Search Results (20)

Ritonavir (RTV), an effective aspartyl protease inhibitor, was originally developed to counter the replication of human immune deficiency virus and then employed as a pharmacokinetic enhancer in antiretroviral therapy. Yet unexpectedly, RTV exerted antitumor effects that added to its antiviral action, as it impacted the migration, invasion, oxidative stress, and proteasome function of human tumor cells. More recently, RTV was shown to directly inhibit DNA repair enzymes, thereby enhancing radiosensitivity and synergizing with chemotherapeutics across multiple cancer models. However, RTV induced oxidative stress and DNA damage also in non-tumor cells, including the reproductive ones. This duality highlights both the possibility of RTV anticancer use and the concern for its safety. In this Perspective, we propose the repurposing of RTV as a novel tool to potentiate DNA-damage-based antitumor therapies such as radiotherapy and/or chemotherapy. At the same time, we underscore the need for a careful assessment of RTV side effects. Full article

Background/Objectives: Molnupiravir (MOV) and nirmatrelvir (NMV) are antiviral drugs that were FDA-approved under the emergency use authorization (EUA) for coronavirus disease-2019 (COVID-19) treatment. MOV and NMV target the viral RNA-dependent RNA polymerase and main protease, respectively. Paxlovid is a combination of NMV and ritonavir (RTV), an inhibitor of the human cytochrome P450-3A4 (hCYP3A4). In this study, the structural consequences in the hCYP3A4 caused by MOV-induced mutations (MIM) were evaluated using in silico tools. Methods: MOV-induced mutations (MIM) were inserted into all the possible hotspots in the active site region of the hCYP3A4 gene, and mutant protein models were built. Structural changes in the heme-porphyrin ring of hCYP3A4 were analyzed in the presence and absence of substrates/inhibitors, including RTV. Molecular dynamics (MD) simulations were performed to analyze the effect of MIM-induced structural changes in hCYP3A4 on drug binding. Results: MD simulations confirm that MIMs, R375G and R440G in hCYP3A4 severely affect the heme-porphyrin ring stability by causing a tilt that in turn affects RTV binding, suggesting a possible inefficiency in the function of hCYP3A4. Similar results were seen for amlodipine, atorvastatin, sildenafil and warfarin, which are substrates of hCYP3A4. Conclusions: The current in silico studies indicate that hCYP3A4 containing MIMs can create complications in the treatment of COVID-19 patients, particularly with co-morbidities due to its functional inefficiency. Hence, clinicians must be vigilant when using MOV in combination with other drugs. Further in vitro studies focused on hCYP3A4 containing MIMs are currently in progress to support our current in silico findings. Full article

Background and Objective: Tofacitinib (TOF), an oral Janus kinase inhibitor used to treat rheumatoid arthritis (RA), is extensively metabolized by cytochrome P450 (CYP) 3A4. Ritonavir (RTV), a protease inhibitor, is commonly used as a pharmacokinetic (PK) enhancer due to its potent CYP3A4 inhibitory effects. Considering the prevalence of comorbidities in RA patients, it is possible to use TOF and RTV concurrently, raising concerns about potential drug–drug interactions (DDIs). The current study aims to assess the potential DDIs between RTV and TOF. Methods: An in vivo rat study was conducted to investigate the impacts of RTV on the PK of TOF. Rats were randomly divided into three groups: vehicle, RTV 10 mg/kg, and RTV 20 mg/kg, each undergoing four days of pretreatment. On the test day, TOF (10 mg/kg) was administered following co-administration of the respective RTV doses. Blood samples were collected at the pre-specified time points. Plasma concentrations of TOF were quantified using liquid chromatography coupled with mass spectrometry, and PK parameters were analyzed using non-compartmental analysis. Results: RTV (10 and 20 mg/kg) increased the area under the curve of TOF by 2.53-fold (95% CI: 1.64–3.43) and 5.39-fold (95% CI: 4.47–6.33), respectively, and the maximum concentration by 1.47-fold (95% CI: 0.99–2.00) and 2.86-fold (95% CI: 2.39–3.37), respectively. Whereas the half-life (t_1/2) remained unchanged. Conclusions: RTV substantially increased TOF exposure in rats. These results suggest the need for dose adjustments of TOF during co-administration with RTV in clinical settings. Further clinical research is needed to confirm these findings. Full article

This study’s integration of molecular dynamics (MD) simulations with non-covalent adaptable networks (NANs) and corroborative wet lab experiments offers a comprehensive approach to understanding the interactions between ritonavir (RTV) and polymers in supersaturated solutions. This multifaceted study not only explored the stabilization mechanisms facilitated by NANs but also examined the influence of polymer selection on the pharmaceutical properties of RTV, a class III compound known for its slow crystallization rate. This research utilized molecular dynamics simulations to model the intermolecular interactions between RTV and two polymers, Polyvinylpyrrolidone (PVP) K30 and Eudragit L100. These simulations were specifically designed to incorporate the effects of NANs, highlighting their dynamic nature and potential to enhance drug stability and solubility. Simultaneously, wet lab experiments were conducted to measure the nucleation induction times and observe the crystallization behavior of RTV under varying conditions of polymer presence. The experimental data demonstrated a significant extension in nucleation induction time, prolonging the duration from 12 to approximately 64 h when PVP K30 and Eudragit L100 were present. This substantial delay in crystallization was attributed to the strong intermolecular interactions between RTV and the polymers, which were effectively stabilized by the non-covalent bonds within the NANs. These findings were consistently confirmed across both computational and experimental settings, illustrating how NANs can effectively inhibit crystallization and enhance the supersaturation state of RTV. This study successfully demonstrates how the physical and chemical properties of polymers influence the crystallization process of poorly water-soluble drugs such as RTV. Leveraging the synergy between computational simulations and empirical laboratory data, this research provides deep insights into the mechanisms at play, ensuring that drug formulations are optimized for both stability and performance. Full article

Lopinavir (LPV) and ritonavir (RTV) are two of the essential antiretroviral active pharmaceutical ingredients (APIs) characterized by poor solubility. Hence, attempts have been made to improve both their solubility and dissolution rate. One of the most effective approaches used for this purpose is to prepare amorphous solid dispersions (ASDs). To our best knowledge, this is the first attempt aimed at developing ASDs via the electrospinning technique in the form of fibers containing LPV and RTV. In particular, the impact of the various polymeric carriers, i.e., Kollidon K30 (PVP), Kollidon VA64 (KVA), and Eudragit^® E100 (E100), as well as the drug content as a result of the LPV and RTV amorphization were investigated. The characterization of the electrospun fibers included microscopic, DSC, and XRD analyses, the assessment of their wettability, and equilibrium solubility and dissolution studies. The application of the electrospinning process led to the full amorphization of both the APIs, regardless of the drug content and the type of polymer matrix used. The utilization of E100 as a polymeric carrier for LPV and KVA for RTV, despite the beads-on-string morphology, had a favorable impact on the equilibrium solubility and dissolution rate. The results showed that the electrospinning method can be successfully used to manufacture ASDs with poorly soluble APIs. Full article

Metal–organic frameworks (MOFs) have attained significant usage as adsorbents for antiviral medicines in contemporary times. This study focused on synthesizing a UiO-67 metal–organic framework using the hydrothermal method. The synthesized framework was then characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analyses (TGA), and zeta potential measurements. The UiO-67 was then employed for the purpose of assessing the efficiency of various adsorption factors in the removal of antiviral medicines from aqueous solutions, including drugs such as ritonavir (RTV) and lopinavir (LPV), which were extensively used for the treatment of coronavirus (COVID-19) during the pandemic. The variables examined were the quantity of adsorbent used, different pH of the solution, temperature, and contact duration. The experimental findings indicate that the highest level of RTV elimination was 91.2% and of experimental adsorption capacity (q_e,exp) was 9.7 mg/g and for LPV this was 85.9%, and (q_e,exp) 8.9 mg/g, using 50 mg of UiO-67 at a pH 8, temperature of 298 K, and for 120 min. The impact of contact duration and temperature on the kinetics of adsorption was examined by employing pseudo-first-order and pseudo-second-order kinetic models. The experimental results showed a good match with the pseudo-second-order kinetic model with value of R² 0.99 and the q_e,calc was 9.7 RTV and 8.9 mg/g LPV, which is a good match with q_e,exp. Also, based on diffusion kinetic studies, the adsorption was confirmed to be catalytic in nature on the surface of the UiO-67 MOFs. A thermodynamic analysis of adsorption was conducted, whereby calculations for the Gibbs free energy change (∆G), enthalpy change (∆H), and entropy change (∆S) were performed. The positive ∆H values confirm the endothermic nature of the adsorption of RTV and LPV by UiO-67. The ΔG values exhibited negativity across all temperatures, suggesting the spontaneous nature of the adsorption process of RTV and LPV by UiO-67 from an aqueous solution. UiO-67 was shown to be highly effective in extracting RTV and LPV from real environmental samples. Full article

Ritonavir (RTV) is an antiviral and a component of COVID-19 treatments. Moreover, RTV demonstrates anti-cancer effects by suppressing AKT. However, RTV has cytotoxicity and suppresses sperm functions by altering AKT activity. Although abnormal AKT activity is known for causing detrimental effects on sperm functions, how RTV alters AKT signaling in spermatozoa remains unknown. Therefore, this study aimed to investigate reproductive toxicity of RTV in spermatozoa through phosphoinositide 3-kinase/phosphoinositide-dependent protein kinase-1/protein kinase B (PI3K/PDK1/AKT) signaling. Duroc spermatozoa were treated with various concentrations of RTV, and capacitation was induced. Sperm functions (sperm motility, motion kinematics, capacitation status, and cell viability) and expression levels of tyrosine-phosphorylated proteins and PI3K/PDK1/AKT pathway-related proteins were evaluated. In the results, RTV significantly suppressed sperm motility, motion kinematics, capacitation, acrosome reactions, and cell viability. Additionally, RTV significantly increased levels of phospho-tyrosine proteins and PI3K/PDK1/AKT pathway-related proteins except for AKT and PI3K. The expression level of AKT was not significantly altered and that of PI3K was significantly decreased. These results suggest RTV may suppress sperm functions by induced alterations of PI3K/PDK1/AKT pathway through abnormally increased tyrosine phosphorylation. Therefore, we suggest people who use or prescribe RTV need to consider its male reproductive toxicity. Full article

Paxlovid^®, a co-packaged medication comprised of separate tablets containing two active ingredients, nirmatrelvir (NRV) and ritonavir (RTV), exhibits good effectiveness against coronavirus disease 2019 (COVID-19). However, the size of the NRV/RTV tablets makes them difficult for some patients to swallow, especially the elderly and those with dysphagia. Therefore, an oral liquid formulation that can overcome this shortcoming and improve patient compliance is required. In this study, we developed a liquid formulation containing NRV and RTV by adopting strategies that used co-solvents and surfactants to enhance the solubility and inhibit possible recrystallization. The in vitro release results showed that NRV and RTV could be maintained at high concentrations in solution for a certain period in the investigated media. In vivo studies in rats showed that the oral bioavailability of NRV/RTV solution was significantly enhanced. Compared to Paxlovid^® tablets, the AUC_(0–t) of NRV and RTV increased by 6.1 and 3.8 times, respectively, while the C_max increased by 5.5 times for both. Furthermore, the promoting effect of the absorption of RTV on the bioavailability of NRV was confirmed. Experiments with a beagle showed a similar trend. Stability studies were also conducted at 4 °C, 25 °C, and 40 °C for 90 days, indicating that the oral liquid formulation was physically and chemically stable. This study can be used as a valuable resource for developing and applying oral liquid NRV/RTV formulations in a clinical context. Full article

The addition of polymeric materials is often used to delay nucleation or crystal growth and maintain the high supersaturation of amorphous drugs. Therefore, this study aimed to investigate the impact of chitosan on the supersaturation behavior of drugs with a low recrystallization tendency and elucidate the mechanism of its crystallization inhibition in an aqueous solution. It was carried out using ritonavir (RTV) as a model of poorly water-soluble drugs categorized as class III of Taylor’s classification, while chitosan was used as a polymer, and hypromellose (HPMC) was used for comparison. The inhibition of the nucleation and crystal growth of RTV by chitosan was examined by measuring the induction time. The interactions of RTV with chitosan and HPMC were evaluated by NMR measurements, FT-IR, and an in silico analysis. The results showed that the solubilities of amorphous RTV with and without HPMC were quite similar, while the amorphous solubility was significantly increased by the chitosan addition due to the solubilization effect. In the absence of the polymer, RTV started to precipitate after 30 min, indicating that it is a slow crystallizer. Chitosan and HPMC effectively inhibited the nucleation of RTV, as reflected by a 48–64-fold enhancement in the induction time. Furthermore, NMR, FT-IR, and in silico analysis demonstrated that the hydrogen bond interaction between the amine group of RTV and a proton of chitosan, as well as the carbonyl group of RTV and a proton of HPMC, was observed. This indicated that the hydrogen bond interaction between RTV and chitosan as well as HPMC can contribute to the crystallization inhibition and maintenance of RTV in a supersaturated state. Therefore, the addition of chitosan can delay nucleation, which is crucial for stabilizing supersaturated drug solutions, specifically for a drug with a low crystallization tendency. Full article

The recent COVID-19 pandemic has drawn attention to health and economics worldwide. Initially, diseases only ravage local populations, while a pandemic could aggravate global economic burdens. Lopinavir/Ritonavir is an anti-HIV drug that was used on small scale patients during SARS, but its effectiveness for COVID-19 treatment is still unclear. Previous studies or meta-analysis have retrieved clinical data of subgroup analysis to evaluate the efficacy and safety of Lopinavir/Ritonavir for the treatment of COVID-19 in a few affected regions. However, geographical diversity and small number of studies bias correction were not achieved in such subgroup analysis of published meta-analysis. The present study demonstrates a practical approach in refining the binary outcome for COVID-19 treatment of Lopinavir/Ritonavir according to geographical location diversity and small number of studies (less than or equal to five) for subgroup analysis. After performing practical approach, the risk of adverse event with LPV/RTV for treatment of COVID-19 becomes nonsignificant compared to previous meta-analysis. Furthermore, we also notice heterogeneity of random effect of meta-analysis may be declined after proposed adjustment. In conclusion, proposed practical approach is recommend for performing a subgroup analysis to avoid concentration in a single geographical location and small number of studies bias. Full article

The incidence of sudden cardiac death (SCD) in people living with HIV infection (PLWH), especially those with inadequate viral suppression, is high and the reasons for this remain incompletely characterized. The timely opening and closing of type 2 ryanodine receptor (RyR2) is critical for ensuring rhythmic cardiac contraction–relaxation cycles, and the disruption of these processes can elicit Ca²⁺ waves, ventricular arrhythmias, and SCD. Herein, we show that the HIV protein Tat (HIV-Tat: 0–52 ng/mL) and therapeutic levels of the antiretroviral drugs atazanavir (ATV: 0–25,344 ng/mL), efavirenz (EFV: 0–11,376 ng/mL), and ritonavir (RTV: 0–25,956 ng/mL) bind to and modulate the opening and closing of RyR2. Abacavir (0–14,315 ng/mL), bictegravir (0–22,469 ng/mL), Rilpivirine (0–14,360 ng/mL), and tenofovir disoproxil fumarate (0–18,321 ng/mL) did not alter [³H]ryanodine binding to RyR2. Pretreating RyR2 with low HIV-Tat (14 ng/mL) potentiated the abilities of ATV and RTV to bind to open RyR2 and enhanced their ability to bind to EFV to close RyR2. In silico molecular docking using a Schrodinger Prime protein–protein docking algorithm identified three thermodynamically favored interacting sites for HIV-Tat on RyR2. The most favored site resides between amino acids (AA) 1702–1963; the second favored site resides between AA 467–1465, and the third site resides between AA 201–1816. Collectively, these new data show that HIV-Tat, ATV, EFV, and RTV can bind to and modulate the activity of RyR2 and that HIV-Tat can exacerbate the actions of ATV, EFV, and RTV on RyR2. Whether the modulation of RyR2 by these agents increases the risk of arrhythmias and SCD remains to be explored. Full article

The formulation of poorly water-soluble drugs is one of the main challenges in the pharmaceutical industry, especially in the development of oral dosage forms. Meanwhile, there is an increase in the number of poorly soluble drugs that have been discovered as new chemical entities. It was also reported that the physical transformation of a drug from a crystalline form into an amorphous state could be used to increase its solubility. Therefore, this study aims to evaluate the pharmaceutical properties of amorphous drug loaded-mesoporous silica (MPS) and pure amorphous drugs. Ritonavir (RTV) was used as a model of a poorly water-soluble drug due to its low recrystallization tendency. RTV loaded-MPS (RTV/MPS) and RTV amorphous were prepared using the solvent evaporation method. Based on observation, a halo pattern in the powder X-ray diffraction pattern and a single glass transition (T_g) in the modulated differential scanning calorimetry (MDSC) curve was discovered in RTV amorphous, indicating its amorphization. The T_g was not detected in RTV/MPS, which showed that the loading RTV was completed. The solid-state NMR and FT-IR spectroscopy also showed the interaction between RTV and the surface of MPS in the mesopores. The high supersaturation of RTV was not achieved for both RTV/MPS and the amorphous state due to its strong interaction with the surface of MPS and was not properly dispersed in the medium, respectively. In the dissolution test, the molecular dispersion of RTV within MPS caused rapid dissolution at the beginning, while the amorphous showed a low rate due to its agglomeration. The stability examination showed that the loading process significantly improved the physical and chemical stability of RTV amorphous. These results indicated that the pharmaceutical properties of amorphous drugs could be improved by loaded-MPS. Full article

The incorporation of a drug into mesoporous silica (MPS) is a promising strategy to stabilize its amorphous form. However, the drug within MPS has shown incomplete release, despite a supersaturated solution being generated. This indicates the determination of maximum drug loading in MPS below what is experimentally necessary to maximize the drug doses in the system. Therefore, this study aimed to characterize the drugs with good glass former loaded-mesoporous silica, determine the maximum drug loading, and compare its theoretical value relevance to monolayer covering the mesoporous (MCM) surface, as well as pore-filling capacity (PFC). Solvent evaporation and melt methods were used to load each drug into MPS. In addition, the glass transition of ritonavir (RTV) and cyclosporine A (CYP), as well as the melting peak of indomethacin (IDM) and saccharin (SAC) in mesoporous silica, were not discovered in the modulated differential scanning calorimetry (MDSC) curve, demonstrating that each drug was successfully incorporated into the mesopores. The amorphization of RTV-loaded MPS (RTV/MPS), CYP-loaded MPS (CYP/MPS), and IDM-loaded MPS (IDM/MPS) were confirmed as a halo pattern in powder X-ray diffraction measurements and a single glass transition event in the MDSC curve. Additionally, the good glass formers, nanoconfinement effect of MPS and silica surface interaction contributed to the amorphization of RTV, CYP and IDM within MPS. Meanwhile, the crystallization of SAC was observed in SAC-loaded MPS (SAC/MPS) due to its weak silica surface interaction and high recrystallization tendency. The maximum loading amount of RTV/MPS was experimentally close to the theoretical amount of MCM, showing monomolecular adsorption of RTV on the silica surface. On the other hand, the maximum loading amount of CYP/MPS and IDM/MPS was experimentally lower than the theoretical amount of MCM due to the lack of surface interaction. However, neither CYP or IDM occupied the entire silica surface, even though some drugs were adsorbed on the MPS surface. Moreover, the maximum loading amount of SAC/MPS was experimentally close to the theoretical amount of PFC, suggesting the multilayers of SAC within the MPS. Therefore, this study demonstrates that the characterization of drugs within MPS, such as molecular size and interaction of drug-silica surface, affects the loading efficiency of drugs within MPS that influence its relevance with the theoretical value of drugs. Full article

SARS-CoV-2 is highly homologous to SARS-CoV. To date, the main protease (Mpro) of SARS-CoV-2 is regarded as an important drug target for the treatment of Coronavirus Disease 2019 (COVID-19). Some experiments confirmed that several HIV protease inhibitors present the inhibitory effects on the replication of SARS-CoV-2 by inhibiting Mpro. However, the mechanism of action has still not been studied very clearly. In this work, the interaction mechanism of four HIV protease inhibitors Darunavir (DRV), Lopinavir (LPV), Nelfinavir (NFV), and Ritonavire (RTV) targeting SARS-CoV-2 Mpro was explored by applying docking, molecular dynamics (MD) simulations, and MM–GBSA methods using the broad-spectrum antiviral drug Ribavirin (RBV) as the negative and nonspecific control. Our results revealed that LPV, RTV, and NFV have higher binding affinities with Mpro, and they all interact with catalytic residues His41 and the other two key amino acids Met49 and Met165. Pharmacophore model analysis further revealed that the aromatic ring, hydrogen bond donor, and hydrophobic group are the essential infrastructure of Mpro inhibitors. Overall, this study applied computational simulation methods to study the interaction mechanism of HIV-1 protease inhibitors with SARS-CoV-2 Mpro, and the findings provide useful insights for the development of novel anti-SARS-CoV-2 agents for the treatment of COVID-19. Full article

Most antiretroviral medications for human immunodeficiency virus treatment and prevention require high levels of patient adherence, such that medications need to be administered daily without missing doses. Here, a long-acting subcutaneous injection of lopinavir (LPV) in combination with ritonavir (RTV) using in situ self-assembly nanoparticles (ISNPs) was developed to potentially overcome adherence barriers. The ISNP approach can improve the pharmacokinetic profiles of the drugs. The ISNPs were characterized in terms of particle size, drug entrapment efficiency, drug loading, in vitro release study, and in vivo pharmacokinetic study. LPV/RTV ISNPs were 167.8 nm in size, with a polydispersity index of less than 0.35. The entrapment efficiency was over 98% for both LPV and RTV, with drug loadings of 25% LPV and 6.3% RTV. A slow release rate of LPV was observed at about 20% on day 5, followed by a sustained release beyond 14 days. RTV released faster than LPV in the first 5 days and slower than LPV thereafter. LPV trough concentration remained above 160 ng/mL and RTV trough concentration was above 50 ng/mL after 6 days with one subcutaneous injection. Overall, the ISNP-based LPV/RTV injection showed sustained release profiles in both in vitro and in vivo studies. Full article