Research Articles (Clinical Pharmacology)
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Browsing Research Articles (Clinical Pharmacology) by Author "Awortwe, Charles"
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- ItemEvaluation of drug interaction potential of Labisia pumila (Kacip Fatimah) and its constituents(Frontiers, 2014-08-08) Manda, Vamshi K.; Dale, Olivia R.; Awortwe, Charles; Ali, Zulfiqar; Khan, Ikhlas A.; Walker, Larry A.; Khan, Shabana I.ENGLISH ABSTRACT: Labisia pumila (Kacip Fatimah) is a popular herb in Malaysia that has been traditionally used in a number of women’s health applications such as to improve libido, relieve postmenopausal symptoms, and to facilitate or hasten delivery in childbirth. In addition, the constituents of this plant have been reported to possess anticancer, antioxidant, and anti-inflammatory properties. Clinical studies have indicated that cytochrome P450s (CYPs), P-glycoprotein (P-gp), and Pregnane X receptor (PXR) are the three main modulators of drug-drug interactions which alter the absorption, distribution, and metabolism of drugs. Given the widespread use of Kacip Fatimah in dietary supplements, the current study focuses on determining the potential of its constituents to affect the activities of CYPs, P-gp, or PXR using in vitro assays which may provide useful information toward the risk of herb-drug interaction with concomitantly used drugs. Six compounds isolated from the roots of L. pumila (2 saponins and 4 alkyl phenols) were tested, in addition to the methanolic extract. The extract of L. pumila showed a significant time dependent inhibition (TDI) of CYP3A4, reversible inhibition of CYP2C9 and 2C19 and a weak inhibition of 1A2 and 2D6 as well as an inhibition of P-gp and rifampicin-induced PXR activation. The alkyl phenols inhibited CYP3A4 (TDI), CYP2C9, and 2C19 (reversible) while saponins inhibited P-gp and PXR. In conclusion, L. pumila and its constituents showed significant modulation of all three regulatory proteins (CYPs, P-gp, and PXR) suggesting a potential to alter the pharmacokinetic and pharmacodynamic properties of conventional drugs if used concomitantly.
- ItemInhibition of CYP2B6 by medicinal plant extracts : implication for use of efavirenz and nevirapine-based highly active anti-retroviral therapy (HAART) in resource-limited settings(MDPI, 2016-02-16) Thomford, Nicholas E.; Awortwe, Charles; Dzobo, Kevin; Adu, Faustina; Chopera, Denis; Wonkam, Ambroise; Skelton, Michelle; Blackhurst, Dee; Dandara, ColletHighly active antiretroviral therapy (HAART) has greatly improved health parameters of HIV infected individuals. However, there are several challenges associated with the chronic nature of HAART administration. For populations in health transition, dual use of medicinal plant extracts and conventional medicine poses a significant challenge. There is need to evaluate interactions between commonly used medicinal plant extracts and antiretroviral drugs used against HIV/AIDS. Efavirenz (EFV) and nevirapine (NVP) are the major components of HAART both metabolized by CYP2B6, an enzyme that can potentially be inhibited or induced by compounds found in medicinal plant extracts. The purpose of this study was to evaluate the effects of extracts of selected commonly used medicinal plants on CYP2B6 enzyme activity. Recombinant human CYP2B6 was used to evaluate inhibition, allowing the assessment of herb-drug interactions (HDI) of medicinal plants Hyptis suaveolens, Myrothamnus flabellifolius, Launaea taraxacifolia, Boerhavia diffusa and Newbouldia laevis. The potential of these medicinal extracts to cause HDI was ranked accordingly for reversible inhibition and also classified as potential time-dependent inhibitor (TDI) candidates. The most potent inhibitor for CYP2B6 was Hyptis suaveolens extract (IC50 = 19.09 ± 1.16 µg/mL), followed by Myrothamnus flabellifolius extract (IC50 = 23.66 ± 4.86 µg/mL), Launaea taraxacifolia extract (IC50 = 33.87 ± 1.54 µg/mL), and Boerhavia diffusa extract (IC50 = 34.93 ± 1.06 µg/mL). Newbouldia laevis extract, however, exhibited weak inhibitory effects (IC50 = 100 ± 8.71 µg/mL) on CYP2B6. Launaea taraxacifolia exhibited a TDI (3.17) effect on CYP2B6 and showed a high concentration of known CYP450 inhibitory phenolic compounds, chlorogenic acid and caffeic acid. The implication for these observations is that drugs that are metabolized by CYP2B6 when co-administered with these herbal medicines and when adequate amounts of the extracts reach the liver, there is a high likelihood of standard doses affecting drug plasma concentrations which could lead to toxicity.
- ItemInhibitory interactions of Aspalathus linearis (Rooibos) extracts and compounds, aspalathin and Z-2-(β-D-glucopyranosyloxy)-3-phenylpropenoic acid, on cytochromes metabolizing hypoglycemic and hypolipidemic drugs(MDPI, 2016-11-12) Patel, Oelfah; Muller, Christo; Joubert, Elizabeth; Louw, Johan; Rosenkranz, Bernd; Awortwe, CharlesRooibos extract, due to its glucose and lipid lowering effects, has potential as a nutraceutical for improvement of metabolic dysfunction. Potential herb-drug interactions as a result of the use of natural products are of increasing concern. Cytochrome P450 enzymes, CYP2C8, CYP2C9, and CYP3A4, are important in the metabolism of hypoglycemic drugs, such as thiazolidinediones (TZDs) and sulfonylureas, and hypocholesterolemic drugs, such as atorvastatin. This study investigated the effects of rooibos extracts, prepared from “unfermented” and “fermented” rooibos plant material and two of the major bioactive compounds, Z-2-(β-d-glucopyranosyloxy)-3-phenylpropenoic acid (PPAG) and aspalathin (ASP), on Vivid® recombinant CYP450 enzymes. Unfermented (GRT) and fermented (FRE) rooibos extracts inhibited the activity of CYP2C8 (7.69 ± 8.85 µg/mL and 8.93 ± 8.88 µg/mL, respectively) and CYP3A4 (31.33 ± 4.69 µg/mL and 51.44 ± 4.31 µg/mL, respectively) based on their respective IC50 concentrations. Both extracts dose- and time-dependently inhibited CYP2C8 activity, but only time-dependently inhibited CYP2C9. CYP3A4 showed concentration-dependent inhibition by ASP, GRT, and FRE at 25, 50, and 100 µg/mL concentrations. ASP, GRT, and FRE time-dependently inhibited CYP3A4 activity with GRT and FRE showing a more potent time-dependent inhibition, comparable to erythromycin. These findings suggest that herb-drug interactions may occur when nutraceuticals containing rooibos extracts are co-administered with hypoglycemic drugs such as TZDs, sulfonylureas, and dyslipidemic drug, atorvastatin.
- ItemMeta-analysis on outcome-worsening comorbidities of COVID-19 and related potential drug-drug interactions(Elsevier, 2020-11) Awortwe, Charles; Cascorbi, IngolfENGLISH ABSTRACT: Drug-drug interactions (DDI) potentially occurring between medications used in the course of COVID-19 infection and medications prescribed for the management of underlying comorbidities may cause adverse drug reactions (ADRs) contributing to worsening of the clinical outcome in affected patients. First, we conducted a meta-analysis to determine comorbidities observed in the course of COVID-19 disease associated with an increased risk of worsened clinical outcome from 24 published studies. In addition, the potential risk of DDI between medications used in the course of COVID-19 treatment in these studies and those for the management of observed comorbidities was evaluated for possible worsening of the clinical outcome. Our meta-analysis revealed an implication cardiometabolic syndrome (e.g. cardiovascular disease, cerebrovascular disease, hypertension, and diabetes), chronic kidney disease and chronic obstructive pulmonary disease as main co-morbidities associated with worsen the clinical outcomes including mortality (risk difference RD 0.12, 95 %-CI 0.05−0.19, p = 0.001), admission to ICU (RD 0.10, 95 %-CI 0.04−0.16, p = 0.001) and severe infection (RD 0.05, 95 %-CI 0.01−0.09, p = 0.01) in COVID-19 patients. Potential DDI on pharmacokinetic level were identified between the antiviral agents atazanavir and lopinavir/ritonavir and some drugs, used in the treatment of cardiovascular diseases such as antiarrhythmics and anti-coagulants possibly affecting the clinical outcome including cardiac injury or arrest because of QTc-time prolongation or bleeding. Concluding, DDI occurring in the course of anti-Covid-19 treatment and co-morbidities could lead to ADRs, increasing the risk of hospitalization, prolonged time to recovery or death on extreme cases. COVID-19 patients with cardiometabolic diseases, chronic kidney disease and chronic obstructive pulmonary disease should be subjected to particular carefully clinical monitoring of adverse events with a possibility of dose adjustment when necessary.