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Fulltext 4'-O-substitutions determine selectivity of aminoglycoside antibiotics

Perez-Fernandez D, Shcherbakov D, Matt T, Leong NC, Kudyba I, Duscha S, et al.

Nat Commun, 2014;5:3112.
PMID: 24473108 DOI: 10.1038/ncomms4112

Clinical use of 2-deoxystreptamine aminoglycoside antibiotics, which target the bacterial ribosome, is compromised by adverse effects related to limited drug selectivity. Here we present a series of 4',6'-O-acetal and 4'-O-ether modifications on glucopyranosyl ring I of aminoglycosides. Chemical modifications were guided by measuring interactions between the compounds synthesized and ribosomes harbouring single point mutations in the drug-binding site, resulting in aminoglycosides that interact poorly with the drug-binding pocket of eukaryotic mitochondrial or cytosolic ribosomes. Yet, these compounds largely retain their inhibitory activity for bacterial ribosomes and show antibacterial activity. Our data indicate that 4'-O-substituted aminoglycosides possess increased selectivity towards bacterial ribosomes and little activity for any of the human drug-binding pockets.

Matched MeSH terms: Drug Interactions
In vitro modulatory effects on three major human cytochrome P450 enzymes by multiple active constituents and extracts of Centella asiatica

Pan Y, Abd-Rashid BA, Ismail Z, Ismail R, Mak JW, Pook PC, et al.

J Ethnopharmacol, 2010 Jul 20;130(2):275-83.
PMID: 20457244 DOI: 10.1016/j.jep.2010.05.002

ETHNOPHARMACOLOGICAL RELEVANCE: Centella asiatica (CA) has been widely cultivated as a vegetable or spice in China, Southeast Asia, India, Sri Lanka, Africa, and Oceanic countries and traditionally used for wound healing and maintaining normal blood pressure.
AIM OF THE STUDY: The present study was carried out to examine the potential modulatory effects of three commercially available active components (asiaticoside, asiatic acid and madecassic acid) and four extracts (aqueous, ethanol, dichloromethane and hexane) of CA on three major cDNA-expressed human cytochrome P450 (CYP) isoforms.
MATERIALS AND METHODS: High-performance liquid chromatography (HPLC)-based enzyme assays, namely tolbutamide 4-methyhydroxylase, dextromethorphan O-demethylase and testosterone 6beta-hydroxylase assays were developed to probe activities of CYP2C9, CYP2D6 and CYP3A4, respectively. Probe substrates were incubated with or without each active component and extract for each isoform, followed by examination of the kinetics parameters, IC(50) and K(i), to characterize modulatory effects.
RESULTS: CYP2C9 was more susceptible to inhibitory effects by CA extracts compared to CYP2D6 and CYP3A4. Moderate degree of inhibition was observed in ethanol (K(i)=39.1 microg/ml) and dichloromethane (K(i)=26.6 microg/ml) extracts implying potential risk of interaction when CYP2C9 substrates are consumed with CA products. The two extracts however showed negligible inhibition towards CYP2D6 and CYP3A4 (IC(50)'s of 123.3 microg/ml and above). Similarly CA aqueous and hexane extracts did not significantly inhibit all three isoforms investigated (IC(50)'s of 117.9 microg/ml and above). Among the active constituents investigated, asiatic acid and madecassic acid appeared to selectively inhibit CYP2C9 and CYP2D6 more than CYP3A4. Of particular interest is the potent inhibitory effect of asiatic acid on CYP2C9 (K(i)=9.1 microg/ml). This signifies potential risk of interaction when substrates for this isoform are taken together with CA products with high asiatic acid content. Inhibitions of asiatic acid with the other isoforms and that of madecassic acid with all isoforms were only moderate (K(i)'s ranged from 17.2 to 84.4 microg/ml). On the other hand, the IC(50) values for asiaticoside were high (1070.2 microg/ml or above) for all three isoforms, indicating negligible or low potential of this compound to modulate CYP enzymatic activity.
CONCLUSION: Centella asiatica extracts and active constituents inhibited CYP2C9, CYP2D6 and CYP3A4 activities with varying potency with CYP2C9 being the most susceptible isoform to inhibition. Significant inhibition was observed for asiatic acid and CA ethanol and dichloromethane extracts, implying involvement of semipolar constituents from CA in the effect. This study suggested that CA could cause drug-herb interactions through CYP2C9 inhibition.

Matched MeSH terms: Herb-Drug Interactions
In vitro modulatory effects of Andrographis paniculata, Centella asiatica and Orthosiphon stamineus on cytochrome P450 2C19 (CYP2C19)

Pan Y, Abd-Rashid BA, Ismail Z, Ismail R, Mak JW, Pook PC, et al.

J Ethnopharmacol, 2011 Jan 27;133(2):881-7.
PMID: 21093571 DOI: 10.1016/j.jep.2010.11.026

Andrographis paniculata (AP), Centella asiatica (CA) and Orthosiphon stamineus (OS) are three popular herbs traditionally used worldwide. AP is known for the treatment of infections and diabetes and CA is good for wound healing and healthy skin while OS is usually consumed as tea to treat kidney and urinary disorders. Interaction of these herbs with human cytochrome P450 2C19 (CYP2C19), a major hepatic CYP isoform involved in metabolism of many clinical drugs has not been investigated to date.

Matched MeSH terms: Herb-Drug Interactions
Fulltext Pharmacogenomics in drug therapy and interaction: the role of cytochrome P450

Ong, Chin-Eng, Yan, Pan, Tiong, Kai-Hung, Yiap, Beow-Chin, Tan, Eng-Lai, Pook, Peter, et al.

International e-Journal of Science, Medicine & Education, 2008;2(3):-.
MyJurnal

Pharmacogenomics (or pharmacogenetics), the study of the effects of genetic differences on a person’s response to drugs, can help in optimizing drug efficacy and minimizing adverse drug reactions. Interperson difference in drug metabolism is one of the important consequences of such genetic variation. This variation is determined in part by mutations in cytochrome P450 enzymes (CYPs). IMU is part of a major collaborative research project in the area of phamacogenetics and drug metabolism. Working together with USM and UiTM, our group has, since 2000, generated useful population database on genetic polymorphism of various CYP isoforms. We have successfully genotyped three major ethnic groups, Malay, Indian and Chinese for their allelic frequency of important isoforms. These include CYP2D6, CYP2C9, CYP2C8 and CYP2A6. Data generated so far collectively have contributed to our effort in mapping and constructing genomic database for Malaysian population.
Since early 2002, our research has been focusing on developing in vitro methods in studying the functional consequences of genetic polymorphism of CYP enzymes. Using site-directed mutagenesis, CYP mutants, carrying nucleotide changes as reported in known alleles in human populations, were generated and expressed in E. coli system, and the expressed recombinant proteins were characterized using enzyme assays to determine the functional consequences of mutations. We have established a series of HPLC (high performance liquid chromatography)-based and fluorescence-based assays to investigate CYP activities. Assays that have been developed include tolbutamide methylhydroxylase, paclitaxel 6α-hydroxylase, dextromethorphan O-demethylation, testosterone 6β-hydroxylation and coumarin 7-hydroxylase assays. These assays serve as activity markers allowing comparison of catalytic activities of mutant proteins generated. Another focus of our work is to use the developed assays as a screening tool to investigate drug-herb interactions. This was achieved by co-incubation of herbal extracts and active constituents with the probe substrates in the assays followed by characterization of the kinetic behaviors of the enzymes involved using various pharmacokinetic parameters such as Km, Vmax, IC50 and Ki. This work is currently carried out with collaboration from the Institute for Medical Research (IMR) and is supported by MOSTI’s eScienceFund under RM9. It is envisaged that this screening work will give us insights on the potential of the commonly used herbs to cause pharmacokinetic interactions with other drug substrates, and allow us to elucidate the mechanisms involved in the interactions.

Matched MeSH terms: Herb-Drug Interactions
Vitamin E, glutathione S-transferase and gamma-glutamyl transpeptidase activities in cultured hepatocytes of rats treated with carcinogens

Ong FB, Wan Ngah WZ, Top AG, Khalid BA, Shamaan NA

Int. J. Biochem., 1994 Mar;26(3):397-402.
PMID: 7910569

1. The effects of alpha-tocopherol and gamma-tocotrienol on glutathione S-transferase (GST) and gamma-glutamyl transpeptidase (gamma-GT) activities in cultured hepatocytes prepared from rats treated with diethylnitrosamine (DEN) and 2-acetylaminofluorene (AAF) were investigated. 2. Both the alpha-tocopherol and gamma-tocotrienol treated hepatocytes showed significantly higher (P < 0.05) GST activities than untreated hepatocytes prepared from the carcinogen treated rats in the first 3 days of culture. Treatment with alpha-tocopherol and gamma-tocotrienol generally resulted in a tendency to increase the GST activities above that in the untreated hepatocytes. 3. Treatment with high doses (125-250 microM) of alpha-tocopherol and low doses (12.5-25 microM) of gamma-tocotrienol generally resulted in a significant reduction in gamma-GT activities at 1-3 days. gamma-GT activities are reduced as the dose of alpha-tocopherol and gamma-tocotrienol are increased.

Matched MeSH terms: Drug Interactions
In vitro approaches to investigate cytochrome P450 activities: update on current status and their applicability

Ong CE, Pan Y, Mak JW, Ismail R

Expert Opin Drug Metab Toxicol, 2013 Sep;9(9):1097-113.
PMID: 23682848 DOI: 10.1517/17425255.2013.800482

Cytochromes P450 (CYPs) play a central role in the Phase I metabolism of drugs and other xenobiotics. It is estimated that CYPs can metabolize up to two-thirds of drugs present in humans. Over the past two decades, there have been numerous advances in in vitro methodologies to characterize drug metabolism and interaction involving CYPs.

Matched MeSH terms: Drug Interactions
Fulltext Involvement of cytochromes p450 in drug-drug interactions: an overview

Ong CE, Teh LK, Ismail R

Med J Malaysia, 2002 Jun;57(2):251-60.
PMID: 24326665

Drug interactions can cause iatrogenic disease. If concurrent medications are taken, the potential exists for a drug interaction to occur. Renewed interest in the topic interactions has been generated by the fatal interactions involving non-sedating histamine H-1 antagonists and the recent intriduction of two therapeutic agents, the selective serotonin reuptake inhibitors (SSRIs) and HIV protease inhibitors, for the treatment of depression and AIDS, respectively. These three therapeutic agents have been implicated in clinically significant drug interactions. The consequences of these interactions vary in clinical significance, extent, and effect. Some interactions are theoretical whereas others may lead to severe iatrogenic adverse experiences including lethal consequences.The purpose of this review is to alert the medical practioner to potential drug interactions that may occur when these drugs are prescribed to patients. The pharmacological basis and clinical signficance of these interactions are reviewed. The pharmacological mechanisms underlying these interactions are illustrative of those that may be involved for many other medications. Doctors should be aware of the potential pitfall that may occur when certain groups of drugs are prescribed with concurrent medications.

Matched MeSH terms: Drug Interactions*
Fulltext Erythromycin induced torsade de pointes in a methadone maintenance patient: case report

Noor Zurani Md Haris Robson, Mohamad Hussain Habil

ASEAN Journal of Psychiatry, 2010;11(1):103-107.
MyJurnal

Objective: This case report highlights the risk of Torsade de Pointes (TdP), a life threatening cardiac arrhythmia in a heroin dependent patient receiving methadone substitution therapy who was prescribed erythromycin for upper respiratory tract infection. Method: We report a case of a 35-year-old Malay man on methadone maintenance treatment who developed TdP possibly due to drug interaction between methadone and erythromycin. Results: The
patient reported feeling unwell, chest pain and feeling dizzy after consuming 2 doses of erythromycin. ECG monitoring showed prolonged rate-corrected QT interval leading to TdP. The patient was admitted to the ward where the cardiac arrhythmia ceased following methadone discontinuation. This cardiac arrhythmia was most likely due to drug interaction between methadone and erythromycin (an enzyme inhibitor) which led to an increase in methadone concentration and potentiated the adverse effects. Conclusion: As methadone is a beneficial treatment for heroin dependent patients, the risk of cardiac arrhythmia is of great concern. To avoid complications of drug interaction, patients on methadone therapy should be advised to seek medical assessment before taking other drugs. As TdP is life threatening, it is thus important that physicians and psychiatrists involved in the treatment of
heroin dependent patients on methadone substitution therapy be made aware of this risk.

Matched MeSH terms: Drug Interactions
Fulltext Piper betle leaf extract enhances the cytotoxicity effect of 5-fluorouracil in inhibiting the growth of HT29 and HCT116 colon cancer cells

Ng PL, Rajab NF, Then SM, Mohd Yusof YA, Wan Ngah WZ, Pin KY, et al.

J Zhejiang Univ Sci B, 2014 Aug;15(8):692-700.
PMID: 25091987 DOI: 10.1631/jzus.B1300303

OBJECTIVE: The combination effect of Piper betle (PB) and 5-fluorouracil (5-FU) in enhancing the cytotoxic potential of 5-FU in inhibiting the growth of colon cancer cells was investigated.
METHODS: HT29 and HCT116 cells were subjected to 5-FU or PB treatment. 5-FU and PB were then combined and their effects on both cell lines were observed after 24 h of treatment. PB-5-FU interaction was elucidated by isobologram analysis. Apoptosis features of the treated cells were revealed by annexin V/PI stain. High-performance liquid chromatography (HPLC) was performed to exclude any possible chemical interaction between the compounds.
RESULTS: In the presence of PB extract, the cytotoxicity of 5-FU was observed at a lower dose (IC50 12.5 µmol/L) and a shorter time (24 h) in both cell lines. Both cell lines treated with 5-FU or PB alone induced a greater apoptosis effect compared with the combination treatment. Isobologram analysis indicated that PB and 5-FU interacted synergistically and antagonistically in inhibiting the growth of HT29 and HCT116 cells, respectively.
CONCLUSIONS: In the presence of PB, a lower dosage of 5-FU is required to achieve the maximum drug effect in inhibiting the growth of HT29 cells. However, PB did not significantly reduce 5-FU dosage in HCT116 cells. Our result showed that this interaction may not solely contribute to the apoptosis pathway.
KEYWORDS: 5-Fluorouracil; Herb-drug interaction; Isobologram analysis; Piper betle L.; Piperaceae

Matched MeSH terms: Herb-Drug Interactions*
Fulltext Histopathological study of the hepatic and renal toxicity associated with the co-administration of imatinib and acetaminophen in a preclinical mouse model

Nassar I, Pasupati T, Judson JP, Segarra I

Malays J Pathol, 2010 Jun;32(1):1-11.
PMID: 20614720 MyJurnal

Imatinib, a selective tyrosine kinase inhibitor, is the first line treatment against chronic myelogenous leukaemia (CML) and gastrointestinal stromal tumors (GIST). Several fatal cases have been associated with imatinib hepatotoxicity. Acetaminophen, an over-the-counter analgesic, anti-pyretic drug, which can cause hepatotoxicity, is commonly used in cancer pain management. We assessed renal and hepatic toxicity after imatinib and acetaminophen co-administration in a preclinical model. Four groups of male ICR mice (30-35 g) were fasted overnight and administered either saline solution orally (baseline control), imatinib 100 mg/kg orally (control), acetaminophen 700 mg/kg intraperitoneally (positive control) or co-administered imatinib 100 mg/kg orally and acetaminophen 700 mg/kg intraperitoneally (study group), and sacrificed at 15 min, 30 min, 1 h, 2 h, 4 h and 6 h post-administration (n = 4 per time point). The liver and kidneys were harvested for histopathology assessment. The liver showed reversible cell damage like feathery degeneration, microvesicular fatty change, sinusoidal congestion and pyknosis, when imatinib or acetaminophen were administered separately. The damage increased gradually with time, peaked at 2 h but resolved by 4 h. When both drugs were administered concurrently, the liver showed irreversible damage (cytolysis, karyolysis and karyorrhexis) which did not resolve by 6 h. Very minor renal changes were observed. Acetaminophen and imatinib co-administration increased hepatoxicity which become irreversible, probably due to shared P450 biotransformation pathways and transporters in the liver.

Matched MeSH terms: Drug Interactions
Effect of acetylcholine and morphine on bronchial smooth muscle contraction and its modulation by steroid hormones

Nabishah BM, Morat PB, Khalid BA, Kadir BA

Clin Exp Pharmacol Physiol, 1990 Dec;17(12):841-7.
PMID: 2092952

1. The effects of corticosteroid pretreatment on acetylcholine (ACH)-induced contraction of bronchial smooth muscle (BSM) were studied. 2. ACH dose-response curves for dexamethasone (DM)- and corticosterone (B)-treated but not deoxycorticosterone (DOC)-treated BSM were significantly shifted to the right; this provides evidence that glucocorticoid treatment reduced the sensitivity of BSM to ACH. 3. Morphine enhanced BSM contraction in response to ACH by 20%. DM suppressed this enhancement. 4. These findings correlated well with the reduction of muscarinic receptor numbers in BSM by glucocorticoids in our previous study. In addition, glucocorticoids reduced the sensitivity of BSM to opioids.

Matched MeSH terms: Drug Interactions
Fulltext Role of bilastine in the management of allergic rhinitis and urticaria: an Asia-Pacific consensus statement

Mösges R, Lee DL, Abong J, Siasoco B, Chow SK, Leong JL, et al.

Asia Pac Allergy, 2016 Jan;6(1):56-66.
PMID: 26844221 DOI: 10.5415/apallergy.2016.6.1.56

The prevalence of allergic diseases is increasing globally, most particularly in middle- to low-income countries. This article examines the burden of allergic rhinitis and chronic urticaria in the Asia-Pacific region, unmet clinical needs, and the potential role of bilastine in the management of these conditions. An International Advisory Group meeting was convened in association with the Asian Pacific Society of Respirology Annual Congress in November 2014, followed by a literature review, and consensus-based outcomes from the meeting and literature review are described. Regional estimates of the prevalence of allergic rhinitis range from 10% to 50%, while little is known regarding the burden of urticaria in the Asia-Pacific region. A survey of allergy patients in the region identified fast, complete, and long-lasting symptom relief as the medication attributes most important to patients. International treatment guidelines for allergic rhinitis and urticaria advocate the first-line use of second-generation, no-sedating H1-antihistamines, such as bilastine, over their first-generation counterparts and a range of these agents are available to Asia-Pacific patients. The newer agents possess many of the properties of an "ideal" antihistamine (once daily administration, rapid and complete symptom relief, limited potential for drug-drug interactions, minimal side effects). The burgeoning prevalence of allergic diseases in the Asia-Pacific region and the uncontrolled symptoms that these patients experience demand a new antihistamine that offers the highest number of positive features according to the international guidelines.

Matched MeSH terms: Drug Interactions
In-vitro inhibitory effect of Tualang honey on cytochrome P450 2C8 activity

Muthiah YD, Ong CE, Sulaiman SA, Tan SC, Ismail R

J Pharm Pharmacol, 2012 Dec;64(12):1761-9.
PMID: 23146039 DOI: 10.1111/j.2042-7158.2012.01551.x

To investigate the effect of Tualang honey on cytochrome P450 2C8 (CYP2C8) activity in vitro using an amodiaquine N-desethylase assay.

Matched MeSH terms: Food-Drug Interactions*
Fulltext Assessment of potential drug-drug interactions and its associated factors in the hospitalized cardiac patients

Murtaza G, Khan MY, Azhar S, Khan SA, Khan TM

Saudi Pharm J, 2016 Mar;24(2):220-5.
PMID: 27013915 DOI: 10.1016/j.jsps.2015.03.009

Drug-drug interactions (DDIs) may result in the alteration of therapeutic response. Sometimes they may increase the untoward effects of many drugs. Hospitalized cardiac patients need more attention regarding drug-drug interactions due to complexity of their disease and therapeutic regimen. This research was performed to find out types, prevalence and association between various predictors of potential drug-drug interactions (pDDIs) in the Department of Cardiology and to report common interactions. This study was performed in the hospitalized cardiac patients at Ayub Teaching Hospital, Abbottabad, Pakistan. Patient charts of 2342 patients were assessed for pDDIs using Micromedex® Drug Information. Logistic regression was applied to find predictors of pDDIs. The main outcome measure in the study was the association of the potential drug-drug interactions with various factors such as age, gender, polypharmacy, and hospital stay of the patients. We identified 53 interacting-combinations that were present in total 5109 pDDIs with median number of 02 pDDIs per patient. Overall, 91.6% patients had at least one pDDI; 86.3% were having at least one major pDDI, and 84.5% patients had at least one moderate pDDI. Among 5109 identified pDDIs, most were of moderate (55%) or major severity (45%); established (24.2%), theoretical (18.8%) or probable (57%) type of scientific evidence. Top 10 common pDDIs included 3 major and 7 moderate interactions. Results obtained by multivariate logistic regression revealed a significant association of the occurrence of pDDIs in patient with age of 60 years or more (p drugs (p drugs were at higher risk of pDDIs.

Matched MeSH terms: Drug Interactions
Fulltext Hypertensive bipolar: chronic lithium toxicity in patients taking ACE inhibitor

Masiran R, Abdul Aziz MF

BMJ Case Rep, 2017 Aug 28;2017.
PMID: 28847993 DOI: 10.1136/bcr-2017-220631

A patient with bipolar I disorder has been treated with lithium and haloperidol for the last 20 years and received an ACE inhibitor for his hypertension since 9 years ago. Despite regular clinic follow-ups and blood monitoring, he recently developed tremors and delirium. On hospital admission, serum level of lithium was far above toxic level. Mental state examination revealed an anxious and disorientated man with irrelevant speech. Immediate discontinuation of lithium resulted in slow reduction of serum lithium levels and gradual resolution of tremor but his delirium persisted for 2 weeks. His condition took a turn for the worse when he developed acute renal failure and arm abscess. We discussed about lithium toxicity and the vulnerability factors which have induced delirium and renal failure in this patient.

Matched MeSH terms: Drug Interactions
Fulltext Evaluation of drug interaction potential of Labisia pumila (Kacip Fatimah) and its constituents

Manda VK, Dale OR, Awortwe C, Ali Z, Khan IA, Walker LA, et al.

Front Pharmacol, 2014;5:178.
PMID: 25152732 DOI: 10.3389/fphar.2014.00178

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.

Matched MeSH terms: Herb-Drug Interactions
Interaction between oxytocin and 'sidaverin' on the gravid and non-gravid rat uterus

Lutterodt GD

Pharmacol Res, 1995 Jul-Aug;32(1-2):89-94.
PMID: 8668653 DOI: 10.1016/S1043-6618(95)80014-X

Sidaverin, a crystalline compound extracted from a polar fraction of Sida veronicaefolia (Lam), elicited oxytocin-like contractions in the non-gravid rat isolated uterus preparation with a concentration-response relationship. Equipotent concentrations of oxytocin and sidaverin, using matched responses, were approximately 0.16 U and 0.4 micrograms ml-1, respectively. Sidaverin-induced contractile response was atropine reversible. The concentration-response curves for sidaverin and oxytocin were parallel, and both responses were inhibited by the specific oxytocin antagonist, Atosiban, indicating possible involvement of oxytocin receptors in the action of sidaverin. There were potentiation of action of one drug to that of the other, irrespective of the order of administration and even after washing off the first before introducing the second drug. In the gravid uterus, sidaverin produced contractions in preparations from day 1 to day 6 or 7, caused relaxation in days 7-11, and elicited contractions in day 11 through term, the sensitivity of the preparations increasing exponentially toward term with strong sustained contractions. With the exception of days 7-11, when sidaverin antagonized oxytocin action, it potentiated action of oxytocin on the gravid uterus.

Matched MeSH terms: Drug Interactions
Effects of iridoids on lipoxygenase and hyaluronidase activities and their activation by beta-glucosidase in the presence of amino acids

Ling SK, Tanaka T, Kouno I

Biol Pharm Bull, 2003 Mar;26(3):352-6.
PMID: 12612446

Enzyme inhibitory activities of 14 iridoids previously obtained from two Malaysian medicinal plants, Saprosma scortechinii and Rothmannia macrophylla, were evaluated in vitro using soybean lipoxygenase and bovine testis hyaluronidase. Most of the iridoids, including asperulosidic acid, paederosidic acid, and an epimeric mixture of gardenogenins A and B, did not show any effect on the enzyme activities, except for the bis-iridoids, which inhibited the lipoxygenase activity with their IC(50) values of approximately 1.3 times that of a known inhibitor, fisetin. Structural modification of asperulosidic acid and paederosidic acid through enzymatic hydrolysis by beta-glucosidase resulted in their inhibition towards the enzyme activities, and these activities were enhanced by the presence of some amino acids (lysine, leucine or glutamic acid) or ammonium acetate. Mixtures of gardenogenins A and B; isomers of non-glucosidic iridoids, incubated with amino acid or ammonium acetate did not show any inhibitory effect on the enzyme activities during the 6 h incubation period, except for lysine where spontaneous reaction between the iridoids and amino acid resulted in the inhibition of lipoxygenase activity. The results from these biomimetic reactions suggested that the iridoid aglycons and the intermediates formed by these reactive species could inhibit the enzyme activities, and thus substantiate previous reports that the formation of iridoidal aglycons is a prerequisite for the iridoid glycosides to demonstrate some of the biological activities. In addition, the results also indicated that it is worthwhile to further explore these intermediates as potential anti-inflammatory agents.

Matched MeSH terms: Drug Interactions
Fulltext Role of Cytochrome P450 2C9 in COVID-19 Treatment: Current Status and Future Directions

Lim SYM, Al Bishtawi B, Lim W

Eur J Drug Metab Pharmacokinet, 2023 May;48(3):221-240.
PMID: 37093458 DOI: 10.1007/s13318-023-00826-8

The major human liver drug metabolising cytochrome P450 (CYP) enzymes are downregulated during inflammation and infectious disease state, especially during coronavirus disease 2019 (COVID-19) infection. The influx of proinflammatory cytokines, known as a 'cytokine storm', during severe COVID-19 leads to the downregulation of CYPs and triggers new cytokine release, which further dampens CYP expression. Impaired drug metabolism, along with the inevitable co-administration of drugs or 'combination therapy' in patients with COVID-19 with various comorbidities, could cause drug-drug interactions, thus worsening the disease condition. Genetic variability or polymorphism in CYP2C9 across different ethnicities could contribute to COVID-19 susceptibility. A number of drugs used in patients with COVID-19 are inducers or inhibitors of, or are metabolised by, CYP2C9, and co-administration might cause pharmacokinetic and pharmacodynamic interactions. It is also worth mentioning that some of the COVID-19 drug interactions are due to altered activity of other CYPs including CYP3A4. Isoniazid/rifampin for COVID-19 and tuberculosis co-infection; lopinavir/ritonavir and cobicistat/remdesivir combination therapy; or multi-drug therapy including ivermectin, azithromycin, montelukast and acetylsalicylic acid, known as TNR4 therapy, all improved recovery in patients with COVID-19. However, a combination of CYP2C9 inducers, inhibitors or both, and plausibly different CYP isoforms could lead to treatment failure, hepatotoxicity or serious side effects including thromboembolism or bleeding, as observed in the combined use of azithromycin/warfarin. Further, herbs that are CYP2C9 inducers and inhibitors, showed anti-COVID-19 properties, and in silico predictions postulated that phytochemical compounds could inhibit SARS-CoV-2 virus particles. COVID-19 vaccines elicit immune responses that activate cytokine release, which in turn suppresses CYP expression that could be the source of compromised CYP2C9 drug metabolism and the subsequent drug-drug interaction. Future studies are recommended to determine CYP regulation in COVID-19, while recognising the involvement of CYP2C9 and possibly utilising CYP2C9 as a target gene to tackle the ever-mutating SARS-CoV-2.

Matched MeSH terms: Drug Interactions
Fulltext Prevalence, risk factors and health outcomes associated with polypharmacy among urban community-dwelling older adults in multi-ethnic Malaysia

Lim LM, McStea M, Chung WW, Nor Azmi N, Abdul Aziz SA, Alwi S, et al.

PLoS One, 2017;12(3):e0173466.
PMID: 28273128 DOI: 10.1371/journal.pone.0173466

BACKGROUND: Polypharmacy has been associated with increased morbidity and mortality in the older population.
OBJECTIVES: The aim of this study was to determine the prevalence, risk factors and health outcomes associated with polypharmacy in a cohort of urban community-dwelling older adults receiving chronic medications in Malaysia.
METHODS: This was a baseline study in the Malaysian Elders Longitudinal Research cohort. The inclusion criteria were individuals aged ≥55years and taking at least one medication chronically (≥3 months). Participants were interviewed using a structured questionnaire during home visits where medications taken were reviewed. Health outcomes assessed were frequency of falls, functional disability, potential inappropriate medication use (PIMs), potential drug-drug interactions (PDDIs), healthcare utilisation and quality of life (QoL). Risk factors and health outcomes associated with polypharmacy (≥5 medications including dietary supplements) were determined using multivariate regression models.
RESULTS: A total of 1256 participants were included with a median (interquartile range) age of 69(63-74) years. The prevalence of polypharmacy was 45.9% while supplement users made up 56.9% of the cohort. The risk factors associated with increasing medication use were increasing age, Indian ethnicity, male, having a higher number of comorbidities specifically those diagnosed with cardiovascular, endocrine and gastrointestinal disorders, as well as supplement use. Health outcomes significantly associated with polypharmacy were PIMS, PDDIs and increased healthcare utilisation.
CONCLUSION: A significant proportion of older adults on chronic medications were exposed to polypharmacy and use of dietary supplements contributed significantly to this. Medication reviews are warranted to reduce significant polypharmacy related issues in the older population.

Matched MeSH terms: Drug Interactions

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