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At least 199 records · Page 11Linked to original sources
PubMed2005

Thermodynamically based profiling of drug metabolism and drug-drug metabolic interactions: a case study of acetaminophen and ethanol toxic interaction.

Drug-drug metabolic interactions can result in unwanted side effects, including reduced drug efficacy and formation of toxic metabolic intermediates. In this work, thermodynamic constraints on non-equilibrium metabolite concentrations are used to reveal the biochemical interactions between the metabolic pathways of ethanol and acetaminophen (N-acetyl-p-aminophenol), two drugs known to interact unfavorably. It is known that many reactions of these pathways are coupled to the central energy metabolic reactions through a number of metabolites and the cellular redox potential. Based on these observations, a metabolic network model has been constructed and a database of thermodynamic properties for all participating metabolites and reactions has been compiled. Constraint-based computational analysis of the feasible metabolite concentrations reveals that the non-toxic pathways for APAP metabolism and the pathway for detoxifying N-acetyl-p-benzoquinoneimine (NAPQI) are inhibited by network interactions with ethanol metabolism. These results point to the potential utility of thermodynamically based profiling of metabolic network interactions in screening of drug candidates and analysis of potential toxicity.

Acetaminophen↗
PubMed1998

The effect of continuous drug exposure on the immune response of lambs challenged with drug-susceptible or drug-resistant nematode larvae.

Groups of lambs either with or without controlled-release albendazole (ABZ) capsules (CRCs) were challenged twice weekly for 6 weeks with either drug-susceptible or drug-resistant Ostertagia circumcincta and Trichostrongylus colubriformis. Groups with and without CRCs remained unchallenged as controls. There was minimal establishment of drug-susceptible parasites of either species in those lambs with CRCs. However, drug-resistant parasites of both species established adult worm burdens in the presence of the capsules. The humoral immune response, as measured by the serum antilarval (L3) antibody (Ab) titre, was pooled for weeks 4-6 and compared for each group. With the exception of anti-T. colubriformis Ab in group 2, anti-L3 Ab titres were significantly higher in all the parasite-challenged groups as compared to the control animals. Also, with the exception of anti-resistant O. circumcincta Ab levels in the CRC-treated animals (group 5), no significant difference was observed in Ab titres between the four groups challenged with either resistant or susceptible larvae. The results demonstrate the inability of CRCs to prevent establishment of drug-resistant parasites and that immune stimulation is not inhibited by the capsules.

Albendazole↗
PubMedDate not supplied

Old and new drugs used in rheumatoid arthritis: a historical perspective. Part 2: the newer drugs and drug strategies.

After a 20-year hiatus, drug development for rheumatoid arthritis resumed in the early 1980s with cyclosporine, continuing in the 1990s with minocycline, leflunomide, and the tumor necrosis factor-alpha antagonists, infliximab and etanercept. Unlike the older disease-modifying antirheumatic drugs (apart from the cytotoxics), the newer drugs were designed with strict reference to proven pathophysiology in rheumatoid arthritis and, apart from minocycline, the intended action of these agents is highly likely the explanation for the observed efficacy. The evidence for the evolution of more rational drug development in rheumatoid arthritis has not altered the fact that efficacy versus toxicity still remains the major determinant in the practical use of these agents, as well as in the use of other, experimental agents briefly discussed. Action, efficacy, and toxicity also determine the rational chronologic use of these drugs alone and, in particular, in combination.

Antibodies, Monoclonal↗
PubMed2005

Prediction of in vivo drug-drug interactions from in vitro data: impact of incorporating parallel pathways of drug elimination and inhibitor absorption rate constant.

AIMS: Success of the quantitative prediction of drug-drug interactions via inhibition of CYP-mediated metabolism from the inhibitor concentration at the enzyme active site ([I]) and the in vitro inhibition constant (K(i)) is variable. The aim of this study was to examine the impact of the fraction of victim drug metabolized by a particular CYP (f(mCYP)) and the inhibitor absorption rate constant (k(a)) on prediction accuracy. METHODS: Drug-drug interaction studies involving inhibition of CYP2C9, CYP2D6 and CYP3A4 (n = 115) were investigated. Data on f(mCYP) for the probe substrates of each enzyme and k(a) values for the inhibitors were incorporated into in vivo predictions, alone or in combination, using either the maximum hepatic input or the average systemic plasma concentration as a surrogate for [I]. The success of prediction (AUC ratio predicted within twofold of in vivo value) was compared using nominal values of f(mCYP) = 1 and k(a) = 0.1 min(-1). RESULTS: The incorporation of f(mCYP) values into in vivo predictions using the hepatic input plasma concentration resulted in 84% of studies within twofold of in vivo value. The effect of k(a) values alone significantly reduced the number of over-predictions for CYP2D6 and CYP3A4; however, less precision was observed compared with the f(mCYP). The incorporation of both f(mCYP) and k(a) values resulted in 81% of studies within twofold of in vivo value. CONCLUSIONS: The incorporation of substrate and inhibitor-related information, namely f(mCYP) and k(a), markedly improved prediction of 115 interaction studies with CYP2C9, CYP2D6 and CYP3A4 in comparison with [I]/K(i) ratio alone.

Area Under Curve↗
PubMed2005

[Anti-drug pattern of drug-resistant Mycobacterium tuberculosis and analysis of mutation in drug-target genes].

The antimycobacterial susceptibility test was performed and minimal inhibitory concentration (MIC) to drugs was determined in 98 strains of Mycobacteium tuberculosis (MTB) isolated in Tokyo from 2000 to 2003, to find which were resistant to any of the four main anti-MTB drugs, isoniazid (INH), rifampicin (RFP), streptomycin (SM), and ethambutol (EMB). 27strains of them were resistant only to SM, and 16 strains were resistant only to INH. 51 strains of them were resistant to not only INH but also other drugs. 38 strains were resistant to both INH and RFP. 19 strains were resistant to all four drugs, including 7 strains resistant to new quinolon anti-biotics also. Nucleotide or amino-acid mutations in drug resistant MTB genome were determined by DNA sequencing method. Mutation of codon 516, 526, or 531 of rpoB gene was detected in 98% of MTBs resistant to RFP. Deletion or insertion of katG gene or nucleotide mutation at regulatory region of ahpC gene was detected in MTBs highly resistant to INH. Amino acid mutation of katG gene, especially at codon 315, was detected in MTBs resistant to INH intermediate. Nucleotide mutations at regulatory region of inhA gene were detected in MTBs resistant to INH at low level. Amino acid mutation at codon 43 or 88 of rpsL gene was detected in MTBs highly resistant to SM, and nucleotide mutation at 512, 513, or 516 of rrs gene was detected in MTBs resistant to SM at low level. Amino acid mutation at codon 306 of embB gene was detected in 87% of MTBs resistant to EMB.

Antitubercular Agents↗
PubMed2003

High-content profiling of drug-drug interactions: cellular targets involved in the modulation of microtubule drug action by the antifungal ketoconazole.

Drug-drug interactions play an important role in the discovery and development of therapeutic agents. High-content profiling was developed to unravel the complexity of these interactions by providing multiparameter measurements of target activity at the cellular and subcellular levels. Two microtubule drugs, vinblastine and curacin A, were shown to modulate multiple cellular processes, including nuclear condensation, the activation of the extracellular signal-regulated kinase pathway as measured by RSK90 phosphorylation, and the regulation of the microtubule cytoskeleton as measured in detergent-extracted cells. The heterogeneity of the response, addressed through population analysis and multiparameter comparisons within single cells, was consistent with vinblastine and curacin A having similar effects on nuclear morphology and 90 kDa ribosomal s6 kinase (RSK90) phosphorylation despite having distinct effects on the microtubule cytoskeleton. Ketoconazole, originally developed as an antifungal agent, exhibited concentration-dependent inhibitory and potentiating effects on both drugs in HeLa and PC-3 cells at concentration ranges near the plasma levels of ketoconazole attained in human subjects. Thus, high-content profiling was used to dissect the cellular and molecular responses to interacting drugs and is therefore a potentially important tool in the selection, characterization, and optimization of lead therapeutic compounds.

Animals↗
PubMed1989

Immunohistochemical detection and quantitation of P-glycoprotein in multiple drug-resistant human myeloma cells: association with level of drug resistance and drug accumulation.

Using several multiple drug-resistant human myeloma cell lines as standards, we developed an immunohistochemical staining technique and means of quantitating P-glycoprotein in individual myeloma cells. The level of staining intensity for P-glycoprotein in individual myeloma cells was quantitated by measuring the average optical density of each cell with a microscopic computerized cell analysis system. Using this system, we observed that the level of P-glycoprotein for individual cells within a cell population of known drug sensitivity was very homogeneous (coefficient of variation less than or equal to 13%). Analysis of cell lines with gradually increasing levels of multidrug resistance (8226/S, 8226/Dox6 and 8226/Dox40) demonstrated a close association between the level of resistance to doxorubicin, defined by the mean lethal dose (D0) and the amount of P-glycoprotein on individual cells determined by the optical density (r = 0.82, P less than 0.0005). Intracellular doxorubicin (DOX) accumulation in the individual cell lines was inversely related to the level of drug resistance expressed as D0. P-glycoprotein was also detected in the marrow-derived myeloma cells of patients with drug refractory disease using immunohistochemical staining. The amount of P-glycoprotein in the cells of one patient was directly compared to the amount found in the simultaneously stained standard cell lines (8226/Dox6 and 8226/Dox40) by comparing the optical densities for individual cells. Using this immunohistochemical technique to detect and quantitate P-glycoprotein in patient myeloma cells and comparing it to standard multidrug resistant myeloma cell lines may be of value in determining the contribution of P-glycoprotein to clinical drug resistance in patients with multiple myeloma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1988

Interactions between antitumor drugs and radiation in mammalian tumor cell lines: differential drug responses and mechanisms of resistance following fractionated X-irradiation or continuous drug exposure in vitro.

Drug-resistant mammalian tumor cell lines have been derived by either fractionated x-irradiation treatment or exposure to vincristine or etoposide (VP-16-213) in vitro. Analyses of the patterns of responses expressed by these differently derived, resistant cell lines have shown variations in responses to a range of antitumor drugs depending upon the agent used to induce resistance. However, all treated cell lines express resistance to vincristine and, with one exception, to VP-16-213. Preliminary evidence has indicated that resistance to vincristine in drug-treated cells, but not x-irradiation-treated cells, is associated with impaired vincristine uptake; resistance to VP-16-213 in both differently derived, resistant sublines is associated with a reduction of VP-16-213-induced DNA single-strand breakage; and collateral sensitivity to cisplatin in x-irradiation-treated cells is associated with enhanced drug-induced DNA cross-linking. These data indicate that patterns of responses to antitumor drugs and the mechanisms associated with these altered responses differ depending upon the agent used to induce resistance.

Animals↗
PubMed1985

Drug interactions between antiepileptic drugs and other drugs.

Antiepileptic drugs interact with a variety of other drugs to affect the pharmacokinetic behavior of either drug. Drug interactions may also occur when antiepileptic drugs are given in combination. The possibility of such interactions is not a contraindication to the use of combinations, but it requires that the clinician be aware of the problem and monitor patients given potentially interacting combinations.

Anticonvulsants↗
PubMed2001

Mismatched double-stranded RNA (polyI-polyC(12)U) is synergistic with multiple anti-HIV drugs and is active against drug-sensitive and drug-resistant HIV-1 in vitro.

Although highly active anti-retroviral therapy (HAART) is successful in the treatment of HIV infection, problems with toxicity, drug-resistant variants, and therapeutic failures have compromised the long-term utility of existing combination regimens. Mismatched double-stranded RNA (polyI-polyC(12)U) is an immune modulator with inherent anti-HIV activity. Cell toxicities and anti-HIV activities of fourteen anti-HIV agents were determined alone and in combination with polyI-polyC(12)U. Combination analyses for anti-HIV activity were performed at three drug ratios. Using Mixed Dose Effect analyses and the CalcuSyn for Windows software package, combination indeces were determined for all drug combinations. In general, polyI-polyC(12)U was synergistic in combination with abacavir, zidovudine, zalcitabine, didanosine, stavudine, efavirenz, indinavir, ritonavir, nelfinavir, and amprenavir. It was synergistic to antagonistic with lamivudine, delavirdine, nevirapine, and saquinavir. Thus, polyI-polyC(12)U is synergistic with most anti-HIV agents at most drug ratios and across most effective concentrations in vitro, although, certain members of each class were exceptions. PolyI-polyC(12)U alone was equally active against wild-type HIV and HIV resistant to nevirapine, protease inhibitors, or nucleoside analogue reverse transcriptase inhibitors. These results suggest that polyI-polyC(12)U should be re-evaluated as a potential adjunct therapy in patients who have failed current anti-retroviral therapeutic regimens.

Animals↗
PubMed2000

[Application study of drug information to proper use of drugs--estimation of adverse drug reactions by the evaluation scores of subjective symptoms (complaints) and background of patients].

We have built a database for CARPIS (Case Reports of Adverse Drug Reaction and Poisoning Information System) since 1987, and the case reports of adverse drug reactions accumulated in the CARPIS database to be total about 20,000. The purpose of our study is to develop, implement, and assess an estimation procedure for preventing the adverse drug reactions by subjective symptoms (complaints) of patients using this CARPIS. The case reports of the adverse reactions are not a systematical study and are elapse reports by the case, which encountered on the way of the cure. Therefore, it might be possible to use as the data if not gaining enough evaluation. Especially, the abstracts in the annual meeting of the society are fragmentary and does not often have objective evidence. Therefore, we contrived an original evaluation method and carefully selected the case reports for our study. Also, the adverse reactions are very colorful and it is difficult to handle them at once. Therefore, we study every organ and want to aim to make a finally all-round format. We reported on the Liver disorders, the Extra-pyramidal symptoms, the Drug eruption, the Leukopenia and so on. We discovered that there was an adverse reaction which shows very peculiar subjective symptoms (ex. Extra-pyramidal symptoms) and unpeculiar subjective symptoms (ex. Leukopenia). We want to show our point of view and the future of our study below.

Adverse Drug Reaction Reporting Systems↗
PubMed2006

ABC drug transporter at the blood-brain barrier: effects on drug metabolism and drug response.

At the blood-brain barrier (BBB) many cellular and dynamic mechanisms influence the cerebral drug metabolism and the drug response. In this review, we focus mainly on the role P-glycoprotein (P-gp) plays at the BBB. This protein is a 170-kDa ATP-dependent drug transport protein, located in the apical membrane of endothelial cells. Utilizing ATP hydrolysis as an energy source, it exports molecules which attempt to pass through the cell membrane from the outside to the inside, protecting cells from toxins and a wide range of substances. We briefly summarize some of the currently available in vivo and in vitro methods to investigate P-gp and its substrates. Hitherto, no chemical characteristic has been discovered that clearly distinguishes substrates from non-substrates of P-gp. We discuss some examples of substrates stressing the diversity of drugs and endogenous substances that relate to P-gp either as a substrate, an inhibitor, an inducer or as a combination of the above. Finally, we discuss genetic polymorphisms of the genes encoding for P-gp and their effects on drug response.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

[Evolution of the prevalence of HIV infection and risk behavior of drug injection among intravenous drug users infected or not infected by HIV in 3 Spanish cities. Working Group of Physicians of the World for the monitoring of HIV infection and risk behaviors in intravenous drug users].

OBJECTIVE: To know the evolution of HIV prevalence and risk behavior practices of drug injection in three spanish cities on the basis of the serologic status of injecting drug users. METHODS: Cross-sectional surveys among users in syringe interchange programmes. RESULTS: HIV prevalence (self-reported) decreased in Madrid from 50% (1992) down to 41% (1996) (p = 0.01) and did not change in Seville and Valencia from 1994 to 1996. Among HIV-positive injecting drug users, a decrease was observed in the practice of giving and taking used syringes in the three cities, although this decrease reached a statistically significance (p = 0.006) only for giving in Valencia from 1994 to 1996 and was almost significant (p = 0.08) for taking in Madrid from 1993 to 1996. Among HIV-negative injecting drug users, no decreases were observed in the practice of giving and taking used syringes and even a significant increase in giving syringes in Seville was recorded (p = 0.01) from 1994 to 1996. CONCLUSIONS: HIV prevalence among injecting drug users is stabilized or decreasing in the three studied cities. The prevalence of injecting risk behavior evolves differently according to the serologic status.

Adult↗
PubMed2004

Qualitative research: contributions to the study of drug use, drug abuse, and drug use(r)-related interventions.

This article describes how qualitative social science research has and can contribute to the emerging field of drug and alcohol studies. An eight-stage model of formative-reformative research is presented as a heuristic to outline the different ways in which qualitative research may be used to better understand micro and macro dimensions of drug use and distribution; more effectively design, monitor and evaluate drug use(r)-related interventions; and address the politics of drug/drug program representation. Tobacco is used as an exemplar to introduce the reader to the range of research issues that a qualitative researcher may focus upon during the initial stage of formative research. Ethnographic research on alcohol use among Native Americans is highlighted to illustrate the importance of closely examining ethnicity as well as class when investigating patterns of drug use. To familiarize the reader with qualitative research, we describe the range of methods commonly employed and the ways in which qualitative research may complement as well as contribute to quantitative research. In describing the later stages of the formative-reformative process, we consider both the use of qualitative research in the evaluation and critical assessment of drug use(r)-intervention programs, and the role of qualitative research in critically assessing the politics of prevention programs. Finally, we discuss the challenges faced by qualitative researchers when engaging in transdisciplinary research.

Anthropology, Cultural↗
PubMed2006

Prediction of cis-regulatory elements for drug-activated transcription factors in the regulation of drug-metabolising enzymes and drug transporters.

The expression of drug-metabolising enzymes is affected by many endogenous and exogenous factors, including sex, age, diet and exposure to xenobiotics and drugs. To understand fully how the organism metabolises a drug, these alterations in gene expression must be taken into account. The central process, the definition of likely regulatory elements in the genes coding for enzymes and transporters involved in drug disposition, can be vastly accelerated using existing and emerging bioinformatics methods to unravel the regulatory networks causing drug-mediated induction of genes. Here, various approaches to predict transcription factor interactions with regulatory DNA elements are reviewed.

Algorithms↗
PubMed2006

Antiplatelet drug resistance and drug-drug interactions: Role of cytochrome P450 3A4.

Antiplatelet therapy provided pivotal advances in the treatment of cardiovascular disease. Aspirin and thienopyridine, clopidogrel, is currently the treatment of choice in acute coronary syndromes and the prevention of thrombosis after coronary stent implantation. Despite the efficacy of this dual antiplatelet therapy in reduction of adverse coronary events in patients with acute coronary syndromes, complications persist in a subgroup of these patients. Emerging causes of aspirin and clopidogrel resistance may translate to increase risk for recurrent myocardial infarction, stroke, or cardiac related mortality. However, the mechanism of antiplatelet drug resistance remains incompletely characterized, and a sensitive and specific assay of aspirin and clopidogrel effect that reliably predicts treatment failure has not emerged. To date, evidence supporting antiplatelet drug resistance are pharmacokinetic response variability, drug-drug interaction through competitive inhibition a specific enzymatic pathway, genetic variability, and variability in the induction of enzymatic pathway in metabolic activation of prodrugs, like clopidogrel. Further investigation or guidelines are needed to optimize antiplatelet treatment strategies to identify and treat patients resistant to aspirin and/or clopidogrel.

Animals↗
PubMed2002

Drugs, leads, and drug-likeness: an analysis of some recently launched drugs.

An analysis of the origins of recently launched drugs reveals that most were derived by modification of known drug structures or from lead structures obtained from the scientific literature. High-throughput screening did not have a significant impact on the derivation of these drugs. The drug structures are very closely related to their leads.

Drug Design↗
PubMed1995

Drug testing in the workplace: could a positive test for one of the mandated drugs be for reasons other than illicit use of the drug?

This manuscript reviews data available in the scientific literature relative to drug testing for the five mandated drug classes and circumstances other than abuse of the drug itself that could result in a positive test. For marijuana, passive inhalation, unknowing oral ingestion, and the use of Marinol are discussed. Data are presented on the concentration of delta9-tetrahydrocannabinol (THC) and its precursors, acid-A and acid-B, in illicit marijuana and the extent of extraction of THC in boiled (tea) or cooked products. For cocaine, passive inhalation and passive exposure issues are reviewed. For opiates, poppy seed ingestion and guidelines for exclusion of poppy seeds as a cause for a positive test are discussed. For amphetamines, issues such as the presence of other phenethylamines, l-methamphetamine (Vicks' inhalers), and other prescription drugs are discussed. Although passive inhalation of methamphetamine and phencyclidine is theoretically possible, no data were available on these issues.

Amphetamines↗