Analysis of CYP3A4-HIV-1 protease drugs interactions by computational methods for Highly Active Antiretroviral Therapy in HIV/AIDS

Inhibition Effect of Okanin Toward Human Cytochrome P450 3A4 and 2D6 with Multi-spectroscopic Studies and Molecular Docking

Okanin, a major flavonoid of a popular herb tea, Coreopsis tinctoria Nutt., showed strong inhibition on CYP3A4 and CYP2D6. The strong interaction between okanin and CYPs were determined by enzyme kinetics, multispectral technique and molecular docking. The inhibition type of two enzymes, CYP3A4 and CYP2D6, by okanin are mixed and non-competitive inhibition type, respectively. The IC50 values and the binding constant of okanin to CYP3A4 can be deduced that the interaction was stronger than that of CYP2D6. The Conformations of CYP3A4 and CYP2D6 were changed by okanin. The evidence from fluorescence measurement along with molecular docking verified that these two CYPs were bound with okanin by hydrogen bonds and hydrophobic forces. Our investigation suggested that okanin may lead to interactions between herb and drug by inhibiting CYP3A4 and CYP2D6 activities, thus its consumption should be taken with caution.

Molecular docking used as an advanced tool to determine novel compounds on emerging infectious diseases: A systematic review

Emerging infectious diseases (EID) as well as reappearing irresistible infections are expanding worldwide. Utmost of similar cases, it was seen that the EIDs have long been perceived as a predominant conclusion of host-pathogen adaption. Here, one should get to analyze their host-pathogen interlink and their by needs to look ways, as an example, by exploitation process methodology particularly molecular docking and molecular dynamics simulation, have been utilized in recent time as the most outstanding tools. Hence, we have overviewed some of important factors that influences on EIDs especially HIV/AIDs, H1N1 and coronavirus. Moreover, here we specified the importance of molecular docking applications especially molecular dynamics simulations approach to determine novel compounds on the emerging infectious diseases. Additionally, in vivo and in vitro studies approach to determine novel compounds on the emerging infectious diseases that has implemented to evaluate the limiting affinities between small particles as well as macromolecule that can further, used as a target of HIV/AIDs, H1N1, and coronavirus were also discussed. These novel drug molecules approved in vivo and in vitro studies with reaffirm results and hence, it is clear that the computational methods (mainly molecular docking and molecular dynamics) are found to be more effective technique for drug discovery and medical practitioners.

The Mechanism-Based Inactivation of CYP3A4 by Ritonavir: What Mechanism?

Ritonavir is the most potent cytochrome P450 (CYP) 3A4 inhibitor in clinical use and is often applied as a booster for drugs with low oral bioavailability due to CYP3A4-mediated biotransformation, as in the treatment of HIV (e.g., lopinavir/ritonavir) and more recently COVID-19 (Paxlovid or nirmatrelvir/ritonavir). Despite its clinical importance, the exact mechanism of ritonavir-mediated CYP3A4 inactivation is still not fully understood. Nonetheless, ritonavir is clearly a potent mechanism-based inactivator, which irreversibly blocks CYP3A4. Here, we discuss four fundamentally different mechanisms proposed for this irreversible inactivation/inhibition, namely the (I) formation of a metabolic-intermediate complex (MIC), tightly coordinating to the heme group; (II) strong ligation of unmodified ritonavir to the heme iron; (III) heme destruction; and (IV) covalent attachment of a reactive ritonavir intermediate to the CYP3A4 apoprotein. Ritonavir further appears to inactivate CYP3A4 and CYP3A5 with similar potency, which is important since ritonavir is applied in patients of all ethnicities. Although it is currently not possible to conclude what the primary mechanism of action in vivo is, it is unlikely that any of the proposed mechanisms are fundamentally wrong. We, therefore, propose that ritonavir markedly inactivates CYP3A through a mixed set of mechanisms. This functional redundancy may well contribute to its overall inhibitory efficacy.

Repurposing of the PDE5 Inhibitor Sildenafil for the Treatment of Persistent Pulmonary Hypertension in Neonates

Nitric oxide (NO), an important endogenous signaling molecule released from vascular endothelial cells and nerves, activates the enzyme soluble guanylate cyclase to catalyze the production of cyclic guanosine monophosphate (cGMP) from guanosine triphosphate. cGMP, in turn, activates protein kinase G to phosphorylate a range of effector proteins in smooth muscle cells that reduce intracellular Ca²⁺ levels to inhibit both contractility and proliferation. The enzyme phosphodiesterase type 5 (PDE5) curtails the actions of cGMP by hydrolyzing it into inactive 5'-GMP. Small molecule PDE5 inhibitors (PDE5is), such as sildenafil, prolong the availability of cGMP and therefore, enhance NO-mediated signaling. PDE5is are the first-line treatment for erectile dysfunction but are also now approved for the treatment of pulmonary arterial hypertension (PAH) in adults. Persistent pulmonary hypertension in neonates (PPHN) is currently treated with inhaled NO, but this is an expensive option and around 1/3 of newborns are unresponsive, resulting in the need for alternative approaches. Here the development, chemistry and pharmacology of PDE5is, the use of sildenafil for erectile dysfunction and PAH, are summarized and then current evidence for the utility of further repurposing of sildenafil, as a treatment for PPHN, is critically reviewed.

In Vitro Metabolism of Auriculasin and Its Inhibitory Effects on Human Cytochrome P450 and UDP-Glucuronosyltransferase Enzymes

Auriculasin has a wide range of pharmacological effects, including anticancer and anti-inflammatory effects. In this work, we explored the metabolic characteristics and inhibitory effect of auriculasin against cytochrome P450 (CYP) and UDP-glucuronosyltransferase (UGT) enzymes in vitro. Auriculasin inhibited UGT1A6, UGT1A8, UGT1A10, UGT2B7, CYP2C9, and CYP3A4 strongly at a concentration of 100 μM. Different species showed significant differences in auriculasin metabolism, and metabolic characteristics were similar between pig and human. We identified seven metabolites, and hydroxylated auriculasin was the main metabolite. In addition, CYP2D6, CYP2C9, CYP2C19, and CYP2C8 were the major CYP isoforms involved in the metabolism of auriculasin. Molecular docking studies showed that noncovalent interactions between auriculasin and the CYPs are dominated by hydrogen bonding, π-π stacking, and hydrophobic interactions. Our in vitro study provides insights into the pharmacological and toxicological mechanisms of auriculasin.

Intracellular accumulation of atazanavir/ritonavir according to plasma concentrations and OATP1B1, ABCB1 and PXR genetic polymorphisms

OBJECTIVES

The rate of accumulation of atazanavir and ritonavir within cells is still debated due to methodological limitations. Our aim was to measure peripheral blood mononuclear cell (PBMC) concentrations of atazanavir and ritonavir and investigate whether single-nucleotide polymorphisms of OATP, ABCB1, CYP3A4 and PXR genes are involved in intracellular drug penetration.

METHODS

HIV-positive patients administered 300 mg of atazanavir/100 mg of ritonavir were enrolled. Blood sampling was performed at the end of the dosing interval (Ctrough). PBMC-associated and plasma atazanavir and ritonavir concentrations were measured by validated HPLC coupled with a single mass detector (HPLC-MS) and HPLC-photodiode array (PDA) methods, respectively. Cell count and mean cellular volume were determined using a Coulter counter. Genotyping was conducted using real-time PCR.

RESULTS

Thirty-five patients were enrolled. Median atazanavir and ritonavir intracellular concentrations were 1844 and 716 ng/mL, respectively. Median plasma concentrations were 645 ng/mL for atazanavir and 75 ng/mL for ritonavir, while median intracellular/plasma concentration ratios were 2.4 and 9.2, respectively. Median ritonavir intracellular concentrations were higher for OATP1B1 521 T→C TC or CC carriers and for PXR 44477 A→G AG or GG carriers. Atazanavir intracellular/plasma concentration ratios were higher in patients GG for the ABCB1 2677 G→T single-nucleotide polymorphism (SNP) compared with GT and TT groups.

CONCLUSIONS

Our study showed a higher intracellular ritonavir accumulation than previously reported. Ritonavir intracellular concentrations were associated with OATP1B1 521 and PXR 44477 SNPs while intracellular atazanavir exposure was associated with the ABCB1 2677 SNP. Further clinical studies are necessary in order to confirm these data.

The Effect of CYP2B6, CYP2D6, and CYP3A4 Alleles on Methadone Binding: A Molecular Docking Study

Current methadone maintenance therapy (MMT) is yet to ensure 100% successful treatment as the optimum dosage has yet to be determined. Overdose leads to death while lower dose causes the opioid withdrawal effect. Single-nucleotide polymorphisms (SNP) in cytochrome P450s (CYPs), the methadone metabolizers, have been showen to be the main factor for the interindividual variability of methadone clinical effects. In this study, we investigated the effect of SNPs in three major methadone metabolizers (CYP2B6, CYP2D6, and CYP3A4) on methadone binding affinity. Results showed thatCYP2B6*11,CYP2B6*12,CYP2B6*18, andCYP3A4*12have significantly higher binding affinity toR-methadone compared to wild type.S-methadone has higher binding affinity inCYP3A4*3,CYP3A4*11, andCYP3A4*12compared to wild type.R-methadone was shown to be the active form of methadone; thus individuals with CYP alleles that binds better toR-methadone will have higher methadone metabolism rate. Therefore, a higher dosage of methadone is necessary to obtain the opiate effect compared to a normal individual and vice versa. These results provide an initial prediction on methadone metabolism rate for individuals with mutant type CYP which enables prescription of optimum methadone dosage for individuals with CYP alleles.

Rapamycin with antiretroviral therapy in AIDS-associated Kaposi sarcoma: an AIDS Malignancy Consortium study

PURPOSE

The mammalian target of rapamycin is activated in Kaposi sarcoma (KS) and its inhibitor, rapamycin, has induced KS regression in transplant-associated KS. This study aimed to evaluate rapamycin's safety and toxicity in HIV-infected individuals with KS receiving antiretroviral therapy (ART), investigate rapamycin interactions with both protease inhibitor (PI)-containing and nonnucleoside reverse transcriptase inhibitor (NNRTI)-containing ART regimens, and assess clinical and biological endpoints including KS response and mammalian target of rapamycin-dependent signaling.

METHODS

Seven participants, 4 on PI-based and 3 on NNRTI-based ART, had rapamycin titrated to achieve trough concentrations of 5-10 ng/mL. Patients were monitored for safety and KS response. KS biopsies were evaluated for changes in phosphoribosomal S6 protein, and phospho-Akt expression. Interleukin 6 and vascular endothelial growth factor levels, HIV and KS-associated herpesvirus viral loads, and CD4 counts were monitored.

RESULTS

Despite pharmacokinetic interactions resulting in >200-fold differences in cumulative weekly rapamycin doses between participants on PI-containing and NNRTI-containing regimens, treatment was well tolerated. There were no significant changes in viral loads or cytokine levels; modest initial decreases in CD4 counts occurred in some patients. Three participants, all on PI-containing regimens and with higher rapamycin exposure, showed partial KS responses. Three of 4 subjects whose biopsies were studied at ≥day 50 showed decreased phosphoribosomal S6 protein staining.

CONCLUSIONS

Rapamycin seems safe in HIV-infected individuals with KS and can, in some cases, induce tumor regression and affect its molecular targets. Significant pharmacokinetic interactions require careful titration to achieve target drug trough concentrations but may be exploited to achieve therapeutic benefit.