Oral erythromycin and the risk of sudden death from cardiac causes

Azithromycin: more lethal than chloramphenicol?

Azithromycin is commonly used in sexual health and respiratory medicine, often when the diagnosis is presumptive. A recent article by Ray et al. reported that 1 out of 20 000 courses of low-dose azithromycin was associated with (sudden) cardiovascular death (including 1 out of 4000 courses in high-risk cardiovascular patients), ascribing these deaths to azithromycin itself. Here, we critique the actual study and examine conflicting data from randomised control trials, animal studies and observational data.

Comparing two types of macrolide antibiotics for the purpose of assessing population-based drug interactions

OBJECTIVE

Clarithromycin strongly inhibits enzyme cytochrome P450 3A4, preventing the metabolism of some other drugs, while azithromycin is a weak inhibitor. Accordingly, blood concentrations of other drugs increase with clarithromycin coprescription leading to adverse events. These macrolide antibiotics also differ on other properties that may impact outcomes. In this study, we compared outcomes in two groups of macrolide antibiotic users in the absence of potentially interacting drugs.

DESIGN

Population-based retrospective cohort study.

SETTING

Ontario, Canada, from 2003 to 2010.

PATIENTS

Patients (mean 74 years) prescribed clarithromycin (n=52 251) or azithromycin (referent group, n=46 618).

MAIN OUTCOMES

The primary outcomes were hospital admission within 30 days of a new antibiotic prescription with any of the 12 conditions examined separately (acute kidney injury, acute myocardial infarction, neuroimaging (proxy for delirium), hypotension, syncope, hyperkalaemia, hyponatraemia, hyperglycaemia, arrhythmia, ischaemic stroke, gastrointestinal bleeding and sepsis). The secondary outcome was mortality.

RESULTS

The baseline characteristics of the two groups, including patient demographics, comorbid conditions, infection type and prescribing physician specialty, were nearly identical. The median daily dose was 1000 mg for clarithromycin and 300 mg for azithromycin and the median duration of dispensing antibiotics was 10 and 5 days, respectively. There was no difference between the groups in the risk of hospitalisation for any condition studied (relative risk ranged from 0.67 to 1.23). Compared with azithromycin, clarithromycin was associated with a slightly higher risk of all-cause mortality (0.46% vs 0.37%, relative risk 1.25, 95% CI 1.03 to 1.52).

CONCLUSIONS

Clarithromycin can be used to assess drug interactions in population-based studies with azithromycin serving as a control group. However, any differences in mortality observed between the two antibiotic groups in the setting of other drug use may be partially attributable to factors beyond the inhibition of drug metabolising enzymes and transporters, as the difference for this outcome was significant.

Antimicrobial drugs

Antibiotics play a vital role in dental practice for managing orofacial infections. They are used to manage existing infection and they are also used as prophylaxis for certain medical conditions and surgical procedures. This article will review pharmacological and therapeutic considerations for the proper use of these agents for dental infections.

[Molecular and genetic background of sudden cardiac death]

Despite recent findings on the functional, structural and genetic background of sudden cardiac death, the incidence is still relatively high in the entire population. A thorough knowledge on susceptibility, as well as pathophysiology behind the development of malignant arrhythmias will help us to identify individuals at risk and prevent sudden cardiac death. This article presents a review of the current literature on the role of altered intracellular Ca2+ handling, acute myocardial ischaemia, cardiac autonomic innervation, renin-angiotensin-aldosterone system, monogenic and complex heritability in the pathogenesis of sudden cardiac death.

Drug-induced arrhythmia: pharmacogenomic prescribing?

Drug-induced Torsades de Pointes is a rare, unpredictable, and life-threatening serious adverse event. It can be caused by both cardiac and non-cardiac drugs and has become a major issue in novel drug development and for the regulatory authorities. This review describes the problem, predisposing factors, and the underlying genetic predisposition as it is understood currently. The future potential for pharmacogenomic-guided and personalized prescription to prevent drug-induced Torsades de Pointes is discussed. Database searches utilized reports from www.qtdrugs.org up to January 2012, case reports and articles from www.pubmed.com up to January 2012, and the British National Formulary edition at www.bnf.org.

The Autopsy and Toxicologic Deaths

Deaths from toxicologic causes is one of the main reasons for performing an autopsy. The approach to performing an autopsy involves knowledge of the scene and history, particularly for the presence of prescribed and illicit drugs. The external and internal examination, while often nonspecific, can provide specific information on route of administration and specific changes seen on naked eye and microscopic examination. Material for toxicologic analysis needs to be collected and may require discussion with the toxicology laboratory to make sure the appropriate material is sent. The opinion relating to cause and manner of death requires an analysis of all stages of the investigation. Such phenomena as postmortem redistribution and tolerance to a drug must be considered before making a determination. This paper reviews the autopsy in toxicologic death.

Motilin receptor neuropharmacology: revised understanding

Although motilin was identified >40 years ago as a gastrointestinal hormone capable of stimulating gastric emptying, the relatively recent availability of molecular tools and focus on its neuronal activities are now clarifying mechanisms of action. In rodents, only motilin receptor pseudogenes are identified. In human stomach, facilitation of enteric cholinergic activity is identified as the main mechanism by which gastric emptying is increased; some motilin agonists act in a prolonged manner, contrasting with motilin itself and with studies using recombinant receptors. As such, assays using recombinant receptors seem poor predictors of in vivo activity. High-throughput screening enabled selective motilin agonists to be identified, which together with enhanced understanding into neuromuscular actions of motilin, promises to deliver rational treatments of disorders with delayed gastric emptying.

Azithromycin and the risk of cardiovascular death

BACKGROUND

Although several macrolide antibiotics are proarrhythmic and associated with an increased risk of sudden cardiac death, azithromycin is thought to have minimal cardiotoxicity. However, published reports of arrhythmias suggest that azithromycin may increase the risk of cardiovascular death.

METHODS

We studied a Tennessee Medicaid cohort designed to detect an increased risk of death related to short-term cardiac effects of medication, excluding patients with serious noncardiovascular illness and person-time during and shortly after hospitalization. The cohort included patients who took azithromycin (347,795 prescriptions), propensity-score-matched persons who took no antibiotics (1,391,180 control periods), and patients who took amoxicillin (1,348,672 prescriptions), ciprofloxacin (264,626 prescriptions), or levofloxacin (193,906 prescriptions).

RESULTS

During 5 days of therapy, patients taking azithromycin, as compared with those who took no antibiotics, had an increased risk of cardiovascular death (hazard ratio, 2.88; 95% confidence interval [CI], 1.79 to 4.63; P<0.001) and death from any cause (hazard ratio, 1.85; 95% CI, 1.25 to 2.75; P=0.002). Patients who took amoxicillin had no increase in the risk of death during this period. Relative to amoxicillin, azithromycin was associated with an increased risk of cardiovascular death (hazard ratio, 2.49; 95% CI, 1.38 to 4.50; P=0.002) and death from any cause (hazard ratio, 2.02; 95% CI, 1.24 to 3.30; P=0.005), with an estimated 47 additional cardiovascular deaths per 1 million courses; patients in the highest decile of risk for cardiovascular disease had an estimated 245 additional cardiovascular deaths per 1 million courses. The risk of cardiovascular death was significantly greater with azithromycin than with ciprofloxacin but did not differ significantly from that with levofloxacin.

CONCLUSIONS

During 5 days of azithromycin therapy, there was a small absolute increase in cardiovascular deaths, which was most pronounced among patients with a high baseline risk of cardiovascular disease. (Funded by the National Heart, Lung, and Blood Institute and the Agency for Healthcare Quality and Research Centers for Education and Research on Therapeutics.).

Effect of azithromycin on small bowel motility in patients with gastrointestinal dysmotility

OBJECTIVE

To investigate the effect of azithromycin (AZI) on small bowel activity in patients with gastrointestinal dysmotility (GID).

MATERIAL AND METHODS

Manometric data on a consecutive series of 21 patients was reviewed. Only those patients with gastroparesis and small bowel dysmotility as defined by antroduodenal manometric criteria were included. Pressure profiles were recorded in three stages: baseline period, fed state and postprandial after administration of erythromycin (ERY) and AZI. The measured parameters included the number and characteristics of activity fronts and migrating motor complexes (MMCs) including duration, amplitude and frequency of contractions. The data were analyzed using repeated measures analysis of variance for comparison of each medication.

RESULTS

AZI induced more MMCs in the duodenum with origin of activity fronts in the antrum than did ERY (18 patients with AZI, 10 patients with ERY). No significant difference between AZI and ERY was seen with respect to the amplitude of MMCs or number of cycles per minute. The average duration of activity fronts was longer with AZI compared with ERY (AZI mean 18.5 min, ERY mean 9.7 min, p < 0.02).

CONCLUSIONS

AZI induces activity fronts in the antrum followed by duodenal contractions more frequently than ERY in patients with GID. AZI potentially promises to be a prokinetic for treatment of small bowel dysmotility.

Metoclopramide, H2 blockers, and proton pump inhibitors: pharmacotherapy for gastroesophageal reflux in neonates

Pharmacotherapy for gastroesophageal reflux (GER) in neonates, aimed at interfering with this physiologic process and potentially reducing the negative sequelae that providers often attribute to GER, consists primarily of drugs that increase the viscosity of feeds, reduce stomach acidity, or improve gut motility. Medications used to treat clinical signs thought to be from GER, such as apnea, bradycardia, or feeding intolerance, are among the most commonly prescribed medications in neonatal intensive care units in the United States, despite the lack of evidence of safety and efficacy in this population.

Long-QT syndrome

Acquired and hereditary long-QT syndromes are important causes of sudden cardiac death. Both categories are characterized by abnormally prolonged cardiac repolarization arising from a complex interaction between genetic and environmental factors. This produces a potentially dangerous substrate for polymorphic ventricular tachycardia and sudden cardiac death. In this review, the pathophysiologic, diagnostic, and prognostic features of long-QT syndromes, as well as recommendations regarding therapy, are reviewed.

Macrolides: from in vitro anti-inflammatory and immunomodulatory properties to clinical practice in respiratory diseases

BACKGROUND

Macrolides have long been recognised to exert immunomodulary and anti-inflammatory actions. They are able to suppress the "cytokine storm" of inflammation and to confer an additional clinical benefit through their immunomodulatory properties.

METHODS

A search of electronic journal articles was performed using combinations of the following keywords: macrolides, COPD, asthma, bronchitis, bronchiolitis obliterans, cystic fibrosis, immunomodulation, anti-inflammatory effect, diabetes, side effects and systemic diseases.

RESULTS

Macrolide effects are time- and dose-dependent, and the mechanisms underlying these effects remain incompletely understood. Both in vitro and in vivo studies have provided ample evidence of their immunomodulary and anti-inflammatory actions. Importantly, this class of antibiotics is efficacious with respect to controlling exacerbations of underlying respiratory problems, such as cystic fibrosis, asthma, bronchiectasis, panbrochiolitis and cryptogenic organising pneumonia. Macrolides have also been reported to reduce airway hyper-responsiveness and improve pulmonary function.

CONCLUSION

This review provides an overview on the properties of macrolides (erythromycin, clarithromycin, roxithromycin, azithromycin), their efficacy in various respiratory diseases and their adverse effects.

G-CSF therapy reduces myocardial repolarization reserve in the presence of increased arteriogenesis, angiogenesis and connexin 43 expression in an experimental model of pacing-induced heart failure

G-CSF (granulocyte colony-stimulating factor) treatment has been shown to cause beneficial effects including a reduction of inducible arrhythmias in rodent models of ischemic cardiomyopathy. The aim of the present study was to test whether these effects do also apply to pacing-induced non-ischemic heart failure. In 24 female rabbits, heart failure was induced by rapid ventricular pacing. 24 rabbits were sham operated. The paced rabbits developed a significant decrease of ejection fraction. 11 heart failure rabbits (CHF) and 11 sham-operated (S) rabbits served as controls, whereas 13 sham (S-G-CSF) and 13 heart failure rabbits (CHF-G-CSF) were treated with 10 μg/kg G-CSF s.c. over 17 ± 4 days. G-CSF treatment caused a ~25% increased arterial and capillary density and a ~60% increased connexin 43 expression in failing hearts. In isolated, Langendorff-perfused rabbit hearts eight monophasic action potential recordings showed prolongation of repolarization in CHF as compared with controls in the presence of the QT prolonging agent erythromycin (+33 ± 12 ms; p < 0.01). Moreover, a significant increase in dispersion of repolarization contributed to a significantly higher rate of ventricular tachyarrhythmias in CHF. G-CSF-pre-treated hearts showed a further increase in prolongation of repolarization as compared with S and CHF. The further increase in dispersion of repolarization [S-G-CSF: +23 ± 9 ms (spatial), +13 ± 7 ms (temporal); CHF-G-CSF: +38 ± 14 ms (spatial), +10 ± 4 ms (temporal); p < 0.05 as compared with S and CHF], increased the incidence of ventricular tachyarrhythmias. In summary, chronic G-CSF treatment has moderate beneficial effects on parameters potentially related to hemodynamic function in the non-ischemic rabbit CHF model. However, a significant reduction of repolarization reserve might seriously challenge its suitability as a therapeutic agent for chronic CHF therapy.

Performance of disease risk scores, propensity scores, and traditional multivariable outcome regression in the presence of multiple confounders

Propensity scores are widely used in cohort studies to improve performance of regression models when considering large numbers of covariates. Another type of summary score, the disease risk score (DRS), which estimates disease probability conditional on nonexposure, has also been suggested. However, little is known about how it compares with propensity scores. Monte Carlo simulations were conducted comparing regression models using the DRS and the propensity score with models that directly adjust for all of the individual covariates. The DRS was calculated in 2 ways: from the unexposed population and from the full cohort. Compared with traditional multivariable outcome regression models, all 3 summary scores had comparable performance for moderate correlation between exposure and covariates and, for strong correlation, the full-cohort DRS and propensity score had comparable performance. When traditional methods had model misspecification, propensity scores and the full-cohort DRS had superior performance. All 4 models were affected by the number of events per covariate, with propensity scores and traditional multivariable outcome regression least affected. These data suggest that, for cohort studies for which covariates are not highly correlated with exposure, the DRS, particularly that calculated from the full cohort, is a useful tool.

Potential and pitfalls of using large administrative claims data to study the safety of osteoporosis therapies

Long-term bisphosphonate use may be associated with several rare adverse events. Such associations are not optimally evaluated in conventional randomized controlled trials due to the requirements of large numbers of patients and long-term follow-up. Alternatively, administrative claims data from various sources such as Medicare have been used. Because claims data are collected for billing and reimbursement purposes, they have limitations, including uncertain diagnostic validity and lack of detailed clinical information. Using such data for pharmacoepidemiologic research requires complex methodologies that may be less familiar to many researchers and clinicians. In this review, we discuss the strengths and limitations of using claims data for osteoporosis drug safety research, summarize recent advancements in methodologies that may be used to address the limitations, and present directions for future research using claims data.

Pharmacy students' retention of knowledge of drug-drug interactions

OBJECTIVES

To evaluate pharmacy students' drug-drug interaction (DDI) knowledge retention over 1 year and to determine whether presenting DDI vignettes increased knowledge retention.

METHODS

A knowledge assessment tool was distributed to fourth-year pharmacy students before and after completing a DDI educational session. The questionnaire was re-administered after 1 year to assess knowledge retention. During the intervening year, students had the option of presenting DDI case vignettes to preceptors and other health professionals as part of their advanced pharmacy practice experiences (APPEs).

RESULTS

Thirty-four of 78 pharmacy students completed both the post-intervention and 1-year follow-up assessments. Students' knowledge of 4 DDI pairs improved, knowledge of 3 DDI pairs did not change, and knowledge of the remainder of DDI pairs decreased. Average scores of the 18 students who completed all tests and presented at least 1 vignette during their APPEs were higher on the 1-year follow-up assessment than students who did not, suggesting greater DDI knowledge retention (p = 0.04).

CONCLUSION

Although pharmacy students' overall DDI knowledge decreased in the year following an educational session, those who presented vignettes to health professionals retained more DDI knowledge, particularly on those DDIs for which they gave presentations. Other methods to enhance pharmacy students' retention of DDI knowledge of clinically important DDIs are needed.

Gastroparesis: pathogenesis, diagnosis and management

Gastroparesis is a prevalent condition that produces symptoms of delayed gastric emptying in the absence of physical blockage. The most common etiologies of gastroparesis are idiopathic, diabetic, and postsurgical disease, although some cases stem from autoimmune, paraneoplastic, neurologic or other conditions. Histologic examination of gastric tissues from patients with severe gastroparesis reveals heterogeneous and inconsistent defects in the morphology of enteric neurons, smooth muscle and interstitial cells of Cajal, and increased levels of inflammatory cells. Diagnosis is most commonly made by gastric emptying scintigraphy; however, wireless motility capsules and nonradioactive isotope breath tests have also been validated. A range of treatments have been used for gastroparesis including dietary modifications and nutritional supplements, gastric motor stimulatory or antiemetic medications, endoscopic or surgical procedures, and psychological interventions. Most treatments have not been subjected to controlled testing in patients with gastroparesis. The natural history of this condition is poorly understood. Active ongoing research is providing important insights into the pathogenesis, diagnosis, treatment and outcomes of this disease.

Use of prokinetics in the preterm infant

PURPOSE OF REVIEW

Functional gastrointestinal dysmotility is a common condition that affects premature infants. Delay in achievement of full enteral nutrition results in dependence on prolonged parenteral nutrition, predisposing to adverse outcomes. Studies in recent years show apparently conflicting results regarding the use of prokinetic agents in preterm infants. This review aims to evaluate these studies to determine whether use of these agents in premature infants is beneficial and justified.

RECENT FINDINGS

Randomized controlled trials in recent years have been performed to investigate the effectiveness of erythromycin in the treatment of nonobstructive gastrointestinal dysmotility in preterm infants. Overall, neither low-dose regimes nor prophylactic trials have been shown to be useful. High-dose regimes used as rescue therapy of infants with established gastrointestinal dysmotility have consistently shown clinical benefit. Theoretical risks of prolonged antibiotic use, such as emergence of antibiotic resistance and abnormal intestinal microbiota, have not been fully evaluated.

SUMMARY

Judicious use of high-dose erythromycin in premature infants as rescue therapy is probably justifiable. Further research in this area is warranted to develop newer prokinetic agents which may improve the safety profile of therapy.

Arrhythmias in children

Arrhythmias in children can be classified according to their effect on central pulse: Fast pulse rate - tachyarrhythmia; Slow pulse rate - bradyarrhythmia; and Absent pulse is pulseless arrest (cardiac arrest). Tachyarrythmia may be narrow complex tachycardia (QRS duration ≤ 0.08 s): sinus tachycardia (ST), supraventricular tachycardia (SVT), atrial flutter or Wide-complex tachycardia (QRS duration >0.08 s): ventricular tachycardia (VT), SVT with aberrant intraventricular conduction. The choice of therapy depends on the patient's degree of hemodynamic instability. Attempt vagal stimulation, if patient is stable and if it does not unduly delay chemical or electrical cardioversion. Bradyarrhythmias include: sinus bradycardia, sinus node arrest with atrial, junctional and idioventricular escape rhythms and AV block. The emergency treatment of bradycardia depends on its hemodynamic consequences. If heart rate is <60 beats per minute with poor perfusion despite effective ventilation with oxygen, it may be treated with chest compressions, epinephrine through IV or endotracheal tube. If bradycardia persists or responds only transiently, consider a continuous infusion of epinephrine or isoproterenol and plan for emergency transcutaneous pacing. If bradycardia is due to vagal stimulation or primary A-V block, giving atropine may be beneficial.

Advantages of azithromycin over erythromycin in improving the gastric emptying half-time in adult patients with gastroparesis

Background/Aims

Current therapy for gastroparesis with prokinetic agents is limited by options and side effects. One macrolide, erythromycin (ERY), is associated with possible sudden cardiac death from QT prolongation due to P450 iso-enzyme inhibition. An alternative, azithromycin (AZI), lacks P450 inhibition. We compared the effect on gastric emptying half-times (t½) between AZI and ERY in patients diagnosed with gastroparesis by gastric emptying scintigraphy.

Methods

Patients stopped medications known to affect gastric emptying prior to the study, and then ingested 1 scrambled egg meal labeled with 18.5-37 MBq of technetium-99m sulfur colloid followed by continuous imaging for 120 minutes, at 1 minute per frame. A simple linear fit was applied to the rate of gastric emptying, and gastric emptying t½ was calculated (normal = 45-90 minutes). At 75-80 minutes, if the stomach had clearly not emptied, patients were given either ERY (n = 60) or AZI (n = 60) 250 mg IV and a new post-treatment gastric emptying t½ was calculated.

Results

Comparison of gastric emptying t½ showed a similar positive effect (mean gastric emptying t½ for AZI = 10.4 ± 7.2 minutes; mean gastric emptying t½ for ERY = 11.9 ± 8.4 minutes; p = 0.30).

Conclusions

AZI is equivalent to ERY in accelerating the gastric emptying of adult patients with gastroparesis. Given the longer duration of action, better side effect profile and lack of P450 interaction for AZI as compared with ERY, further research should evaluate the long term effectiveness and safety of AZI as a gastroparesis treatment.

Azole antimycotics and drug interactions in the perioperative period

PURPOSE OF REVIEW

A beneficial effect of antifungal prophylaxis on the prevention of invasive fungal infections has increased the use of azole antimycotics in intensive care and during the perioperative period. At the same time more severe illnesses are treated and multiple drug therapies are employed. Thus, the potential for severe drug-drug interactions has increased. Previous studies have shown that azole antimycotics increase the risk of many clinically significant drug interactions with potentially hazardous consequences.

RECENT FINDINGS

A recent pharmacoepidemiological study has found a more than five-fold incidence ratio in the adjusted rate of sudden death from cardiac diseases among those patients who were given simultaneously inhibitors of cytochrome P450 (CYP) enzymes and their substrates. Although new triazole antifungals are well tolerated, they still cause significant inhibition of CYP enzymes.

SUMMARY

This review focuses on azole antimycotics and anesthetic drugs being used during the perioperative period and discusses the possible clinically significant drug-drug interactions. Azole antimycotics are amongst the strongest inhibitors of CYP-mediated drug metabolism. Anesthesiologists must be aware of the interaction potential of azole antimycotics to be able to adjust their perioperative strategies according to the patient's condition and concomitant medication.

Validation of diagnostic codes for outpatient-originating sudden cardiac death and ventricular arrhythmia in Medicaid and Medicare claims data

PURPOSE

Sudden cardiac death (SD) and ventricular arrhythmias (VAs) caused by medications have arisen as an important public health concern in recent years. The validity of diagnostic codes in identifying SD/VA events originating in the ambulatory setting is not well known. This study examined the positive predictive value (PPV) of hospitalization and emergency department encounter diagnoses in identifying SD/VA events originating in the outpatient setting.

METHODS

We selected random samples of hospitalizations and emergency department claims with principal or first-listed discharge diagnosis codes indicative of SD/VA in individuals contributing at least 6 months of baseline time within 1999-2002 Medicaid and Medicare data from five large states. We then obtained and reviewed medical records corresponding to these events to serve as the reference standard.

RESULTS

We identified 5239 inpatient and 29 135 emergency department events, randomly selected 100 of each, and obtained 119 medical records, 116 of which were for the requested courses of care. The PPVs for an outpatient-originating SD/VA precipitating hospitalization or emergency department treatment were 85.3% (95% confidence interval [CI] = 77.6-91.2) overall, 79.7% (95%CI = 68.3-88.4) for hospitalization claims, and 93.6% (95%CI = 82.5-98.7) for emergency department claims.

CONCLUSIONS

First-listed SD/VA diagnostic codes identified in inpatient or emergency department encounters had very good agreement with clinical diagnoses and functioned well to identify outpatient-originating events. Researchers using such codes can be confident of the PPV when conducting studies of SD/VA originating in the outpatient setting.

How Does Genetics Influence the Efficacy and Safety of Antiarrhythmic Drugs?

Recent progress in genomic sequencing has begun to elucidate the basic mechanisms for several adverse responses, as well as the clinical efficacy, for antiarrhythmic drugs. DNA variants in drug metabolizing enzymes have been implicated in excessive drug accumulation, and genetic variability in drug targets can identify individuals at increased risk for serious side effects, in particular proarrhythmia. It is hoped that future advances in the area of genomic medicine will lead to more individually tailored or personalized pharmacologic therapy in the management of cardiac arrhythmias.

Common drug interactions leading to adverse drug events in the intensive care unit: management and pharmacokinetic considerations

Critically ill patients are predisposed to drug interactions because of the complexity of the drug regimens they receive in the intensive care setting. Drugs may affect the absorption, distribution, metabolism, and/or elimination of an object drug and consequently alter the intended pharmacologic response and potentially lead to an adverse event. Certain disease states that afflict critically ill patients may also amplify an intended pharmacologic response and potentially result in an unintended effect. A team approach is important to identify, prevent, and address drug interactions in the intensive care setting and optimize patient outcomes.

A computer case definition for sudden cardiac death

PURPOSE

To facilitate studies of medications and sudden cardiac death, we developed and validated a computer case definition for these deaths. The study of community dwelling Tennessee Medicaid enrollees 30-74 years of age utilized a linked database with Medicaid inpatient/outpatient files, state death certificate files, and a state 'all-payers' hospital discharge file.

METHODS

The computerized case definition was developed from a retrospective cohort study of sudden cardiac deaths occurring between 1990 and 1993. Medical records for 926 potential cases had been adjudicated for this study to determine if they met the clinical definition for sudden cardiac death occurring in the community and were likely to be due to ventricular tachyarrhythmias. The computerized case definition included deaths with (1) no evidence of a terminal hospital admission/nursing home stay in any of the data sources; (2) an underlying cause of death code consistent with sudden cardiac death; and (3) no terminal procedures inconsistent with unresuscitated cardiac arrest. This definition was validated in an independent sample of 174 adjudicated deaths occurring between 1994 and 2005.

RESULTS

The positive predictive value of the computer case definition was 86.0% in the development sample and 86.8% in the validation sample. The positive predictive value did not vary materially for deaths coded according to the ICO-9 (1994-1998, positive predictive value = 85.1%) or ICD-10 (1999-2005, 87.4%) systems.

CONCLUSION

A computerized Medicaid database, linked with death certificate files and a state hospital discharge database, can be used for a computer case definition of sudden cardiac death.

Sudden death in patients receiving drugs tending to prolong the QT interval

AIMS

To examine risks of sudden death in the community associated with drugs grouped by their risk of causing torsades de pointes (TdP) and to explore the risks for individual drugs.

METHODS

Case-control study comparing prior drug intakes and morbidities, using the Arizona classification of drugs causing TdP. Participants included 1010 patients dying suddenly where post-mortem examination did not identify a clear cause of death, and 3030 matched living controls from primary care.

RESULTS

Noncardiac drug risk was posed by antipsychotics and antidepressants. Significantly raised odds ratios (ORs) were found for takers of typical and atypical antipsychotics, ORs [95% confidence interval] 3.94 (2.05, 7.55) and 4.36 (2.54, 7.51), and of selective serotonin reuptake inhibitors [SSRIs] rather than tricyclic antidepressants, ORs 2.21 (1.61, 3.05) and 1.44 (0.96, 2.13). No significant risk was associated with other, noncardiac or psychiatric drugs, OR 1.09 (0.85, 1.41). Arizona classified drugs considered to raise risk of TdP were associated with raised risk of sudden death, as were those only weakly associated with TdP and not considered to pose a risk in normal use, ORs 2.08 (1.45, 3.00) and 1.74 (1.33, 2.28), respectively.

CONCLUSIONS

Atypical and typical antipsychotic drug use were both strongly associated with raised risks, as were SSRIs. Tricyclic antidepressants were not associated with raised risks. The Arizona classification of risk of TdP was a poor predictor of likelihood of noncardiac drug-associated sudden death.

Non-aspirin NSAIDs, cyclooxygenase-2 inhibitors and risk for cardiovascular events-stroke, acute myocardial infarction, and death from coronary heart disease

PURPOSE

To determine if certain non-steroidal anti-inflammatory drugs (NSAIDs) are associated with increased risk of cardiovascular events: acute myocardial infarction (AMI), stroke, and death from coronary heart disease (CHD).

METHODS

We conducted a retrospective cohort study of Tennessee Medicaid enrollees aged 35-94 years between 1 January 1999 and 31 December 2005. Eligible persons were non-institutionalized, had continuous enrollment, and had no serious illness prior to cohort entry. Exposure to celecoxib, rofecoxib, valdecoxib, ibuprofen, naproxen, diclofenac, and indomethacin was studied. The outcome was hospitalization for AMI, stroke, or death from CHD among those with and without a history of cardiovascular disease (CVD). Adjusted hazard ratios (aHR) and 95% confidence intervals (95% CI) are reported.

RESULTS

There were 610 001 persons in the final cohort and 14% had a baseline history of CVD. In those without CVD (N = 525 249) there were 1 566 678 person-years of follow-up and 12 184 events. In this group, non-users had 7.90 events/1000 person-years. Events/1000 person-years were 10.41 for current use of celecoxib (aHR 1.00, 95% CI 0.89-1.13), 10.91 for rofecoxib (aHR 1.21, 95% CI 1.07-1.37), 12.46 for valdecoxib (aHR 1.30 95% CI 1.04-1.61), and 13.25 for indomethacin (aHR 1.36, 95% CI 1.11-1.66) compared to non-users. Among patients with a past history of CVD (N = 84 752) there were 397 977 person-years of follow-up and 10 248 events. Non-users had 28.30 events/1000 person-years. Among those with CVD, rofecoxib use was associated with increased event rate (30.28 events/1000 person-years [aHR 1.21, 95% CI 1.08-1.37]) and naproxen was associated with a decreased event rate (22.66 events/1000 person-years [aHR 0.88, 95% CI 0.79-0.99]). Among new users, the results were similar except risk among naproxen users was no longer different than non-users.

CONCLUSIONS

We found an increased risk of cardiovascular events among all and new current users of rofecoxib, valdecoxib, and indomethacin in patients with no history of CVD. Among patients with CVD, all and new current rofecoxib use was associated with an increased risk of a cardiovascular event.

Transforming Healthcare

The healthcare system is facing several major quality challenges. In 2005, the Institute of Medicine published a report on how systems engineering and improvements in information technology can help address and solve some of these challenges. Systems engineering (SE) and health informatics (HI) have been undergoing advancements over the years. Health systems engineering is an interdisciplinary field that has grown to encompass the design, analysis, and management of complex health systems to improve quality and performance. HI is another interdisciplinary field around collection, storage, retrieval and analysis of data, reporting and enabling use of information, and (re)design and maintenance of systems to do all of these. SE and HI are complementary in their approach to identification of problems and solution procedure for (re)design and improvement. This combination has major implications for care delivery, research, and education to address the challenges.

Updates on cytochrome p450-mediated cardiovascular drug interactions

Cytochrome P (CYP) 450 is a superfamily of hemoproteins that play an important role in the metabolism of steroid hormones, fatty acids, and many medications. Many agents used for management of cardiovascular diseases are substrates, inhibitors, or inducers of CYP450 enzymes. When two agents that are substrates, inhibitors, or inducers of CYP450 are administered together, drug interactions with significant clinical consequences may occur. This review discusses CYP450-mediated cardiovascular drug interactions as well as noncardiovascular drug interactions that produced significant cardiovascular side effects. The principles in predicting drug interactions are also discussed.

Disparate response to metoclopramide therapy for gastric feeding intolerance in trauma patients with and without traumatic brain injury

Patients with traumatic brain injury (TBI) have delayed gastric emptying and often require prokinetic drug therapy to improve enteral feeding tolerance. The authors hypothesized that metoclopramide was less efficacious for improving gastric feeding tolerance for trauma patients with TBI compared to trauma patients without TBI. A retrospective analysis was conducted of patients admitted to the trauma or neurosurgical intensive care unit who received gastric feeding from January 2006 to April 2008. Gastric feeding intolerance was defined by a gastric residual volume >200 mL or emesis with abdominal distension or discomfort. Patients with gastric feeding intolerance were given metoclopramide 10 mg intravenously every 6 hours, followed by a dose escalation to 20 mg, and then combination therapy with metoclopramide and erythromycin 250 mg intravenously every 6 hours if intolerance persisted. In total, 882 trauma patients (49% with TBI) were evaluated. TBI patients had a higher incidence of gastric feeding intolerance than those without TBI (18.6% vs 10.4%, P < or = .001). Efficacy rates for metoclopramide 10 mg, metoclopramide 20 mg, and metoclopramide-erythromycin were 55%, 62%, and 79%, respectively (P < or = .03). Metoclopramide failure occurred in 54% of patients with TBI compared to 35% of patients without TBI, respectively (P < or = .02), due to a greater prevalence of tachyphylaxis. Single-drug therapy with metoclopramide was less effective for TBI trauma patients compared to trauma patients without TBI. Combination therapy with erythromycin as first-line therapy for TBI trauma patients with gastric feeding intolerance is indicated if there are no contraindications or significant drug interactions.

Comparison of the effect of azithromycin versus erythromycin on antroduodenal pressure profiles of patients with chronic functional gastrointestinal pain and gastroparesis

BACKGROUND

Current pharmacologic treatments for gastroparesis have been disappointing due to the limited options available. Erythromycin ethylsuccinate is a potent prokinetic agent that stimulates gastric emptying. Recently, erythromycin has been linked to the occurrences of sudden cardiac death due to QT prolongation. Azithromycin is similar to erythromycin in structure but does not have significant drug-drug interactions as seen with erythromycin.

PURPOSE

This study aims to determine whether azithromycin stimulates antral activity in patients with chronic gastrointestinal pain and refractory gastroparesis.

METHODS

Small bowel manometric data on 30 patients undergoing clinical evaluation for chronic digestive problems or documented refractory gastroparesis were reviewed. Antral activity was measured after infusion of erythromycin 250 mg intravenous and azithromycin (500 or 250 mg intravenous) given at different intervals during the small bowel manometry. The parameters measured included the total duration of effect, mean amplitude of antral contractions, duration of the highest antral contraction phase, number of cycles per minute, and the motility index.

RESULTS

Comparison of erythromycin and azithromycin at similar doses showed a similar positive effect on antral activity. However, comparison of erythromycin and azithromycin at the higher dose of 500 mg showed that the mean amplitude, duration of antral activity, and motility index were significantly increased with azithromycin (P < 0.05).

CONCLUSIONS

Azithromycin stimulates antral activity similar to erythromycin and moreover has a longer duration of effect. However, unlike erythromycin, azithromycin does not have significant drug-drug interactions and maybe a potential new medication for the treatment of gastroparesis and gastrointestinal dysmotility.

The time course of new T-wave ECG descriptors following single- and double-dose administration of sotalol in healthy subjects

INTRODUCTION

The aim of the study was to assess the time course effect of IKr blockade on ECG biomarkers of ventricular repolarization and to evaluate the accuracy of a fully automatic approach for QT duration evaluation.

METHODS

Twelve-lead digital ECG Holter was recorded in 38 healthy subjects (27 males, mean age = 27.4 + or - 8.0 years) on baseline conditions (day 0) and after administration of 160 mg (day 1) and 320 mg (day 2) of d-l sotalol. For each 24-hour period and each subject, ECGs were extracted every 10 minutes during the 4-hour period following drug dosage. Ventricular repolarization was characterized using three biomarker categories: conventional ECG time intervals, principal component analysis (PCA) analysis on the T wave, and fully automatic biomarkers computed from a mathematical model of the T wave.

RESULTS

QT interval was significantly prolonged starting 1 hour 20 minutes after drug dosing with 160 mg and 1 hour 10 minutes after drug dosing with 320 mg. PCA ventricular repolarization parameters sotalol-induced changes were delayed (>3 hours). After sotalol dosing, the early phase of the T wave changed earlier than the late phase prolongation. Globally, the modeled surrogate QT paralleled manual QT changes. The duration of manual QT and automatic surrogate QT were strongly correlated (R(2) = 0.92, P < 0.001). The Bland and Altman plot revealed a nonstationary systematic bias (bias = 26.5 ms + or - 1.96*SD = 16 ms).

CONCLUSIONS

Changes in different ECG biomarkers of ventricular repolarization display different kinetics after administration of a potent potassium channel blocker. These differences need to be taken into account when designing ventricular repolarization ECG studies.

Structure-activity relationships of 9-substituted-9-dihydroerythromycin-based motilin agonists: optimizing for potency and safety

A series of 9-dihydro-9-acetamido-N-desmethyl-N-isopropyl erythromycin A analogues and related derivatives was generated as motilin agonists. The compounds were optimized for potency while showing both minimal antibacterial activity and hERG inhibition. As the substituent on the amide was increased in lipophilicity the potency and hERG inhibition increased, while polar groups lowered potency, without significantly impacting hERG inhibition. The N-methyl acetamide 7a showed the optimal in vitro profile and was probed further by varying the chain length to the macrocycle as well as changing the macrocycle scaffold. 7a remained the compound with the best in vitro properties.

[Promotility drugs use in critical care: indications and limits?]

Enteral feeding is often limited by gastric and intestinal motility disturbances in critically ill patients, particularly in patients with shock. So, promotility agents are frequently used to improve tolerance to enteral nutrition. This review summaries the pathophysiology, presents the available pharmacological strategies, the clinical data, the counter-indications and the principal limits. The clinical data are poor. No study demonstrates a positive effect on clinical outcomes. Metoclopramide and erythromycin seems to be the more effective. Considering the risk of antibiotic resistance, the first line use of erythromycin should be avoided in favor of metoclopramide.

Patterns of use and risks associated with erythropoiesis-stimulating agents among Medicare patients with cancer

BACKGROUND

Erythropoiesis-stimulating agents (erythropoietin and darbepoietin) have been approved to reduce the number of blood transfusions required during chemotherapy; however, concerns about the risks of venous thromboembolism and mortality exist.

METHODS

We identified patients who were aged 65 years or older in the Surveillance, Epidemiology, and End Results-Medicare database; who were diagnosed with colon, non-small cell lung, or breast cancer or with diffuse large B-cell lymphoma from January 1, 1991, through December 31, 2002; and who received chemotherapy. The main outcome measures were claims for use of an erythropoiesis-stimulating agent, blood transfusion, venous thromboembolism (ie, deep vein thrombosis or pulmonary embolism), and overall survival. We used multivariable logistic regression models to analyze the association of erythropoiesis-stimulating agent use with clinical and demographic variables. We used time-dependent Cox proportional hazards models to analyze the association of time to receipt of first erythropoiesis-stimulating agent with venous thromboembolism and overall survival. All statistical tests were two-sided.

RESULTS

Among 56,210 patients treated with chemotherapy from 1991 through 2002, 15,346 (27%) received an erythropoiesis-stimulating agent. The proportion of patients receiving erythropoiesis-stimulating agents increased from 4.8% in 1991 to 45.9% in 2002 (P < .001). Use was associated with more recent diagnosis, younger age, urban residence, comorbidities, receipt of radiation therapy, female sex, and metastatic or recurrent cancer. The rate of blood transfusion per year during 1991-2002 remained constant at 22%. Venous thromboembolism developed in 1796 (14.3%) of the 12,522 patients who received erythropoiesis-stimulating agent and 3400 (9.8%) of the 34,820 patients who did not (hazard ratio = 1.93, 95% confidence interval = 1.79 to 2.07). Overall survival was similar in both groups.

CONCLUSION

Use of erythropoiesis-stimulating agent increased rapidly after its approval in 1991, but the blood transfusion rate did not change. Use of erythropoiesis-stimulating agents was associated with an increased risk of venous thromboembolism but not of mortality.