Disposition of flurbiprofen in man: influence of stereochemistry and age

1. The stereoselective metabolism and pharmacokinetics of the enantiomers of flurbiprofen were investigated following the oral administration of the racemic drug (100 mg) to four young and four elderly healthy volunteers (two males and two females per group). 2. The stereochemical composition of the drug and the 4'-hydroxy- metabolite in serum and the drug, 4'-hydroxy- and 3'-hydroxy-4'-methoxy- metabolites, both free and conjugated, in urine were determined by a direct chromatographic method of enantiomeric analysis. 3. Modest enantioselectivity in clearance (CL S/R: young, 0.86; elderly, 0.88) was largely responsible for the apparent elimination half-life of (S)-flurbiprofen being significantly greater (p<0.01) than that of the R-enantiomer in both age groups (young, S: 5.2 +/- 0.7 versus R: 4.5 +/- 0.6 h; elderly, S: 9.6 +/- 1.2 versus R: 7.1 +/- 1.0 h). The serum concentrations of 4'-hydroxyflurbiprofen were five- to 20-fold lower than those of the corresponding drug enantiomers, stereoselective disposition being evident in the significantly greater (p<0.05) apparent half-lives of the S- compared with the R-enantiomer in both groups (young, S: 10.6 +/- 2.4 versus R: 6.7 +/- 1.1 h; elderly, S: 13.7 +/- 1.7 versus R: 10.2 +/- 1.2 h). 4. Some 60 and 72% of the dose was excreted in 24-h urine in elderly and young volunteers, respectively, a significantly greater (p<0.05) proportion of which was of the R-configuration in both age groups (S/R: young, 0.87; elderly, 0.81). The major urinary excretion products were flurbiprofen and 4'-hydroxyflurbiprofen, and their acyl-conjugates in both groups. 5. Age-associated differences in the pharmacokinetics of flurbiprofen occurred in a non-stereoselective manner and were primarily as a consequence of a significant approximately 40% decrease (p<0.01) in clearance of both enantiomers in the elderly due to reduced metabolic activity. Consequently, the elderly had greater exposure to both enantiomers, as reflected by the AUCs(0-inf) being significantly higher (p<0.05), by 60%, in this age group compared with the young. 6. The findings suggest that age-related alterations in the disposition of flurbiprofen could have significant implications for the use of the drug in the elderly.

Selective AT1 Receptor Antagonism Enhances Sympathetically Mediated Vasoconstriction in Man

The vasoconstrictive action of angiotensin II (AII) is partly, sympathetically mediated and angiotensin-converting enzyme (ACE) inhibitors appear to exert a sympatholytic effect. We examine the effect of an orally administered, selective AT(1) receptor antagonist (losartan 50 mg) on sympathetically mediated vasoconstriction in healthy volunteers in an observer blind crossover study. Seven healthy, normotensive volunteers (21-32 years), were studied on two occasions at the end of each 6-week treatment period (losartan or placebo). Forearm blood flow (FABF) (ml/dl forearm/min) was measured by venous occlusion plethysmography during the application of lower body negative pressure (LBNP) (-20 cm H(2)O) and at the end of each incremental infusion of norepinephrine (60, 120, and 240 pmol/min). Comparison of blood flow changes was by repeated measures analysis of variance; P<0.05 was taken as statistically significant. Losartan did not alter blood pressure compared to placebo. It did significantly enhance LBNP-induced vasoconstriction in both the left arm compared to placebo (-36.6+/-3.4 vs -23.5+/-3.3%; P=0.017) and the right arm compared to placebo (-39.5+/-3.8 vs -21.0+/-3.6%; P=0.005). The FABF response to all doses of infused norepinephrine (60, 120, and 240 pmol/min) was also enhanced by losartan compared to placebo (-35.0+/-2.7 vs -18.2+/-6.0%; -43.6+/-4.3 vs -28.6+/-5.8%, and -53.9+/-3.2 vs -42.5+/-6.8%; P=0.057, respectively. Losartan enhances locally mediated sympathetic vasoconstriction in the forearm circulation of man, probably through its effect on circulating AII concentrations and we postulate that the adrenergic sympathetic constrictor action of AII is not mediated by the AT(1) receptor or is surmountable at this receptor.

Effect of methionine loading on pulse wave analysis in elderly volunteers

OBJECTIVE

To test the hypothesis that an acute increase in plasma homocysteine produced by methionine is associated with an acute increase in pulse wave velocity.

DESIGN

A double blind, cross over, placebo controlled design was used and pulse wave velocity, plasma homocysteine, total cholesterol: high density lipoprotein ratio, plasma triglyceride, oxidised low density lipoprotein cholesterol concentrations, apolipoproteins A1 and B, and C reactive protein were measured between 12.5 and 20 hours after methionine loading or placebo.

RESULTS

Between 12.5 and 20 hours after exposure to a methionine loading test, arterial pulse wave velocity showed no significant difference compared with placebo. At 12 hours after exposure to the methionine loading test, in the presence of a controlled diet, triglyceride concentration significantly increased by 32.6% (p<0.02), cholesterol: high density lipoprotein ratio increased significantly by 22.5% (p<0.05) compared with placebo. Simultaneously, systolic blood pressure increased significantly by 4.9% (p<0.02).

CONCLUSION

In elderly volunteers, acute hyperhomocysteinaemia induced by methionine loading resulted in no overall significant delayed reduction in peripheral arterial distensibility. A significant deterioration in the lipid profile and increased blood pressure was seen during acute hyperhomocysteinaemia.

Premedication for bronchoscopy in older patients: a double-blind comparison of two regimens

INTRODUCTION

Older patients are the most prevalent age cohort requiring bronchoscopy. Prior sedation should be offered to improve patient comfort and operator technical ease. Older patients have increased sensitivity to centrally acting drugs increasing the procedural risk. This perceived risk may limit access to bronchoscopy in older patients. There have been no systematic prospective placebo-controlled studies in older patients. We compared a novel premedication regimen-oral temazepam plus nebulised Lignocaine (new treatment) to an established regimen of intravenous alfentanyl (control).

METHODS

Consecutive patients 75 years and older referred for bronchoscopy were considered. Twenty-five patients were randomly assigned to each group. The primary outcome measure was the lowest oxygen saturation recorded from the administration of IV drugs and for 30 min post-bronchoscopy.

RESULTS

The lowest mean oxygen saturation in the new treatment group was 92.2% (90.3-94.2) and in the control group 91.1% (89.2-93.1). This was not statistically different (P = 0.370). There were no adverse events.

CONCLUSION

This is the largest prospective study to date on an older population undergoing bronchoscopy supporting previous retrospective findings regarding the safety of this procedure. Determined by oxygen saturations there is no difference in safety between premedication regimens comprising oral temazepam/nebulised lignocaine or intravenous alfentanyl.

Predictors of falls in a high risk population: results from the prevention of falls in the elderly trial (PROFET)

OBJECTIVES

The prevention of falls in the elderly trial (PROFET) provides evidence of the benefits of structured interdisciplinary assessment of older people presenting to the accident and emergency department with a fall. However, the service implications of implementing this effective intervention are significant. This study therefore examined risk factors from PROFET and used these to devise a practical approach to streamlining referrals from accident and emergency departments to specialist falls services.

METHODS

Logistic regression analysis was used in the control group to identify patients with an increased risk of falling in the absence of any intervention. The derived predictors were investigated to see whether they also predicted loss to follow up. A second regression analysis was undertaken to test for interaction with intervention.

RESULTS

Significant positive predictors of further falls were; history of falls in the previous year (OR 1.5 (95%CI 1.1 to 1.9)), falling indoors (OR 2.4 (95%CI 1.1 to 5.2)), and inability to get up after a fall (OR 5.5 (95%CI 2.3 to 13.0)). Negative predictors were moderate alcohol consumption (OR 0.55 (95%CI 0.28 to 1.1)), a reduced abbreviated mental test score (OR 0.7 (95%CI 0.53 to 0.93)), and admission to hospital as a result of the fall (OR 0.26 (95%CI 0.11 to 0.61)). A history of falls (OR 1.2 (95%CI 1.0 to 1.3)), falling indoors (OR 3.2 (95%CI 1.5 to 6.6)) and a reduced abbreviated mental test score (OR 1.3 (95%CI 1.0 to 1.6)) were found to predict loss to follow up.

CONCLUSIONS

The study has focused on a readily identifiable high risk group of people presenting at a key interface between the primary and secondary health care sectors. Analysis of derived predictors offers a practical risk based approach to streamlining referrals that is consistent with an attainable level of service commitment.

The clinical pharmacology of ageing

The ageing of populations and individuals continues to be as vital, yet to some extent as neglected, a topic in pharmacology and therapeutics as was first realised about 30 years ago. In parallel with the realisation of the predicted demographic shifts in both the developed and developing world, there have since been major developments in the basic biological concepts of ageing, in the physiology of ageing, in the study of pathogenetic mechanisms underlying a variety of age-associated disorders and syndromes, and in the evidence base for therapeutic intervention in elderly patient populations. These all present new challenges both in the practical delivery of effective medical care and in clinical and biological research. The scale of prescribing for an ageing population has continued to rise as anticipated. Whether there has now been any improvement in the quality or rationality of prescribing, or in the previously demonstrated unacceptable level of susceptibility to adverse drug reactions in the (now expanded) older patient population is largely unknown. We urgently need to find out using up-to-date research methods. National and international guidelines for drug development and regulation have more recently been followed by broader policy initiatives on prescribing for older people, but the impact of these on standards of medication use and on clinical outcome remains to be seen. A new series in this journal on the clinical pharmacology of ageing is timely. The required focus and framework for research have often tended in the past to emerge as afterthoughts behind the merely disease specific, and it is to be hoped that a sequential review of some of the key topics may help to re-ignite a more sound and less short-sighted agenda than previously.

Stereoselectivity of ibuprofen metabolism and pharmacokinetics following the administration of the racemate to healthy volunteers

1. The stereoselective metabolism and pharmacokinetics of the enantiomers of ibuprofen have been investigated following the oral administration of the racemic drug (400 mg) to 12 healthy volunteers.2. The stereochemical composition of the drug in serum, both total and unbound, and drug and metabolites, both free and conjugated, in urine were determined by a combination of the direct and indirect chromatographic procedures to enantiomeric analysis. 3. The oral clearance of (S)-ibuprofen was significantly greater than that of the R-enantiomer (74.5 +/- 18.1 versus 57.1 +/- 11.7 ml min(-1); p < 0.05) and the clearance of (R)-ibuprofen via inversion was ca two fold that via alternative pathways. 4. Some 74.0 +/- 9.6% of the dose was recovered in urine over 24 h as ibuprofen, 2-hydroxyibuprofen and carboxyibuprofen, both free and conjugated with glucuronic acid. Analysis of the stereochemical composition of the urinary excretion products indicated that 68% of the dose of (R)-ibuprofen had undergone chiral inversion. 5. Metabolism via glucuronidation and both routes of oxidation, showed enantio-selectivity for (S)-ibuprofen, the enantiomeric ratios (S/R) in partial metabolic clearance being 7.1, 4.8 and 3.4 for formation of ibuprofen glucuronide, 2-hydroxyibuprofen and carboxyibuprofen respectively.6. Modest stereoselectivity was observed in the formation of (2'R, 2R)- and (2'S, 2S)-carboxyibuprofen in comparison to the alternative diastereoisomers, the ratios in formation clearance being 1.6 and 1.2 respectively.

Folic acid enhances endothelial function and reduces blood pressure in smokers: a randomized controlled trial

OBJECTIVE

Cigarette smoking is associated with increased plasma homocysteine concentrations, endothelial dysfunction and arterial stiffening. Homocysteine per se induces endothelial dysfunction and arterial stiffening and might account, at least partly, for the vascular abnormalities observed in smokers. We sought to determine whether folic acid supplementation, by reducing plasma homocysteine concentrations, enhanced endothelial function and reduced arterial stiffness in smokers.

DESIGN

Double-blind, randomized controlled, parallel-group, trial.

SETTING

Academic medical centre.

SUBJECTS

A consecutive sample of 24 healthy cigarette smokers (age 37.8 +/- 2.5 years, mean +/- SEM).

INTERVENTION

Subjects were randomly assigned to 4-week folic acid 5 mg day-1 or placebo.

MAIN OUTCOME MEASURES

The following were measured before and after treatment: (i) peripheral vasoreactivity (forearm arterial blood flow, FABF) during intra-arterial administration of endothelium-dependent (acetylcholine 1.5, 4.5 and 15 microg min-1) and endothelium-independent (sodium nitroprusside 1, 2 and 4 microg min-1) vasodilators; (ii) carotid-femoral pulse-wave velocity (PWV); (iii) blood pressure (BP).

RESULTS

Folic acid reduced homocysteine concentrations (10.8 +/- 0.6 vs. 8.2 +/- 0.5 micromol L-1, P < 0.001) and enhanced endothelium-dependent vasodilatation during each acetylcholine infusion rate (ratio between the FABF in the infused and control arm during increasing infusion rates at baseline 1.09 +/- 0.03 vs. 1.41 +/- 0.09 after treatment, P < 0.01; 1.39 +/- 0.07 vs. 1.83 +/- 0.12, P < 0.01; 1.65 +/- 0.16 vs. 2.72 +/- 0.36, P < 0.05) whilst endothelium-independent vasodilatation was unaffected. A significant fall in BP was also observed (mean BP 88 +/- 2 vs. 83 +/- 1 mmHg, P < 0.01). By contrast, PWV did not significantly change (8.4 +/- 0.3 vs. 7.8 +/- 0.4 m s-1). No significant changes in plasma homocysteine concentrations, FABF, BP, and PWV were observed in the placebo group. A multiple regression analysis showed that changes in folic acid plasma concentrations independently predicted both FABF changes during maximal acetylcholine-mediated vasodilatation (P < 0.01) and BP changes (P = 0.01).

CONCLUSIONS

Short-term folic acid supplementation significantly enhanced endothelial function and reduced BP in young chronic smokers. These effects were largely independent from the homocysteine lowering effects. Thus, a simple, nontoxic, and relatively inexpensive vitamin intervention might be useful in primary cardiovascular prevention in this high-risk group.

Neuromuscular and psychomotor function in elderly subjects who fall and the relationship with vitamin D status

Vitamin D and calcium supplementation significantly reduces the incidence of fractures. Evidence suggests vitamin D deficiency impairs neuromuscular function, causing an increase in falls and thereby fractures. The relationship between vitamin D, functional performance, and psychomotor function in elderly people who fall was examined in a prospective cross-sectional study. Patients were recruited from a falls clinic and stratified according to serum 25-hydroxyvitamin-D levels (25OHD): group 1, 25OHD < 12 microg/liter; group 2 25OHD, 12-17 microg/liter; and group 3, 25OHD > 17 microg/liter. Healthy elderly volunteers with 25OHD > 17 microg/liter comprised group 4 (n = 20/group). Measures included aggregate functional performance time (AFPT, seconds), isometric quadriceps strength (Newtons), postural sway (degrees), and choice reaction time (CRT, seconds). Serum bone biochemistry, 25OHD, and parathyroid hormone levels were measured. Patients who fell had significantly impaired functional performance, psychomotor function, and quadriceps strength compared with healthy subjects (AFPT: 51.0 s vs. 32.8 s,p < 0.05; CRT: 1.66 s vs. 0.98 s,p < 0.05; strength: 223N vs. 271N, t = 2.35, p = 0.02). Group 1 had significantly slower AFPT (66.0 s vs. 44.8 s, t = 4.15, p < 0.05) and CRT (2.37 s vs. 0.98 s, t = 3.59, p < 0.05) than groups 2 and 3. Group 1 had the greatest degree of postural sway and the weakest quadriceps strength, although this did not reach significance. Multivariate analysis revealed 25OHD as an independent variable for AFPT, CRT, and postural sway. PTH was an independent variable for muscle strength. Older people who fall have impaired functional performance, psychomotor function, and muscle strength. Within this group, those with 25OHD < 12 microg/liter are the most significantly affected.

Serum cystatin C is not a better marker of creatinine or digoxin clearance than serum creatinine

AIMS

To assess whether cystatin C, a new serum marker of renal function, is a better index of creatinine or digoxin clearance than serum creatinine in older people.

METHODS

Twenty-two volunteers over the age of 65 years (mean 73 +/- 5) were recruited from a healthy elderly volunteer database. None of the volunteers was taking digoxin or other medication known to interfere with digoxin kinetics or assay. Digoxin was infused at a dose of 7-10 microg kg(-1) and blood samples were taken over the following 48 h and assayed for serum digoxin. Serum cystatin C, creatinine and creatinine clearance were measured and a calculated creatinine clearance was estimated using the Cockcroft Gault formula. Digoxin clearance was calculated using a pharmacokinetic software package. All values were log transformed to normalize their distribution.

RESULTS

Of the 22 volunteers enrolled into the study, 18 completed the study. Serum cystatin C ranged between 0.72 and 1.89 mg l(-1) and serum creatinine ranged from 69.6 to 153.9 micromol l(-1). Measured creatinine clearance ranged from 38 to 123 ml min(-1) and calculated creatinine clearance from 29.5 to 88.0 ml min(-1). Digoxin clearance ranged from 51.0 to 103.5 ml min(-1). Cystatin C correlated extremely well with creatinine (r=0.93, P<0.001, 95% CI 0.82, 0.97) and with creatinine clearance (r=0.67, P=0.002, 95% CI 0.3, 0.87). Neither serum cystatin C nor serum creatinine correlated with digoxin clearance (r=0.25, P=0.31, 95% CI -0.25, 0.64 and r=0.44, P=0.068, 95% CI -0.03, 0.75, respectively). Measured creatinine clearance, however, did correlate well with digoxin clearance (r=0.55, P=0.018, 95% CI 0.11, 0.81).

CONCLUSIONS

Serum cystatin C and serum creatinine show very similar correlations with creatinine and digoxin clearances. Serum cystatin C does not offer any advantages in this respect. It remains to be seen whether cystatin C offers any advantage over creatinine in elderly people in other respects.

Functional magnetic resonance imaging of odor identification: the effect of aging

BACKGROUND

Sense of smell declines with age and impairment in olfaction has been observed in some neurodegenerative disorders such as Alzheimer's disease. Functional neuroimaging techniques enable researchers to observe brain regions activated by olfactory stimuli.

METHODS

We gave three mainly olfactory-mediated odors (limonene, methylsalicylate, and eugenol) to six young and six elderly subjects and observed the areas activated by using blood oxygen level dependent contrast functional magnetic resonance imaging.

RESULTS

The group mapping of young subjects showed extensive activation in the orbitofrontal cortex, commonly believed to be the olfactory cortex, some limbic areas (the hippocampus and the thalamus), regions involved with gustatory sensation (the anterior insula and the inferior postcentral gyrus), superior and inferior temporal gyri, and cerebellum. In the elderly group, only the left inferior temporal gyrus and the primary visual cortex reached accepted significance levels.

CONCLUSIONS

We have therefore confirmed previous reports of brain regions involved in olfactory processing in young volunteers and demonstrated decreased activation in elderly volunteers.

Development of an indicator to identify inappropriate use of benzodiazepines in elderly medical in-patients

Studies reporting the quantity of benzodiazepines used are purely descriptive and cannot comment on the quality or appropriateness of prescribing benzodiazepines. An indicator to assess the appropriateness of prescribing benzodiazepines was developed from published literature. The applicability of the indicator was discussed in a multidisciplinary forum. The indicator uses clinical data currently available to the prescriber. The indicator, in the form of an algorithm, was applied to assess the appropriateness of prescribing of benzodiazepines to medical in-patients aged < or =65 years at 17 hospitals in England and Wales. Prescribing data were collected on 1391 patients. Appropriateness of prescribing of 311 benzodiazepines were assessed. Benzodiazepines were prescribed appropriately for 110/311 (35%) prescriptions and inappropriately for 201/311 (65%) prescriptions. Initiation of benzodiazepine for no acceptable indication was the commonest reason for inappropriate prescribing. The instrument identifies the appropriateness of prescribing of benzodiazepines and can be utilised by non-physicians.

Alternative strategies for stroke care: a prospective randomised controlled trial

BACKGROUND

Organised specialist care for stroke improves outcome, but the merits of different methods of organisation are in doubt. This study compares the efficacy of stroke unit with stroke team or domiciliary care.

METHODS

A single-blind, randomised, controlled trial was undertaken in 457 acute-stroke patients (average age 76 years, 48% women) randomly assigned to stroke unit, general wards with stroke team support, or domiciliary stroke care, within 72 h of stroke onset. Outcome was assessed at 3, 6, and 12 months. The primary outcome measure was death or institutionalisation at 12 months. Analyses were by intention to treat.

FINDINGS

152 patients were allocated to the stroke unit, 152 to stroke team, and 153 to domiciliary stroke care. 51 (34%) patients in the domiciliary group were admitted to hospital after randomisation. Mortality or institutionalisation at 1 year were lower in patients on a stroke unit than for those receiving care from a stroke team (21/152 [14%] vs 45/149 [30%]; p<0.001) or domiciliary care (21/152 [14%] vs 34/144 [24%]; p=0.03), mainly as a result of reduction in mortality. The proportion of patients alive without severe disability at 1 year was also significantly higher on the stroke unit compared with stroke team (129/152 [85%] vs 99/149 [66%]; p<0.001) or domiciliary care (129/152 [85%] vs 102/144 [71%]; p=0.002). These differences were present at 3 and 6 months after stroke.

INTERPRETATION

Stroke units are more effective than a specialist stroke team or specialist domiciliary care in reducing mortality, institutionalisation, and dependence after stroke.

Ibuprofen stereochemistry: double-the-trouble?

Racemic ibuprofen is an important NSAID used in the treatment of pain and inflammation in a variety of musculoskeletal and rheumatic disorders. The metabolism of ibuprofen, and that of a number of the related 2-arylpropionic acid NSAIDs, involves chiral inversion of the relatively inactive R-enantiomers to their active S-antipodes, together with other potentially stereoselective conjugative and oxidative pathways. Enantiospecific analytical methodology suitable for the determination of both the drug and its metabolites is essential in order to evaluate the significance of stereoselectivity both in terms of drug action and disposition. Recent investigations have also indicated that the R-enantiomers of these agents may not be totally devoid of useful biological activity, that the formation of acyl-coenzyme A derivatives results in interactions with lipid biochemistry, and has provided new insights into the disposition of these drugs in man. Ibuprofen represents a classical example of a drug where stereochemical considerations are essential for an understanding of its biological properties.

Single dose pharmacodynamics of thioridazine and remoxipride in healthy younger and older volunteers

Phenothiazines are widely used in older patients, but little experimental work has been carried out in this age group. Two groups of healthy volunteers, a younger group (Y: six males and six females, aged 20-42 years) and an older group (O: six males and eight females, aged 65-77 years) took part in a randomized double-blind three-period crossover study in which they received by mouth single doses of thioridazine (Y: 50 mg; O: 25 mg) remoxipride (Y: 100 mg; O: 50 mg) or placebo. Measures of central nervous system (CNS) and haemodynamic function were carried out before drug administration and at 1.5-h intervals up to 9 h post-dose, and blood samples were collected over a 24-h period. No significant differences in dose-corrected pharmacokinetic variables were found between the two groups. There was evidence of marked CNS depressant effects of thioridazine from both objective and subjective measures. The effects for remoxipride were similar, though generally less marked. After allowance was made for dose, there was little indication of any difference in degree of CNS depression between the two age groups. Haemodynamic measures showed orthostatic reductions in blood pressure with thioridazine which were particularly marked in the older group, who also showed lower compensatory increases in pulse rate. These results indicate potential problems with orthostatic hypotension with thioridazine in older patients. CNS depression may also be a problem, especially in patients with compromised cholinergic function.

Psychomotor performance: investigating the dose-response relationship for caffeine and theophylline in elderly volunteers

OBJECTIVE

The aim of the study was to investigate the dose-response relationship for psychomotor performance, caffeine and theophylline in healthy elderly volunteers.

METHODS

In a randomized, double-blind, placebo-controlled, six-period cross-over study we compared the effect of three doses of theophylline (predicted peak concentrations of 3, 6 mg. 1(-1) and 12 mg . 1(-1), two doses of caffeine (predicted peak concentrations of 4.5 mg. 1(-1) and 9 mg. 1 (-1) and placebo on ten healthy elderly volunteers. Psychomotor performance was measured using a continuous attention task, symbol digit substitution test and choice reaction time. Subjective effects were assessed using visual analogue scales. Following drug administration, subjects received the test battery at 30-min intervals, up to 150 min. Maximum and mean effects from baseline on each variable were included in the analysis.

RESULTS

Significant improvement on the continuous attention task was seen at the lowest concentration of caffeine and theophylline used, while at higher concentrations there was a non-significant trend towards placebo scores. There was little effect of either drug on the subjective effects measured by visual analogue scales.

CONCLUSION

Caffeine and theophylline increase psychomotor performance measures of attention at low plasma concentrations in healthy elderly volunteers. This effect is not increased by higher drug concentrations and there is trend towards a return to placebo scores. The lack of effect of both caffeine and theophylline on subjective measures is consistent with previous studies of caffeine in the elderly.

Validity and sensitivity of visual analogue scales in young and older healthy subjects

BACKGROUND

Previous findings from studies on the acute effects of drugs indicate that older subjects report less change on visual analogue scales than do younger subjects, when the observed drug effects on objective performance measures are as great or greater.

AIM

To validate the use of visual analogue scales independently of internal perceptions.

SUBJECTS AND METHODS

50 younger and 50 older subjects rated attributes of four animals--tortoise, crow, tiger and wasp--on a series of 10 cm lines. The attributes rated included physical qualities (size, noise) and psychological aspects (danger).

RESULTS

Ratings were generally similar for the two groups, although older subjects tended to rate slightly greater differences between animals, but the variability was also slightly greater. Thus the mean difference between tiger and wasp for size was 60.1 (SD 15.6) in the younger group and 68.8 (SD 18.4) in the older group.

CONCLUSIONS

These results support the validity of the use of visual analogue scales in both groups. Explanations for the previously observed discrepancy may need to be sought in terms of an effect of age on the perception of internal changes rather than on any difference in the use of the scales.

Impaired nitric oxide-mediated vasodilatation and total body nitric oxide production in healthy old age

1. Basal release of nitric oxide from the vascular endothelium maintains a constant vasodilating tone. Impaired nitric oxide-mediated vasodilatation has been described in hypertension and atheromatous disease. Circulatory diseases account for considerable morbidity and almost half of all deaths in people over the age of 75 years. 2. We have therefore compared nitric oxide-dependent vasorelaxation in 12 healthy elderly subjects with 12 young volunteers matched for blood pressure, cholesterol and glucose, using forearm occlusion venous plethysmography combined with brachial artery infusions of the nitric oxide synthase inhibitor, NG-monomethyl-L-arginine (L-NMMA; 1, 2 and 4 mumol/min) with noradrenaline (60, 120 and 240 pmol/min) as a control vasoconstrictor. We also measured urinary nitrate excretion after a controlled 48 h low nitrate diet as an index of total body nitric oxide production and correlated these changes with forearm blood flow responses to L-NMMA and noradrenaline in both groups. 3. The mean age and blood pressure of the elderly subjects was 76 (range 66-82) years and 132/76 (SEM 4/3) mmHg respectively, while in the young these were 27 (20-35) years and 131/72 (4/3) mmHg respectively. L-NMMA and noradrenaline produced dose-dependent reductions in forearm blood flow in both groups. L-NMMA (4 mumol/min) produced less vasoconstriction in the elderly than in the young (-37.7 +/- 2.6 versus -48.3 +/- 4.2%; P = 0.017). The mean slope of the L-NMMA dose-response curves in the elderly was significantly less than the younger group (-35.2 +/- 3.1 versus -63.7 +/- 10.6; P = 0.041). Noradrenaline, 240 pmol/min, also produced less vasoconstriction in the elderly compared with the young (-22.8 +/- 2.9 versus -35.3 +/- 5.0%; P = 0.029) although the slopes of the dose-response curves did not differ significantly. 4. Urinary nitrate adjusted for creatinine clearance was also significantly higher in the younger group (460.6 +/- 97.7 versus 205.9 +/- 64.8 mumol/day; P = 0.042) and showed a significant correlation with the percentage change in forearm blood flow in response to the maximum dose of L-NMMA (r = 0.5, P = 0.046). 5. We conclude that nitric oxide-mediated vasodilatation in the forearm vascular bed is diminished in old age and this reflects a more generalized reduction in nitric oxide production (as measured by urinary nitrate) in the circulation of older people. The blunted response to noradrenaline points to a more generalized reduction in vascular reactivity in the elderly.

Stereospecific analysis of the major metabolites of ibuprofen in urine by sequential achiral-chiral high-performance liquid chromatography

A sequential achiral-chiral HPLC method has been developed for the stereospecific analysis of the two major urinary metabolites of ibuprofen, namely hydroxyibuprofen and carboxyibuprofen. Achiral analysis was carried out using a Partisil column (250x4.6 mm, 5 microm) and a mobile phase of hexane:ethanol (98.2:1.8, v/v) containing trifluoroacetic acid (TFA; 0.05%, v/v) at a flow-rate of 2.0 ml/min. The HPLC eluate containing the two metabolites was separately collected, evaporated under nitrogen and the residue dissolved in the mobile phase used for chiral chromatography. Chiral-phase analysis was carried out using a Chiralpak AD CSP (250x4.6 mm, 10 microm) with a mobile phase of hexane:ethanol (92:8, v/v) containing TFA (0.05%, v/v) at a flow-rate of 1.0 ml/min. In both assays the analytes were quantified by ultraviolet detection at a wavelength of 220 nm. Modification of the mobile-phase composition allowed the resolution of all six analytes in a single chromatographic run but with an increase in run time and consequent band broadening. The analytical method described allows the direct quantitation of the stereoisomers of both metabolites of ibuprofen in urine following the administration of therapeutic doses of the racemic drug to man.

The use of over-the-counter medication by elderly medical in-patients

Use of over-the-counter (OTC) medications by elderly patients is often not identified. This survey was performed to study the use of OTCs by medical in-patients aged 65 and over. Data on the use of OTC medications before and during hospital admission were collected by questioning patients and case notes were examined for documentation of their use of OTC medications. OTC medications were used by 44 of 138 (32%) patients interviewed. Patients used a total of 70 OTC medications before admission and six OTC medications were being used during hospital admission. There was no documentation of pre-admission and in-hospital OTC medicine use in the clinical notes and patients had little knowledge of the potential harm some products can cause. As more products become available over the counter, doctors should record their use in patients' notes and patients should be encouraged to seek professional advice before purchasing OTC medicines and to read the product information leaflets.

ACE inhibition: postsynaptic adrenergic sympatholytic action in men

BACKGROUND

The mechanisms by which ACE inhibitors produce a sustained clinical benefit are not entirely clear but may involve the sympathetic nervous system. We compared the effect of local brachial artery infusions of an ACE inhibitor (perindoprilat) with the effect of placebo (0.9% NaCl) on endogenously mediated (lower body negative pressure [LBNP]) and exogenously mediated (brachial artery infusions of norepinephrine) sympathetic vasoconstriction.

METHODS AND RESULTS

Eight healthy, normotensive male volunteers (20 to 32 years) were studied on one occasion. Forearm blood flow (FABF; mL x dL forearm(-1) x min(-1)) responses to LBNP (-20 cm H2O) and increasing increments of norepinephrine (60, 120, and 240 pmol/min) were compared when coinfused with placebo and perindoprilat (5 nmol/mL). FABF was measured simultaneously in both arms by venous occlusion plethysmography with mercury-in-Silastic strain gauges with drugs infused locally at the left brachial artery. The right arm served as a control. Baseline FABFs did not differ between the infused and control arms (3.04+/-0.52 versus 3.05+/-0.42 mL x dL forearm(-1) x min(-1); P=.98). Perindoprilat did not alter FABF when infused alone, but the FABF response to LBNP in the infused arm was attenuated during the perindoprilat infusion compared with placebo (-17.8+/-4.3% versus -33.8+/-3.1%, respectively; P=.015). The FABF response to the maximum dose of norepinephrine was also attenuated during the perindoprilat infusion compared with placebo (-28.3+/-1.4% versus -36.9+/-2.8%, respectively; P=.015). The mean slope of the FABF (log transformed) versus norepinephrine dose-response curve was significantly attenuated by perindoprilat compared with placebo (-0.11+/-0.019 versus -0.02+/-0.02; P=.001).

CONCLUSIONS

We conclude that ACE inhibition has a significant postsynaptic sympatholytic effect in the forearm circulation of men.

Development of prescribing indicators for elderly medical inpatients

AIMS

To identify and improve suboptimal prescribing for elderly patients we have developed a number of prescribing indicators which focus on areas of concern and allow evaluation of the benefit of interventions. We report here on fourteen indicators.

METHODS

The indicators are of three types: a) purely descriptive with no attempt to define optimal values, e.g. number of items prescribed per patient; b) based on unnecessary or potentially harmful prescribing, e.g. duplication; c) assessing the appropriateness of prescribing specific drugs or combinations e.g. digoxin and warfarin/aspirin in atrial fibrillation (AF). Appropriateness was defined on the basis of objective research findings and involved comparing individual patient clinical records to criteria for appropriate prescribing. Prescribing and personal data were collected for medical inpatients aged 65 years or over in 19 hospitals in England and Wales. A total of 1686 patients were included, median age 81 years, 41% were male.

RESULTS

Patients were prescribed 11475 items, mean 4.6 regular items per patient. Completion of drug allergy/sensitivity statements varied from 3 to 93% between units. Use of generic name and specification of a maximum frequency of administration for "as required' medicines were more consistent, ranging from 76-94% and 52-81% respectively. Little duplication of therapy was seen. Benzodiazepines were prescribed for 22% patients, but were appropriate in only approximately one third of these. Of the 2% patients prescribed an angiotensin converting enzyme inhibitor with a potassium-sparing diuretic or potassium supplement, prescription of the combination was appropriate in 84%. Coprescription of steroids with beta 2-adrenoceptor agonists appeared excessive in 67% patients receiving a beta 2-adrenoceptor agonist, as only 51% had documented evidence of steroid responsiveness or another indication for steroids. Stroke prophylaxis in AF was inadequate: 22% patients prescribed digoxin also received warfarin or aspirin 300 mg whereas 64% should have received the coprescription.

CONCLUSIONS

These prescribing indicators are sensitive to inappropriate prescribing for elderly medical inpatients and cover a wide range of therapeutic areas. They should enable changes in prescribing quality to be measured objectively. Interhospital variation in casemix resulted in substantial differences in the proportion of patients in whom it would have been appropriate to prescribe specific drugs or combinations and prevented derivation of reference ranges of optimal prescribing for four indicators.

Aspartame pharmacokinetics - the effect of ageing

Aspartame is an intense sweetener which is increasingly used in the UK. It is registered at an acceptable daily intake (ADI) of 40 mg/kg, although there are no previous data relating to the metabolism of aspartame in older people. Twelve young and 12 elderly volunteers each received a single dose of approximately 40 mg/kg of aspartame. Baseline concentrations of phenylalanine (the main metabolite of aspartame) rose after ingestion with a significantly higher maximum concentration (Cmax) (81.3 vs. 63.3 micromol/1, p<0.01) and area under the plasma concentration-time curve extrapolated to infinity AUC 9(0-infinity)(518.7 vs. 353.5 micromol . h/l, p<0.01) in the elderly group. The higher concentrations reflected a significant fall in volume of distribution (V) from 2.03 to 1.59 1/kg (p <0.05) and clearance (CL) from 7.3 to 4.9 ml/min/kg (p <0.005) in the elderly group. The greater effect on CL than on V resulted in a small but non-significant rise in elimination half life (3.5 to 3.9 hours). The sizes of the differences were modest implying that there is no need on pharmacokinetic grounds for a change in the ADI for older people.

Hawksley random zero sphygmomanometer versus the standard sphygmomanometer: an investigation of mechanisms

There has been recent controversy over the accuracy of the Hawksley random zero sphygmomanometer (RZS). In most instances, there has been a bias towards lower recordings with the RZS. In an attempt to identify the mechanism, we designed a study to test the hypothesis that biased error is due to: (1) the magnitude of the random zero; and (2) the magnitude of the pressure being recorded. A RZS (60 mm Hg zero UK version) was connected via a Y-tube to a standard mercury sphygmomanometer (SMS). The circumference of the cam responsible for the variable reservoir size in the RZS was marked into quarters. Within each 10 mm Hg band from 300 to 60 mm Hg, 12 paired readings were taken randomly: three within each of the four quarters of the cam circumference. The mean SMS value was 148.8 vs. 148.2 mm Hg for the RZS. Although of minimal biological significance this difference was highly significant (t = 6.2; p < 0.0001). Our findings fail to confirm the difference between RZS and SMS previously reported and we did not find any evidence of a relation in the difference between SMS and RZS and either the random zero value or the height of the blood pressure. Our findings suggest that if the RZS does under record BP versus the SMS it may relate to a patient-machine interaction not detectable in our system.

Twenty-four-hour ambulatory blood pressure monitoring in healthy elderly people: reference values

One hundred and two healthy elderly volunteers (aged 65-83 years) underwent 24-hour ambulatory blood pressure monitoring. Mean day- and night-time pressures were higher than reported for younger subjects. Removing outlying BP measurements from individual 24-hour recordings only minimally affected mean figures of the group but in some individuals mean day diastolic BP may be up to 5 mmHg lower on editing. Using unedited data, mean day and night pressures were 134/81 mmHg and 119/67 mmHg respectively (corresponding 95th centiles 160/96 mmHg and 146/84 mmHg) and systolic and diastolic BP loads were 36% and 21%. These values may be used as temporary reference values for elderly subjects pending the results of longitudinal studies. Studies quoting ABPM data should specify whether data editing has been employed and, if so, the editing thresholds should be stated.

Investigation of ambulatory blood pressure monitoring data editing criteria

Ambulatory blood pressure monitoring (ABPM) allows multiple measurements of BP over a 24h period but often produces a proportion of measurements which are distant from the mean and unlikely to be genuine. The software which accompanies the SpaceLabs 90207 monitor requires criteria to be set which excludes outliers (autoediting) but there is no published data evaluating at what levels these autoediting criteria should be set. This study set out to ascertain whether outlying BP measurements represent true blood pressures or machine error, the determinants of machine error and appropriate autoedit criteria. Twenty subjects, both normotensive and hypertensive, were studied by ABPM with a blinded observer recording BP using a standard mercury sphygmomanometer (SMS) connected via a T-tube during three activity phases: sitting with cuffed arm still, walking but keeping arm still during measurement and sitting but gently moving the arm during measurement. The results show that a high ABPM/SMS discrepancy is associated with arm movement. After studying different autoediting criteria which aimed to eliminate the maximum number of conflicting readings while excluding the minimum number of unconflicting readings, an autoediting threshold of between 1.75 and 2 s.d.s from the mean based separately on sleep and awake measurements is suggested.

Pharmacokinetics and prescribing in the elderly

The use of prescribed medication in general is higher in the elderly than in the young and it is possible that existing patterns of antimicrobial agent prescribing may predispose to suboptimal response, certain adverse drug reactions (ADR) and the emergence of resistant strains of organisms. Age is an important variable affecting the pharmacokinetics of drugs, including many antimicrobials. Changes which may affect Cmax/MIC ratios and/or the time above MIC include reduced first-pass metabolism, altered distribution volume, reduced binding to albumin, reduced metabolic biotransformation and reduced renal elimination. Application of a knowledge of antimicrobial agent pharmacokinetic changes with age and their implications for response may enable more precise determination of dose regimens for older patients, which is probably desirable for the prevention of both ADR and bacterial resistance.

The pharmacokinetics and pharmacodynamics of medifoxamine after oral administration in healthy elderly volunteers

The pharmacokinetics and psychomotor effects of medifoxamine, a 5 HT reuptake inhibitory antidepressant, were studied in healthy elderly volunteers after single and multiple dosing. The elimination half life (t1/2z) after single doses of 300 mg was 2.8 h--almost identical to that found in young volunteers. After seven days of dosing at 100 mg three times daily the mean corrected AUC after 300 mg significantly increased from 1.04 to 1.34 mg.h.l-1 and t1/2z increased to 4.0 h (NS). There were no significant changes in critical flicker fusion frequency, symbol digit substitution, continuous attention or choice reaction times.

Psychomotor performance and antihypertensive treatment

1. The aim of treatment of hypertension is prevention of cardiovascular complications without adverse drug reactions. Psychomotor performance can be measured objectively yet there remains uncertainty concerning the psychomotor effects of antihypertensive drugs during chronic treatment. This uncertainty is partly due to the confounding adverse effects of cerebrovascular disease and hypertension itself. There are as yet insufficient good quality data on psychomotor effects with which to differentiate between the commonly used agents. However, in general, the beneficial effect of lowering blood pressure tends to more than offset any adverse effects of the agent used.

Assessment of changes in psychomotor performance of elderly subjects

1. The repeatability of a computerised psychomotor test battery on a day-to-day and week-to-week basis was assessed by determining its test-retest reliability and variations in group-means and intraindividual psychomotor performance scores of elderly people. 2. Psychomotor performance was assessed in 50 well-screened elderly subjects (21 males, 29 females; mean age 70.4 +/- 5.0 (s.d.) years) on 5 consecutive days and over 4 weeks in standardised test conditions. 3. The psychomotor test battery consisted of computerised versions of symbol digit substitution test (SDST), continuous attention test (CAT), choice reaction time (CRT), critical flicker fusion test (CFFT), cognitive flexibility test (FLEX), paired word association test (PWAT) and inspection time (INSP). 4. Main outcome measures were test-retest reliability, group variability and intraindividual variability. 5. There was no significant variation in group-means for all components of the test battery over 5 days or 4 weeks on two way analysis of variance. The intraindividual coefficient of variation was low for SDST, CRT, CFFT, FLEX, PWAT and INSP during the period of assessment. Test retest reliability was greater than 0.8 for SDST, CAT, CRT and PWAT. 6. Tests in the Automated Psychomotor Test Battery are reliable and repeatable measures of psychomotor performance on a day-to-day and week-to-week basis.

Computerised psychomotor performance testing: a comparative study of the single dose pharmacodynamics of minaprine and amitriptyline in young and elderly subjects

The psychomotor and cardiovascular effects of minaprine 100 mg, a novel antidepressant, were compared with amitriptyline 25 mg, as a positive control, and placebo in a single dose randomised double-blind crossover trial using an automated psychomotor test battery (APT), postural sway (PS), blood pressure (BP) and pulse in nine young and nine elderly healthy subjects. Analysis of variance, taking into account baseline values, showed that continuous attention test (CAT), critical flicker fusion threshold (CFFT), decision making test (DMT) and paired word association (PWA) were significantly impaired with amitriptyline compared with minaprine and placebo. Minaprine did not differ from placebo. Amitriptyline significantly lowered supine systolic blood pressure (BP) and all treatments produced significant decreases in heart rate in young and elderly. No age effect on psychomotor performance was seen. Minaprine compared favourably with amitriptyline using the APT with the doses used. The APT is useful in the evaluation of new drugs on psychomotor performance.

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.

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.

ABC of sleep disorders. Sleep and sleep problems in elderly people

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The association of age with gastric emptying

Gastric emptying is important as a rate-limiting step in the absorption of orally administered drugs. Paracetamol absorption kinetics were used to compare gastric emptying in 19 fit elderly and 19 fit young volunteers. The results showed no significant difference in any of the derived parameters (t1/2abs, tlag and tmax) between the two groups. These results suggest that ageing does not impair this rate-limiting step in drug absorption.

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.

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.

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.

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.

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.

Effects of caffeine on vigilance and other performance tests in normal subjects

In two randomized double-blind crossover studies, 8 and 10 healthy volunteers took either 200 mg caffeine or placebo. Objective and subjective measures of caffeine effects were carried out over the following 1-3.5 h. Auditory vigilance, a test lasting 1 h, showed significantly better performance on caffeine than on placebo. In the second study, this effect was only apparent in the second half of the test. Of the shorter objective tests used, only finger tapping showed a significant effect of caffeine, the rate of tapping over 1 min being increased. The subjective assessments showed increased interest and alertness in the caffeine session. Reliable detection of the effects of mild stimulant drugs using objective measures may require the use of tests of long duration.

"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.