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At least 19 recordsLinked to original sources

PubMed1986

Drug discrimination procedures: differential characteristics of the drug A vs drug B and the drug A vs drug B vs no drug cases.

Two groups of pigeons with a history of two choice operant drug discrimination tasks (3.0 mg/kg morphine versus 5.6 mg/kg cocaine, and 3.0 mg/kg morphine versus 3.0 mg/kg cocaine, respectively; Swedberg and Järbe 1985) were subjected to three choice tasks in which responses on a third manipulandum were reinforced in the no drug condition. Training drugs generalization gradients in both groups were similar to those normally obtained in two choice drug versus no drug tasks. The salience differences between the training stimuli within the groups observed in the previous two choice task did not differentially affect the three choice discrimination gradients. Tests with novel drugs after the introduction of the no drug condition yielded increased responding to the no drug condition with the exception of the dopamine agonist apomorphine. Results are discussed in terms of a discrimination learning model specifying principles of relative discriminative stimulus control in various discrimination cases.

Animals↗

PubMed2002

Herb-drug, food-drug, nutrient-drug, and drug-drug interactions: mechanisms involved and their medical implications.

Adverse drug reactions (ADRs) and iatrogenic diseases have been identified as significant factors responsible for patient morbidity and mortality. Significant studies on drug metabolism in humans have been published during the last few years, offering a deeper comprehension of the mechanisms underlying adverse drug reactions and interactions. More understanding of these mechanisms, and of recent advances in laboratory technology, can help to evaluate potential drug interactions when drugs are prescribed concurrently. Increasing knowledge of interindividual variation in drug breakdown capacity and recent findings concerning the influence of environment, diet, nutrients, and herbal products can be used to reduce ADRs and iatrogenic diseases. Reviewed data suggest that drug treatment should be increasingly custom tailored to suit the individual patient and that appropriately co-prescribed diet and herbal remedies, could increase drug efficacy and lessen drug toxicity. This review focuses mainly on recently published research material. The cytochrome p450 enzymes, their role in metabolism, and their mechanisms of action are reviewed, and their role in drug-drug interactions are discussed. Drug-food and drug-herb interactions have garnered attention. Interdisciplinary communication among medical herbalists, medical doctors, and dietetic experts needs to be improved and encouraged. Internet resources for obtaining current information regarding drug-drug, drug-herb, and drug-nutrient interactions are provided.

Adverse Drug Reaction Reporting Systems↗

PubMed1985

Continuous five-drug versus alternating three-drug and two-drug chemotherapy after five-drug or three-drug induction in extensive small cell lung cancer.

Fifty-six patients with extensive small cell lung cancer were treated with vincristine, doxorubicin, cisplatin, etoposide, and cyclophosphamide in a prospective randomized trial using all five drugs together or as three-drug (cisplatin, etoposide, cyclophosphamide) and two-drug (doxorubicin, vincristine) combinations given sequentially, then alternatively. The five-drug combination was associated with a higher overall regression rate (p = 0.03), higher complete regression rate (p = 0.09), prolonged time to first progression (p = 0.03), more nervous system initial failures (p = 0.07), more anemia requiring transfusion (p = 0.04), but no prolongation of overall survival (median 332 days for five-drug, median 303 days for three-drug and two-drug). Until more and better chemotherapeutic agents become available, little or no advantage is likely to be gained for patients with small cell lung cancer given sequential, or alternating chemotherapy.

Adult↗

PubMed2000

Short-term low-dose corticosteroids vs placebo and nonsteroidal antiinflammatory drugs in rheumatoid arthritis.

BACKGROUND: The effect of low dose corticosteroids, equivalent to 15 mg prednisolone daily or less, in patients with rheumatoid arthritis has been questioned. We therefore performed a systematic review of trials which compared corticosteroids with placebo or non-steroidal, anti-inflammatory drugs. OBJECTIVES: To determine whether short-term (i.e. as recorded within the first month of therapy), oral low-dose corticosteroids (corresponding to a maximum of 15 mg prednisolone daily) is superior to placebo and nonsteroidal, antiinflammatory drugs in patients with rheumatoid arthritis. SEARCH STRATEGY: Medline Silverplatter, The Cochrane Controlled Trials Register, reference lists and a personal archive. SELECTION CRITERIA: All randomised studies comparing an oral corticosteroid (not exceeding an equivalent of 15 mg prednisolone daily) with placebo or a nonsteroidal, antiinflammatory drug were eligible if they reported clinical outcomes within one month after start of therapy. DATA COLLECTION AND ANALYSIS: Decisions on which trials to include were made independently by two observers based on the methods sections of the trials only. Standardised effect measures were used for the statistical analyses; the random effects model was used if P<0.10 for the test of heterogeneity. MAIN RESULTS: Ten studies, involving 320 patients, were included in the meta-analysis. Prednisolone had a marked effect over placebo on joint tenderness (standardised effect size 1.31, 95% confidence interval 0.78 to 1.83), pain (standardised effect size 1.75, 0.87 to 2.64) and grip strength (standardised effect size 0.41, 0.13 to 0.69). Measured in the original units, the differences were 12 tender joints (6 to 18) and 22 mm Hg (5 to 40) for grip strength. Prednisolone also had a greater effect than nonsteroidal, antiinflammatory drugs on joint tenderness (standardised effect size 0.63, 0.11 to 1.16) and pain (standardised effect size 1.25, 0.26 to 2.24), whereas the difference in grip strength was not significant (standardised effect size 0.31, -0.02 to 0.64). Measured in the original units, the differences were 9 tender joints (5 to 12) and 12 mm Hg (-6 to 31). The risk of adverse effects, also during moderate- and long-term use, seemed acceptable. REVIEWER'S CONCLUSIONS: Prednisolone in low doses (not exceeding 15 mg daily) may be used intermittently in patients with rheumatoid arthritis, particularly if the disease cannot be controlled by other means. Since prednisolone is highly effective, short-term placebo controlled trials studying the clinical effect of low-dose prednisolone or other oral corticosteroids are no longer necessary.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2000

Detecting drug-drug interactions using a database for spontaneous adverse drug reactions: an example with diuretics and non-steroidal anti-inflammatory drugs.

OBJECTIVE: Drug-drug interactions are relatively rarely reported to spontaneous reporting systems (SRSs) for adverse drug reactions. For this reason, the traditional approach for analysing SRS has major limitations for the detection of drug-drug interactions. We developed a method that may enable signalling of these possible interactions, which are often not explicitly reported, utilising reports of adverse drug reactions in data sets of SRS. As an example, the influence of concomitant use of diuretics and non-steroidal anti-inflammatory drugs (NSAIDs) on symptoms indicating a decreased efficacy of diuretics was examined using reports received by the Netherlands Pharmacovigilance Foundation Lareb. METHODS: Reports received between 1 January 1990 and 1 January 1999 of patients older than 50 years were included in the study. Cases were defined as reports with symptoms indicating a decreased efficacy of diuretics, non-cases as all other reports. Exposure categories were the use of NSAIDs or diuretics versus the use of neither of these drugs. The influence of the combined use of both drugs was examined using logistic regression analysis. RESULTS: The odds ratio of the statistical interaction term of the combined use of both drugs was increased [adjusted odds ratio 2.0, 95% confidence interval (CI) 1.1-3.7], which may indicate an enhanced effect of concomitant drug use. CONCLUSION: The findings illustrate that spontaneous reporting systems have a potential for signal detection and the analysis of possible drug-drug interactions. The method described may enable a more active approach in the detection of drug-drug interactions after marketing.

Adverse Drug Reaction Reporting Systems↗

PubMed2002

Evaluation of drug interactions with P-glycoprotein in drug discovery: in vitro assessment of the potential for drug-drug interactions with P-glycoprotein.

The pharmacological effects of a drug are highly dependent on the absorption, metabolism, elimination, and distribution of the drug. In the past few years it has become apparent that transport proteins play a major role in regulating the distribution, elimination and metabolism of some drugs. As a consequence of our new understanding of the influence of transport proteins on the pharmacokinetic and pharmacodynamic behavior of drugs, increasing attention has been focused on the potential for drug-drug interactions arising from interactions with drug transport proteins. The efflux transporter P-glycoprotein (P-gp) has received the most attention with regard to its role in restricting drug absorption and distribution and as a potential source for variability in drug pharmacokinetics and pharmacodynamics. This review will focus on the evaluation of drug candidates to assess the potential for drug interactions at the level of P-gp. We will discuss the role of P-gp in drug disposition, the biochemistry of P-gp efflux as it relates to model systems to study drug interactions with P-gp, and the implementation of P-gp assay models within the drug discovery process.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1990

Increased drug sensitivity in the drug discrimination procedure afforded by drug versus drug training.

Rats were trained to discriminate norfenfluramine (NF) 1.4 mg/kg from its vehicle or amphetamine (AMPH) 0.8 mg/kg or pentobarbital (PB) 6.0 mg/kg in order to determine the role that drug combination training plays in the rate of learning and sensitivity to lower drug doses. The results suggest that drug versus drug training can increase the rate of drug discrimination learning for some drugs that are learned slowly when trained in a drug versus vehicle training procedure, whereas drug versus drug training does not increase the rate of learning for other drugs that are learned rapidly. Drug versus drug training does, however, appear to increase the level of stimulus control of the training drug for all drugs examined in this study.

Amphetamine↗

PubMed2004

Drug-drug, drug-dietary supplement, and drug-citrus fruit and other food interactions: what have we learned?

Serious drug-drug interactions have contributed to recent U.S. market withdrawals and also recent nonapprovals of a few new molecular entities. Many of these interactions involved the inhibition or induction of metabolizing enzymes and efflux transporters, resulting in altered systemic exposure and adverse drug reactions or loss of efficacy. In addition to drug-drug interactions, drug-dietary supplement and drug-citrus fruit interactions, among others, could also cause adverse drug reactions or loss of efficacy and are important issues to consider in the evaluation of new drug candidates. This commentary reviews (1). the current understanding of the mechanistic basis of these interactions, (2). issues to consider in the interpretation of study results, and (3). recent labeling examples to illustrate the translation of study results to information useful for patients and health care providers.

Beverages↗

PubMed2006

Drug-drug interactions of anti-infective drugs: utility of fluorescence cyp inhibition assays in drug discovery.

Drug interactions are often a result of induction or inhibition of cytochrome P450 (CYP) enzymes by co-administered drugs. A high throughput fluorescence assay using cDNA-expressed human CYP isozymes and fluorogenic substrates has been reported for the study of CYP inhibition. We used this assay to evaluate CYP inhibition profiles of 21 marketed anti-infective drugs. We found that six of the eight potent inhibitors identified in this screen (IC50 <10 microM against at least one CYP isozyme) correlated with significant drug-drug interactions in the clinic. In contrast, the intermediate and weak inhibitors (IC50 >10 microM) did not indicate clinically significant drug interactions. Furthermore, we observed that results obtained in the fluorescence assay correlated with conventional, well-established, low throughput methods that utilize human liver microsomes. These data suggest that in the early stages of drug discovery, the fluorescence assay for CYP inhibition could be used in conjunction with a human liver microsomal assay to identify new chemical entities with a potential for drug-drug interactions.

Anti-Infective Agents↗

PubMed2003

A human drug metabolism database: potential roles in the quantitative predictions of drug metabolism and metabolism-related drug-drug interactions.

Previous attempts to predict drug metabolism and drug-drug interaction possibilities by deploying databases that house established drug metabolism results have been only marginally successful. Consideration of some of the key issues and concerns derived from these efforts suggests that three major hurdles loom in front of using xenobiotic metabolism databases more effectively in the future. These hurdles include: the need for an improved treatment of chemical structure in three-dimensions (3D); a better quantitative accounting of competitive and complementary biotransformation pathways; and, the critical need for a comprehensive, human drug metabolism database (hDMdb) that can serve as a bio/chemoinformatic resource pertaining to drug metabolism and drug metabolism-related drug-drug interactions in general. Approaches that might be taken to traverse each of these hurdles are discussed herein where: the first involves maturation of chemical structures from simple 2D entries into more sophisticated 3D displays that can also account for interactions with relevant biological surfaces; the second involves a systematic, pair-wise comparison of various metabolic options in a statistically driven manner relative to chemical structure descriptors; and, the third involves mounting a hDMdb on the Internet in a user-friendly manner that it is available via a non-profit format.

Databases, Factual↗

PubMed2005

Therapeutic drug monitoring and drug-drug interactions involving antiretroviral drugs.

The consensus of current international guidelines for the treatment of HIV infection is that data on therapeutic drug monitoring (TDM) of non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (Pls) provide a framework for the implementation of TDM in certain defined scenarios in clinical practice. However, the utility of TDM is considered to be on an individual basis until more data are obtained from large clinical trials showing the benefit of TDM. In April 2004, a panel of experts met for the second time in Rome, Italy. This was following the inaugural meeting in Perugia, Italy, in October 2000, which resulted in the manuscript published in AIDS 2002, 16(Suppl 1):S5-S37. The objectives of this second meeting were to review and update the numerous questions surrounding TDM of antiretroviral drugs and discuss the clinical utility, current concerns and future prospects of drug concentration monitoring in the care of HIV-1-infected individuals. A major focus of the meeting was to discuss and critically analyse recent and precedent clinical drug-drug interaction data to provide a clear framework of the pharmacological basis of how one drug may impact the disposition of another. This report, which has been updated to include material published or presented at international conferences up to the end of December 2004, reviews recent pivotal pharmacokinetic interaction data and provides advice to clinical care providers on how some drug-drug interactions may be prevented, avoided or managed, and, when data are available, on what dose adjustments and interventions should be performed.

Anti-HIV Agents↗

PubMed1994

A novel skeletal drug delivery system using a self-setting calcium phosphate cement. 5. Drug release behavior from a heterogeneous drug-loaded cement containing an anticancer drug.

A novel drug delivery device based on a self-setting bioactive calcium phosphate cement formed from tetracalcium phosphate and dicalcium phosphate has been developed and tested in vitro using the anticancer agent 6-mercaptopurine (6-MP) as a model compound. X-ray diffraction results suggest that equimolar mixtures of the calcium phosphate salts were transformed into hydroxyapatite after being mixed with a dilute phosphoric acid solution, even in the presence of various amounts of 6-MP powder. The inclusion of 6-MP in the reaction mixture resulted in the formation of a homogeneous drug-containing cement. Alternatively, the drug was loaded after cement formation to produce a heterogeneous drug-containing pellet. In vitro drug release from both the homogeneous and heterogeneous drug-loaded cement pellets into simulated body fluid (pH 7.25, 37.0 degrees C) was measured using the rotating-disk method. Release from the homogeneous 5% drug-loaded cements did not obey the Higuchi equation. The release rate from the heterogeneous drug-loaded cements of different thicknesses (1, 2, and 3 mm) was a function of thickness, indicating that release kinetics could be controlled by the design of the cement formulation.

Antineoplastic Agents↗

PubMed1986

Drug-drug and drug-disease interactions with nonsteroidal anti-inflammatory drugs.

Nonsteroidal anti-inflammatory drugs may cause a number of drug interactions. They can displace other drugs from serum proteins, and some can affect the metabolism or decrease the renal elimination of other drugs. In addition, they can attenuate the pharmacologic effect of other drugs, such as diuretic and antihypertensive agents, without affecting their disposition. Lastly, many disease states and aging can affect the handling of nonsteroidal anti-inflammatory drugs, mandating dose adjustment of some of these agents in certain clinical conditions. Some drugs may require more of these adjustments than others.

Aging↗

PubMed1992

The method of relative drug accumulation: a simple method for illustrating the effects of different drug dosing regimens and variability in drug elimination on time courses of drug concentrations.

A simple method is presented for graphically illustrating time courses of relative drug concentrations and accumulation during multiple dosing. This method is based on the drug amount ratio and requires knowledge of only the elimination half-life and the dosing interval. It involves the use of relative drug concentrations, where a concentration of unity is assigned to the time-averaged concentration at steady state in a reference subject for the dosing regimen(s) being evaluated. Examples of application of the method of relative drug accumulation involve simulations of the effects of different multiple-dose regimens and variability in drug elimination on time courses of drug concentrations and drug accumulation.

Computer Simulation↗

PubMed1976

[Cutaneous side effects of systemic drugs. Part 4 of a synopsis. 6/7. Drugs affecting the central nervous system. C. Drug-induced photosensitivity. D. Drug-induced changes of skin color].

This, the fourth part of a synopisis of cutaneous side effects of drugs, covers the drugs affecting the central nervous system: antiepileptics, hypnotics, narcotics and psychopharmaceutics; the myorelaxants and antiallergics follow, and lastly there is a section on drug addiction and placebo. The various cutaneous side effects are listed in chart form referring to more than 500 sources. A drug index is attached for handy reference. The reviews of certain drug induced skin disorders are continued with tables covering photosensitivity and changes in skin colour. Phototoxicity, photoallergy and light sensitivity by porphyria are differentiated. The various pigmentation disorders, colour changes due to metal deposits as well as different localisations are included.

Anticonvulsants↗

PubMedDate not supplied

Identification of serious drug-drug interactions: results of the partnership to prevent drug-drug interactions.

OBJECTIVE: To develop a list of clinically important drug-drug interactions (DDIs) likely to be encountered in community and ambulatory pharmacy settings and detected by a computerized pharmacy system. DESIGN: Cross-sectional, one-time evaluation. SETTING: United States in fall 2001. PARTICIPANTS: An expert panel comprising two physicians, two clinical pharmacists, and an expert on DDIs. INTERVENTIONS: Systematic review of drug interaction compendia and published literature, ratings (on a 1 to 10 scale) of various clinical aspects of DDIs (e.g., clinical importance, quality and quantity of evidence, causal relationship, risk of morbidity and mortality), and a modified Delphi consensus-building process. MAIN OUTCOME MEASURE: Panelists' opinions about clinical importance of DDIs. RESULTS: The expert panel considered 56 DDIs. Of these, 28 had a mean clinical importance score of 8.0 or more. The ratings for clinical importance ranged from 3.2 to 9.6, with a mean +/- SD of 7.5 +/- 1.5 across the combinations examined. The mean score for the quality of literature suggesting the interaction exists ranged from 1.0 to 9.6, with a mean +/- SD of 5.8 +/- 2.5. In terms of substantiation of the interactions evaluated, the mean +/- SD rating was 6.3 +/- 2.2, with a range from 1.4 to 9.2. Through the modified Delphi process, the panel determined that 25 interactions were clinically important. CONCLUSION: Using an expert panel and a standard evaluation tool, 25 clinically important drug interactions that are likely to occur in the community and ambulatory pharmacy settings were identified. Pharmacists should take steps to prevent patients from receiving these interacting medications, and computer software vendors should focus interaction alerts on these and similarly important DDIs.

Community Pharmacy Services↗

PubMed2006

Prediction of in vivo drug-drug interactions from in vitro data : factors affecting prototypic drug-drug interactions involving CYP2C9, CYP2D6 and CYP3A4.

BACKGROUND: Quantitative predictions of in vivo drug-drug interactions (DDIs) resulting from metabolic inhibition are commonly made based upon the inhibitor concentration at the enzyme active site [I] and the in vitro inhibition constant (K(i)). Previous studies have involved the use of various plasma inhibitor concentrations as surrogates for [I] along with K(i) values obtained from published literature. Although this approach has resulted in a high proportion of successful predictions, a number of falsely predicted interactions are also observed. OBJECTIVES: To focus on three issues that may influence the predictive value of the [I]/K(i) ratio approach: (i) the use of unbound K(i) (K(i,u)) values generated from standardised in vitro experiments compared with literature values; (ii) the selection of an appropriate [I]; and (iii) incorporation of the impact of intestinal metabolic inhibition for cytochrome P450 (CYP) 3A4 predictions. To this end we have selected eight inhibitors of CYP2C9, CYP2D6 and CYP3A4 and 18 victim drugs from a previous database analysis to allow prediction of 45 clinical DDI studies. METHODS: In vitro kinetic and inhibition studies were performed in human liver microsomes using prototypic probe substrates of CYP2C9 and CYP2D6, with various inhibitors (miconazole, sulfaphenazole, fluconazole, ketoconazole, quinidine, fluoxetine, fluvoxamine). The K(i) estimates obtained were corrected for non-specific microsomal binding, and the K(i,u) was incorporated into in vivo predictions using various [I] values. Predictions for CYP3A4 were based upon in vitro data obtained from a previous publication within our laboratory, and an assessment of the impact of the interaction in the gut wall is included. Predictions were validated against 45 in vivo studies and those within 2-fold of the in vivo ratio of area under the plasma concentration-time curve of the substrate, in the presence and absence of the inhibitor (AUC(i)/AUC) were considered successful. RESULTS: Predictions based upon the average systemic total plasma drug concentration ([I](av)) [incorporating the effects of parallel drug elimination pathways] and the K(i,u) value resulted in 91% of studies predicted to within 2-fold of the in vivo AUC(i)/AUC. This represents a 35% improvement in prediction accuracy compared with predictions based upon total K(i) values obtained from various published literature sources. A corresponding reduction in bias and an increase in precision were also observed compared with the use of other [I] surrogates (e.g. the total and new unbound maximum hepatic input plasma concentrations). No significant improvement in prediction accuracy was observed by incorporating consideration of gut wall inhibition for CYP3A4. CONCLUSION: DDI predictions based upon the use of K(i,u) data obtained under a set of optimal standardised conditions were significantly improved compared with predictions using in vitro data collated from various sources. The use of [I](av) as the [I] surrogate generated the most successful predictions as judged by several criteria. Incorporation of either plasma protein binding of inhibitor or gut wall CYP3A4 inhibition did not result in a general improvement of DDI predictions.

Algorithms↗

PubMed2002

Safety evaluation and drug development based on biological fate of drugs -efforts made to overcome drug interaction in drug development-.

1. Assay methods to detect drug interaction in toxicological samples were established by determining cytochrome P450 content and its activity in liver samples. The O-dealkylation reaction of 7-alkoxycoumarin was indicated to reflect changes in the molecular forms of P450s, and the enzyme induction or inhibition in the toxicological samples was easily detected by using the established methods. 2. During toxicological studies of 450191-S or the sleep inducer rilmazafone, a phenobarbital type-induction of hepatic drug metabolizing enzymes was observed in animals, and the doses required for the induction differed markedly between rats and dogs. Enzyme induction was caused by some specific metabolites of 450191-S, and the plasma concentrations of these metabolites were comparable when the enzyme induction was developed in both animals. 3. A nonsteroidal antiinflammatory compound 480156-S showed a slight or no effect on microsomal drug metabolizing activity in rats. On the other hand, repeated administration of this compound to humans resulted in a marked decrease in the oxidative metabolism of 480156-S, followed by a marked increase in the plasma concentrations of the compound. When volunteers were given 480156-S followed by several drugs, such as tolubutamide, the plasma clearance was delayed remarkably, indicating a severe drug interaction. 4. Cytochrome P450 belonging to the CYP2C family was indicated to participate in the oxidative metabolism of 480156-S in both rat and human liver microsomes. The preincubation of microsomes with 480156-S caused a concentration-dependent inhibition of CYP2C-dependent tolubutamide hydroxylation reaction in both rats and humans. There was a marked species difference in the susceptibility to the inhibitory effect of 480156-S, and the concentration required to inhibit rat CYP2C was almost 10 times higher than that required in humans. 5. The cephem antibiotics having N-methyltetrazolethiol (NMTT) at the 3'-position substituent were demonstrated to inhibit mitochondrial low K(m) aldehyde dehydrogenase (ALDH), and produced disulfiram-like (Antabuse) reaction during alcohol metabolism. Pharmacokinetic studies indicated that NMTT released from the antibiotics in bile duct or intestine cause the inhibitory action followed by the development of disulfiram-like reaction. 6. Attempts had been made to develop new cephem antibiotics lacking the disulfiram-like reaction by changing the chemical structure of 3'-position substituents, and a hydroxyethyltetrazolethiol was found not to inhibit the enzyme. Based on this result, together with the antibacterial activity, we have developed a new oxacephem antibiotic flomoxef (6315-S). Flomoxef showed no disulfiram-like reaction both in rats and human.

Journal Article↗