Post-release drug treatment risks: strategies to minimise harm to patients

This paper examines the perceptions and causes of drug treatment-related error, and suggests some risk reducing strategies. Interest in medical error surged recently, culminating with an estimate by the US Institute of Medicine in 1999 of 44,000 to 98,000 annual care-related deaths. Public media pressure elicited responses from health care providers, purchasers, internists and health professionals' organisations. A search was made using PubMed, focusing on papers from 1980 to date giving data on trends and causes of in-hospital drug-related error. Papers with estimates of prevalence rates of drug-induced injury in large denominator populations were selected. One hundred and seven papers on drug-related error were identified; 36 clearly defined denominators and compared rates in different groups. Occurrence rates of drug-induced harm were similar (2.2% to 6.7%) in the US and British hospital surveys. The Harvard Medical Practice Study first reliably measured the frequency of care-related patient harm. More reliable and accurate information is needed on the base-line rates of drug-related injury. Whereas there are few precise estimates of drug-induced injury, the evidence suggests that between half and two-thirds of hospital-related harmful events are preventable. Most experts agree that hospitals need to change radically their approach to professional error from one of blaming individuals to overhauling the systems for monitoring, detecting and preventing drug-related error. Hospital managers should implement voluntary, non-punitive, and confidential systems for reporting error, and apply methods of safety enhancement which succeed in high-risk industries. A realistic and achievable target could be halving of current risk. Incentives can be given to event monitoring and pharmacotherapy quality assurance, to encourage timely and accurate reporting. On-line doctors' entry of drug orders and computerised adverse event monitoring also promote error reduction.

Effect of extracellular potassium concentration on the sodium-potassium pump rate in human lymphocytes

1. The purpose of this study was to determine whether physiological changes in extracellular free [K+] cause significant changes in the Na(+)-K+ pump rate and intracellular free [Na+]. 2. The Na(+)-K+ pump rate was measured in human lymphocytes by determining ouabain-sensitive 86Rb+ influx at several concentrations of K+. The Na(+)-K+ pump rate increased within the physiological range of extracellular free [K+] (K1/2 = 1.5 mmol/l). 3. To test the hypothesis that elevation of extracellular free [K+] reduces intracellular free [Na+] rapidly, which in turn then slows the pump rate during experimental incubations, lymphocyte intracellular free [Na+] was measured using the fluorochrome sodium-binding benzofuran isophthalate. With larger elevations of extracellular free [K+], intracellular free [Na+] dropped more rapidly. Thus previous discrepancies among determinations of K1/2 may be the result of variations in incubation times, which can skew the pump rates measured during incubations in various extracellular free [K+] values. Steady-state intracellular free [Na+] varied inversely with extracellular free [K+].

Iron dextran and systemic lupus erythematosus

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Protection: risk ratio of antihypertensive drug treatment in the elderly

In recent controlled trials using clinic-based manometry, thiazides and beta-blockers prevented cerebrovascular and coronary deaths in patients aged 60-79 years with cryptogenic hypertension (diastolic 90-119 mm Hg). Elderly patients should usually take low-dose thiazide with potassium replacement. beta-Blockers also postpone death, but may mask hypoglycaemia. Calcium blockers and low-dose angiotensin-converting enzyme (ACE) inhibitors appear preferable in diabetes, and thiazides or ACE inhibitors in heart failure or peripheral vascular disease. Maintaining average diastolic pressure at 80-84 mm Hg impairs function of the kidneys, and possibly the myocardium. Metabolic reactions worsen with age. Drug treatment should match individual daily function. By clinic manometry, the protection:risk ratio of antihypertensive treatment progressively decreases with age, reaching less than 1.0 in patients over 80-85 years. Twenty-four-hour ambulatory blood pressure information should guide treatment more reliably in patients greater than or equal to 60 years.

Multiple medication: problems of the elderly patient

Elderly persons are apt to receive multiple drugs for many diseases. Prescribers should take extra care in persons aged over 65-70 years, and especially the very old. The main problem of the elderly is the unpredictability of their response to drugs. Self-medication with both prescribed and over-the-counter drugs worsens this problem. Drug actions may be altered by impairment of the liver, kidneys and brain, or acute illness, or both. Unwanted (adverse) drug reactions often produce rapid and unduly severe illness in the old. Some antibacterial antibiotics like the sulphonamides are best avoided. Taking many drugs together promotes adverse interactions between the drugs. Drugs with a narrow therapeutic ratio, such as warfarin, digoxin, the aminoglycosides, and many antiarrhythmic drugs, cause clinical problems. Old persons respond more abruptly to drugs like benzodiazepines, opioid analgesics, and antiparkinsonian drugs. Anaesthesia given on top of psychotropic drugs may damage the central nervous system. The elderly brain is more sensitive to induction agents and short-acting intravenous anaesthetics, like alfentanil and midazolam; the elderly liver is more easily damaged by inhalational anaesthetics like halothane. The overall benefit:risk ratio should be judged for every drug in each patient. Wherever possible, drug treatment should be avoided. If drugs are given, safe drugs with broad therapeutic ratios and tissue- or receptor-specific actions are preferable. Drug doses are usually, but not always, reduced. Benefit from a drug should be assessed early. Severe unpredictable adverse reactions need immediate cessation of the drug and prompt patient support. The practitioner should frequently review the patient's continuing need for drugs.

Hyperinsulinaemia in thyrotoxic hypokalaemic periodic paralysis

To test the hypothesis that there is an abnormal serum insulin response to a carbohydrate load in thyrotoxic hypokalaemic periodic paralysis (THPP), 18 men with THPP and 15 with uncomplicated thyrotoxicosis were studied during an oral glucose tolerance test. The THPP group had significantly higher fasting insulin concentrations (27.6 [3.6] vs 13.4 [1.8] mU/l; p less than 0.005) and a higher overall insulin response to oral glucose (p less than 0.001 by ANOVA) than the thyrotoxicosis group. There were no significant differences in fasting or stimulated glucose. Hyperinsulinaemia may be an important factor in the precipitation of acute paralysis in THPP.

Endothelin-1 mRNA expression in the rat kidney

Cultured pig and bovine endothelial cells are capable of synthesizing endothelin-1 (ET-1). Thus the observation that the kidney contains a large number of binding sites for ET distributed in close proximity to endothelial cells suggests that ET-1 may be released from the endothelium to act locally on these receptors. In support of this hypothesis, using the technique of reverse transcription with specific amplification of cDNA, we report here that ET-1 mRNA is expressed in the rat kidney. The partial sequence of the amplified rat ET-1 cDNA confirms that the mature rat peptide is identical to that of the mouse, man and pig, but with some differences in codon usage.

Influence of family history of cryptogenic hypertension, age, sex and race on lymphocyte sodium/potassium pumps

To determine the effects of age, sex, race, and family history of hypertension on cellular cation transport, we measured specific tritiated-ouabain binding (sodium/potassium pump number), and sodium/potassium pump-mediated rubidium-86 uptake in blood lymphocytes from 105 healthy normotensive adults, comprising 23 Chinese and 19 Indian subjects who had first-degree relatives with cryptogenic hypertension, and 40 Chinese and 23 Indian matched subjects without such history. Both Chinese and Indian subjects with family history had significantly fewer sodium/potassium pumps than control subjects. Sodium/potassium pump-mediated rubidium-86 uptake was similar in these four subject groups. Seven Indian patients with untreated cryptogenic hypertension had fewer sodium/potassium pumps than normotensive Indians without family history. Age did not affect sodium/potassium pump numbers in cells from normotensive subjects. In normotensive subjects without family history. Chinese women had more sodium/potassium pumps than Chinese men, but Indian subjects did not show this pattern. We conclude that a family history of cryptogenic hypertension is associated with fewer lymphocyte sodium/potassium pumps than normal. The reduction in cellular pump number might be only a marker, or an epiphenomenon. However, the reduction in pump number might contribute to the pathogenesis of cryptogenic hypertension if it produces sodium retention in renal tubular or peripheral vascular cells.

Magic or medicine? Clinical pharmacological basis of placebo medication

A placebo may be a pharmacologically active or an inert substance, a procedure, or a patient-doctor interview. Placebos work best in symptoms or disease which vary over time and between patients. The placebo works best in behaviour disorders, somatic autonomic disorders like pain, and neurohumoral disorders like hypertension. However, placebo action is incompletely defined in its molecular pharmacology. The endogenous brain systems of opioid, antiopioid, and gamma-aminobutyric acid polypeptide transmitters and neuronal receptors account in part for placebo analgesia. Non-painful stress may be mediated through other neurohumoral systems. A separate neural system might control these subsystems. Confidence based on the doctor's empathy commonly evokes the placebo effect. How the symbolic input of thought or emotion is translated into neuronal events is unknown. Double-masked 'controlled' clinical trials use placebo to reduce bias; overuse of placebo here may harm some patients. Oral placebos for routine use include thiamine at low dose. Potent drugs like glucocorticoids cannot be justified as placebo in mild disease or non-disease. Both patient and doctor are usually unaware of the placebo effect during interviews. Doctors may increase placebo efficacy by improving interpersonal skills.

Optimising drug management of individuals with cryptogenic hypertension

Regular drug treatment in mild hypertension (diastolic blood pressure 90-104 mm Hg) reduces death from stroke, and other non-coronary vascular events. The optimum strategy remains sequential monotherapy with the lowest effective dose, with drug combinations as an option. A beta-adrenoceptor blocker or low-dose thiazide is good value treatment for many patients. beta-Blockers are good for young (under 50 years), anxious non-smoking men, men after myocardial infarction, and renal failure patients. Older persons over about 65 years, women, smokers, stroke victims, and liver disease patients should generally take a thiazide or calcium ion-channel blocker. Pregnant women and untreated gouty patients should avoid diuretics. Calcium blockers and angiotensin-converting enzyme inhibitors are preferable in severe or insulin-dependent diabetes and renal failure, and angiotensin manipulators or thiazides in heart failure or peripheral vessel disease. Hyperlipidaemia should not generally exclude thiazides or beta-blockers. Some hypertensive stroke patients without encephalopathy may not need antihypertensive drug treatment for the first 24-48 hours. Drug treatment should be tailored to individuals according to their general condition, physiological age, and any concurrent disease or medication. Unwanted drug reactions should not deter patients from fulfilling social and economic goals. The desired treatment end-point is a diastolic pressure of 85-89 mm Hg, but a compromise is usual in poorly motivated young men, and the elderly.

Sodium pump numbers and cation transport of lymphocytes in pregnancy-induced hypertension

Pregnancy-induced hypertension may be linked with sodium pump inhibition and an increase in vascular myocytic tone and, hence, flow impedance. All of the findings of studies on circulating plasma and blood cells are not, however, consistent with this hypothesis. We therefore assessed sodium pump numbers and cation transport in lymphocytes from 23 women with untreated pregnancy-induced hypertension, 28 normotensive pregnant women and 28 healthy non-pregnant women. We measured the maximum 3H-ouabain binding capacity to determine the sodium pump activity and the apparent dissociation constant (the reciprocal of which estimates binding affinity) by Scatchard analysis, ouabain-sensitive (pump-mediated) 86rubidium influx and ouabain-resistant (pump-independent) influx in lymphocytes in vitro. Pregnant women, whether normotensive or hypertensive, had significantly more sodium pump activity and a higher pump-mediated and pump-independent 86rubidium influx than non-pregnant women. Sodium pump activity and the pump-mediated and pump-independent 86rubidium influx all reached normal, non-pregnant levels in normotensive pregnant women 6 weeks after delivery, but remained high in women with pregnancy-induced hypertension. The normotensive and hypertensive pregnant women and non-pregnant women all had similar ouabain binding affinity. The results of our study do not support the circulating sodium pump inhibitor hypothesis in pregnancy-induced hypertension.

Cation transport across lymphocyte plasma membranes in euthyroid and thyrotoxic men with and without hypokalaemic periodic paralysis

1. To study potassium transport in hypokalaemic periodic paralysis in a model of striated muscle cells, we measured specific [3H]ouabain binding (the number of sodium-potassium pumps), sodium-potassium-pump-mediated (ouabain-sensitive) 86Rb+ influx and sodium-potassium-pump-independent (ouabain-resistant) 86Rb+ influx in lymphocytes in vitro. 2. The subjects comprised euthyroid and thyrotoxic men with hypokalaemic periodic paralysis between attacks, men with uncomplicated thyrotoxicosis, and healthy men matched for age and weight. 3. Thyrotoxic patients, both with and without periodic paralysis, had significantly more lymphocyte sodium-potassium pumps than normal, and a significantly greater sodium-potassium-pump-mediated 86Rb+ influx. Anti-thyroid treatment corrected this defect in patients with thyrotoxic periodic paralysis. Euthyroid patients with cryptogenic periodic paralysis had significantly increased sodium-potassium-pump-mediated 86Rb+ influx, but a normal number of sodium-potassium pumps. 4. Only untreated thyrotoxic and euthyroid patients with periodic paralysis showed a significant increase in sodium-potassium-pump-independent 86Rb+ influx (5.2 +/- 2.8 and 4.5 +/- 1.8 respectively, vs control 2.8 +/- 1.0 pmol h-1 10(-6) cells; mean +/- SD; P less than 0.001, P less than 0.005). 5. We conclude that thyrotoxicosis increases the number and activity of sodium-potassium pumps and facilitates, but is probably not necessary for, periodic paralysis. Hypokalaemic periodic paralysis is associated with an increase in sodium-potassium-pump-independent potassium influx.

Treatment of allergic adverse drug reactions

Allergic adverse drug reactions are unpredictable and dose-independent. The cellular events which comprise an allergic reaction cannot be effectively altered until we understand how, for instance, the provoking drug forms an immunoglobulin-like factor which releases chemical mediators of inflammation from effector cells, or how these mediators act on target tissues. Nor do we know how and why different patterns of drug allergy vary over time. The post hoc treatment of reactions is largely empirical and supportive, and depends on the type of reaction and its clinical setting. The treatment of acute severe reactions like analphylaxis include resuscitating the patient, ensuring airway patency, injecting adrenaline i.m., setting up an i.v. infusion of a plasma expander, and injecting an anti-histamine and hydrocortisone. After anaphylaxis the vital signs, the ECG, and respiratory function should be monitored in the intensive care unit; supportive drugs may be needed for 72 hours. Some other systemic disorders induced by allergic drug reactions are well defined, but their treatment is either nonspecific or highly specialised. Because disease and death due to drug allergy are becoming more frequent, clinicians must try to limit them by recording careful drug histories, using radiocontrast agents only when necessary, and prescribing drugs only when benefit will probably exceed risk. Doctors should also advise their patients against the misuse of drugs.

Metabolic effects of antihypertensive drugs

Metabolic changes in essential hypertension may complicate the primary disease, or drug and nondrug intervention, or both. These changes include disturbances in renal function, the metabolism of urate, glucose and lipids, and in cation transport across plasma membranes. Some of these disorders may be worsened by the chronic administration of antihypertensive drugs like diuretics, beta-adrenoceptor antagonists, and the angiotensin converting enzyme inhibitors. Recent randomised controlled trials of antihypertensive drugs showed that the apparently adequate control of hypertension with a thiazide or beta-antagonist does not consistently prevent cerebrovascular and cardiac deaths and morbidity, and that beta-antagonists protect only nonsmoking men against cardiac death. One explanation is that blood pressure may not have been lowered enough. By contrast, cardiac deaths may be increased in patients whose diastolic pressure is reduced below 85-90 mmHg. The adverse metabolic effects of antihypertensive drugs may in part offset their protective benefits. However, population evidence does not support the general avoidance of thiazides or beta-antagonists in mild hypertension. Where possible drug treatment should be tailored to individuals according to their general condition, age, and any concurrent disease or medication.

Agranulocytosis and anaemia induced by sulfametopyrazine in a sulfametopyrazine-trimethoprim combination

We report a case of prolonged fever, agranulocytosis, and anaemia associated with the long acting sulphametopyrazine-trimethoprim combination (Kelfiprim). A woman of 23 years took an overdose of 13 tablets over five days for presumed cystitis. One day after the last dose the patient developed fever and a generalised rash. The fever persisted and her previously normal leukocyte count decreased to 1.8 x 10(9)/1. After treatment with paracetamol the fever settled briefly, and then recurred for another 16 days. A later peripheral blood leukocyte count of 0.77 x 10(9)/1, haemoglobin of 10.8 g/dl, and a hypocellular bone marrow with depressed granulopoiesis and haemopoiesis suggested marrow suppression induced by sulfametopyrazine. Since the IgM antibody against the Epstein-Barr virus capsid antigen was detected, the adverse drug reaction might have been aggravated by this virus. The case highlights the risk of severe haematological adverse reactions associated with sulphonamide treatment, and argues for the use of trimethoprim alone for uncomplicated cystitis.

Enhancement of specific [3H]ouabain binding and ouabain sensitive 86rubidium influx in intact human lymphocytes by a dialysable factor in human and fetal calf serum

We have measured specific [3H]ouabain binding and ouabain sensitive 86rubidium influx in intact human lymphocytes incubated for up to 7 days in media containing different concentrations of fetal calf serum and human serum. Incubation for periods of up to 7 days with fetal calf serum and human serum produced increases in both specific [3H]ouabain binding and ouabain sensitive 86rubidium influx that were dependent on concentration and time. Neither specific [3H]ouabain binding nor ouabain sensitive 86rubidium influx was altered when dialysed serum was used, suggesting that both fetal calf serum and human serum contain a dialysable factor or factors which stimulate specific [3H]ouabain binding and ouabain sensitive 86rubidium influx in intact human lymphocytes. To further elucidate the mechanisms underlying these changes we also measured the activity of two other enzymes of the lymphocyte plasma membrane, 5'-nucleotidase and gamma-glutamyltransferase, the uptake of [3H]thymidine by the intact cells, and the effects of cycloheximide, puromycin, and anisomycin, inhibitors of protein synthesis. The activity of 5'-nucleotidase was increased after incubation of the lymphocytes in fetal calf serum for 72 h, but the activity of gamma-glutamyltransferase was not changed, suggesting some selectivity of the stimulatory effect. Measurements of [3H]thymidine uptake by the lymphocytes showed that the major part of the observed changes in specific [3H]ouabain binding and ouabain sensitive 86rubidium influx was not attributable to transformation of the lymphocytes to lymphoblasts. All three inhibitors of protein synthesis prevented the increase in specific [3H]ouabain binding due to fetal calf serum.

Reversible inhibition of leucocyte sodium pumps by a circulating serum factor in essential hypertension

To test whether leucocyte sodium pumps function abnormally in patients with essential hypertension specific tritium-ouabain binding (number of pumps) and ouabain sensitive uptake of rubidium-86 (86Rb+) (transport activity) were measured in mononuclear leucocytes from 37 untreated hypertensive patients and 85 normotensive subjects. Ouabain binding was lower and transport activity per binding site higher in the hypertensive patients before incubation (p less than 0.001), but both variables were normal after incubation for 72 hours with fetal calf serum. To determine whether a circulating inhibitor of sodium pumps was present in patients with hypertension ouabain binding and 86Rb+ uptake were measured in normal leucocytes before and after incubation for 72 hours with serum from 13 untreated hypertensive patients and 18 normotensive subjects. Ouabain binding was lower after incubation of cells with serum from hypertensive patients than after incubation with normal serum both before (p less than 0.01) and after (p less than 0.001) dialysis of the serum. The results suggest that in hypertension a circulating serum inhibitor of the sodium pump causes a chronic but reversible reduction in the number of pumps.

Adrenal phaeochromocytoma and neurofibromatosis presenting with hypotension

We report a case of adrenal phaeochromocytoma with the stigmata of neurofibromatosis, who presented with acute hypotension. The patient later had episodes of hypertension alternating with hypotension, associated with electrocardiographic changes simulating myocardial infarction, and finally a completed stroke. The circumstances illustrate the problem of early recognition of the protean clinical effects of an excess of circulating adrenal medullary hormones. They also emphasise the need to consider phaeochromocytoma as a differential diagnosis of apparent clinical shock.

Effects of long-acting propranolol on blood pressure and heart rate in hypertensive Chinese

In a double-blind, balanced and randomised study we used treadmill exercise to assess the effects of long-acting propranolol (LA propranolol) 160 or 320 mg or placebo, given once daily for 4 weeks, on heart rate (HR) and blood pressure (BP) in 15 Chinese subjects with mild primary hypertension (PHT). We used 24 h ECG monitoring to assess drug effects on HR. Another 18 patients were similarly assessed without exercise. Steady-state plasma propranolol concentrations after LA propranolol 160 and 320 mg were comparable to those after ordinary propranolol 80 and 160 mg daily measured in 11 and 12 separate patients. LA propranolol 160 and 320 mg reduced HR and BP before and during vigorous exercise. LA propranolol 160 and 320 mg reduced HR for 17.6 and 21.4 h of the day, and 320 mg significantly reduced the mean 24 h HR, and the mean maximum HR. The drug effects on BP and HR, and the average plasma propranolol levels after LA propranolol were similar to those reported in European subjects.

Measurement of specific [3H]-ouabain binding to different types of human leucocytes

We have studied the specific binding of [3H]-ouabain to intact mononuclear leucocytes (82% lymphocytes) and polymorphonuclear leucocytes. In both types of cells [3H]-ouabain binding was saturable, confined to a single site of high affinity, slow to reach equilibrium, slow to reverse, temperature-dependent, competitively antagonized by potassium, and facilitated by the presence of divalent cations. The equilibrium dissociation constants were 2.4 +/- 0.7 nmol/l (polymorphs) and 2.4 +/- 0.4 nmol/l (mononuclear cells) (NS). The values of maximal specific ouabain binding, measured by Scatchard analysis of concentration vs binding curves (Bmax), were 33.9 +/- 6.0 fmol/10(6) cells (polymorphs) and 59.3 +/- 11.6 fmol/10(6) cells (mononuclear cells) (P less than 0.02). The corresponding numbers of sites per cell were 20415 +/- 3616 and 35712 +/- 6986 respectively (P less than 0.02). When the numbers of binding sites were expressed per square micron of cell surface area the difference between the two cell types was proportionately greater (83 and 186 sites per micron 2 respectively). We conclude that the [3H]-ouabain binding sites on mononuclear and polymorphonuclear leucocytes are similar in nature, but different in both number and density on the cell surface. Measurements of Bmax in mixed cell populations should therefore take account of cell type as well as cell size and number.

Clinical pharmacology of beta-adrenoceptor antagonism in angina pectoris: an overview

Beta antagonists competitively block beta 1-adrenoceptors that mediate both the rate and force of myocardial contraction. Their precise mechanism of anti-anginal action is uncertain. A reduction in oxygen demand may relative pain and improve effort tolerance. Alternatively inhibition of the adrenergic drive to contraction may offset the increased ventricular wall tension due to incomplete relaxation. Partial agonist activity in a beta-antagonist does not influence efficacy nor protect against airflow obstruction. Membrane stabilising activity is clinically trivial. Cardioselectivity makes airflow obstruction less likely at low but not at high blood concentrations of drug. Alpha-receptor antagonism may also prevent broncho-constriction; it has not been assessed in coronary vasospasm. The dosage and choice of drugs are based on pharmaco-kinetic and dynamic data in animals and man. The major side-effects of beta-blockade are heart failure and airflow obstruction. Cardiotoxicity from overdosage may be treated with isoprenaline, dopamine or glucagon while beta 2-agonists will reverse bronchoconstriction. Since beta-antagonists raise-peripheral vascular impedance, reduction of preload with nitrates enhances their antianginal efficacy. Combining a beta-antagonist with nifedipine seems especially useful. Beta-blockade is worth trying in angina with normal coronary arteries. In acute coronary insufficiency beta-blockade reduces both the work-load on the heart and the somatic features of anxiety, so preparing patients for investigations, like coronary arteriography, aimed at definitive treatment.

Relationship between bronchial effects and plasma practolol concentration in man

A double-blind, balanced and randomised study in 8 healthy volunteers examined the effects of relatively high versus low single doses of practolol on heart rate and ventilation at rest and during standardised exercise. Practolol 1 and 4 mg/kg, a typically non-selective drug propranolol 0.2 mg/kg, and placebo were given intravenously at weekly intervals. Cardiac beta-adrenoceptor blockade was measured by the reduction in exercise heart rate greater than 160 beats/min, and bronchial beta-adrenoceptor blockade by the reduction in exercise peak expiratory flow rate (PEFR) up to 4 h after each treatment. Results were assessed by analysis of co-variance. All three active treatments reduced exercise heart rate markedly, practolol 4 mg/kg causing most reduction. Exercise PEFR was significantly reduced by propranolol 0.2 mg/kg compared with both practolol 1 mg/kg and placebo at all times of measurement, and by practolol 4 mg/kg compared with practolol 1 mg/kg and placebo at most times. Mean plasma concentrations after practolol 4 mg/kg were 3.5 to 4.5 times higher than after 1 mg/kg. Practolol may lose its 'cardioselectivity' and cause airflow obstruction at relatively high plasma concentrations above about 2 microgram/ml.

Influence of ciclazindol on monoamine uptake and CNS function in normal subjects

The potential antidepressant drug ciclazindol inhibited dopamine uptake into human platelets without affecting 5-hydroxytryptamine uptake as compared with a control. It inhibited the tyramine pressor response less than desipramine after single 50-mg oral doses in 6 healthy volunteers under double-blind conditions. Compared with tandamine in a double-blind placebo-controlled study in nine healthy subjects, ciclazindol 50 mg orally caused no significant anticholinergic effects but reduced appetite according to an analysis of variance. Nonparametric analysis did not confirm the anorectic effect. Previous studies had shown that ciclazindol increased glucose uptake into isolated human skeletal muscle independently of insulin. Overall, ciclazindol resembles the antiobesity drug mazindol in molecular structure and pharmacological effects in man. Interactions with sympathomimetic amines and adrenergic neurone-blocking drugs cannot be excluded on the basis of these studies.

Studies of cardioselectivity and partial agonist activity in beta-adrenoceptor blockade comparing effects on heart rate and peak expiratory flow rate during exercise

1 The effects of beta-adrenoceptor antagonists given in single doses by oral or intravenous routes were examined in two double-blind controlled studies performed in healthy volunteers. Heart rate and peak expiratory flow rate (PEFR) were measured at rest and during standardized exercise. 2 Propranolol 80 mg and metoprolol 100 mg orally tended to reduce, and propranolol and metoprolol 0.2 mg/kg intravenously did reduce the physiological increase in PEFR during exercise; oxprenolol 80 mg orally and 0.2 mg/kg intravenously did not. Practolol 200 mg orally reduced this increase, but practolol 1 mg/kg intravenously did not. 3 In a third study of similar design, pindolol 0.05 mg/kg intravenously did not affect exercise-induced increase in PEFR. 4 Heart rate during exercise was reduced to a comparable extent at different times by all the active treatments. 5 Oxprenolol and pindolol share with practolol the property of partial agonist activity, which might contribute to their apparent lack of effect on airways resistance. A further possibility is that alpha-adrenoceptor blockade helps to maintain exercise-induced increase in PEFR.

The different effects of sodium bicarbonate and aluminium hydroxide on the absorption of indomethacin in man

The influence of oral sodium bicarbonate and aluminium hydroxide on the absorption of indomethacin has been studied in normal volunteers. While sodium bicarbonate appeared to increase indomethacin absorption, aluminium hydroxide markedly reduced both the rate and extent of absorption. The buccal absorption of indomethacin over the pH range 5-9 was also studied in normal volunteers, and showed that the percentage absorption increased markedly as the pH was reduced. The clinical importance both of pH-partition and of adsorption are discussed in the context of antacid interactions. It is concluded that caution must be exercised when prescribing an antacid with other orally-administered drugs.