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Biomedical subjects

J Crooks

Publications and source records attributed to J Crooks.

At least 37 records · Page 2Linked to original sources
PubMed1983

Rational therapeutics in the elderly.

The potential for altered responsiveness to drugs in elderly patients together with their high frequency of multiple disease states for which drug therapy might be indicated makes it important to define certain basic principles of prescribing for them in order to obtain maximum efficacy with minimum unwanted effects. Many diseases from which the elderly suffer do not require drug treatment and, if it is required, the decision should be made in light of the pharmacokinetic and pharmacodynamic characteristics of the alternatives, the increased potential of certain drugs to produce adverse effects in the elderly and a regular review of the need for continued medication. In order to improve compliance with prescribing instructions, the minimum number of drugs and doses should be prescribed, the size, shape and colour of tablets and capsules should also determine choice, and attention paid to packaging and labelling. The methods by which the patient living at home can manage his/her medication effectively should be carefully considered.

Aged↗
PubMed1983

Aging and drug disposition--pharmacodynamics.

The pharmacodynamics of a drug is defined as the effect of the drug on physiological functions and pathological processes and can be modified in the elderly by (a) pharmacokinetics, (b) receptor sensitivity (or density), (c) impaired homeostasis or (d) pathology. The alterations in pharmacokinetics in the elderly often result in a reduction of the dose required to achieve the optimum pharmacodynamic effect. Changes in the sensitivity of receptors may be decreased in the elderly (perhaps by a diminution in the number of receptors) as in the case of the beta-adrenergic blockers, but increase in sensitivity may also be found as in the case of warfarin. Impairment of homeostatic mechanisms, while related to aging, are frequently produced by pathological processes and have an important influence on the pharmacodynamics of many drugs. The effect of the multiple pathology often found in the elderly is likely to be the dominant factor in changes in pharmacodynamics in this population. The interaction of the above factors results in a heterogeneity of pharmacodynamic response in the elderly which requires the careful monitoring of both the efficacy and toxicity of their drug treatment.

Aged↗
PubMed1982

Nadolol and potassium iodide in combination in the surgical treatment of thyrotoxicosis.

With the two aims of rapidly reducing circulating thyroid hormone levels and controlling the symptoms of thyrotoxicosis, we have prepared 17 thyrotoxic patients for subtotal thyroidectomy, using a combination of potassium iodide administered for 10 days and the long acting beta-adrenoceptor antagonist nadolol. All 17 patients had normal serum thyroxine levels after 10 days of such treatment although 10 still showed elevation of serum tri-iodothyronine and considerable elevation in the most severely toxic patient. All patients were, however, clinically euthyroid preoperatively. Nadolol was administered once daily, hence avoiding the problems of drug administration in the immediate postoperative period, and plasma nadolol concentrations were high throughout the perioperative period. Serum thyroxine and tri-iodothyronine levels were significantly lower and reverse tri-iodothyronine levels higher 24 h postoperatively than before operation. All patients remained stable throughout the perioperative period. We conclude that this regimen has a number of advantages in the preparation of patients for thyroidectomy, in reducing the degree of thyrotoxicosis, in convenience of drug administration and in ensuring adequate circulating concentrations of beta-adrenoceptor antagonist whilst still retaining a relatively short preoperative phase of drug treatment.

Adrenergic beta-Antagonists↗
PubMed1982

Nadolol in thyrotoxicosis.

1 Twenty outpatients with thyrotoxicosis received the non-selective beta-adrenoceptor antagonist nadolol as sole treatment for 3 weeks. 2 Clinical improvement as measured by reduction in thyrotoxicosis therapeutic index occurred during the first week of treatment and was continued thereafter, and was accompanied by a significant reduction in serum T3 and elevation of serum reverse T3. 3 As measured by reduction in exercise heart rate, during chronic dosing nadolol 160 mg once daily produced blockade of beta-adrenoceptors for 12 h in all patients and 24 h in all but 2. 4 Wide interindividual variability was noted in steady state plasma nadolol concentrations, in part related to age and renal function. 5 Steady state plasma nadolol concentrations were related to reduction in heart rate.

Adrenergic beta-Antagonists↗
PubMed1982

A method of estimating nursing workload.

A real-time nursing computer system operational on six medical wards allows the automatic data capture of all nursing procedures carried out for all patients. Each nursing procedure has been graded by an experienced nurse on a 5-point scale (Ninewells Index I), with grade 5 representing the greatest workload. A Delphi type survey was carried out by a questionnaire involving 115 medical charge nurses in Scotland who graded the same procedures on a 5-point scale (Delphi Index I). Good agreement with the two indices was found. The Delphi Index I was transferred from the original scale to an interval scale (Delphi Index II) to facilitate statistical handling of data and conversion to timings. The conversion of Delphi Index II to timings (Ninewells Index II) was achieved by using data from three extensive work studies. It is suggested that Ninewells Index II is a practical problem of staff allocation in medical wards.

Abstracting and Indexing↗
PubMed1982

The problem of psilocybin mushroom abuse.

1 We have reviewed the clinical features and management of 44 consecutive patients presenting to hospital over a 5 week period during an outbreak of ingestion of psilocybin containing mushrooms. 2 Patients presented to hospital usually because of dysphoric effects an average of 3.8 h after ingesting mushrooms. 3 Mydriasis was present in 40 patients but fewer than half showed other sympathomimetic features--tachycardia, hypertension or hyperreflexia. 4 Twenty-three patients experienced nausea and vomiting. 5 Distortions of perception chiefly visual were frequent as were paraesthesiae and feelings of depersonalization. 6 The effects of the mushrooms were short-lived and had worn off within 12 h in all but one patient. 7 Inducing emesis did not appear to hasten recovery from the effects of the mushrooms.

Adolescent↗
PubMed1981

Propranolol in the surgical treatment of hyperthyroidism, including severely thyrotoxic patients.

The perioperative course of 44 hyperthyroid patients prepared for surgery with propranolol alone, including 11 with severe thyrotoxicosis was compared to that of 20 euthyroid patients prepared for surgery with carbimazole. Conventional propranolol at a dosage of 160 mg/day was frequently insufficient to produce a high degree of beta-adrenergic blockade, particularly in severely thyrotoxic patients. A greater than 25 per cent reduction in sitting pulse rate was associated with a high degree of beta-blockade. The clinical course of patients with mild or moderate thyrotoxicosis was similar to that of the patients prepared with carbimazole. In contrast, the course of severely thyrotoxic patients was complicated and, in addition to a higher preoperative propranolol dosage, these patients commonly required supplemental propranolol after operation. Although thyroid crisis did not occur in any patient, we cannot recommend the use of propranolol alone for the severely thyrotoxic patient.

Adult↗
PubMed1981

Plasma propranolol steady state concentrations in thyroid disorders.

Plasma propranolol steady-state concentrations (Css) were measured in 24 hyperthyroid and 6 hypothyroid patients before and after correction of the thyroid disorder. Following treatment of hyperthyroidism by surgery, antithyroid drugs or radioiodine, there was a significant rise in the plasma propranolol Css in patients receiving propranolol either 160 mg/day, 240 mg/day, or 480 mg/day. In addition, in five patients the area under the plasma propranolol concentration versus time curve during a dosing interval increased significantly from 405 ng/ml/h when hyperthyroid to 778 ng/ml/h when euthyroid. In the hypothyroid patients given propranolol 160 mg/day concomitantly with 1-thyroxine therapy the plasma propranolol Css fell significantly when euthyroid. There was a small but significant increase in the degree of plasma protein binding of propranolol, following treatment of hyperthyroidism and a significant decrease following correction of hypothyroidism. It is concluded that thyroid disorders markedly influence propranolol handling.

Adolescent↗
PubMed1981

Drug response in the elderly--sensitivity and pharmacokinetic considerations.

There is now a considerable body of evidence to indicate that response to many drugs changes as people ages. As a result, interest has increased in recent years in the investigation of mechanisms contributing to altered drug responsiveness with age. Significant changes in pharmacokinetics and/or tissue sensitivity have been shown to occur. In the former cases, decreased renal elimination is undoubtedly the most important factor but decreased plasma protein binding and rate of metabolism may also be of clinical significance. In the case of tissue sensitivity, there have been few opportunities so far to determine age-related changes in the number and sensitivity of drug receptors and studies have been largely confined to relating drug effect to plasma levels in patients of different age. Such studies in the elderly have been complicated by alteration in the normal homoeostatic mechanisms and by the presence of disease. Further work in both healthy volunteers and patients is necessary to provide a comprehensive data base from which drug regimens appropriate for elderly patients may be developed.

Aged↗
PubMed1981

The influence of age, smoking and hyperthyroidism on plasma propranolol steady state concentration.

1 Plasma propranolol steady state concentration (Css) was determined during chronic dosage (160 mg/day) in 22 hyperthyroid patients (aged 16-75 years, 11 smokers, 11 non-smokers) and again following treatment when euthyroid. 2 There was a positive correlation between plasma propranolol Css and age in patients both when hyperthyroid (r = 0.74, P less than 0.01) and when euthyroid (r = 0.58, P less than 0.05). 3 Plasma propranolol Css in hyperthyroid patients were lower (P less than 0.05) in smokers than in non-smokers. 4 Following correction of hyperthyroidism there was a significant increase (P less than 0.01) in both the plasma propranolol Css and degree of plasma protein binding of propranolol. 5 Hyperthyroidism and smoking are known to increase the rate of drug metabolism and it is suggested that these variables may give rise to or accentuate an age related reduction in propranolol clearance.

Adolescent↗
PubMed1981

Altered endocrine response to partial thyroidectomy in propranolol-prepared hyperthyroid patients.

The endocrine response to partial thyroidectomy in a group of twenty hyperthyroid patients prepared with propranolol alone was compared to that of a matched control group of ten euthyroid patients. In propranolol-prepared patients the glucose response to surgery was reduced (P less than 0.05) for up to 4 h post-operatively and biochemical hypoglycaemia was noted in one patient. Both thyroxine and triiodothyronine (T3) fell significantly, associated with a marked rise in reverse T3. Growth hormone levels were higher (P less than 0.05) both pre- and post-operatively in propranolol-prepared patients, whereas prolactin levels, although similar pre-operatively, were lower (P less than 0.05) in these patients post-operatively. Cortisol and ACTH levels were lower (P less than 0.05) both before and following thyroidectomy in propranolol-prepared patients. These results suggest that the endocrine response to surgical stress is markedly altered in propranolol-prepared hyperthyroid patients.

Adrenocorticotropic Hormone↗
PubMed1981

The relationships between surgical histometry, outcome and pre-treatment in Graves' disease.

Quantitative histometric methods were used to established the relationships between the extent of thyroid lymphocytic infiltration at operation, and outcome exactly 18 months later in 50 surgically-treated Graves' disease patients prepared by carbimazole and triiodothyronine. Periods of pre-operative treatment, surgical technique, histometric analysis and diagnostic criteria were all standardised. Controls (107) were obtained from the forensic laboratory. Thirty-seven patients became euthyroid, but there was no relationship between outcome and epithelial or lymphoid content of the thyroid gland. Neither was there any correlation between the size of lymphoid infiltrate and epithelial mass of the resected thyroids, suggesting that simple lymphocyte infiltrations do not replace thyroid tissue as once thought. The variation in thyroid epithelial content was nearly 3-fold, so that a surgeon, even if able accurately to judge the anatomical mass of the remnant, would still have little or no idea of its functional mass. The scatter of epithelial content was even greater in glands from patients prepared for surgery by propranolol alone (38 glands, variation X 5.5) or propranolol and iodide (32 glands, variation X 5.9). Outcome after sub-total thyroidectomy for Graves' disease seems unrelated to the lymphocyte content of the gland and it is questionable to what extent the surgeon can either predict or control the outcome of thyroidectomy in individual Graves' disease patients.

Adult↗