Search PubMed⌕ Search

Biomedical subjects

C G Swift

Publications and source records attributed to C G Swift.

At least 55 records · Page 3Linked to original sources
PubMed1993

Psychomotor performance in elderly hypertensive patients.

The psychomotor performance of 25 elderly patients with mild to moderate hypertension (aged 62-78 years, SBP = 162-212 mmHg; DBP = 98-124 mmHg) was compared with 25 age-matched controls (SBP = 110-160 mmHg; DBP = 64-92 mmHg). The hypertensive subjects did not have evidence of target-organ damage and were on no antihypertensive treatment at the time of assessment. Performance on a range of tests: symbol/digit substitution test (SDST) (34.3 vs. 39.5, P < 0.01), continuous attention test (CAT) (33 vs. 36.2, P < 0.01), choice reaction time (CRT) (270 ms vs. 320 ms, P < 0.01), paired word association test (PWAT) (4.1 vs. 7.0, P < 0.001) and inspection time threshold (INSP) (158 ms vs. 52 ms, P < 0.001), showed significant impairment in the hypertensive group compared with controls. These differences did not correlate with the duration of hypertension or degree of BP elevation. The impairment in hypertensive subjects was stable over a four week period. These results suggest the occurrence of a functional and possibly reversible impairment of psychomotor performance in elderly hypertensive patients which may have implications for antihypertensive treatment.

Aged↗
PubMed1993

Effect of antihypertensive treatment on psychomotor performance in the elderly.

The psychomotor effects of control of hypertension were studied in a parallel group comparison of 25 elderly hypertensives (aged 61-79 years; SBP = 192 (range 162-212) mmHg; DBP = 112 (range 98-124) mmHg) shown to have psychomotor impairment when not on antihypertensive treatment. Single blind treatment was commenced with placebo or a diuretic: atenolol, nifedipine or captopril (5 x n = 5). A range of tests using an automated psychomotor test battery showed a significant improvement compared with placebo in tests of attention and psychomotor speed in subjects rendered normotensive (n = 18) after treatment for one week (SDST + 3.8, P < 0.001; CAT + 1.2, P < 0.03; PWAT + 1.9, P < 0.004; INSP -49.5 ms, P < 0.001). Subgroup analysis suggested greater improvement in psychomotor performance with captopril, but this was equivocal because of the small sample size in each group. Hence, the psychomotor effects of treatment with nifedipine and captopril were compared in a further 13 hypertensives (aged 62-76 years; SBP = 178 (range 169-193) mmHg; DBP = 106 (range 97-117) mmHg) in a double-blind crossover study. With both drugs, control of hypertension was associated with a significant and comparable improvement in several psychomotor performance measures. The results suggest that impaired psychomotor performance due to hypertension improves with antihypertensive treatment. The improvement appears to be related to control of hypertension rather than to the direct CNS effects of antihypertensive drugs.

Aged↗
PubMed1991

A comparison of the central nervous system effects of caffeine and theophylline in elderly subjects.

1. The effects of oral administration of 250 mg caffeine or theophylline and placebo on subjective ratings and psychological test performance were studied in a double-blind crossover experiment in 20 healthy elderly subjects. 2. Performance on the continuous attention task showed a significant improvement compared with placebo with both active treatments. Performance with caffeine was significantly better than with theophylline. Mean error index scores (normalised AUCs) were: placebo--0.130; caffeine--0.083; theophylline--0.093. No other objective measure shows significant treatment effects. 3. Subjective ratings showed that subjects felt significantly more alert on caffeine than on either theophylline or placebo. Subjects also rated themselves as more energetic and interested on caffeine than on placebo. 4. Plasma concentrations of caffeine were lower than those of theophylline (mean 5.76 and 8.72 mg l-1 respectively at 2 h post-drug. 5. These results suggest that caffeine is a more potent CNS stimulant than theophylline.

Aged↗
PubMed1990

Comparative assessment of enprofylline and theophylline for chronic obstructive airways disease in the elderly.

Enprofylline, a recently developed xanthine derivative, is a more potent bronchodilator than theophylline. This study compares the efficacy and safety of enprofylline with theophylline for chronic obstructive airways disease (COAD) in elderly subjects. The study was of a randomized double-blind parallel design and commenced with a 1-week reference period when oral bronchodilators were withdrawn. Patients were then treated with either enprofylline or theophylline 150 mg bd for 2 weeks (period 1) followed by 300 mg bd for a further 3 weeks (period 2). Patients recorded peak expiratory flow rate (PEFR) and adverse experiences, if any, in a diary, daily. Of 111 patients recruited for the study, 85 entered active treatment (theophylline, n = 44; enprofylline, n = 41). Mean age was 72 years and mean bronchodilator reversibility was 22%. Enprofylline increased mean morning PEFR by 11% (period 1) and 19% (period 2) whereas theophylline increased PEFR by 13% and 19%, respectively. From the enprofylline group 29% were withdrawn from the study due mainly to headache and nausea/vomiting and from the theophylline group 7% were withdrawn due mainly to nausea/vomiting. Mean plasma concentrations of enprofylline were 2.0 mg l-1 and 3.4 mg l-1, and with theophylline 5.4 mg l-1 and 10.0 mg l-1 at the end of periods 1 and 2, respectively. Enprofylline and theophylline produced similar improvements in lung functions and symptoms of chronic obstructive airways disease, but enprofylline was less well tolerated than theophylline.

Aged↗
PubMed1990

Pharmacodynamics: changes in homeostatic mechanisms, receptor and target organ sensitivity in the elderly.

Response to drugs in the elderly may be accentuated or modified by age related changes in homeostatic mechanisms such as postural control, orthostatic circulatory responses, thermoregulation, visceral muscle function and higher cognitive function. Changes in specific receptor and target organ responses have also been described. beta-Adrenoceptor-mediated effects are apparently attenuated by a reduction in high affinity binding sites and altered post receptor mechanisms resembling desensitization. alpha 2-Adrenoceptor and cholinergic effects may also be attenuated though there is no evidence for altered alpha 1-adrenoceptor sensitivity. The effects of age on sensitivity to benzodiazepines, calcium channel blocking agents, angiotensin converting enzyme inhibitors, anticoagulants and cardiac glycosides are also discussed. There is a major requirement for further work in this field.

Aged↗
PubMed1989

Adenosine-induced respiratory and heart rate changes in young and elderly adults.

The effects of intravenous boluses of adenosine on respiration and heart rate were compared in young and elderly individuals. Respiratory stimulation and biphasic changes in heart rate were confirmed. The dose-response relationship for the effects of adenosine on respiration and heart-rate did not differ significantly between 10 young (mean age 25.2 +/- 4.9 years) and 10 elderly (mean age 66 +/- 3.1 years) drug-free individuals, indicating that age is unlikely to be a major determinant of adenosine responsiveness.

Adenosine↗
PubMed1988

"First-dose" response to mianserin: effects of age.

The effects of single 10 mg oral doses of the antidepressant mianserin on psychomotor performance, subjective sedation and supine and standing blood pressure were compared in ten young and nine elderly healthy volunteers. Immediate and residual sedation following this subtherapeutic dose was readily detected in both groups. In contrast to previous studies with benzodiazepines, the sedation effect was not accentuated in the older subjects. Subjective awareness of sedation was significant in the young but not, however, in the elderly. "First-dose" postural hypotension, presumably due to post-synaptic alpha-blockade also occurred in young subjects only. Caution may be needed on initial dosage of mianserin in young individuals who drive or undertake skilled tasks and in the elderly who may be unaware of psychomotor impairment. The reported alpha 2 receptor selectivity of mianserin might explain the lack of postural effects in the elderly, and might constitute a potentially useful characteristic in the development of new compounds.

Adult↗
PubMed1988

The effects of age on the response to caffeine.

Twelve healthy subjects, six young and six elderly, of either sex, took part in this two-period crossover study. In each session, a dose of trial drug--either 200 mg caffeine or a matching placebo--was given orally at 0900 hours. A battery of psychomotor tests and visual analogue scales was administered before treatment and at 1, 2 and 3 h post-treatment. The objective tests showed a significant increase in tapping rate in the young, while the elderly showed improved attention, faster choice-reaction time, and greater body sway on caffeine. The visual analogue scales showed that the young subjects felt more alert, calmer, more interested, and steadier on caffeine, while no significant changes were seen in the elderly. These results show that caffeine produces changes predominantly in the direction of improved performance and feeling of well-being, and suggest that the elderly are more sensitive to the objective effects of the drug, while reporting less subjective effect than the young.

Adolescent↗
PubMed1988

Ethical aspects of clinical research in the elderly.

It is of major importance to acquire hard information on which to base more accurate diagnostic criteria and to decide which forms of treatment are of proven benefit to older patients. At the same time the ethical and practical difficulties entailed demand special care, sensitivity, expertise and patience.

Aged↗
PubMed1987

Significance of single serum urate estimations in acutely hospitalized elderly patients.

Clinical, pharmacological and biochemical correlates of hyperuricaemia were studied in 399 consecutive patients aged over 70 years admitted to hospital with acute medical illness. Hyperuricaemia was significantly related to renal impairment and to the use of diuretics, but to no other recognized associations of gout, including typical or atypical joint symptoms. 'Routine' measurement of serum uric acid alone or as a component of biochemical profiles in acute illness in the elderly appears unjustified, particularly since raised levels may encourage inappropriate use of urate-lowering therapy.

Aged↗
PubMed1986

Special problems relating to the use of hypnotics in the elderly.

The problems experienced by elderly patients taking hypnotic drugs are reviewed. They include those associated with accumulation, tolerance, drug dependence and the intensity and duration of response. Biological mechanisms associated with ageing enhance some of these effects in the elderly. Care should be taken to define the precise indications for hypnotic use and to choose the correct drug and dose for the patient's condition and age.

Aged↗
PubMed1985

Responsiveness to oral diazepam in the elderly: relationship to total and free plasma concentrations.

The immediate and residual response to single doses of oral diazepam 10 mg was measured in 11 young and 12 elderly healthy volunteers using postural sway, digit symbol substitution scores and subjective ratings. The effect on postural sway was markedly accentuated in the older volunteers, but the difference between groups in the effect on the other measures used did not achieve significance. The corresponding plasma total diazepam concentrations were lower in the older subjects beyond 0.5 h post dose and the concentrations of plasma desmethyldiazepam did not differ between the groups. Diazepam plasma protein binding was significantly reduced in the elderly subjects, but the plasma free (unbound) diazepam concentrations did not exceed those in the young group. There was poor correlation between the responses measured and the concentrations of either total diazepam, desmethyldiazepam or free diazepam. The results suggest the occurrence of a non-uniform effect of age on different aspects of benzodiazepine response, and that where an accentuated effect occurs the mechanisms are substantially pharmacodynamic.

Adult↗
PubMed1985

Single dose pharmacokinetics and pharmacodynamics of oral loprazolam in the elderly.

The pharmacokinetics of the benzodiazepine hypnotic, loprazolam (1.0 mg orally), and the pharmacodynamic response to single oral doses (0.5 mg and 1.0 mg) have been compared in young and elderly healthy volunteers. No difference between the groups in peak plasma concentration (Cmax) or in the time to peak (tmax) was found, but the elimination half-life t1/2,z and area under the plasma concentration-time curve (AUC) were significantly greater in the elderly group. The immediate effects of loprazolam on all three performance tests used (postural sway, critical flicker fusion threshold (CFFT) and choice reaction time (CRT] and on subjective sedation tended to be more pronounced in the elderly subjects, though intersubject variability in response was high in both groups. The corresponding plasma concentrations did not differ significantly between the two groups. The higher (1.0 mg) dosage was associated with significant residual (11 h) impairment of standing steadiness in the elderly subjects. No other hangover effects were observed. The results are compatible with previous evidence of increased 'sensitivity' to benzodiazepines in the elderly and suggest that a lower (0.5 mg) starting dose of loprazolam would be appropriate for older recipients. Further investigation would be necessary to establish whether clinically relevant accumulation of loprazolam occurs in the elderly following repeated dosage.

Administration, Oral↗
PubMed1984

Side-effect 'tolerance' in elderly long-term recipients of benzodiazepine hypnotics.

The outcome of long-term benzodiazepine hypnotic therapy has been investigated in a group of elderly patients in the community; 220 receiving nitrazepam and 33 flurazepam. The estimated duration of therapy was as long as 15 years in some cases. More than half were taking doses greater than 5 mg and 15 mg, respectively, the majority on a regular nightly basis in accordance with the instructions on containers. The plasma concentrations of nitrazepam and the active desalkyl metabolite of flurazepam correlated positively with weight-related dose. In the case of desalkyl-flurazepam, but not nitrazepam, the levels were substantially higher than those previously reported in young individuals. There was sustained patient satisfaction with the effectiveness of the hypnotics and, despite the high plasma levels, little subjective or objective evidence of unwanted sedation, confusion or unsteadiness. The findings of the survey suggest the development of both pharmacodynamic tolerance to the unwanted sedative effects of these drugs and a degree of dependence in long-term recipients.

Aged↗