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PubMed1989

A two-stage trial design for testing treatment, self-selection and treatment preference effects.

We propose a two-stage randomized clinical trial design for separating treatment effects from those resulting from choosing treatment. At the first stage all patients are randomly allocated to one of two groups, the random group and the option group. At the second stage, patients in the random group are randomized a second time to treatment A or B, whereas patients in the option group are given a free choice between the two treatments. If there are differences in treatment response between the random group and the option group, there are two potential sources of bias: self-selection by choosing treatment, and effects of suggestion by receiving the preferred treatment. A linear model is presented to estimate these effects separately along with test statistics which are approximately normally distributed.

Clinical Trials as Topic↗

PubMedDate not supplied

Treatment of atopic dermatitis with antihistamines: lessons from a single-patient, randomized clinical trial.

BACKGROUND: Single-patient randomized clinical trials (RCTs) can be utilized to maintain methodologic precision in the analysis of treatment effect in individual patients. We describe the results of a single-patient RCT in a patient with atopic dermatitis and review practical considerations regarding the use of antihistamines. METHODS: Using double-blind, crossover techniques, the patient was randomly allocated to four 2-week treatment periods with the following regimens: chlorpheniramine, 8 mg twice daily; chlorpheniramine, 12 mg twice daily; terfenadine, 120 mg twice daily; and placebo (phase 1). The drug that produced superior results from phase 1 (chlorpheniramine, 8 mg) was subsequently compared with astemizole, 10 mg/d, during phase 2, consisting of four 4-week, double-blind, crossover trial periods with random allocation of study drugs. Daily symptom scores, as well as end of treatment period summary impressions by patient and investigator, were analyzed. RESULTS: In both phases, chlorpheniramine produced the most noticeable positive therapeutic effect on the patient's mild but most disturbing symptoms (pruritus and eye irritation) associated with atopic dermatitis. Drowsiness was reported with chlorpheniramine. Tolerance to this side effect, however, developed quickly. CONCLUSIONS: A single-patient RCT with different antihistamines in a patient with chronic atopic dermatitis was a useful tool in achieving a favorable balance among efficacy, toxicity, and cost of therapy.

Adult↗

PubMed1990

Influence of humoral and volume factors on altered osmoregulation of normal human pregnancy.

These studies were designed to characterize mechanisms leading to decreased plasma osmolality (Posmol) and osmotic thresholds (T) for arginine vasopressin (AVP) release (TAVP) and thirst (Tthirst) in pregnancy. First, the influence of the pregnancy hormone, human chorionic gonadotrophin (hCG), was tested in six nonpregnant women who received hypertonic saline during the luteal phase of the menstrual cycle on two occasions (randomly allocated), once after 15,000 IU of hCG when Posmol, TAVP, and Tthirst decreased 6, 5, and 5 mosmol/kgH2O, respectively (P less than 0.01). In contrast, hCG pretreatment of males (n = 6) had no significant effect. Next, the role of decreased effective vascular volume (underfilling) was evaluated in seven women undergoing hypertonic saline infusion in the presence and absence of head-out water immersion (randomly allocated) during early and late pregnancy and postpartum. Posmol, TAVP, and Tthirst were not influenced by immersion and remained 10 mosmol/kgH2O lower in pregnancy (P less than 0.01). Central redistribution of intravascular volume consistently lowered hematocrit and rate of rise of PAVP per unit increment in Posmol (P less than 0.01). Although these data failed to support the hypothesis that the osmoregulatory change in human pregnancy is attributable to decrements in effective central volume (underfill), they do suggest that hCG may play a role.

Adult↗

PubMed1981

Acute intervention studies in patients with myocardial infarction using atenolol, propranolol, oxprenolol and disopyramide phosphate.

The value of beta-blockade and of disopyramide phosphate in the immediate treatment of patients with suspected acute myocardial infarction was assessed in two placebo controlled trials. In the first study 388 patients with suspected acute myocardial infarction were randomly allocated to treatment with propranolol, atenolol, or placebo, and when analysed on an initial intention to treat basis there was no significant difference between the three groups in respect of the mortality at one year. In addition, there was no evidence to suggest that either atenolol, or propranolol reduced the incidence of 'serious' ventricular arrhythmias in the coronary care unit. In the second study 473 patients with suspected acute myocardial infarction were randomly allocated to treatment with oxprenolol, disopyramide phosphate, or placebo. Again no significant differences were seen with respect to the mortality at six weeks. There was, however, a significantly increased incidence of heart failure in the group which received disopyramide phosphate. Patients who received this drug also showed a reduced number of dysrhythmic episodes on 24-hour ECG recordings, but this trend did not achieve statistical significance. These results suggest that none of the three beta-blockers tested nor disopyramide phosphate is likely to reduce the mortality from acute myocardial infarction when given prophylactically, although disopyramide phosphate does reduce the incidence of 'serious' ventriicular arrhythmias.

Adrenergic beta-Antagonists↗

PubMed1991

A double blind, randomised, multicentre comparison of two doses of intravenous iloprost in the treatment of Raynaud's phenomenon secondary to connective tissue diseases.

OBJECTIVE: To compare low (0.5 ng/kg/min) and standard dose (2 ng/kg/min) iloprost (a stable carbacyclin analogue of prostacyclin) in patients with Raynaud's phenomenon secondary to connective tissue disorders. DESIGN: Double blind, random allocation, three six hour infusions on consecutive days. Follow up period eight weeks. SETTING: Rheumatology units, five teaching hospitals. PATIENTS: 55 Patients with Raynaud's phenomenon (greater than seven attacks per week), 32 secondary to well documented classical progressive systemic sclerosis (American Rheumatism Association criteria), 11 CREST syndrome, 5 mixed connective tissue disease, 1 rheumatoid arthritis, 1 Sjögren's syndrome, 1 childhood dermatomyositis, and 4 abnormal nailfold capillaroscopy and antibody profiles but no definite diagnosis. INTERVENTIONS: All other treatment for Raynaud's phenomenon was discontinued two weeks before entry. 28 Patients were randomly allocated to receive the low dose, 27 the standard dose. Differing dilutions allowed infusion rates to be started at 10 ml/h with increments of 10 ml/h every 15 minutes until infusion rates reached 0.5 ng/kg/min and 2 ng/kg/min respectively. MAIN OUTCOME MEASURE(s)--Reduction in frequency, duration, and severity of attacks of Raynaud's phenomenon. Assessment of ulcer and ischaemic lesion healing. RESULTS: Both dosage regimens were equally effective in reducing severity, frequency, and duration of Raynaud's attacks. Ulcer healing occurred to similar degree in both treatment groups (standard dose 44%, low dose 39%). Low dose was associated with significantly fewer side effects. CONCLUSIONS: Both dosage regimens reduce severity of Raynaud's phenomenon and encourage ulcer healing. Low dose was associated with fewer side effects and was better tolerated by the patients.

Adult↗

PubMed1992

Effects of lorazepam on psychomotor performance: a comparison of independent-groups and repeated-measures designs.

The purpose of this study was to compare the sensitivity to the effects of lorazepam (2.5 mg) of a design using independent groups (random allocation of subjects to either a placebo or a lorazepam treatment) with a repeated-measures design (subjects tested both before and after lorazepam treatment). With both designs, it was possible to demonstrate significant and equal effects of lorazepam in tests based upon speed of responding: Lorazepam significantly increased simple reaction time and significantly decreased performance in number cancellation and symbol copying tasks. The independent-groups design was more sensitive (i.e., showed effects at a higher level of significance) to the lorazepam-induced impairment in episodic memory, as assessed in a picture recognition task, and to the lorazepam-induced impairment in a word completion task. Comparisons between the two control condition scores indicated that there were unlikely to be significant group differences with random allocation of a relative homogeneous group of volunteers, such as medical students. While either design would be appropriate for homogeneous populations, for a heterogeneous clinical population where groups cannot be matched the repeated-measures design would be preferable.

Adult↗

PubMed1984

Effect of ranitidine and cimetidine on gastric ulcer healing and recurrence.

Fifty-eight patients with endoscopically confirmed benign gastric ulceration were randomly allocated to treatment with 150 mg ranitidine twice daily, placebo matching ranitidine twice daily, or 200 mg cimetidine three times daily and 400 mg at night. Patients were endoscoped at monthly intervals for up to 3 months, the endoscopist being unaware of the treatment. Significantly more ulcers (p less than 0.05) had healed after 2 months of ranitidine (14 of 18, 78%) and cimetidine (17 of 20, 85%) than with placebo (9 of 20, 45%; p less than 0.05) and after 3 months of ranitidine (15 of 18, 88%) and cimetidine (18 of 20, 90%) than with placebo (11 of 20, 55%; p less than 0.05). Forty-eight patients with healed ulcers were randomly allocated in a double-blind prophylactic study to receive 150 mg ranitidine at night or matching placebo. After 6 months recurrent ulcers were found in 2 of 24 (8%) of patients receiving ranitidine and 10 of 24 (42%) of patients receiving placebo (p less than 0.05). These data indicate that H2-receptor antagonists are significantly better than placebo in healing gastric ulceration and that ranitidine and cimetidine are equally effective. Ranitidine is significantly superior to placebo in preventing gastric ulcer recurrence.

Cimetidine↗

PubMed1992

Alternatives to randomization in surgical studies.

The purpose of randomization is to provide unbiased estimates of treatment effects and valid probability statements for hypothesis tests in comparative studies. Difficulties with randomized allocation of patients in surgical studies include: patient selection--due to protocol limitations, possible changes in referral patterns, the need for patient consent, and physician co-operation; disruption of the patient-physician relationship; static protocol not responsive to changes as surgical skill evolves and experience regarding patient selection is acquired; the larger number of patients required causes a longer study and more patients receiving what may be a worse therapy. Moreover, for evaluating a new heart valve, the primary purpose should be estimation rather than comparison with a current device. This can be accomplished faster, in a more generalizable way and with more concern for patient care by using non-randomized comparison groups.

Ethics, Medical↗

PubMed1992

Relationship between the onset of oestrus, the preovulatory surge in luteinizing hormone and ovulation following oestrous synchronization and superovulation of farmed red deer (Cervus elaphus).

The timing of ovulation relative to the onset of oestrus and the preovulatory surge in luteinizing hormone (LH) was studied in red deer following treatments to synchronize oestrus and induce either a monovulatory or superovulatory response. Mature hinds (n = 36) were allocated randomly to two mating groups (n = 16 + 20), with respective treatments staggered by 4 weeks during the 1990 rut (March-April). Each hind was treated with an intravaginal controlled internal drug releasing (CIDR)-type S device for 14 days. Treatments to induce a monovulatory response included CIDR device alone (treatment A; n = 4 + 8) and additional injection of 200 iu pregnant mares' serum gonadotrophin (PMSG) at device removal (treatment B; n = 4 + 4). Treatments to induce a superovulatory response included injections of 200 iu PMSG and 0.5 units ovine follicle-stimulating hormone (FSH) at about time of removal of CIDR devices (treatment C; n = 4 + 4) and further treatment with gonadotrophin-releasing hormone (GnRH) analogue 18 h after removal of CIDR devices (treatment D; n = 4 + 4). The hinds were run with crayon-harnessed stags from insertion of CIDR devices (12 March or 9 April) and blood samples were taken every second day to determine plasma progesterone. Further blood samples were collected for determination of plasma LH and progesterone via indwelling jugular cannulae every 2 h for 72 h from removal of CIDR devices. Hinds were allocated randomly to an initial ovarian examination by laparoscopy at either 16 or 20 h (A and B), or 12 or 16 h (C and D) after the onset of oestrus, with laparoscopy repeated at intervals of 8 h until either ovulation was recorded (A and B), or for four successive occasions (C and D). All hinds received cloprostenol injections 15 days after device removal. A total of 28 hinds (78%) exhibited oestrus and a preovulatory LH surge, with mean (+/- SEM) times to onset of oestrus of 44.6 +/- 1.0 h (A; n = 7), 37.4 +/- 2.0 h (B; n = 7), 16.3 +/- 1.7 h (C; n = 6) or 14.0 +/- 1.7 h (D; n = 8). Failure to exhibit oestrus or LH surge was most prevalent among hinds in treatment A early in the rut.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1990

Double blind comparative study of omeprazole and ranitidine in patients with duodenal or gastric ulcer: a multicentre trial. Cooperative study group.

We studied omeprazole and ranitidine in promoting duodenal ulcer healing in a multicentre trial by comparing the proportion of healed ulcers after two, four, and eight weeks of treatment. Altogether, 194 patients (143 men) were randomly allocated according to a prearranged treatment schedule to either drug and were treated double blind. Each received 40 mg omeprazole in the morning and a ranitidine placebo morning and evening or 150 mg ranitidine morning and evening with an omeprazole placebo in the morning. A total of 188 patients (94 taking omeprazole, 94 taking ranitidine) completed the trial. Sixty four (68%) omeprazole treated and 45 (48%) ranitidine treated patients had healed ulcers at two weeks, 91 (99%) omeprazole treated and 79 (88%) ranitidine treated had healed ulcers by four weeks, and 91 (100%) omeprazole treated and 86 (97%) ranitidine treated patients had healed ulcers by eight weeks. The overall difference in healing rates was significant (p = 0.0008, Mantel-Haenszel test). The differences were significant also at two weeks (20%, 95% confidence interval 5.6 to 34.4, p less than 0.01) and at four weeks (11%, 95% CI 3.7 to 17.3, p less than 0.01), but not at eight weeks (3%, 95% CI -0.5 to + 7.3, p = 0.25), using the chi 2 statistic, the study having a power to detect a 20% difference on 90% of occasions. After two weeks of treatment complete symptom relief was observed in 70 (74%) patients receiving omeprazole and in 58 (62%) receiving ranitidine. Diary cards showed a significantly lower percentage of days with pain in the omeprazole treated group (7.4% v 21.4%, p < 0.02) when assessed over either the first two weeks or over weeks three and four treatment. A total of 144 patients with healed duodenal ulcer were followed up, with no treatment, for six months. At the end of this period 19 (26%) of 74 patients healed with omeprazole and 17 (24%) of 70 patients healed with ranitidine were still in remission. A similar protocol was used for 46 patients (25 men) with gastric ulcer who were randomly allocated to treatment with omeprazole or ranitidine as described above. Forty patients (16 omeprazole, 24 ranitidine) completed trial. Thirteen (81%) omeprazole treated and 14 (58%) ranitidine treated patients had healed ulcers at four weeks; at eight weeks 14 (93%) omeprazole treated and 20 (87%) ranitidine treated patients had healed ulcers. These differences were not significant at four weeks (p = 0.25) or eight weeks (p = 0.96). Twenty seven gastric ulcer patients were followed up for six months and seven (58%) of the 12 omeprazole healed and five (33%) of the 15 ranitidine healed patients were in remission at six months. Unwanted adverse events were trivial except for one fatality in a 67 year old women, who died from bronchopneumonia and myocardial ischaemia while receiving treatment with omeprazole, which was judged to be unrelated to her death.

Aged↗

PubMed1986

A three year follow up of patients allocated to placebo, or oral or injectable gold therapy for rheumatoid arthritis.

Ninety patients randomly allocated to receive auranofin, matching placebo, or sodium aurothiomalate have been followed up for three years. Inefficacy led to cessation of treatment in 14 patients receiving auranofin, 27 receiving placebo, and one receiving sodium aurothiomalate. Twenty seven of the patients receiving placebo were reallocated within the study and 16 continued therapy at three years. This group showed similar statistically significant improvement in clinical and laboratory parameters at one, two, and three years to those on an active drug from the outset. Patients who discontinued auranofin because of inefficacy were offered sodium aurothiomalate therapy--eight patients in this group completed three years of treatment on sodium aurothiomalate and showed significant improvement in some but not all parameters. A hand radiograph erosion score showed a deterioration in 80% of patients remaining on auranofin, 75% of those on sodium aurothiomalate, and 80% of the original placebo group who continued an active drug for three years. Although more patients discontinued auranofin over the study period because of inefficacy, no difference could be shown between the degree of improvement in the subgroup who remained on auranofin and those receiving sodium aurothiomalate. No disadvantage in outcome could be shown for patients originally assigned to placebo.

Arthritis, Rheumatoid↗

PubMed1981

Effect on mortality of metoprolol in acute myocardial infarction. A double-blind randomised trial.

The effect of metoprolol on mortality was compared with that of placebo in a double blind randomised trial in patients with definite or suspected acute myocardial infarction. Treatment with metoprolol or placebo started as soon as possible after the patient's arrival in hospital and was continued for 90 days. Metoprolol was given as a 15 mg intravenous dose followed by oral administration of 100 mg twice daily. 1395 patients (697 on placebo and 698 on metoprolol) were included in the trial. Definite acute myocardial infarction developed in 809 and probable infarction in 162. Patients were allocated to various risk groups and within each group patients were randomly assigned to treatment with metoprolol or placebo. There were 62 deaths in the placebo group (8.9%) and 40 deaths in the metoprolol group (5.7%), a reduction of 36% (p less than 0.03). Mortality rates are given according to the treatment group to which the patients were initially randomly allocated.

Adult↗

PubMed1988

Early and late discharge after hospital birth: father's involvement in infant care.

The father's involvement in his baby's care was studied in three groups of fathers: 49 randomly allocated to an experimental group (EG) with mother and infant discharged from hospital 24-48 h after birth, 52 allocated to a control group (CG) with traditional hospital postpartum care, and 237 randomly selected from parents not interested in participating in an evaluative study of early discharge (NPG). The ordinary length of hospital postpartum stay was 5-6 days. Fathers in EG spent more time with the baby (nappy changing, bathing, holding etc...) than fathers in CG during days 2-4 after the birth. No effect of this extended contact was observed measured as father involvement in infant care during the 2nd and 6th week after the birth, and utilization of parental leave during the first year.

Adult↗

PubMed1987

Experimental comparison of the effectivity of individually adapted and standardized dosages of haloperidol.

Experimental tests of whether an individual neuroleptic treatment for compensation of acute schizophrenic disorders is more effective and has fewer side effects than a standard therapy were performed under double-blind conditions. For this purpose, a group of 16 patients was treated with 10 mg haloperidol/day for the duration of 14 days, and another group of 16 patients was treated with 20 mg haloperidol/day for the same period. 16 patients of a third group were treated for 14 days with an individual haloperidol dose adapted to the psychopathological findings. Patients were randomly allocated to the treatment groups. The medication was laid down in accordance with the randomization plan without informing the ward staff and raters by a leading physician of the hospital who was not involved in the data collection in the investigation. The psychological findings were registered by means of the BPRS and the global appraisal by the doctor (CGI) on days 0, 7 and 14. Extrapyramidal side effects were registered by means of the Simpson scale on days 0, 7 and 14. A superiority of the individually adapted treatment over standardized treatment could be demonstrated neither for the therapeutic target parameters nor for the side effect variables. On the contrary, a tendency to superiority in the groups treated with fixed doses was found. The results are discussed in terms of their significance for treatment practice.

Acute Disease↗

PubMed1980

[Early or delayed operation in patients with acute cholecystitis. Results of a prospective randomized controlled clinical trial (author's transl)].

In a prospective controlled randomized clinical trial, 60 patients with acute cholecystitis (diagnosed according to well defined criteria) were allocated randomly to early operation (n=28) or conservative treatment followed by delayed operation (n=30). The formed groups were well balanced. Total duration of hospitalization was 12 days for the early and 22 days for the delayed operation group. One case of death in the second group appeared to be due to pancreatic necrosis. From other complications recorded, only stitch sinus seemed to occur more frequently in the early operation group. For the first time the success of the two therapeutic procedures was evaluated by means of a systematic follow-up 6 weeks and 6 months after operation. The outcome was the same in both groups and "very good" and "good" for all patients. From these results early operation as the routine method for acute cholecystitis can be recommended unconditionally.

Acute Disease↗

PubMedDate not supplied

[Treatment of hemorrhage caused by rupture of esophageal varices in the cirrhotic patient: remote results of a practical controlled study comparing the esophageal clip to conventional medical treatment].

From 1974 to 1979, a prospective controlled study was conducted in 100 patients with cirrhosis and bleeding esophageal varices. The patients were randomly allocated to either portal disconnection of the esophagus with a clip or medical treatment. Randomization and treatment were performed in emergency situation for 50 patients and electively in 50 patients. All survivors had at least 5 years of observation after randomization. Concerning rebleeding, in the group randomized in emergency, 33 p. cent of patients had recurrent bleeding in the surgical group (mean delay: 64.1 +/- 12.4 months) and 84 p. cent among the medically treated patients (mean delay: 10.6 +/- 4.7 months). This difference is statistically significant (p less than 0.001). For the group randomized electively, 25 p. cent of the surgical patients had recurrent bleeding (mean delay: 76.3 +/- 6.4 months) and 92 p. cent of the medically treated patients had recurrent haemorrhage (mean delay: 20 +/- 5.9 months). The difference is statistically significant p less than 0.001). Concerning survival, among the patients randomized in emergency, 20 died in the surgical group (mean survival: 38.9 +/- 9.3 months) and 22 in the medical group (mean survival: 10.8 +/- 4.6 months). Among the patients randomized electively, there were 19 deaths in the surgical group (mean survival: 46.6 +/- 6.8 months) and 21 in the medical group (mean survival: 32.2 +/- 7.6 months). The difference of survival between the medical and the surgical group is not statistically significant.

Aged↗

PubMed1988

Statistical properties of randomization in clinical trials.

This is the first of five articles on the properties of different randomization procedures used in clinical trials. This paper presents definitions and discussions of the statistical properties of randomization procedures as they relate to both the design of a clinical trial and the statistical analysis of trial results. The subsequent papers consider, respectively, the properties of simple (complete), permuted-block (i.e., blocked), and urn (adaptive biased-coin) randomization. The properties described herein are the probabilities of treatment imbalances and the potential effects on the power of statistical tests; the permutational basis for statistical tests; and the potential for experimental biases in the assessment of treatment effects due either to the predictability of the random allocations (selection bias) or the susceptibility of the randomization procedure to covariate imbalances (accidental bias). For most randomization procedures, the probabilities of overall treatment imbalances are readily computed, even when a stratified randomization is used. This is important because treatment imbalance may affect statistical power. It is shown, however, that treatment imbalance must be substantial before power is more than trivially affected. The differences between a population versus a permutation model as a basis for a statistical test are reviewed. It is argued that a population model can only be invoked in clinical trials as an untestable assumption, rather than being formally based on sampling at random from a population. On the other hand, a permutational analysis based on the randomization actually employed requires no assumptions regarding the origin of the samples of patients studied. The large sample permutational distribution of the family of linear rank tests is described as a basis for easily conducting a variety of permutation tests. Subgroup (stratified) analyses, analyses when some data are missing, and regression model analyses are also discussed. The Blackwell-Hodges model for selection bias in the composition of the study groups is described. The expected selection bias associated with a randomization procedure is a function of the predictability of the treatment allocations and is readily evaluated for any sequence of treatment assignments. In an unmasked study, the potential for selection bias may be substantial with highly predictable sequences. Finally, the Efron model for accidental bias in the estimate of treatment effect in a linear model is described. This is important because the potential for accidental bias is equivalent to the potential for a covariate imbalance.(ABSTRACT TRUNCATED AT 400 WORDS)

Clinical Trials as Topic↗

PubMed1985

[Isolated stenosis of the anterior interventricular artery. Comparison of the effects of medical and surgical treatment (in a randomised series)].

Forty-five patients presenting with unstable angina having 70 p. 100 stenosis of the left anterior descending artery judged acceptable for coronary bypass surgery were randomly allocated, using a table of random numbers, for medical (21 patients) or surgical treatment (24 patients). There were no significant differences between the two groups with regards to age (53 +/- 10 years for the medical group; 55 +/- 9 years for the surgical group), the length of follow-up (55 +/- 26 vs 61 +/- 28 months), left ventricular end diastolic volumes (87 +/- 27 vs 84 +/- 18 ml/m2) or ejection fraction (62 +/- 8 vs 59 +/- 11 p. 100). There were no deaths in the medical group; two patients developed uncomplicated myocardial infarction 19 days and 7 months after coronary angiography, respectively. 5 patients had recurrent angina and were referred for surgery. This operation of second intention did not pose any special problems. 6 of the 14 patients with stenosis of the LAD before the origin of the first septal artery had complications (infarction in 1 case, recurrent angina in 5 cases). In the surgical group, 1 patient died in the immediate postoperative period, of resistant cardiac arrhythmia; 2 patients developed uncomplicated peroperative myocardial infarction; 21 patients had no complications at all. The surgical patients were heparinised in the immediate postoperative period and anticoagulant therapy was continued with oral vitamin K antagonists for 6 months to 1 year, followed in some cases, by platelet antiaggregant therapy. 20 patients in this group underwent maximal exercise stress testing which was negative in 19 cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗