Effect of grapefruit juice and ritonavir on pharmacokinetics of lopinavir in Wistar rats

Inhibition of drug-metabolizing enzymes by Jingyin granules: implications of herb-drug interactions in antiviral therapy

Jingyin granules, a marketed antiviral herbal medicine, have been recommended for treating H1N1 influenza A virus infection and Coronavirus disease 2019 (COVID-19) in China. To fight viral diseases in a more efficient way, Jingyin granules are frequently co-administered in clinical settings with a variety of therapeutic agents, including antiviral drugs, anti-inflammatory drugs, and other Western medicines. However, it is unclear whether Jingyin granules modulate the pharmacokinetics of Western drugs or trigger clinically significant herb-drug interactions. This study aims to assess the inhibitory potency of the herbal extract of Jingyin granules (HEJG) against human drug-metabolizing enzymes and to clarify whether HEJG can modulate the pharmacokinetic profiles of Western drug(s) in vivo. The results clearly demonstrated that HEJG dose-dependently inhibited human CES1A, CES2A, CYPs1A, 2A6, 2C8, 2C9, 2D6, and 2E1; this herbal medicine also time- and NADPH-dependently inhibited human CYP2C19 and CYP3A. In vivo tests showed that HEJG significantly increased the plasma exposure of lopinavir (a CYP3A-substrate drug) by 2.43-fold and strongly prolonged its half-life by 1.91-fold when HEJG (3 g/kg) was co-administered with lopinavir to rats. Further investigation revealed licochalcone A, licochalcone B, licochalcone C and echinatin in Radix Glycyrrhizae, as well as quercetin and kaempferol in Folium Llicis Purpureae, to be time-dependent CYP3A inhibitors. Collectively, our findings reveal that HEJG modulates the pharmacokinetics of CYP substrate-drug(s) by inactivating CYP3A, providing key information for both clinicians and patients to use herb-drug combinations for antiviral therapy in a scientific and reasonable way.

Interactions between antiretroviral therapy and complementary and alternative medicine: a narrative review

BACKGROUND

The use of complementary and alternative medicine including herbal medicine (phytotherapy), vitamins, minerals and food supplements is frequent among people living with HIV/AIDS (PLWHAs) who take antiretroviral (ARV) drugs, but is often not known by their prescribing physicians. Some drug-supplement combinations may result in clinically meaningful interactions.

AIMS

In this literature review, we aimed to investigate the evidence for complementary and alternative medicine interactions with ARVs.

SOURCES

A bibliographic search of all in vitro, human studies and case reports of the PubMed database was performed to assess the risk of interactions between complementary and alternative self-medication products and ARVs. The 'HIV drug interaction' (https://www.hiv-druginteractions.org) and 'Natural medicines comprehensive database' (https://naturalmedicines.therapeuticresearch.com) interaction checkers were also analysed.

CONTENT

St John's wort, some forms of garlic, grapefruit and red rice yeast are known to have significant interaction and thus should not be co-administered, or should be used with caution with certain ARV classes. Data on other plant-based supplements come from in vitro studies or very small size in vivo studies and are thus insufficient to conclude the real in vivo impact in case of concomitant administration with ARVs. Some polyvalent minerals such as calcium, magnesium, and iron salts can reduce the absorption of integrase inhibitors by chelation. Potential interactions with vitamin C and quercetin with some ARVs should be noted and efficacy and tolerance of the treatment should be monitored.

IMPLICATIONS

This review shows the importance of screening all PLWHAs for complementary and alternative medicine use to prevent treatment failure or adverse effects related to an interaction with ARVs. Further human studies are warranted to describe the clinical significance of in vitro interactions between numerous complementary and alternative medicine and ARVs.

Improving the clinical relevance of a mouse pregnancy model of antiretroviral toxicity; a pharmacokinetic dosing-optimization study of current HIV antiretroviral regimens

Animal models can be useful tools for the study of HIV antiretroviral (ARV) safety/toxicity in pregnancy and the mechanisms that underlie ARV-associated adverse events. The utility and translatability of animal model-based ARV safety/toxicity data is improved if ARVs are tested in clinically relevant concentrations. The objective of this work was to improve the clinical relevance of our mouse pregnancy model of ARV toxicity, by determining the doses of currently prescribed ARV regimens that would yield human therapeutic plasma concentrations. Pregnant mice were administered increasing doses of ARV combinations by oral gavage, followed by measurement of drug concentrations in the maternal plasma and amniotic fluid. Concentrations of ten different ARVs in maternal plasma and amniotic fluid samples of pregnant mice are presented, with dosing optimization to yield human pregnancy-relevant plasma drug concentrations. We have proposed optimal dosing for different regimen component drugs to achieve human therapeutic plasma levels, so that a clinically relevant standard dosing is established. A review of related ARV pharmacokinetic studies in (pregnant/non-pregnant) rodents and human pregnancy is also shown. We hope these data will inform and encourage the use of mouse pregnancy models in the study of ARV safety/toxicity.

Comparative pharmacokinetic evaluation of lopinavir and lopinavir-loaded solid lipid nanoparticles in hepatic impaired rat model

Objective

Drug-induced hepatotoxicity is a major cause of concern in patients receiving HIV/TB co-treatment. Lopinavir (LPV), an anti-HIV drug, shows poor plasma exposure due to hepatic first-pass metabolism. In this study, we investigated the effect of hepatotoxicity on pharmacokinetics of free LPV and LPV-loaded solid lipid nanoparticles (LPV SLNs) in male Wistar rats.

Methods

Hepatic impairment model in rats was developed by injecting CCl4 (i.p., 2 ml/kg). Comparative pharmacokinetic (n = 5) and tissue distribution studies (n = 3) were conducted following oral administration (20 mg/kg) of free LPV and LPV SLNs in normal and hepatic impaired rats. Isolated perfused liver (IPL) model (n = 3) and cycloheximide intervened lymphatic uptake studies (n = 3) were conducted to appreciate disposition pattern of LPV.

Key findings

In contrary to free LPV, pharmacokinetic results demonstrated no significant (P > 0.05) difference in drug plasma profile of LPV SLNs in normal and impaired rats. IPL model demonstrated trivial role of liver in disposition of LPV SLNs. Tissue distribution studies of SLNs showed higher (P < 0.05) LPV accumulation in lymphoidal organs. Pretreatment of cycloheximide significantly (P < 0.05) reduced AUC and Cmax of LPV SLNs.

Conclusion

From the results, we conclude that unlike conventional formulations of LPV, disposition characteristics of LPV SLNs were similar both in normal and hepatic impaired rats.

Effect of ciprofloxacin and grapefruit juice on oral pharmacokinetics of riluzole in Wistar rats

Objectives

The objective of this study was to explore potential drug–drug/food interactions of ciprofloxacin and grapefruit juice, known hepatic cytochrome P450 (CYP) 1A2 inhibitors, on single-dose oral pharmacokinetics of riluzole, a substrate of CYP 1A2 enzymes.

Methods

Pharmacokinetic parameters of riluzole were determined in Wistar rats after single-dose co-administration with ciprofloxacin and grapefruit juice. In-vitro metabolic inhibition studies using rat and human liver microsomes and intestinal absorption studies of riluzole in a rat everted gut-sac model were conducted to elucidate the mechanism of interaction. A validated HPLC method was employed to quantify riluzole in the samples obtained in various studies.

Key findings

Co-administration of ciprofloxacin with riluzole caused significant increase in systemic exposure of riluzole (area under the curve, maximum plasma concentration and mean residence time were found to increase). Co-administration of grapefruit juice with riluzole did not cause any significant difference in the pharmacokinetic parameters of riluzole. In-vitro metabolism studies demonstrated significant inhibition of riluzole metabolism when it was co-incubated with ciprofloxacin or grapefruit juice. No significant change was observed in apparent permeability of riluzole.

Conclusions

Co-administration of ciprofloxacin with riluzole increases the systemic levels of riluzole and thereby the oral pharmacokinetic properties of riluzole while co-administration of grapefruit juice with riluzole has no significant effect.

Mechanisms underlying food-drug interactions: inhibition of intestinal metabolism and transport

Food-drug interaction studies are critical to evaluate appropriate dosing, timing, and formulation of new drug candidates. These interactions often reflect prandial-associated changes in the extent and/or rate of systemic drug exposure. Physiologic and physicochemical mechanisms underlying food effects on drug disposition are well-characterized. However, biochemical mechanisms involving drug metabolizing enzymes and transport proteins remain underexplored. Several plant-derived beverages have been shown to modulate enzymes and transporters in the intestine, leading to altered pharmacokinetic (PK) and potentially negative pharmacodynamic (PD) outcomes. Commonly consumed fruit juices, teas, and alcoholic drinks contain phytochemicals that inhibit intestinal cytochrome P450 and phase II conjugation enzymes, as well as uptake and efflux transport proteins. Whereas myriad phytochemicals have been shown to inhibit these processes in vitro, translation to the clinic has been deemed insignificant or undetermined. An overlooked prerequisite for elucidating food effects on drug PK is thorough knowledge of causative bioactive ingredients. Substantial variability in bioactive ingredient composition and activity of a given dietary substance poses a challenge in conducting robust food-drug interaction studies. This confounding factor can be addressed by identifying and characterizing specific components, which could be used as marker compounds to improve clinical trial design and quantitatively predict food effects. Interpretation and integration of data from in vitro, in vivo, and in silico studies require collaborative expertise from multiple disciplines, from botany to clinical pharmacology (i.e., plant to patient). Development of more systematic methods and guidelines is needed to address the general lack of information on examining drug-dietary substance interactions prospectively.

Effect of multidose cilostazol on pharmacokinetic and lipid profile of atorvastatin in male Wistar rats

Objectives

Atorvastatin (ATV) and cilostazol (CLZ) are often co-prescribed to treat conditions such as peripheral arterial disease. In the present study, the drug–drug interaction potential of multi-dose CLZ on both pharmacokinetics and the lipid-lowering ability of single-dose ATV is demonstrated.

Method

The pharmacokinetic parameters of ATV were determined in Wistar rats after per-oral pre-treatment with CLZ for 7 days in order to assess the interaction potential between ATV and CLZ. In-vitro metabolic inhibition and everted gut sac studies were conducted to elucidate the mechanism of this interaction. Biochemistry analyser was used to estimate lipid profiles in Wistar rats. A validated LC-MS/MS method was employed to simultaneously quantify both ATV and CLZ in rat plasma matrix.

Key findings

A statistically significant increase in systemic exposure to ATV after a single dose was observed in CLZ pre-treated rats. In-vitro metabolism studies using rat liver microsome (RLM) demonstrated statistically significant inhibition of ATV metabolism when co-incubated with CLZ. No change in apparent permeability of ATV was observed in the presence of CLZ. The blood lipid profile study after ATV administration indicated a statistically significant decrease in total cholesterol, triglycerides and LDL-cholesterol.

Conclusions

Multi-dose administration of CLZ influences the pharmacokinetics and lipid-lowering properties of ATV. Collectively, an apparent interaction between selected drugs was evident.