Amlodipine and captopril in moderate-severe essential hypertension

The therapeutic usefulness of adding once-daily amlodipine (10 mg) for four weeks in moderate-severe hypertensive patients uncontrolled on low dose captopril (25 mg twice daily) alone was studied in 29 patients in a double-blind, placebo-controlled two-way crossover comparison. Once daily amlodipine was shown to be an effective antihypertensive drug when combined with captopril. The amlodipine minus placebo differences in mean changes from captopril baseline values were: -18/-12 mmHg and -20/-12 mmHg for supine and standing systolic/diastolic pressures (P less than 0.001 for all four pressure variables). The combination was well tolerated, and no patient discontinued therapy. Five patients experienced ankle oedema and four patients reported flushing while receiving amlodipine/captopril.

A comparison of bisoprolol and atenolol in the treatment of mild to moderate hypertension

1. Fourteen patients (mean age 56.0, range 37-61 years; eight females) with mild essential hypertension (DBP greater than 90 mm Hg on placebo) completed a randomised, double-blind placebo controlled crossover study comparing the hypotensive effects of bisoprolol (10-20 mg) and atenolol (50-100 mg) each taken once daily. 2. Bisoprolol had a significantly greater antihypertensive effect than atenolol, reducing sitting blood pressures by 15.9 mm Hg (diastolic) and 21.9 mm Hg (systolic) compared with placebo. Corresponding figures for atenolol were 10.7 and 5.7 mm Hg respectively. Bisoprolol reduced standing blood pressures by 15.9 mm Hg (diastolic) and 22.8 mm Hg (systolic) compared with 7.3 and 8.6 mm Hg respectively for atenolol. 3. Examination of the pharmacokinetic data showed that bisoprolol had a median elimination half-life of 11.2 h during chronic dosing, compared with 6.4 h for atenolol. For bisoprolol, the median clearance fell from 264 ml min-1 after a single dose to 212 ml min-1 during chronic dosing, although clinically significant accumulation would not be expected during chronic administration. 4. Overall, the results suggest that bisoprolol may be a more effective antihypertensive agent than atenolol but larger studies are necessary to confirm these findings.

Bevantolol vs propranolol: a double-blind controlled trial in essential hypertension

Bevantolol is a novel beta 1-selective beta-adrenoceptor antagonist. The Study Group evaluated its therapeutic utility (100-300 mg bid) compared with propranolol (80-240 mg bid) in 266 patients with mild to moderate essential hypertension (WHO Grades I and II, sitting diastolic blood pressure (DBP) greater than or equal to 95 mmHg). There was no difference in their antihypertensive efficacy over six months, 77% being controlled (DBP less than or equal to 90 mmHg) on bevantolol and 81% on propranolol. Hydrochlorothiazide 25-50 mg bid added later improved BP control in those incompletely controlled on bevantolol monotherapy. Both beta-adrenoceptor antagonists also reduced intraocular pressure. Bevantolol caused significantly fewer adverse effects than propranolol with many fewer withdrawals during long-term therapy. This unique clinical pharmacologic profile of bevantolol enhances its therapeutic usefulness and may relate to alpha-adrenoceptor antagonist activity, as well as to its beta 1-selectivity.

Atenolol-nifedipine combinations compared to atenolol alone in hypertension: efficacy and tolerability

1. In a double-blind, randomised, three-way-crossover study, 25 patients with sitting diastolic blood pressure between 95 and 120 mm Hg (Phase V) after 4 weeks' run-in on atenolol 50 mg twice daily, received atenolol 50 mg twice daily alone, atenolol 50 mg plus nifedipine 20 mg each twice daily and atenolol 50 mg plus nifedipine 40 mg each twice daily in three treatment periods each lasting 4 weeks. 'Washout' periods were not included. 2. The two combination treatment regimes lowered the 12 h post-dose blood pressure more effectively than did atenolol alone, but the high dose nifedipine combination was no more effective than the low dose nifedipine combination. Sitting systolic BP (+/- s.e. mean) at the end of each period was 174 +/- 5 mm Hg after the atenolol run-in, 170 +/- 5 mm Hg with atenolol alone, 156 +/- 5 mm Hg with the low dose combination and 158 +/- 4 mm Hg with the high dose combination. Corresponding diastolic BP readings were 106 +/- 2 mm Hg, 106 +/- 2 mm Hg, 97 +/- 2 mm Hg and 99 +/- 2 mm Hg respectively. 3. Side-effects tended to occur less commonly with the low dose of the fixed combination than with atenolol alone. An increased number of side-effects occurred with the 40 mg twice daily doses of nifedipine, particularly flushing/erythema, oedema of the ankles/feet, and a hot feeling in the legs. These differences did not reach significance. 4. Overall compliance was good (98 +/- 0.7 s.e. mean %) and was similar within the different treatment regimes.(ABSTRACT TRUNCATED AT 250 WORDS)

Thrombolytic treatment and new calcium antagonists

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Plasma prilocaine concentrations after three techniques of brachial plexus blockade

Brachial plexus blockade (n = 30: 10 axillary, 10 perivascular subclavian, 10 interscalene) was performed on 28 patients, using 35 ml of 1.5% prilocaine in plain solution. Plasma prilocaine concentrations were measured at intervals over the following 60 min. There was no significant difference in the prilocaine concentrations between the three groups. One asymptomatic patient in the interscalene group had a peak prilocaine concentration greater than the accepted threshold for toxic symptoms.

Aims of combination therapy--improved quality of life or better blood pressure control?

The combination of nifedipine and atenolol must be evaluated in terms of risks and benefits to the hypertensive patient. Disadvantages with single-agent therapy justify trials of combination regimens. beta-Blockers may be unacceptable to some patients because of gastrointestinal upset, musculoskeletal symptoms, tiredness, malaise, insomnia, depression or confusion, sweating, breathlessness or cold extremities. The side effect profile varies from patient to patient and between different beta-blockers. Calcium antagonists also have characteristic side effects, including severe headaches, flushing and oedema, tachycardia and possibly worrying palpitations, and polyuria. Combining a calcium antagonist and a beta-blocker can reduce some side effects; for example, tachycardia is offset by addition of beta-blocker to calcium antagonist therapy, and beta-blocker-induced cold extremities may be reversed with a drug such as nifedipine. Moreover, the antihypertensive efficacy is increased, which is useful in previously resistant patients. However, an excessive fall in blood pressure is a possible adverse effect of the combination. There is also the possibility of precipitating heart failure in patients with cardiomegaly and severely compromised left ventricular function. The combination of nifedipine and atenolol was evaluated in 25 patients in a randomised, crossover trial following a month's treatment with atenolol 50mg twice daily. Patients received either atenolol 50mg twice daily alone, or atenolol 50mg twice daily with sustained release nifedipine 20mg or 40mg twice daily, or placebo twice daily during three 4-week treatment periods. Additional antihypertensive benefit was obtained by addition of the low dose of nifedipine compared with atenolol alone, but no further advantage was obtained with the higher nifedipine dose.(ABSTRACT TRUNCATED AT 400 WORDS)

A double-blind crossover comparison of amlodipine and placebo added to captopril in moderate to severe hypertension

Amlodipine 10 mg once daily added to captopril 25 mg twice daily for 4 weeks in patients with moderate to severe hypertension significantly improved blood pressure control (by -18/-12 and -20/-12 mm Hg for supine and standing systolic/diastolic pressures respectively, p less than 0.001). Few side effects related to amlodipine were noted and none was serious.

Felodipine compared to nifedipine as "third-line drug" in resistant hypertension

Felodipine is a new dihydropyridine calcium antagonist, and in hypertension it is a much more effective "third-line" drug than hydralazine. Nifedipine, on the other hand, is the established dihydropyridine calcium antagonist that has been increasingly used to treat hypertension. Information is now needed on the relative merits and demerits of these two drugs. This study appraised, therefore, the therapeutic utility of twelve months' treatment with nifedipine 20-60 mg twice daily in 55 patients with previous drug-resistant hypertension who had been successfully treated for the previous year with felodipine 5-20 mg twice daily, each calcium antagonist being used in combination with atenolol 100 mg daily with or without chlorthalidone 25 mg daily. Initially, nifedipine maintained comparable blood pressure control to that which had been achieved by felodipine, although in the longer term (over eight months) nifedipine proved less effective than felodipine had (p less than 0.02) and more patients became uncontrolled (supine diastolic blood pressure, Phase V, greater than or equal to 90 mmHg) on the maximum tolerated dose of the calcium antagonist (chi 2 = 4.13, p less than 0.05 greater than 0.025). The former degree of blood pressure control was, however, reestablished by increasing the dose of nifedipine or reintroducing the diuretic as necessary, and this control was maintained over the next four months. Minor side effects were less common on nifedipine than they had been during the preceding felodipine treatment phase. Felodipine thus has more pronounced and sustained antihypertensive effects than nifedipine, though its side effect burden may appear to be greater.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of response and production protocols for assessing perceived exertion

Two cycle ergometer protocols for assessing perceived exertion were compared before and after a fatiguing run. In the response (R) protocol, the subject rated the perceived exertion (RPE) of a series of power outputs assigned by the investigator. In the production (P) protocol, the investigator selected the RPE values and the subject adjusted his power output using a hand-held control. The relationship between RPE and power output (the regression coefficient and the slope and intercept of the regression line) was the same for both protocols. Fatigue due to the run caused a small increase in RPE (average 1.5 units) at a given exercise intensity and a commensurate decrease in power output (average 19 W) for a given RPE. The P protocol is safer than the R protocol because it makes no assumptions with regard to the physical condition of the subject. It is superior to the R protocol because it is an interval scale. These advantages suggest that the P protocol should be used instead of, or at least in addition to, the more traditional R protocol.

Future/novel uses of beta blockers in clinical therapeutics

Beta-blocker usage in the United Kingdom centers around propranolol and oxprenolol as noncardioselective drugs, atenolol and metoprolol as cardioselective agents, and pindolol or oxprenolol when partial agonist activity is desired. Any meaningful comparison of a novel beta blocker against the established drugs must be a variable-dose trial, for the optimum dose of any beta blocker that can be tolerated varies widely. Effective beta blockade is considered to have been achieved when the standing heart rate has been lowered to about 55 beats/minute.

Relation of early mononuclear and polymorphonuclear cell infiltration to late scar thickness after experimentally induced myocardial infarction in the rat

This report describes the relationship between the intensity of early inflammation after acute myocardial infarction and the later thickness of the left ventricular (LV) scar. Histologic sections of hearts from methylprednisolone-treated (MP), cobra venom factor-treated (CVF), and untreated control rats that had been subjected to either 2 or 21 days of coronary artery occlusion were studied. In the rats examined at 2 days (n = 20 for MP, n = 16 for CVF, and n = 20 for controls), a semiquantitative inflammation score (1-4) was attributed to each infarct. Mononuclear (MN) cells were counted in 4 oil-immersion fields per section and polymorphonuclear (PMN) cells in 9 oil-immersion fields per section. In the rats examined at 21 days (n = 22 for MP, n = 22 for CVF, and n = 26 for controls), the thickness of the LV scar was measured every 1.6 mm along its circumference. Inflammation scores at 2 days were 3.5 +/- .6 for controls, 1.5 +/- .5 for MP, and 2.9 +/- .8 for CVF (p less than .05 among groups). The MN cells counted were 73 +/- 7 for controls, 47 +/- 5 for MP, and 61 +/- 9 for CVF (p less than .05 among groups). There was no difference in PMN infiltrate among groups. Scar thickness at 21 days were .9 +/- .1 mm for controls, .7 +/- .1 mm for MP, and .9 +/- .1 mm for CVF (MP compared to CVF and controls, p less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Early and late remodeling of the left ventricle after acute myocardial infarction

This report describes early and later structural changes that occur in infarcted and noninfarcted ventricular myocardium after coronary arterial ligation in the rat. Histologic analysis was conducted of hearts subjected to 2 days (n = 22) and 21 days (n = 22) of coronary arterial occlusion, or to a sham operation (n = 22). Lengths, circumferences and areas of the left ventricle, of infarcted myocardium and of noninfarcted myocardium were obtained by videoplanimetry. Although the left ventricular (LV) endocardial circumference was similarly increased at 2 days (19 +/- 3 mm, mean +/- standard deviation) and 21 days (20 +/- 3 mm) compared with shams (13 +/- 3 mm, p less than 0.01), LV epicardial circumference was similar in all 3 groups (30 +/- 2, 31 +/- 2 and 31 +/- 2 mm, respectively). The area enclosed by the endocardial circumference was significantly (p less than 0.01) increased at 2 days (20 +/- 6 mm2) and 21 days (22 +/- 6 mm2) compared with shams (7 +/- 4 mm2); however, the area enclosed by the epicardial circumference was similar at 2 days, 21 days and in shams (70 +/- 9, 72 +/- 9 and 73 +/- 10 mm2, respectively). The total LV tissue area was similar at 2 and 21 days, but was less than that in shams (p less than 0.01). Between 2 and 21 days, 3 measures of infarcted myocardium significantly decreased: its segments of endocardial and epicardial circumference, its circumference and its area.(ABSTRACT TRUNCATED AT 250 WORDS)

Topographic changes in the left ventricle after experimentally induced myocardial infarction in the rat

The factors that determine the thickness of transmural myocardial infarcts are unknown. Therefore, the relation between the size and thickness of transmural infarcts in 67 rats 21 days after occlusion of the left main coronary artery was studied. On examination of histologic sections, infarct size was determined by planimetry and expressed as a percentage of the left ventricular (LV) area, and thickness was expressed as a percentage of noninfarcted ventricular septal wall thickness. The circumferential length of the infarcted ventricle was measured in millimeters, as well as the circumferential length of the noninfarcted ventricular septum. Septal wall thickness was similar in rats with transmural infarcts and in sham-operated rats. No significant correlation was observed between infarct size and thickness (r = 0.10) or between circumferential length of the infarct and infarct thickness (r = 0.17). However, large (greater than or equal to 20% of the left ventricle, n = 37) and small (less than 20% of the left ventricle, n = 30) infarcts which were similarly thin (37 +/- 1% and 34 +/- 2% of septal wall thickness, respectively) affected LV topography differently. Large infarcts resulted in a 23% greater loss of myocardium (p less than 0.001), greater expansion of the LV cavity (18 +/- 9 mm2 compared with 14 +/- 1 mm2 in small infarcts, p less than 0.005), and lengthening of the septal wall (7.2 +/- 1.1 mm and 6.7 +/- 1.0 mm in large and small infarcts, respectively [p less than 0.05], and 6.3 +/- 0.1 mm in shams). Increase in cavity area and septal length in infarcted ventricles suggested a volume overload hypertrophy, which at 3 weeks was nonetheless inadequate to provide as much normal muscle as was present in sham-operated rats. In an additional 9 rats with subendocardial infarctions (involving less than 75% of the LV wall from endocardium to epicardium), the LV walls were thicker (94 +/- 5% of septal wall thickness, compared with 35 +/- 1% for transmural infarcts, p less than 0.001) and an inverse correlation was observed between infarct size and thickness. In conclusion, neither the size of a transmural infarct in rat nor the circumferential length of infarction determines the thickness of the infarct; however, infarct size does affect LV topography by increasing LV cavity area and the length of the noninfarcted septal wall. Subendocardial infarcts result in less myocardial thinning than do transmural infarcts.

Antithyroid effect of chlorpropamide?

1 The relationship between plasma chlorpropamide concentration and thyroid function was examined in 87 maturity onset diabetic patients receiving chronic therapy. 2 Although plasma chlorpropamide concentration was weakly negatively correlated with serum thyroxine (r = 0.33, P less than 0.01) the mean serum thyroxine and thyrotrophin (TSH) were not different from that of a matched control group of diabetics treated with diet alone. 3 Serum thyroxine was negatively correlated with the duration of diabetes in both groups. 4 These results suggest that chlorpropamide does not have a clinically significant antithyroid effect.