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Biomedical subjects

N H Shear

Publications and source records attributed to N H Shear.

At least 37 records · Page 2Linked to original sources
PubMed2001

Reporting of fatal adverse drug reactions.

OBJECTIVES: To review the reports of fatal adverse drug reactions (ADRs) submitted to the Ontario Medical Association Adverse Drug Reactions Monitoring Program between 1990 and 1994; to identify drugs associated with fatal outcomes; and to assess the causative role of the drug in these events and the completeness of the data in these reports. METHODS: Drug(s) identified on each ADR report as being responsible for the reaction were considered. Agents were classified by the Anatomical Therapeutic and Chemical classification system. The causality of each ADR report was evaluated by using an algorithmic rating scale. RESULTS: From the Ontario Medical Association database, 97 cases of ADRs that resulted in death were reviewed. One hundred fourteen medications were implicated as "suspect" drugs in the 97 deaths. The most commonly implicated drug classes were musculoskeletal agents, blood and blood-forming organ agents, and nervous system agents. Patients over 65 years of age comprised 60% of this series. After independent assessment as to causality, 13% of the cases were rated as probable, 86% were rated as possible and 1% were rated as doubtful. Seventy per cent of reports did not include information regarding medical history. Forty-two per cent of cases failed to provide adequate information to evaluate the feasibility of the time to onset of the ADR. The use of concomitant drugs was not reported in 12% of cases. CONCLUSIONS: The drugs most frequently implicated in fatal ADRs were consistent with those reported in other studies. Algorithmic causality assessments were of limited value in these reports. The completeness of the reports and adequacy of the information were poor. The type of reporting forms and information provided were not homogenous. There is a need to improve quality of reporting and harmonize reporting forms between monitoring bodies. The feasibility of unique data collection forms and obligatory reporting for fatal ADRs should be considered.

Adult↗
PubMed2001

The science of health technology assessment: the safety perspective.

Efforts to enhance the reporting and analysis of drug reactions have increased over recent years. Research into the pathogenesis, diagnosis and epidemiology has yielded important insights, yet major gaps in our management of drug safety still exist. Drug-induced diseases are an important cause of morbidity and mortality. Current ad hoc reporting systems fail to collect more than 10% of even the most serious of reactions. Drug reaction syndromes lack universally accepted definitions and names. Effective therapies for drug-induced diseases are few and poorly studied. Information about how to diagnose and treat drug-induced diseases is not reaching practitioners. Stakeholders, including regulatory agencies, funding agencies, the pharmaceutical industry, physicians, pharmacists and patient advocacy groups, need to work together to improve the systematic approach to drug safety and to make all stakeholders aware of advances in the technology surrounding drug-induced disease. The technology is available to make major strides in improving the overall management of drug-induced disease. The major barrier to progress is the lack of leadership from any of the powerful sectors involved in drug use.

Adverse Drug Reaction Reporting Systems↗
PubMed2000

Idiosyncratic drug reactions: the reactive metabolite syndromes.

Idiosyncratic drug reactions are unpredictable reactions that can result in significant morbidity and mortality. Severe reactions are often characterised by fever and internal organ involvement. Despite progress in the identification of reactive metabolites believed to be the cause of idiosyncratic reactions, the basic mechanisms remain elusive. Furthermore, because of the lack of consensus regarding definition of these syndromes, reporting, and therefore epidemiological data, are often unreliable. Research is needed to explore further the pathophysiology of these reactions, so that better diagnostic tests and treatment methods can be developed.

Drug Hypersensitivity↗
PubMed2000

A novel lymphocyte toxicity assay to assess drug hypersensitivity syndromes.

OBJECTIVES: To validate the novel lymphocyte toxicity assay (LTA) based on the mitochondrial succinate dehydrogenase (SDH) activity vs. the LTA by using trypan blue exclusion and to determine the utility of the assay to confirm drug hypersensitivity syndrome (DHS) to sulphonamides (SMX) and aromatic anticonvulsants. METHODS: Incubation of patient lymphocytes, with or without murine hepatic microsomes with anticonvulsants or SMX. The viability of lymphocytes was based on SDH activity that can be measured spectrophotometrically. The percentage of cells displaying cytotoxicity compared to controls (cells treated only with drug) was calculated. Seventy-two immunocompetent and 16 immunocompromised (HIV) patients with DHS to SMX were sampled. The results were validated vs. 26 controls that had not experienced DHS to SMX. Sixty-two patients who had DHS to anticonvulsants were compared with 24 controls that did not have any DHS to the same anticonvulsants. RESULTS: The results showed a very good percentage of sensitivity 98 and specificity 96 with a kappa-score of 0.96. LTA higher than 13.5% was considered positive for the immunocompetent population and LTA higher than 22% was positive for the immunocompromised population. In two of the 26 controls, LTA was positive. CONCLUSION: The high quantitative kappa-value 0.96 emphasizes that the novel LTA is at least as good as the trypan blue assay. The latter is labor intensive, time consuming, and prone to human error. The new assay is objective, faster, and has been reproducible in assessing cytotoxicity.

Adolescent↗
PubMed2000

Open-label study to evaluate the healing rate and safety of the Profore Extra Four-Layer Bandage System in patients with venous leg ulceration.

BACKGROUND: Venous ulcers are increasing in prevalence, especially since these are observed more frequently in the elderly, and the number of individuals in this age group is becoming a larger portion of the population. OBJECTIVE: To determine the healing rate and safety of the Profore Extra Four-Layer Bandage System in the management of venous leg ulcers. METHODS: In an open-label study, patients aged 18 years or older with venous leg ulcers were treated with a high compression four-layer bandage system in which a hydrocellular dressing was placed in contact with the wound. The combination is designated the "Profore Extra Four-Layer Bandage System." Follow-up visits took place weekly unless there was heavy exudation from the ulcer or if there was marked edema of the leg at the start of the study requiring reapplication of the bandage system. RESULTS: Fifteen patients were entered into the study (men 8, women 7, mean age 66 years, mean duration of ulcers 1.3 years). Thirteen of the 15 patients completed the study, with two withdrawals. In one patient who withdrew, the ulcer became infected and required treatment with antibiotics. The other termination from the study occurred for reasons unrelated to treatment. The ulcer in this patient healed in 7 weeks. Ten of the 13 patients (77%) who completed the study, and 10 (67%) of 15, who had enrolled experienced complete (100%) healing. Healing of > 80% of the ulcers occurred in 11 of 13 patients (85%) who completed the study and in 12 (80%) of 15 enrolled patients. No patient experienced a study-related adverse event. One patient developed contact dermatitis and was later found to have stasis dermatitis. It is unclear whether the initial event was contact or stasis dermatitis. CONCLUSION: In this open-label study, a high compression system, using the Profore Extra Four-Layer Bandage with a hydrocellular dressing in contact with the wound, was found to be effective and safe for the treatment of venous leg ulcers.

Aged↗
PubMed2000

A risk-benefit assessment of the newer oral antifungal agents used to treat onychomycosis.

The newer antifungal agents itraconazole, terbinafine and fluconazole have become available to treat onychomycosis over the last 10 years. During this time period these agents have superseded griseofulvin as the agent of choice for onychomycosis. Unlike griseofulvin, the new agents have a broad spectrum of action that includes dermatophytes, Candida species and nondermatophyte moulds. Each of the 3 oral antifungal agents, terbinafine, itraconazole and fluconazole, is effective against dermatophytes with relatively fewer data being available for the treatment of Candida species and nondermatophyte moulds. Itraconazole is effective against Candida onychomycosis. Terbinafine may be more effective against C. parapsilosis compared with C. albicans; furthermore with Candida species a higher dose of terbinafine or a longer duration of therapy may be required compared with the regimen for dermatophytes. The least amount of experience in treating onychomycosis is with fluconazole. Griseofulvin is not effective against Candida species or the nondermatophyte moulds. The main use of griseo-fulvin currently is to treat tinea capitis. Ketoconazole may be used by some to treat tinea versicolor with the dosage regimens being short and requiring the use of only a few doses. The preferred regimens for the 3 oral antimycotic agents are as follows: itraconazole - pulse therapy with the drug being administered for 1 week with 3 weeks off treatment between successive pulses; terbinafine - continuous once daily therapy; and fluconazole - once weekly treatment. The regimen for the treatment of dermatophyte onychomycosis is: itraconazole - 200mg twice daily for I week per month x 3 pulses; terbinafine - 250 mg/day for 12 weeks; or, fluconazole - 150 mg/wk until the abnormal-appearing nail plate has grown out, typically over a period of 9 to 18 months. For the 3 oral antifungal agents the more common adverse reactions pertain to the following systems, gastrointestinal (for example, nausea, gastrointestinal distress, diarrhoea, abdominal pain), cutaneous eruption, and CNS (for example, headache and malaise). Each of the new antifungal agents is more cost-effective than griseofulvin for the treatment of onychomycosis and is associated with high compliance, in part because of the shorter duration of therapy. The newer antifungal agents are generally well tolerated with drug interactions that are usually predictable.

Administration, Oral↗
PubMed1999

Utilization of health care resources by obese Canadians.

BACKGROUND: The prevalence of obesity in Canada has been increasing in recent years. Using data from the National Population Health Survey (NPHS), the authors determined the prevalence of obesity among Canadians, the associated comorbidities and the patterns of resource utilization by obese people. METHODS: The NPHS, a cross-sectional survey conducted in 1994, was administered to 17,626 Canadians 12 years of age or older who were not long-term residents of hospitals or long-term care facilities and were not residing on First Nations reserves or Canadian Armed Forces bases, or in the Yukon and Northwest Territories. For the authors' analysis, the study population consisted of 12,318 Canadians aged 20-64 years who were not pregnant and for whom the body mass index (BMI) had been calculated. The prevalence of comorbidities, health status index scores, self-esteem, self-rated health, restriction of activity, health care resource utilization (physician visits, disability days, admissions to hospital and medication use) were determined for obese people (BMI of 27 or greater) and nonobese people. RESULTS: The NPHS data revealed that 35.2% of men and 25.8% of women in Canada were obese in 1994. Obese respondents were more likely than nonobese respondents to suffer from stress (adjusted odds ratio [OR] 1.20, 95% confidence interval [CI] 1.11-1.31), activity restrictions (adjusted OR 1.39, 95% CI 1.26-1.54) and a number of chronic comorbidities. Obese respondents were also more likely to consult with physicians (adjusted OR 1.32, 95% CI 1.22-1.43), be prescribed a number of medications and to require excess disability days (adjusted OR 1.22, 95% CI 1.08-1.36). INTERPRETATION: Obesity represents a substantial burden on the health of Canadians and on Canada's health care resources.

Adult↗
PubMed1999

Inducers of cytochrome P450 2E1 enhance methotrexate-induced hepatocytoxicity.

OBJECTIVES: To study the effect of cytochrome P450 2E1-inducers on methotrexate (MTX)-induced cytotoxicity in human hepatocytes, and investigate the role of silymarin in preventing this toxicity. DESIGN AND METHODS: Cells were exposed to MTX in the presence of either ethanol (EtOH) or acetaminophen (APAP), or either combined with silymarin (S). Apoptosis and necrosis were measured by analyzing 6000 cells/sample using transmission electron microscopy, while cytokine release and apoptosis were quantitated by ELISA. Cytokine expression was measured by RT-PCR. Gluthatione (GSH) content was determined in cytosolic (c) and mitochondrial (m) fractions. RESULTS: MTX+EtOH and MTX+APAP increased MTX cytotoxicity 2.9-fold and 1.9-fold, respectively. S abolished this toxicity. MTX + EtOH increased the release of IL 6, IL 8 and TNF alpha by 1.0, 1.2, and 1.1 times, respectively. Cytokine expression was upregulated versus control for IL 6 (22%), IL 8 (38%), and TNF alpha (29%). Addition of 0.5 mmol/L S downregulated TNF alpha expression and reduced cytokine release. TNF alpha increased cytotoxicity by 22%, while anti-TNFalpha antibody eradicated it. MTX+EtOH depleted 45% mGSH (0 < 0.001) while S replenished it to 87% (p < 0.001), when both were compared to control levels. CONCLUSIONS: Cytochrome P450 2E1-inducers contribute to increase oxidative stress in MTX-exposed cells by increasing TNF alpha and depleting both cGSH and mGSH. This enhances MTX-cytotoxicity and promotes apoptosis.

Apoptosis↗
PubMed1999

Predictors of sustained response to alpha interferon therapy in chronic hepatitis C.

OBJECTIVES: To utilize cytokine levels to predict sustained response (SR) to alpha interferon (IFN alpha) therapy in chronic hepatitis C patients, and to determine the relationship between serum tumor necrosis factor alpha (TNF alpha), interleukin (IL) IL 6, IL 8, IL 12, transforming growth factor beta (TGF beta 1) and the degree of liver damage as reflected by traditional markers. DESIGN AND METHODS: Serum cytokine levels were assessed using ELISA in 18 patients included in a controlled clinical trial of IFN alpha. RESULTS: Of the 18 patients, 27% were sustained responders (SR), 27% were response and relapse responders (RR), and 46% were non-responders (NR). Multivariate analysis showed that a low serum TNF alpha level and high serum IL 8 levels were independent factors associated with SR to IFN alpha therapy. Serum TNF alpha level highly correlated with viral load and genotype predictive values (p < 0.001). Therapy lowered the IL 6 and IL 12 profile. TGF beta 1 levels in serum are positively correlated with fibrinogenesis. CONCLUSIONS: IFN alpha therapy modulates immune response to hepatitis C virus, contributing to sustained response.

Adult↗
PubMed1999

Ethanol-induced apoptosis in vitro.

OBJECTIVES: The aim is to study the apoptotic process in a human hepatocyte model for ethanol (EtOH)-induced apoptosis. DESIGN AND METHODS: Normal human primary hepatocytes (HPH) and Hep G2 cells were exposed to increasing EtOH. 6000 cells/ sample were analyzed by transmission electron microscopy. RESULTS: Apoptotic cells were observed (mmol/L EtOH): 40: 6 +/-0.5%, 60:13 +/- 2% (p < 0.05), 80: 26 +/- 1% (p < 0.001) (vs. control). Two consecutive doses of 80 mmol/L for 24 h each additionally increased apoptosis 55 +/- 3% (p < 0.0001 vs. control and p < 0.001 vs. single dose). In response to this exposure, there is a stronger apoptotic activity in HPH when compared to Hep G2 (p < 0.05). CONCLUSIONS: In vitro, EtOH-induced apoptosis is regulated by dose level and the frequency of exposure.

Apoptosis↗
PubMed1999

Drug interactions with itraconazole, fluconazole, and terbinafine and their management.

A drug interaction develops when the effect of a drug is increased or decreased or when a new effect is produced by the prior, concurrent, or subsequent administration of the other. Before prescribing a drug, it is important to obtain a thorough drug history of the prescription and nonprescription medications taken by the patient. The nonprescription medications may include items such as nutritional supplements and herbal medications. The risk of side effects is an inevitable consequence of drug use. The frequency of adverse reactions is increased in those patients receiving multiple medications. Drug interactions reported in animal or in vitro studies may not necessarily develop in humans. When drug interactions are observed with a particular agent, it cannot be automatically assumed that all closely related drugs will necessarily produce the same interaction. However, caution is advised until sufficient experience accrues. The prescriber should not overestimate or underestimate the potential for a given drug interaction on the basis of personal experience alone. Drug interactions will not necessarily occur in every patient who is given a particular combination of drugs known to produce an interaction. For a clinically significant drug interaction to be manifest, several other factors may be relevant other than just using the two drugs. In many instances drug interactions can be predicted and therefore avoided if the pharmacodynamic effects, the pharmacokinetic properties, and the mechanisms of action of the 2 drugs in question are known. In the case of contraindicated drugs, it may be possible to use an alternative agent.

Animals↗