reported in macrophages, a cell type that coexists with, and modulates, adipocyte function in fat tissue. In HIV-infected patients under ART, a decreased expression of PPARγ and of PPARγ-related genes was observed in adipose tissue, these anomalies being more severe in patients with ART-induced lipoatrophy. Altered PPARγ expression was reversed in patients stopping PIs. Treatment of patients with agonists of PPARγ could improve, at least partially, the subcutaneous lipoatrophy. These data indicate that decreased PPARγ expression and PPARγ-related function, resulting from ART-induced adipose tissue toxicity, play a central role in HIV-related lipoatrophy and metabolic consequences.

Pharmacokinetics of high-dose lopinavir-ritonavir with and without saquinavir or nonnucleoside reverse transcriptase inhibitors in human immunodeficiency virus-infected pediatric and adolescent patients previously treated with protease inhibitors

Human immunodeficiency virus (HIV)-infected children and adolescents who are failing antiretrovirals may have a better virologic response when drug exposures are increased, using higher protease inhibitor doses or ritonavir boosting. We studied the pharmacokinetics and safety of high-dose lopinavir-ritonavir (LPV/r) in treatment-experienced patients, using an LPV/r dose of 400/100 mg/m(2) orally every 12 h (p.o. q12h) (without nonnucleoside reverse transcriptase inhibitor [NNRTI]), or 480/120 mg/m(2) p.o. q12h (with NNRTI). We calculated the LPV inhibitory quotient (IQ), and when the IQ was <15, saquinavir (SQV) 750 mg/m(2) p.o. q12h was added to the regimen. We studied 26 HIV-infected patients. The median age was 15 years (range, 7 to 17), with 11.5 prior antiretroviral medications, 197 CD4 cells/ml, viral load of 75,577 copies/ml, and a 133-fold change in LPV resistance. By treatment week 2, 14 patients had a viral-load decrease of >0.75 log(10), with a median maximal decrease in viral load of -1.57 log(10) copies/ml at week 8. At week 2, 19 subjects showed a median LPV area under the concentration-time curve (AUC) of 157.2 (range, 62.8 to 305.5) microg x h/ml and median LPV trough concentration (C(trough)) of 10.8 (range, 4.1 to 25.3) microg/ml. In 16 subjects with SQV added, the SQV median AUC was 33.7 (range, 4.4 to 76.5) microg x h/ml and the median SQV C(trough) was 2.1 (range, 0.2 to 4.1) microg/ml. At week 24, 18 of 26 (69%) subjects remained in the study. Between weeks 24 and 48, one subject withdrew for nonadherence and nine withdrew for persistently high virus load. In antiretroviral-experienced children and adolescents with HIV, high doses of LPV/r with or without SQV offer safe options for salvage therapy, but the modest virologic response and the challenge of adherence to a regimen with a high pill burden may limit the usefulness of this approach.