Tyrosine kinase-targeting drugs-associated heart failure.

BACKGROUND: The impact of cancer therapies on cardiac disease in the general adult cancer survivor population is largely unknown. Our objective was to evaluate which tyrosine kinase-targeting drugs are associated with greater risk for new-onset heart failure (HF). METHODS: A nested case-control analysis was conducted within a cohort of 27 992 patients of Clalit Health Services, newly treated with a tyrosine kinase-targeting, and/or chemotherapeutic drug, for a malignant disease, between 1 January 2005 and 31 December 2012. Each new case of HF was matched to up to 30 controls from the cohort on calendar year of cohort entry, age, gender, and duration of follow-up. Main outcome measure was odds ratio (OR) with 95% confidence interval (CI) of new-onset HF. RESULTS: There were 936 incident cases of HF during 71 742 person-years of follow-up. Trastuzumab (OR 1.90, 95% CI 1.46-2.49), cetuximab (OR 1.72, 1.10-2.69), panitumumab (OR 3.01, 1.02-8.85), and sunitinib (OR 3.39, 1.78-6.47) were associated with increased HF risk. Comorbidity independently associated with higher risk in a multivariable conditional regression model was diabetes mellitus, hypertension, chronic renal failure, ischaemic heart disease, valvular heart disease, arrhythmia, and smoking. CONCLUSIONS: Trastuzumab, cetuximab, panitumumab, and sunitinib are associated with increased risk for new-onset HF.

GPS for QSP: A Summary of the ACoP6 Symposium on Quantitative Systems Pharmacology and a Stage for Near-Term Efforts in the Field.

Quantitative Systems Pharmacology (QSP) is experiencing increased application in the drug discovery and development process. Like its older sibling, systems biology, the QSP field is comprised of a mix of established disciplines and methods, from molecular biology to engineering to pharmacometrics. As a result, there exist critical segments of the discipline that differ dramatically in approach and a need to bring these groups together toward a common goal.

Systematic and quantitative assessment of the effect of chronic kidney disease on CYP2D6 and CYP3A4/5.

Recent reviews suggest that chronic kidney disease (CKD) can affect the pharmacokinetics of nonrenally eliminated drugs, but the impact of CKD on individual elimination pathways has not been systematically evaluated. In this study we developed a comprehensive dataset of the effect of CKD on the pharmacokinetics of CYP2D6- and CYP3A4/5-metabolized drugs. Drugs for evaluation were selected based on clinical drug-drug interaction (CYP3A4/5 and CYP2D6) and pharmacogenetic (CYP2D6) studies. Information from dedicated CKD studies was available for 13 and 18 of the CYP2D6 and CYP3A4/5 model drugs, respectively. Analysis of these data suggested that CYP2D6-mediated clearance is generally decreased in parallel with the severity of CKD. There was no apparent relationship between the severity of CKD and CYP3A4/5-mediated clearance. The observed elimination-route dependency in CKD effects between CYP2D6 and CYP3A4/5 may inform the need to conduct clinical CKD studies with nonrenally eliminated drugs for optimal use of drugs in patients with CKD.

Application of systems pharmacology to explore mechanisms of hepatotoxicity.

Advances in systems biology have allowed the development of a highly characterized systems pharmacology model to study mechanisms of drug-induced hepatotoxicity. In this issue of CPT, Yang et al. describe a model, DILIsym, used to characterize mechanisms of hepatotoxicity of troglitazone. Their modeling approach has provided new insight into troglitazone-induced hepatotoxicity in humans but is not associated with hepatotoxicity in rats, consistent with preclinical data for this drug.

Use of internet search logs to evaluate potential drug adverse events.

Internet search logs provide an abundant source of data that can be explored for purposes such as identifying drug exposure-adverse event relationships. The methodology to rigorously conduct such evaluations is not well characterized, and the utility of such analyses is not well defined. In this issue, White and colleagues propose an approach using Internet search logs for this purpose and compare it to parallel analyses conducted using the US Food and Drug Administration's spontaneous reporting database.

Needs for an expanded ontology-based classification of adverse drug reactions and related mechanisms.

The growing significance of bioinformatics and systems biology in drug safety research requires a system of adverse-event classification that goes beyond a simple vocabulary. This opinion piece outlines the need for development of an ontology-based framework of describing adverse drug reactions (ADRs) and describes the potential applications for such a framework.

High-risk prescribing and incidence of frailty among older community-dwelling men.

Evidence about the association between treatment with high-risk medicines and frailty in older individuals is limited. We investigated the relationship between high-risk prescribing and frailty at baseline, as well as 2-year incident frailty, in 1,662 men ≥70 years of age. High-risk prescribing was defined as polypharmacy (≥5 medicines), hyperpolypharmacy (≥10 medicines), and by the Drug Burden Index (DBI), a dose-normalized measure of anticholinergic and sedative medicines. At baseline, frail participants had adjusted odds ratios (ORs) of 2.55 (95% confidence interval, CI: 1.69-3.84) for polypharmacy, 5.80 (95% CI: 2.90-11.61) for hyperpolypharmacy, and 2.33 (95% CI: 1.58-3.45) for DBI exposure, as compared with robust participants. Of the 1,242 men who were robust at baseline, 6.2% developed frailty over two years. Adjusted ORs of incident frailty were 2.45 (95% CI: 1.42-4.23) for polypharmacy, 2.50 (95% CI: 0.76-8.26) for hyperpolypharmacy, and 2.14 (95% CI: 1.25-3.64) for DBI exposure. High-risk prescribing may contribute to frailty in community-dwelling older men.

Integration of diverse data sources for prediction of adverse drug events.

The rapid evolution of large biological, pharmacological, and chemical databases has led to optimism that such data resources can be leveraged for prediction of drug action based on molecular descriptors of the drug. Challenges to realize this possibility include organization of each type of database in a manner that allows extraction of information across disparate data sources and the linkage of information across the biological, pharmacological, and chemical domains.

Pharmacological mechanism-based drug safety assessment and prediction.

Advances in cheminformatics, bioinformatics, and pharmacology in the context of biological systems are now at a point that these tools can be applied to mechanism-based drug safety assessment and prediction. The development of such predictive tools at the US Food and Drug Administration (FDA) will complement ongoing efforts in drug safety that are focused on spontaneous adverse event reporting and active surveillance to monitor drug safety. This effort will require the active collaboration of scientists in the pharmaceutical industry, academe, and the National Institutes of Health, as well as those at the FDA, to reach its full potential. Here, we describe the approaches and goals for the mechanism-based drug safety assessment and prediction program.

Pediatric dose selection.

Selection of a drug dose in pediatrics is generally based on no or incomplete pharmacokinetic data. Traditionally, allometric, or scaling, techniques have been used; however, they have inherent limitations and may not make optimal use of the drug-specific clinical pharmacokinetic information that is available. Modeling is a tool that holds promise. The future challenge is to create a structured approach to determining pediatric doses for new therapeutic agents.

Serum protein signatures detect early radiographic osteoarthritis.

OBJECTIVE: To test the hypothesis that early knee and hand osteoarthritis (OA) development is characterized by detectable changes in serum proteins relevant to inflammation, cell growth, activation, and metabolism several years before OA becomes radiographically evident. METHODS: Using microarray platforms that simultaneously test 169 proteins relevant to inflammation, cell growth, activation and metabolism, we conducted a case-control study nested within the Baltimore Longitudinal Study of Aging (BLSA). Subjects included 22 incident cases of OA and 66 age-, sex- and body mass index (BMI)-matched controls. Serum samples tested were obtained at the time of radiographic classification as either case or control, and up to 10 years earlier at a time when all participants were free of radiographic OA. Proteins with mean signal intensities fourfold higher than background were compared between cases and controls using multivariate techniques. RESULTS: Sixteen proteins were different between OA cases compared to controls. Four of these proteins [matrix metalloproteinase (MMP)-7, interleukin (IL)-15, plasminogen activator inhibitor (PAI)-1 and soluble vascular adhesion protein (sVAP)-1] were already different in samples obtained 10 years before radiographic classification and remained different at the time of diagnosis. Six additional proteins were only associated with subsequent OA development and not with established OA. CONCLUSIONS: Changes in serum proteins implicated in matrix degradation, cell activation, inflammation and bone collagen degradation products accompany early OA development and can precede radiographic detection by several years.

Finding the right research question: quality science depends on quality careers.

When making the transition from trainee to principal investigator, there are few steps more important than selecting the first independent research project. The project must synthesize the excitement and idealism of contributing to the well-being of humankind and the practical realities of an area of inquiry that is likely to lead to a successful career.

Physical and cognitive performance and burden of anticholinergics, sedatives, and ACE inhibitors in older women.

Polypharmacy, common in older people, confers both risk of adverse outcomes and benefits. We assessed the relationship of commonly prescribed medications with anticholinergic and sedative effects to physical and cognitive performance in older individuals. The study population comprised 932 moderately to severely disabled community-resident women aged 65 years or older who were participants in the Women's Health and Aging Study I. A scale based on pharmacodynamic principles was developed and utilized as a measure of drug burden. This was related to measures of physical and cognitive function. After adjusting for demographics and comorbidities, anticholinergic drug burden was independently associated with greater difficulty in four physical function domains with adjusted odds ratios (95% confidence interval (CI)) of 4.9 (2.0-12.0) for balance difficulty; 3.2 (1.5-6.9) for mobility difficulty; 3.6 (1.6-8.0) for slow gait; 4.2 (2.0-8.7) for chair stands difficulty; 2.4 (1.1-5.3) for weak grip strength; 2.7 (1.3-5.4) for upper extremity limitations; 3.4 (1.7-6.9) for difficulty in activities of daily living; and 2.4 (95% CI, 1.1-5.1) for poor performance on the Mini-Mental State Examination. Sedative burden was associated only with impaired grip strength (3.3 (1.5-7.3)) and mobility difficulty (2.4 (1.1-5.3)). The burden of multiple drugs can be quantified by incorporating the recommended dose regimen and the actual dose and frequency of drug taken. Anticholinergic drug burden is strongly associated with limitations in physical and cognitive function. Sedative burden is associated with impaired functioning in more limited domains. The risk associated with exposure of vulnerable older women to drugs with anticholinergic properties, and to a lesser extent those with sedative properties, implies that such drugs should not be used in this patient group without compelling clinical indication.

Electromyographic patterns suggest changes in motor unit physiology associated with early osteoarthritis of the knee.

OBJECTIVE: To assess characteristics of active motor units (MUs) during volitional vastus medialis (VM) activation in adults with symptomatic knee osteoarthritis (OA) across the spectrum of radiographic severity and age-comparable healthy control volunteers. METHODS: We evaluated 39 participants (age 65+/-3 years) in whom weight-bearing knee X-rays were assigned a Kellgren & Lawrence (KL) grade (18 with KL grade=0; four each with KL grades=1, 2 and 4; nine with grade 3). Electromyography (EMG) signals were simultaneously acquired using surface [surface EMG (S-EMG)] and intramuscular needle electrodes, and analyzed by decomposition-enhanced spike-triggered averaging to obtain estimates of size [surface-represented MU action potentials (S-MUAP) area], number [MU recruitment index (MURI)] and firing rates [MU firing rates (mFR)] of active MUs at 10%, 20%, 30% and 50% effort relative to maximum voluntary force [maximal voluntary isometric contraction (MVIC)] during isometric knee extension. RESULTS: Knee extensor MVIC was lower in OA participants, especially at higher KL grades (P=0.05). Taking the observed force differences into account, OA was also associated with activation of larger MUs (S-MUAP area/MVICx%effort; P<0.0001). In contrast, the estimated number of active units (MURI/MVICx%effort) changed differently as effort increased from 10% to 50% and was higher with advanced OA (KL=3, 4) than controls (P=0.0002). CONCLUSION: VM activation changes at the level of the MU with symptomatic knee OA, and this change is influenced by radiographic severity. Poor muscle quality may explain the pattern observed with higher KL grades, but alternative factors (e.g., nerve or joint injury, physical inactivity or muscle composition changes) should be examined in early OA.

Stereoselective halofantrine disposition and effect: concentration-related QTc prolongation.

AIMS: 1) To characterize the variability of multiple-dose halofantrine pharmacokinetics over time in healthy adults, 2) to correlate the pharmacodynamic measure electrocardiographic (ECG) QT interval with (+)- and (-)-halofantrine plasma concentration and 3) to evaluate the safety and tolerance of halofantrine hydrochloride given over time to healthy adults. METHODS: Twenty-one healthy subjects were enrolled and 13 completed the study (180 days). Subjects received either 500 mg of racemic halofantrine once daily in the fasted state for 42 days, or placebo, and then halofantrine washout was documented for the following 138 days. Pharmacokinetic and pharmacodynamic (ECG QTc) measurements were obtained. RESULTS: Mean accumulation half-times (days) for halofantrine were: 7.0 +/- 4.8 [(+)-halofantrine] and 7.3 +/- 4.8 [(-)-halofantrine]. Mean steady-state concentrations were: 97.6 +/- 52.0 ng ml(-1) [(+)-halofantrine] and 48.5 +/- 20.8 [(-)-halofantrine]. Steady-state oral clearance was: 139 +/- 73 l h(-1) [(+)-halofantrine] and 265 +/- 135 l h(-1) [(-)-halofantrine]. Peak plasma concentrations of both (+)- and (-)-halofantrine were attained at 6 h and maximal ECG QTc prolongation was at 4-8 h following drug administration. Fourteen of 16 subjects who received active drug had ECG QTc prolongation that was positively correlated with both (+)- and (-)-halofantrine concentration. The five subjects who received placebo had no demonstrable change in ECG QTc throughout the study. Conclusions Halofantrine accumulates extensively and shows high intersubject pharmacokinetic variability, is associated with concentration-related ECG QTc prolongation in healthy subjects, and is clinically well tolerated in this subject group.

Loratadine and terfenadine interaction with nefazodone: Both antihistamines are associated with QTc prolongation.

BACKGROUND AND OBJECTIVE: Nefazodone inhibits CYP3A; therefore coadministration with CYP3A substrates such as terfenadine or loratadine may result in increased exposure to these drugs. A potential pharmacodynamic consequence is electrocardiographic QTc prolongation, which has been associated with torsade de pointes cardiac arrhythmia. Therefore a clinical pharmacokinetic-pharmacodynamic evaluation of this potential interaction was conducted. METHODS: A randomized, double-blind, double-dummy, parallel group, multiple-dose design was used. Healthy men and women who were given doses of 60 mg of terfenadine every 12 hours, 20 mg of loratadine once daily, and 300 mg of nefazodone every 12 hours were studied. Descriptive pharmacokinetics (time to maximum concentration, maximum concentration, and area under the plasma concentration-time curve) were used for the examination of interactions among the respective parent drugs and metabolites. QTc prolongation (mean value over the dosing interval) was the pharmacodynamic parameter measured. Kinetic and dynamic analysis was used for the examination of pooled concentration and QTc data with the use of a linear model. RESULTS: Concomitant nefazodone treatment markedly increased the dose interval area under the plasma concentration-time curve of both terfenadine (mean value, 17.3 +/- 8.5 ng. mL/h versus 97.4 +/- 48.9 ng. mL/h; P <.001) and carboxyterfenadine (mean value, 1.69 +/- 0.48 microg. h/mL versus 2.88 +/- 0.53 microg. h/mL; P <.001) and moderately increased the dose interval area under the plasma concentration-time curve of both loratadine (mean value, 31.5 +/- 27.9 ng. h/mL versus 43.7 +/- 25.9 ng. h/mL; P <.014) and descarboethoxyloratadine (mean value, 73.4 +/- 54.9 ng. h/mL versus 81.9 +/- 26.2 ng. h/mL; P <.002). The mean QTc was unchanged with terfenadine alone; however, it was markedly prolonged with concomitant nefazodone and terfenadine (mean [90% confidence interval] prolongation 42.4 ms [34.2, 50.6 ms]; P <.05). Similarly, the mean QTc was unchanged with loratadine alone; however, it was prolonged with concomitant nefazodone and loratadine (21.6 ms [13.7, 29.4 ms]; P <.05). Nefazodone alone did not change mean QTc. QTc was positively correlated with terfenadine plasma concentration (r (2) = 0.21; P =.0001). Similarly, QTc was positively correlated with loratadine plasma concentration (r (2) = 0.056; P =.0008) but with a flatter slope. There was no relationship between QTc and nefazodone plasma concentration during treatment with nefazodone alone (r (2) = 0.002, not significant). CONCLUSIONS: In healthy men and women, concomitant nefazodone treatment at a therapeutic dose increases exposure to both terfenadine and carboxyterfenadine. This increased exposure is associated with marked QTc prolongation, which is correlated with terfenadine plasma concentration. A similar interaction occurs with loratadine, although it is of lesser magnitude. Concomitant administration of nefazodone with terfenadine may have predisposed individuals to the arrhythmia associated with QTc prolongation, torsade de pointes, when terfenadine was available for clinical use. However, a new finding is that in the context of higher than clinically recommended daily doses (20 mg) of loratadine concomitant administration with a metabolic inhibitor such as nefazodone can also result in QTc prolongation.

New molecular determinant for inactivation of the human L-type alpha1C Ca2+ channel.

Molecular cloning of the human fibroblast Ca2+ channel pore-forming alpha1C subunit revealed (Soldatov, 1992. Proc. Natl. Acad. Sci. USA 89:4628-4632) a naturally occurring mutation g2254 --> a that causes the replacement of the conservative alanine for threonine at the position 752 at the cytoplasmic end of transmembrane segment IIS6. Using stably transfected HEK293 cell lines, we have compared electrophysiological properties of the conventional alpha(1C,77) human recombinant L-type Ca2+ channel with those of its mutated isoform alpha(1C,94) containing the A752T replacement. Comparative quantification of steady-state availability of the current carried by alpha(1C,94) and alpha(1C,77) showed that A752T mutation prevented a large (approximately 25%) fraction of the current carried by Ca2+ or Ba2+ from fully inactivating. This mutation, however, did not appear to alter significantly the Ca2+-dependence and kinetics of decay of the inactivating fraction of the current or its voltage-dependence. The data suggests that Ala752 at the cytoplasmic end of IIS6 might serve as a molecular determinant of the Ca2+ channel inactivation, possibly regulating the voltage-dependence of its availability.

Verapamil metabolite exposure in older and younger men during steady-state oral verapamil administration.

To determine the effect of age on exposure to the circulating major verapamil metabolites norverapamil, N-dealkylverapamil (D-617), and N-dealkylnorverapamil (D-620), plasma concentrations of verapamil and the three metabolites were determined during the last dose interval of a 14-day administration period of 240 mg of sustained release verapamil once daily in 11 older (aged 65-75 years) and 8 younger (20-28 years) healthy male volunteers. Area under the plasma concentration time curve (AUC) was greater for verapamil (mean +/- S. D.) (2815 +/- 733 older versus 1639 +/- 466 ng/ml.h(-1) young; P <. 0007) and norverapamil (2927 +/- 655 versus 2143 +/- 471 ng/ml. h(-1); P <.007); however, it was not significantly different for D-617 [2386 +/- 772 versus 1894 +/- 418 ng/ml.h(-1); not significantly different (NS)] and N-dealkylnorverapamil (897 +/- 366 versus 757 +/- 104 ng/ml.h(-1); NS) in older as compared with young subjects. These data indicate that impaired verapamil oral clearance previously described in older men does not result in decreased exposure to the formed major metabolites, rather there is increased exposure to norverapamil and the same or a trend toward greater exposure to D-617 as well. This suggests that in addition to the impaired clearance mechanisms for verapamil, which are thought to be primarily mediated by CYP3A, biotransformation processes distal to the formation of norverapamil and D-617 are impaired as well.