Simultaneous measurement of cardiac output and its distribution with microspheres in the rat.
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Biomedical subjects
Publications and source records attributed to D G McDevitt.
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BACKGROUND: Psychomotor studies suggest that commonly prescribed psychoactive drugs impair driving skills. We have examined the association between the use of psychoactive drugs and road-traffic accidents. METHODS: We used dispensed prescribing as a measure of exposure in a within-person case-crossover study of drivers aged 18 years and over, resident in Tayside, UK, who experienced a first road-traffic accident between Aug 1, 1992, and June 30, 1995, and had used a psychoactive drug (tricyclic antidepressant, benzodiazepine, selective serotonin-reuptake inhibitor, or other psychoactive drug [mainly major tranquillisers]) between Aug 1, 1992, and the date of the accident. For each driver, the risks of having a road-traffic accident while exposed and not exposed to a drug were compared. FINDINGS: 19386 drivers were involved in a first road-traffic accident during the study period. 1731 were users of any study drug. On the day of the accident, 189 individuals were taking tricyclic antidepressants (within-patient exposure odds ratio for an accident 0.93 [95% CI 0.72-1.21]), 84 selective serotonin-reuptake inhibitors (0.85 [0.55-1.33]), 235 benzodiazepines (1.62 [1.24-2.12]), and 47 other psychoactive drugs (0.88 [0.62-1.25]). The risk associated with benzodiazepine use decreased with increasing driver's age and was greater when the breath test for alcohol was positive. A dose-response relation was evident with benzodiazepines. The increased risk with benzodiazepines was significant for long-half-life drugs, used as anxiolytics, and for short-half-life hypnotics (all zopiclone). INTERPRETATION: Users of anxiolytic benzodiazepines and zopiclone were at increased risk of experiencing a road-traffic accident. Users of anxiolytic benzodiazepines and zopiclone should be advised not to drive.
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OBJECTIVES: To determine the profile of risk of upper gastrointestinal toxicity during continuous treatment with, and after cessation of, non-steroidal anti-inflammatory drugs. DESIGN: Cohort study with a prospectively constructed, population based, record linkage database containing details of exposure to all community dispensed non-steroidal anti-inflammatory drugs and also all admissions to hospital for upper gastrointestinal diagnoses. SETTING: The population of Tayside, Scotland. SUBJECTS: 52,293 subjects aged 50 and over who received one or more non-steroidal anti-inflammatory between 1 January 1989 and 31 December 1991 and 73,792 subjects who did not receive one during the same period (controls). MAIN OUTCOME MEASURES: Admission to hospital for upper gastrointestinal bleeding and perforation, and admission for other upper gastrointestinal diagnoses. RESULTS: About 2% of the non-steroidal anti-inflammatory cohort were admitted with an upper gastrointestinal event during the study period compared with 1.4% of controls. The risk of admission for upper gastrointestinal haemorrhage and perforation was constant during continuous non-steroidal anti-inflammatory exposure and carried over after the end of exposure. The results were similar for admissions for all upper gastrointestinal events. CONCLUSION: This study provides evidence that non-steroidal anti-inflammatory toxicity persists with continuous exposure. There seems to be carryover toxicity after the end of prescribing. These findings have implications for the management of patients requiring non-steroidal anti-inflammatory drugs.
This cohort study examined the relationship between newly prescribed NSAIDs (none in the previous six months) and upper gastrointestinal hemorrhage and perforation in Tayside, Scotland. Exposure was classified by prescription duration. The study population consisted of the population of Tayside. A Comparator Group was chosen at random (within age and sex strata). Two hundred re-sampled comparator groups were created. Statistical analyses were carried out by Poisson regression (repeated for each of the re-samples). The analyses controlled for age, sex, prior hospitalization for upper gastrointestinal events, prior endoscopy, and the use of ulcer healing drugs. There were 78,191 subjects in the NSAID group, and 78,207 in each of the comparator groups. The increased risk with NSAIDs was only apparent for subjects without a history of upper gastrointestinal events; univariate rate ratio = 2.76 (1.90, 4.01). The final, re-sampled estimate of NSAID risk was rate ratio = 2.48 (1.87, 3.29).
BACKGROUND: To evaluate the relation between non-steroidal anti-inflammatory drugs (NSAIDs) and colitis due to inflammatory bowel disease. METHODS: A case-control study was conducted using a prospectively constructed, record linkage database containing hospital event and dispensed drug data (1989-93). The study population consisted of 319,465 people resident in Tayside in January 1989, and still resident (or dead) in October 1994. RESULTS: Of the 785 patients admitted to hospital as emergencies with colitis between July 1989 and June 1993, 200 fulfilled the case criterion of colitis due to inflammatory bowel disease. A further 1198 persons were used as community controls. Odds ratios were calculated for three exposure periods (current, recent, and past exposure). The overall odds ratios (with 95% confidence intervals) for current and recent exposure to NSAIDs were 1.77 (1.01 to 3.10) and 1.93 (1.20 to 3.09) respectively. Current and recent exposure to NSAIDs was also associated for incident cases, with odds ratios of 2.96 (1.32 to 6.64) and 2.51 (1.13 to 5.55). There was a trend for recent exposure among non-incident cases. CONCLUSION: The use of NSAIDs may be associated with an increased risk of emergency admission to hospital for colitis due to inflammatory bowel disease, particularly among patients with no previous history.
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OBJECTIVE: To evaluate the relation between topically applied non-steroidal anti-inflammatory drugs and upper gastrointestinal bleeding and perforation. DESIGN: A case-control study with 1103 patients admitted to hospital for upper gastrointestinal bleeding or perforation between January 1990 and December 1992 (cases). Two different control groups were used, with six community controls and with two hospital controls for each case. Previous exposure to topical and oral non-steroidal anti-inflammatory drugs and ulcer healing drugs was assessed. STUDY POPULATION: The population of 319,465 people who were resident in Tayside and were registered with a Tayside general practitioner between January 1989 and October 1994. A record linkage database containing all data on hospital events and dispensed drugs between 1989 and 1992 was used for this population. MAIN OUTCOME MEASURES: Unadjusted and adjusted odds ratios of exposure in those admitted to hospital compared with controls. RESULTS: Significant unadjusted associations were detected between all three classes of drug and upper gastrointestinal complications. The significant association detected for topical non-steroidal anti-inflammatory drugs was no longer evident in analyses which adjusted for the confounding effect of concomitant exposure to oral anti-inflammatories and ulcer healing drugs (odds ratio = 1.45; 95% confidence interval 0.84 to 2.50 with community controls; 1.06; 0.60 to 1.88 with hospital controls). CONCLUSION: In this study topical non-steroidal anti-inflammatory drugs were not significantly associated with upper gastrointestinal bleeding and perforation after adjustment for the confounding effects of concomitant use of oral anti-inflammatories and ulcer healing drugs.
The aim of the present study was to evaluate the central effects of single doses of the beta-adrenoceptor antagonist atenolol and the calcium antagonist nifedipine retard, alone and in combination, in normal subjects. Twelve normal males received single oral doses of atenolol 100 mg, nifedipine retard 20 mg, atenolol 100 mg and nifedipine retard 20 mg in combination, diazepam 5 mg (active control), and each of two matching placebos in a double-blind, randomised fashion. Psychomotor performance was assessed using digit symbol substitution, letter cancellation (LCT), continuous attention, choice reaction time, finger tapping, immediate recall and short-term memory. Two flash fusion and critical flicker fusion thresholds were measured and subjective assessments made using visual analogue scales (VAS). Diazepam 5 mg significantly worsened LCT scores at 4h, significantly impaired alertness at 2 h and 4 h, and tended to increase reaction time and impair continuous attention and physiological measurements. Atenolol 100 mg alone significantly reduced alertness at 2 h and 4 h, and also tended to impair physiological measurements. Nifedipine retard 20 mg produced no significant psychomotor effects. Combined atenolol and nifedipine retard administration produced a small but significant improvement in continuous attention and a reduction in body sway, with no adverse effects being evident on performance or subjective awareness. The results suggest that no significant adverse effects on psychomotor performance are produced by single doses of atenolol 100 mg and nifedipine retard 20 mg when given together in normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
This was an observational study of efficacy and resource utilisation over three years in a cohort of 917 patients who received at least one prescription for an oral antibiotic between January and March 1989 in a large rural primary care health centre in Tayside, Scotland. Three thousand, six hundred and sixty three prescriptions were issued (2286 to females) for; 1502 upper respiratory tract infections, 419 lower respiratory tract infections, 441 urinary tract infections, 177 skin and soft tissue infections, 97 gynaecological infections, 103 cases of acne and 71 other infections. Excluding acne, 14% of infections required more than one antibiotic to achieve a successful outcome. The highest success rates for antibiotics were amoxycillin (92%) and penicillin V (92%) in upper respiratory tract infections, erythromycin (90%) in lower respiratory tract infections and co-trimoxazole (83%) in urinary tract infections. The most cost-effective antibiotics were penicillin V for upper respiratory tract infection, erythromycin for lower respiratory tract infection and co-trimoxazole for urinary tract infection. Varying the value placed on general practitioners' time did not change the rank order of antibiotic cost-effectiveness. The efficacy and cost-effectiveness of the treatment of acute infections in primary care varies considerably with the antibiotic used as first choice. More expensive antibiotics might be justified in cost-effectiveness terms if they had high cure rates in clinical practice.
BACKGROUND: There is controversy as to the relative safety of fenoterol and salbutamol. No differences have been found in the relative cardiac beta 1/beta 2 receptor activity of inhaled fenoterol and salbutamol in normal subjects. These initial findings have been extended by comparing the respective potencies of equivalent doses by weight of fenoterol and salbutamol in asthmatic subjects, in terms of airways and systemic responses. METHODS: Eighteen asthmatic patients of mean (SD) age 40 (14) years and a forced expiratory volume in one second (FEV1)% predicted of 56 (14)% (1.97 (0.66)1) were randomised to inhale fenoterol (100 micrograms/puff or 200 micrograms/puff), salbutamol, or placebo (100 micrograms/puff or 200 micrograms/puff) on three separate days. Dose-response curves were constructed using cumulative doses of 100 micrograms, 200 micrograms, 400 micrograms, 1000 micrograms, 2000 micrograms, and 4000 micrograms, and airways and systemic responses were measured 20 minutes after each dose with 40 minute increments. Dose ratios for the relative potency of fenoterol versus salbutamol were calculated from the dose-response curves using regression analysis of parallel slopes. RESULTS: There was no difference in bronchodilator potency between fenoterol and salbutamol (as median dose ratio): FEV1 1.1 (95% CI 0.4 to 4.6). In contrast, dose ratios for systemic responses showed that fenoterol was more potent than salbutamol: serum potassium 3.7 (95% CI 2.0 to 6.0), tremor 5.7 (95% CI 1.4 to 10.2), heart rate 1.6 (95% CI 1.0 to 2.3). At a conventional dose of 200 micrograms the only difference in response between the two drugs was observed for tremor (as mean difference): 0.23 log units (95% CI 0.06 to 0.41 log units). CONCLUSIONS: There was no difference in the bronchodilator potency between fenoterol and salbutamol on a microgram equivalent basis. In contrast, systemic potency was greater with fenoterol, although this difference was not clinically relevant at conventional dosages up to 200 micrograms.
BACKGROUND: There is controversy as to the role of long acting beta 2 agonists such as eformoterol and, in particular, whether bronchodilator tolerance occurs during continuous therapy. The purpose of this study was to extend previous observations of bronchodilator subsensitivity with metered dose eformoterol aerosol in order to assess whether tolerance also occurs with a dry powder formulation of the same drug. METHODS: Sixteen asthmatic patients of mean age 33 (range 18-53) years and FEV1 (% predicted) of 64 (3)%, of whom 13 were receiving inhaled corticosteroids, received regular treatment with eformoterol 24 micrograms twice daily or placebo twice daily (without beta 2 agonists) given concurrently for four weeks in a randomised double blind cross-over design. An initial two week run-in was used when beta 2 agonists were withdrawn and substituted with ipratropium bromide. Dose-response curves to eformoterol (cumulative dose 6-102 micrograms) for airways and systemic beta 2 responses were constructed at the end of each treatment period. RESULTS: Baseline values for airways and systemic responses were similar. The peak delta FEV1 response from the dose-response curve (as change from baseline) and the delta response for FEV1 and FEF25-75 at six hours after the last dose were attenuated after eformoterol compared with placebo: peak delta FEV1 response 1.001 with placebo v 0.841 with eformoterol (95% CI 0.04 to 0.28); at six hours 0.931 with placebo v 0.581 with eformoterol (95% CI 0.20 to 0.50); and for delta FEF25-75 at six hours 1.29 1/s with placebo v 0.87 1/s with eformoterol (95% CI 0.15 to 0.69). Morning peak expiratory flow rate was significantly improved during treatment with eformoterol (451 1/min) compared with placebo (399 1/min) (95% CI 21 to 82). Systemic beta 2 responses were blunted after eformoterol, together with a reduction in lymphocyte beta 2 receptor binding density. CONCLUSIONS: Regular twice daily eformoterol dry powder may produce bronchodilator subsensitivity in terms of both peak and duration of response to cumulative repeated doses of eformoterol. Systemic beta 2-mediated adverse effects also showed tolerance, which was mirrored by downregulation of lymphocyte beta 2 adrenoceptors.
INTRODUCTION: Scottish Morbidity Record (SMR1) data are coded by trained clerical staff from case records and discharge summaries. They form the basis of many strategic NHS decisions. Their accuracy for upper gastrointestinal (UGI) diagnosis is unknown and the study was undertaken to assess this accuracy in Tayside. METHOD: Patients who fulfilled the following criteria were identified using a record-linkage pharmacoepidemiological database, and their case records retrieved: over 50 years of age, had encashed at least one prescription for a non-steroidal anti-inflammatory drug at a Tayside pharmacy and who had SMR1 records containing one or more symptom/diagnosis codes between January 1989 and December 1991. Medically qualified staff were trained to examine case records and to code UGI diagnoses. They searched the case records for every UGI SMR1 entry for these patients from 1980-1992 and produced re-coded diagnoses (RCD) for each hospital event (admission and discharge), using all the data available in the case records. They also abstracted data on the clinical presentation, investigations and management of patients. Each event was then examined by a single medically qualified researcher who compared the original SMR1 codes with the RCDs. RESULTS: 2,101 patients had a total of 3,764 events in 1989-1991. 317 events were either day case procedures or elective surgery or the case records were not found. They were therefore excluded. Of the remainder, the SMR1 and RCD codes were judged equivalent in 1,608 events (46.6%). However, 1,005 SMR1 events (29.2%) contained a symptom code but no diagnosis code and the remaining 834 (24.2%) were judged suboptimal for other reasons. Of those with a symptom code only, 406 could not be improved upon and were transformed into RCD symptom codes only, 435 were assigned symptom and diagnostic RCDs and 164 were assigned diagnostic RCDs only. In the other 834 events, 279 had one or more diagnoses missing, 425 had one or more diagnoses inaccurate, 23 had both missing and inaccurate diagnoses and 107 were not UGI. Thus 1,433 (41.6%) of UGI SMR1 events could be more accurately coded. Examination of investigation data revealed that coding inaccuracy was not due to diagnostic procedures being carried out after admission. CONCLUSION: UGI SMR1 data were satisfactory in about half of all events. In about a quarter there were symptom codes but no satisfactory diagnosis codes, whilst in another quarter the data were inaccurate. These findings have implications for health care activities and research that use these data.
Non-steroidal anti-inflammatory drugs (NSAIDs) have been implicated in the aetiology of acute renal failure (ARF), but epidemiological studies examining this association have produced disparate results. We conducted a case-control study using a purpose-built record-linkage database for a population of 420,600 patients, resident in Tayside since May 1990. Patients (n = 207) hospitalized with a diagnostic code for ARF between 1990 and 1992 had their diagnosis validated by a renal physician. Six community controls and two hospital controls, matched for age and sex, were generated for each of these cases. Exposure to dispensed oral NSAIDs, topical NSAIDs and aspirin during the 90 days prior to the index date were investigated (recent exposure), as was exposure at any time since January 1989 (previous exposure). The most significant associations were modelled using conditional logistic regression. When community controls were used, recent exposure to NSAIDs and previous exposure to aspirin were independently associated with hospitalization for ARF, with adjusted odds ratios of 2.20 (1.49-3.25) and 2.19 (1.46-3.30), respectively. Only recent exposure to oral NSAIDs was associated when hospital controls were used: 1.84 (1.14-2.93). No significant interactions were present with previous chronic renal failure, other possible causes of ARF or whether the diagnosis was primary or secondary. There is an approximate doubling of the risk of hospitalization for ARF with use of oral NSAIDs.
We compared the beta 1-selective adrenoceptor antagonists bisoprolol and atenolol in a double-blind, randomized crossover study. After 4 weeks placebo phase, 59 patients with essential hypertension received either 10 mg bisoprolol or 50 mg atenolol once daily for 8 weeks, increased if necessary (target BP < or = 150/90 mmHg) to 20 and 100 mg, respectively, after 4 weeks. After a second placebo phase, crossover occurred to the alternative drug. We measured resting systolic and diastolic blood pressures and heart rate at 24 h post-dose baseline and after 4 and 8 weeks treatment. Both drugs significantly lowered systolic and diastolic blood pressures and heart rate at 8 weeks compared to baseline (all p < 0.05). Bisoprolol reduced heart rate significantly more than atenolol (p < 0.01), but systolic and diastolic blood pressure changes were not different between the two drugs. There was no difference in patient acceptability of the drugs as assessed by visual analogue scale. Despite theoretical and circumstantial evidence to suggest superiority of bisoprolol over atenolol, no significant difference between the two was found except for greater heart rate reduction with bisoprolol.
The central effects of atenolol (50 mg tds) and captopril (50 mg tds) ingested for a period of seven days were studied in ten healthy volunteers. A placebo and two active control drugs, methyldopa (250 mg tds) and oxazepam (10 mg), were included in the design. Oxazepam was ingested on the seventh day only, with a placebo being taken on the preceding six days. On the seventh day, central effects of the drugs were tested at 10.00-11.00 h (session 1), immediately before the subjects' last dose of each drug and at 2.5-3.5 h after the final dose of each drug (1330-1430 h, session 2). Performance was assessed using digit symbol substitution, continuous attention, letter cancellation, choice reaction time, finger tapping, immediate and short-term memory, critical flicker fusion and two flash fusion. Subjects assessed their mood and well-being on a series of 12 visual analogue scales. Recordings of the EEG and body sway were carried out. Neither atenolol nor captopril altered performance at any of the skills tested. There were no effects on subjectively assessed alertness or mood with captopril, while atenolol significantly increased wakefulness in session 2 and when the two sessions were meaned. Similarly, captopril did not modify body sway, while with atenolol there was a significant decrease in activity in the frequency range 1.0-2.75 Hz from session 1 to session 2.(ABSTRACT TRUNCATED AT 250 WORDS)
Extrapulmonary beta 2-adrenoceptor mediated responses to salbutamol were evaluated in 9 healthy female subjects during the follicular (day 2-4, Visit 1) and luteal (day 21-23, Visit 2) phases of the menstrual cycle, and were compared with those of 9 age-matched male controls. At each visit, salbutamol was given by intravenous infusion for 30 minutes at a dose of 0.2 mg.kg-1.min-1. Plasma salbutamol concentration and responses in heart rate (HR), finger tremor (Tr), Q-T interval (Q-Tc), serum potassium (K), serum insulin (Ins) and serum glucose (Glu) were measured at baseline and at 10, 20 and 30 minutes after commencing the infusion. Comparisons were made between sexes and between visits for peak responses calculated as percentage change from baseline. Mean plasma salbutamol concentration (ng.ml-1) were not significantly different between males and females on Visit 1: 6.9 (95% CI 6.01, 7.82) vs 7.3 (95% CI 6.4, 8.3), or on Visit 2: 6.9 (95% CI 6.0, 7.8) vs 7.2 (95% CI 6.3, 8.1). On Visit 1, significantly greater responses were demonstrated in females, compared with males for K (as mean difference): 6 (95% CI 1, 11)%, Tr: 17 (95% CI 1, 33)%, Q-Tc: 8 (95% CI 2, 14)% and Ins: 276 (95% CI 71, 481)%. In addition, a significantly greater response was demonstrated in females on Visit 1 compared with males on Visit 2 for HR (as mean difference): 32 (95% CI 1, 63)%, and for Ins: 262 (95% CI 57, 467)%. Thus, despite no difference in plasma salbutamol concentrations, female subjects exhibited greater responsiveness to salbutamol compared with males during the follicular phase of the menstrual cycle. This suggests that in vivo, females have enhanced sensitivity of extrapulmonary beta 2-adrenoceptors.
PURPOSE: The aim of the present study was to evaluate in vivo and in vitro beta 2-adrenoceptor responsiveness after chronic inhaled therapy with the long-acting beta 2-agonist eformoterol or placebo, given twice daily, in patients with mild to moderate asthma. PATIENTS AND METHODS: Seven asthmatic patients, age 34 +/- 5 years were evaluated. Mean forced expiratory volume in 1 second (FEV1) (% predicted) at entry was 58 +/- 5%. After at least 2 weeks run-in without beta 2-agonist therapy, patients were randomized to receive regular treatment with eformoterol 24 micrograms twice daily or placebo twice daily given by metered-dose inhaler for 4 weeks, in a double-blind, crossover design. Dose-response curves (DRC) to eformoterol (cumulative dose 6 micrograms to 126 micrograms) for airways and systemic beta 2-responses were constructed at the end of each treatment period. Responses were measured at baseline, 30 minutes after each dose, and for 6 hours after the last dose. In addition, in vitro parameters of lymphocyte beta 2-receptor function were evaluated prior to the DRC after each treatment period. RESULTS: There was a nonsignificant trend towards higher baseline values after eformoterol compared with placebo for FEV1: 0.16 L (95% CI -0.04 to 0.36) and forced expiratory flow (FEF25-75): 0.27 L/sec (95% CI -0.08 to 0.62). The peak bronchodilator response from the DRC and response 6 hours after the last dose were both significantly (P < 0.05) attenuated after chronic therapy with eformoterol compared with placebo. The mean differences between eformoterol and placebo for delta FEV1 were as follows: peak: 0.26 L (95% CI 0.09 to 0.43), and at 6 hours: 0.39 L (95% CI 0.20 to 0.58). Corresponding values for delta FEF25-75 were as follows: peak: 0.41 L/sec (95% CI 0.10 to 0.71), 6 hours 0.52 L/sec (95% CI 0.22 to 0.82). Systemic responses were likewise significantly blunted after eformoterol treatment compared with placebo. There was also subsensitivity of lymphocyte beta 2-adrenoceptor function after treatment with eformoterol compared with placebo. CONCLUSIONS: Our results suggest that chronic therapy with eformoterol produces (1) tachyphylaxis to its bronchodilator response, which was greatest at 6 hours after the last dose, (2) tachyphylaxis of extrapulmonary beta 2-mediated responses, and (3) subsensitivity of in vitro beta 2-adrenoceptor function.