Population pharmacokinetics and dose optimisation of ritonavir-boosted atazanavir in Thai HIV-infected patients

Need for a Standardized Translational Drug Development Platform: Lessons Learned from the Repurposing of Drugs for COVID-19

In the absence of drugs to treat or prevent COVID-19, drug repurposing can be a valuable strategy. Despite a substantial number of clinical trials, drug repurposing did not deliver on its promise. While success was observed with some repurposed drugs (e.g., remdesivir, dexamethasone, tocilizumab, baricitinib), others failed to show clinical efficacy. One reason is the lack of clear translational processes based on adequate preclinical profiling before clinical evaluation. Combined with limitations of existing in vitro and in vivo models, there is a need for a systematic approach to urgent antiviral drug development in the context of a global pandemic. We implemented a methodology to test repurposed and experimental drugs to generate robust preclinical evidence for further clinical development. This translational drug development platform comprises in vitro, ex vivo, and in vivo models of SARS-CoV-2, along with pharmacokinetic modeling and simulation approaches to evaluate exposure levels in plasma and target organs. Here, we provide examples of identified repurposed antiviral drugs tested within our multidisciplinary collaboration to highlight lessons learned in urgent antiviral drug development during the COVID-19 pandemic. Our data confirm the importance of assessing in vitro and in vivo potency in multiple assays to boost the translatability of pre-clinical data. The value of pharmacokinetic modeling and simulations for compound prioritization is also discussed. We advocate the need for a standardized translational drug development platform for mild-to-moderate COVID-19 to generate preclinical evidence in support of clinical trials. We propose clear prerequisites for progression of drug candidates for repurposing into clinical trials. Further research is needed to gain a deeper understanding of the scope and limitations of the presented translational drug development platform.

A pharmacometric approach to evaluate drugs for potential repurposing as COVID-19 therapeutics

INTRODUCTION

Developing and evaluating novel compounds for treatment or prophylaxis of emerging infectious diseases is costly and time-consuming. Repurposing of already available marketed compounds is an appealing option as they already have an established safety profile. This approach could substantially reduce cost and time required to make effective treatments available to fight the COVID-19 pandemic. However, this approach is challenging since many drug candidates show efficacy in in vitro experiments, but fail to deliver effect when evaluated in clinical trials. Better approaches to evaluate in vitro data are needed, in order to prioritize drugs for repurposing.

AREAS COVERED

This article evaluates potential drugs that might be of interest for repurposing in the treatment of patients with COVID-19 disease. A pharmacometric simulation-based approach was developed to evaluate in vitro activity data in combination with expected clinical drug exposure, in order to evaluate the likelihood of achieving effective concentrations in patients.

EXPERT OPINION

The presented pharmacometric approach bridges in vitro activity data to clinically expected drug exposures, and could therefore be a useful compliment to other methods in order to prioritize repurposed drugs for evaluation in prospective randomized controlled clinical trials.

Pharmacogenetics-based population pharmacokinetic analysis for dose optimization of ritonavir-boosted atazanavir in Thai adult HIV-infected patients

BACKGROUND

This population pharmacokinetic-pharmacogenetic study aimed to investigate the optimal dose of RTV-boosted ATV (ATV/RTV) for Thai adult HIV-infected patients.

METHODS

A total of 1460 concentrations of ATV and RTV from 544 patients receiving an ATV/RTV-based regimen were analyzed. The CYP3A5 6986 A > G, ABCB1 3435 C > T, ABCB1 2677 G > T, SLCO1B1 521 T > C, and NR1I2 63396 C > T were genotyped. A population pharmacokinetic model was performed using a nonlinear mixed-effect model (NONMEM®). Monte Carlo simulations were conducted to compare the percentages of patients achieving the therapeutic range of ATV through concentrations (C_trough).

RESULTS

The apparent oral clearance of ATV (CL/F_ATV) without RTV was 7.69 L/h with interindividual variability (IIV) of 28.7%. Patients with CYP3A5 6986 GG had a 7.1% lower CL/F_ATV than those with AA or AG genotype. The CL/F_ATV decreased by 10.8% for females compared with males. Simulation results showed higher percentages (~70%) of patient receiving doses of 200/100 or 200/50 mg achieved the target ATV C_trough, while more patients (~40%) receiving a standard dose (300/100 mg) had ATV C_trough above this target.

CONCLUSIONS

Both CYP3A5 6986 A > G and female decreased CL/F_ATV in Thai HIV-infected patients. Simulations supported that the reduced dose of ATV/RTV was sufficient to achieve the target concentration for Thai population.

Interaction of two peptide drugs with biomacromolecules analyzed by molecular docking and multi-spectroscopic methods

Peptide drugs, which are mainly used for the treatment of AIDS, myeloma, and breast cancer, have evolved rapidly owing to their high efficacy and low side effects. The interaction mechanisms of two peptide drugs with two biological macromolecules (protein and DNA), which are of great significance in disease prevention and drug design, were investigated using molecular docking, fluorescence spectroscopy, circular dichroism (CD) spectroscopy, UV-visible spectroscopy and viscosity measurements. The interaction between a series of common drugs and ovalbumin (OVA) was simulated by molecular docking, and two peptide drugs with the highest energy values, namely atazanavir and carfilzomib, were selected; the binding energy values of these drugs with OVA were -59.20 and -55.93 kcal/mol, respectively. The K_b values of the interaction of the two drugs with OVA/DNA were in the range of 10⁴-10⁷ M^-1, and the binding affinity of the drugs was stronger with OVA than with DNA. Hydrogen bonds and van der Waals forces were very important for the binding between drugs and OVA through molecular docking studies, and it was consistent with experimental results (ΔH < 0, ΔH < 0). The synchronous fluorescence spectrum showed that the interaction caused a change to the original structure of OVA, and atazanavir had a greater effect on OVA than carfilzomib. CD spectrum analysis also demonstrated that the conformation of OVA changed slightly. The interaction between atazanavir and DNA was mainly driven by hydrophobic forces (ΔH > 0 and ΔH > 0), whereas the major interaction forces involved in the binding of carfilzomib with DNA were hydrogen bonds and van der Waals forces. DNA melting studies, UV-visible spectroscopy, CD spectroscopy and viscosity measurements established that the interaction between the drugs and DNA was groove binding.

Influence of CYP3A5 and SLCO1B1 polymorphisms on atazanavir/r concentrations in Thai HIV-infected patients

Aim: To evaluate the influence of genetic polymorphisms on plasma trough concentrations of atazanavir (ATV) and ritonavir (RTV). Patients & methods: The concentration-to-dose ratios were compared between different genotype groups of CYP3A5, ABCB1, SLCO1B1 and NR1I2 in 490 patients. Multiple regression analysis was used to examine the association between genetic and clinical factors and log-transformed concentration-to-dose ratio of ATV and RTV. Results: Higher concentrations of ATV and RTV were significantly associated with CYP3A5 6986 GG and SLCO1B1 521 TC or CC. Female patients had significantly higher ATV plasma concentration than male patients. Conclusion: Genetic polymorphisms and gender are factors affecting the variability of ATV and RTV concentrations in the Thai population. Thus, genetic testing is worth considering when atazanavir + low dose ritonavir is prescribed.