In vitro testing for diagnosis of idiosyncratic adverse drug reactions: Implications for pathophysiology

Idiosyncratic drug reactions (IDRs) represent a major health problem, as they are unpredictable, often severe and can be life threatening. The low incidence of IDRs makes their detection during drug development stages very difficult causing many post-marketing drug withdrawals and black box warnings. The fact that IDRs are always not predictable based on the drug\u27s known pharmacology and have no clear dose-effect relationship with the culprit drug renders diagnosis of IDRs very challenging, if not impossible, without the aid of a reliable diagnostic test. The drug provocation test (DPT) is considered the gold standard for diagnosis of IDRs but it is not always safe to perform on patients. In vitro tests have the advantage of bearing no potential harm to patients. However, available in vitro tests are not commonly used clinically because of lack of validation and their complex and expensive procedures. This review discusses the current role of in vitro diagnostic testing for diagnosis of IDRs and gives a brief account of their technical and mechanistic aspects. Advantages, disadvantages and major challenges that prevent these tests from becoming mainstream diagnostic tools are also discussed here

Variations in the management of pneumonia in pediatric emergency departments: Compliance with the guidelines

Objective: We sought to assess compliance with evidence-based guidelines for the management of pediatric pneumonia, including the variations in tests ordered and antimicrobials prescribed. Our primary hypothesis was that compliance with the treatment recommendations from the most current guidelines would be low for antimicrobial prescriptions. Methods: We conducted a chart review at the Children\u27s Hospital in London, Ont., to assess variation in the management of pediatric pneumonia. All patients aged 3 months to 18 years seen at the pediatric emergency department between Apr. 1, 2006, and Mar. 31, 2007, with a diagnosis of pneumonia were eligible for inclusion in the study. Results: Compliance with management guidelines was 59.7% (95% confidence interval [CI] 53%-66%, n = 211) in children 5-18 years old and 83.0% (95% CI 80%-86%, n = 605) in children 3 months to 5 years old. Significant variation existed in the choice of antimicrobial agent for children with pneumonia, with nonrecommended agents frequently prescribed. Conclusion: Significant variation existed in the management of pediatric pneumonia, and adherence to guidelines was low for the group of patients aged 5-18 years. Future studies should attempt to provide guidance to distinguish between viral and bacterial etiology to allow judicious use of antimicrobials

Cytoplasmic Distribution of HIV-1 Tat Sensitizes Jurkat T Cells to Sulphamethoxazole-Hydroxylamine Induced Toxicity

Background: One medication commonly used by HIV-1-infected individuals is the antimicrobial sulphamethoxazole (SMX), which is used in the treatment and prophylaxis of pneumocystis pneumonia. However, SMX is responsible for a very high incidence of hypersensitivity adverse drug reactions (ADRs) in the HIV-1 population. While the pathophysiology of ADRs in general is unknown, sulphamethoxazole-mediated ADRs have been linked to its reactive metabolite sulphamethoxazole-hydroxylamine (SMX-HA). Our previous work has shown that increased expression of the HIV-1 Tat protein in T cells correlated with increased apoptosis after incubation with SMX-HA. In this study we sought to determine the region of the Tat protein responsible for this effect and the mechanism by which Tat contributed to SMX-HA mediated apoptosis. Methods: We established Jurkat T and Cos 7 cell lines that stably expressed full-length Tat (Tat101) and deletion mutants (Tat86, Tat72, Tat48 and Tat∆). These cell lines were then incubated with SMX-HA and assayed for cell viability and production of reactive oxygen species (ROS). We further used confocal microscopy to assess the intracellular distribution of the Tat proteins and to determine if changes in the expression and/or localization of key cytoskeleton proteins contributed to Tat-mediated apoptosis after SMX-HA treatment. Results: Deletion of regions of Tat that lead to increased cytoplasmic accumulation significantly contributed to increased cell death in the presence of SMX-HA. The increased cell death did not require induction of ROS. Quantitative analysis also showed that the Tat-expressing cell lines had significantly lower levels of β-actin and α-tubulin present both before and after treatment with SMX-HA. Increased cytoplasmic localization of Tat correlated with greater disturbances in the distribution of actin filaments. Conclusion: The presence of cytoplasmic Tat in T and epithelial cell lines increases their sensitivity to SMX-HA induced cell death, an effect mediated by the first 48 amino acids of TAT

Drug-induced acute kidney injury in children

Acute kidney injury (AKI) is a serious problem occurring in anywhere between 8 and 30% of children in the intensive care unit. Up to 25% of these cases are believed to be the result of pharmacotherapy. In this review we have focused on several relevant drugs and/or drug classes, which are known to cause AKI in children, including cancer chemotherapeutics, non-steroidal anti-inflammatory drugs and antimicrobials. AKI demonstrates a steady association with increased long term risk of poor outcomes including chronic kidney disease and death as determined by the extent of injury. For this reason it is important to understand the causality and implications of these drugs and drug classes. Children occupy a unique patient population, advocating the importance of understanding how they are affected dissimilarly compared with adults. While the kidney itself is likely more susceptible to injury than other organs, the inherent toxicity of these drugs also plays a major role in the resulting AKI. Mechanisms involved in the toxicity of these drugs include oxidative damage, hypersensitivity reactions, altered haemodynamics and tubule obstruction and may affect the glomerulus and/or the tubules. Understanding these mechanisms is critical in determining the most effective strategies for treatment and/or prevention, whether these strategies are less toxic versions of the same drugs or add-on agents to mitigate the toxic effect of the existing therapy

Propranolol therapy for infantile hemangioma is less toxic but longer in duration than corticosteroid therapy

BACKGROUND: Infantile hemangioma is the most common benign, self-limiting tumour of childhood. Treatment is reserved for hemangiomas that obstruct vital structures or cause significant disfigurement. Traditionally, corticosteroids have been the medical treatment of choice. Since 2008, however, propranolol has been rapidly adopted as an effective pharmacological treatment for infantile hemangioma. Published data regarding the long-term side effects of propranolol are currently lacking. OBJECTIVE: To describe the long-term effects of propranolol and corticosteroids on anthropometric measurements (height, body mass index [BMI]) and blood pressure in children. METHODS: A prospective database analysis of all infantile hemangioma patient visits to the pediatric vascular abnormality clinic at the authors\u27 institution between October 2007 and February 2012 was performed. Anthropometric measures (height and BMI) and blood pressure were analyzed. RESULTS: A total of 290 visits (119 patients) to the pediatric vascular abnormality clinic were reviewed. Of these, 18 patients received medical treatment and their anthropometry was analyzed. BMI percentile increased significantly in patients treated with corticosteroids (P=0.0039). Corticosteroid treatment also resulted in a significant decrease in height percentile (P=0.0078). Anthropometric measures did not cross percentiles in children treated with propranolol. A significant decrease in systolic blood pressure was noted in the propranolol group (P=0.03), but no hypotensive values were recorded. Median treatment duration was significantly longer when patients received propranolol (372 versus 133 days; P=0.0033). CONCLUSION: Propranolol for the treatment of infantile vascular abnormalities does not share the unfavourable effects on patient anthropometry that corticosteroids exhibit; however, a longer duration of therapy is required

Quality of life in children with adverse drug reactions: A narrative and systematic review

Aims Adverse drug reactions are a common problem affecting adults and children. The economic impact of the adverse drug reactions has been widely evaluated; however, studies of the impact on the quality of life of children with adverse drug reactions are scarce. The aim was to evaluate studies assessing the health-related quality of life of children with adverse drug reactions. Methods We conducted a systematic review that included the following electronic databases: MEDLINE, EMBASE and the Cochrane Library (including the Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effects, the Cochrane Controlled Trials Register and the Health Technology Assessment Databases). Results Nine studies were included. Four of the studies were conducted in children with epilepsy; the rest of them involved children with chronic viral hepatitis, Crohn\u27s disease, paediatric cancer and multiple adverse drug reactions compared with healthy children. Based on their findings, authors of all studies concluded that adverse drug reactions had a negative impact on the quality of life of children. No meta-analysis was conducted given the heterogeneous nature of the studies. Conclusions To date, there is no specific instrument that measures quality of life of children with adverse drug reactions, and the information available is poor and variable. In general, adverse drug reactions have a negative impact on the quality of life of affected children. For those interested in this area, more work needs to be done to improve tools that help to evaluate efficiently the health-related quality of life of children with adverse drug reactions and chronic diseases

HIV-1 tat Expression and Sulphamethoxazole Hydroxylamine Mediated Oxidative Stress Alter the Disulfide Proteome in Jurkat T Cells

Background Adverse drug reactions (ADRs) are a significant problem for HIV patients, with the risk of developing ADRs increasing as the infection progresses to AIDS. However, the pathophysiology underlying ADRs remains unknown. Sulphamethoxazole (SMX) via its active metabolite SMX-hydroxlyamine, when used prophylactically for pneumocystis pneumonia in HIV-positive individuals, is responsible for a high incidence of ADRs. We previously demonstrated that the HIV infection and, more specifically, that the HIV-1 Tat protein can exacerbate SMX-HA-mediated ADRs. In the current study, Jurkat T cell lines expressing Tat and its deletion mutants were used to determine the effect of Tat on the thiol proteome in the presence and absence of SMX-HA revealing drug-dependent changes in the disulfide proteome in HIV infected cells. Protein lysates from HIV infected Jurkat T cells and Jurkat T cells stably transfected with HIV Tat and Tat deletion mutants were subjected to quantitative slot blot analysis, western blot analysis and redox 2 dimensional (2D) gel electrophoresis to analyze the effects of SMX-HA on the thiol proteome. Results Redox 2D gel electrophoresis demonstrated that untreated, Tat-expressing cells contain a number of proteins with oxidized thiols. The most prominent of these protein thiols was identified as peroxiredoxin. The untreated, Tat-expressing cell lines had lower levels of peroxiredoxin compared to the parental Jurkat E6.1 T cell line. Conversely, incubation with SMX-HA led to a 2- to 3-fold increase in thiol protein oxidation as well as a significant reduction in the level of peroxiredoxin in all the cell lines, particularly in the Tat-expressing cell lines. Conclusion SMX-HA is an oxidant capable of inducing the oxidation of reactive protein cysteine thiols, the majority of which formed intermolecular protein bonds. The HIV Tat-expressing cell lines showed greater levels of oxidative stress than the Jurkat E6.1 cell line when treated with SMX-HA. Therefore, the combination of HIV Tat and SMX-HA appears to alter the activity of cellular proteins required for redox homeostasis and thereby accentuate the cytopathic effects associated with HIV infection of T cells that sets the stage for the initiation of an ADR