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Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been reported that the first-dose response to prazosin is more common in patients who are salt-depleted or already receiving beta blockers. The relationship between the first-dose blood pressure and plasma renin responses to oral administration of 1 mg prazosin in 13 (seven male, six female) patients with essential hypertension (average blood pressure = 150/100 +/- 5/2 mm Hg) was studied. Eight of 13 patients experienced marked orthostatic decreases in blood pressure associated with nausea and dizziness. The degree of the orthostatic depressor response was inversely correlated with the baseline plasma renin activity (p less than 0.005). This unique sensitivity of low-renin essential hypertension to prazosin may reflect an underlying increased alpha tone and/or an attendant blunted renin reactivity in this form of human essential hypertension.
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PMID:Relationship of blood pressure response and the renin-angiotensin system to first-dose prazosin. 388 42

Pinacidil, a new cyanoguanidine derivative, is an antihypertensive agent with arteriolar vasodilating properties, which acts on precapillary resistance vessels. A trial was carried out in 30 patients with essential hypertension WHO I-II. The treatment period was divided into three phases. Hydrochlorothiazide (HCTZ) and amiloride were administered for 4 weeks in Phase 1 and supine and standing blood pressure decreased significantly. During Phase 2 pinacidil was added to HCTZ/amiloride for the following 3 months. A further significant reduction in blood pressure was obtained. In the next period of treatment (Phase 3) patients were divided into two groups. For 1 month Group A (15 patients) received pinacidil alone and Group B (15 patients) received HCTZ/amiloride. Conventional laboratory blood tests in all patients remained unchanged during treatment. Reported side effects during Phase 2 were headache (2 patients), dizziness (3 patients), palpitations (2 patients) and ankle oedema (2 patients). Plasma renin activity was slightly increased at the end both of Phases 1 and 2. Plasma catecholamines were increased but not significantly at the end of Phase 2 as compared to Phase 1. The results indicate that pinacidil is effective in lowering blood pressure in mild to moderate essential hypertension.
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PMID:Effect of pinacidil on blood pressure, plasma catecholamines and plasma renin activity in essential hypertension. 389 69

To determine whether E-643, a new alpha-blocking agent, would reduce the blood pressure, regardless of the posture, a 1 mg dose was given 3 times daily for 7 consecutive days, to 8 male and 7 female inpatients, aged 37--73 years, with essential hypertension. Blood pressure and pulse rate were measured daily in the supine, sitting and standing positions. Before and after the treatment with E-643, plasma levels of noradrenaline, adrenaline, dopamine-beta-hydroxylase, renin and aldosterone were determined, samples being obtained with the subjects recumbent and after standing upright for 60 min. A significant reduction in the systolic and diastolic blood pressures was evident in the supine (172 +/- 31/100 +/- 12 leads to 151 +/- 28/89 +/- 14 mmHg), sitting (158 +/- 22/101 +/- 11 leads to 138 +/- 28/89 +/- 15 mmHg) and standing (153 +/- 32/103 +/- 21 leads to 129 +/- 31/89 +/- 20 mmHg) positions. The reduction in blood pressure remained unchanged throughout the period of administration of E-643. Pulse rate was not affected when the subjects were supine (67 +/- 10 leads to 69 +/- 10 beats/min), but was increased in the sitting (68 +/- 10 leads to 73 +/- 9 beats/min) and standing (73 +/- 10 leads to 81 +/- 11 beats/min) positions. The increased pulse rate tended to decline during continued administration of E-643. Treatment with E-643 produced no significant change in plasma levels of adrenaline, noradrenaline, dopamine-beta-hydroxylase, renin and aldosterone. The antihypertensive effect of treatment was more prominent in the patients with higher levels of plasma catecholamines and dopamine-beta-hydroxylase, and was less prominent in those with higher plasma renin and aldosterone. Two patients had temporary bouts of dizziness and visual disturbances, but there were no subjective complaints during treatment.
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PMID:Antihypertensive effect of E-643, a new alpha-adrenergic blocking agent. 611 9

Prizidilol is a new antihypertensive agent reported to possess combined precapillary vasodilator and betareceptor-blocking properties. To clarify the profile of the acute effects of prizidilol in man, a variable dose study was performed in 8 patients with benign essential hypertension. Blood pressure, heart rate, plasma renin activity, aldosterone, plasma and urinary catecholamines and electrolytes were determined at short intervals before and up to 23 h after oral administration of placebo and prizidilol 150, 300 and 600 mg. The 4 studies were performed at weekly intervals according to a Latin square design. Prizidilol produced dose-dependent decreases in supine and upright blood pressure, with an initial change after about 2 h and maximal effects from 4 to 8 h after drug ingestion. Following a high dose of prizidilol, supine mean blood pressure (average 128 mmHg prior to treatment) was normalised (less than 107 mmHg) from 3 to 7 h and was still below predose level 23 h after ingestion. The only reported side effects were postural dizziness in 2 cases (corresponding to a fall in systolic upright blood pressure to less than 95 mmHg) and headache in one case. A biphasic variation in heart rate and plasma renin activity, with an early drop and a subsequent tendency to a slight rise, was observed after an intermediate or high dose of prizidilol. Plasma norepinephrine levels were increased by a high dose of prizidilol, while plasma epinephrine, aldosterone and plasma and urinary electrolytes were not consistently changed. Prizidilol in a a single oral dose appeared to be a potent antihypertensive agent. The profile of heart rate and plasma renin point to early dominance of beta-blockade followed by appearance of the concomitant vasodilator properties of prizidiol.
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PMID:Acute effects of prizidilol on blood pressure, heart rate, catecholamines, renin and aldosterone in essential hypertension. 612 41

Labetalol is a combined alpha- and beta-adrenoceptor blocking agent for oral and intravenous use in the treatment of hypertension. It is a nonselective antagonist at beta-adrenoceptors and a competitive antagonist of postsynaptic alpha 1-adrenoceptors. Labetalol is more potent at beta that at alpha 1 adrenoceptors in man; the ratio of beta-alpha antagonism is 3:1 after oral and 6.9:1 after intravenous administration. Labetalol is readily absorbed in man after oral administration, but the drug, which is lipid soluble, undergoes considerable hepatic first-pass metabolism and has an absolute bioavailability of approximately 25%. There are no active metabolites, and the elimination half-life of the drug is approximately 6 hours. Unlike conventional beta-adrenoceptor blocking drugs without intrinsic sympathomimetic activity, labetalol, when given acutely, produces a decrease in peripheral vascular resistance and blood pressure with little alteration in heart rate or cardiac output. However, like conventional beta-blockers, labetalol may influence the renin-angiotensin-aldosterone system and respiratory function. Clinical studies have shown that the antihypertensive efficacy of labetalol is superior to placebo and to diuretic therapy and is at least comparable to that of conventional beta-blockers, methyldopa, clonidine and various adrenergic neuronal blockers. Labetalol administered alone or with a diuretic is often effective when other antihypertensive regimens have failed. Studies have shown that labetalol is effective in the treatment of essential hypertension, renal hypertension, pheochromocytoma, pregnancy hypertension and hypertensive emergencies. In addition, preliminary studies indicate that labetalol may be of value in the management of ischemic heart disease. The most troublesome side effect of labetalol therapy is posture-related dizziness. Other reported side effects of the drug include gastrointestinal disturbances, tiredness, headache, scalp tingling, skin rashes, urinary retention and impotence. Side effects related to the beta-adrenoceptor blocking effect of labetalol, including asthma, heart failure and Raynaud's phenomenon, have been reported in rare instances.
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PMID:Labetalol: a review of its pharmacology, pharmacokinetics, clinical uses and adverse effects. 631 May 29

Nineteen patients with uncomplicated essential hypertension and low activity of plasma renin in response to a change from recumbency to an upright posture along with furosemide administration were given spironolactone, 400 mg/d, or chlorthalidone, 100mg/d, in a double-blind, random-sequence, crossover trial. The sequence of treatments was placebo for 2 months, one active drug for 2 months, placebo again for 1 month and the other active drug for 2 months. With both active treatments the average systolic, diastolic and mean arterial pressures decreased significantly. The two agents were equally efficacious in lowering the blood pressure regardless of the severity of hypertension during placebo treatment. Body weight, 24--hour urinary excretion of sodium, the plasma renin activity and the plasma aldosterone level at the end of the initial placebo period did not allow us to predict the response to either drug. Both drugs reduced the body weight and increased the stimulated plasma renin level activity. Chlorthalidone significantly increased the serum uric acid level and significantly reduced the serum potassium level. Three patients experienced orthostatic dizziness during spironolactone therapy, but no adverse symptoms were observed with chlorthalidone therapy. Thus, spironolactone is an effective alternative to thiazide-type drugs in patients with low-renin essential hypertension.
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PMID:Comparison of chlorthalidone and spironolactone in low--renin essential hypertension. 633

The effect of the converting enzyme inhibitor captopril as long term treatment was investigated in 14 patients with severe congestive heart failure in a double blind trial. Captopril reduced plasma concentrations of angiotensin II and noradrenaline, with a converse increase in active renin concentration. Effective renal plasma flow increased and renal vascular resistance fell; glomerular filtration rate did not change. Serum urea and creatinine concentrations rose. Both serum and total body potassium contents increased; there were no long term changes in serum concentration or total body content of sodium. Exercise tolerance was appreciably improved, and dyspnoea and fatigue lessened. Left ventricular end systolic and end diastolic dimensions were reduced. There was an appreciable reduction in complex ventricular ectopic rhythms. Adverse effects were few: weight gain and fluid retention were evident in five patients when captopril was introduced and two patients initially experienced mild postural dizziness; rashes in two patients did not recur when the drug was reintroduced at a lower dose; there was a significant reduction in white cell count overall, but the lowest individual white cell count was 4000 X 10(6)/l. Captopril thus seemed to be of considerable value in the long term treatment of severe cardiac failure.
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PMID:Captopril in heart failure. A double blind controlled trial. 638 12

The blood pressure response to the first dose of captopril (6.25 mg, 12.5 mg, or 25 mg) was measured in 65 treated, severely hypertensive patients. Mean supine blood pressure was 187/108 mm Hg immediately before captopril was given. Twenty one patients experienced a fall in supine systolic pressure greater than 50 mm Hg, including five whose pressure fell more than 100 mm Hg and two whose pressure fell more than 150 mm Hg. Six patients developed symptoms of acute hypotension, including dizziness, stupor, dysphasia, and hemiparesis. Percentage reductions in blood pressure were greatest in those with secondary hypertension (p less than 0.05), high pretreatment blood pressure (p less than 0.05), and high concentrations of plasma renin and angiotensin II (p less than 0.01). No significant correlation was found between fall in blood pressure and serum sodium concentration, age, renal function, and the dose of captopril given. A severe first dose effect cannot be consistently predicted in individual patients who have received other antihypertensive drugs for severe hypertension. Such patients should have close medical supervision for at least three hours after the first dose of captopril.
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PMID:Factors related to first dose hypotensive effect of captopril: prediction and treatment. 640 3

Eight hypertensive patients with normal renal function and receiving diuretic therapy for at least 28 days received captopril in small increasing doses (6.25, 12.5, and 25 mg). Supine and standing blood pressure (BP) and pulse rate, plasma renin activity (PRA), and plasma aldosterone concentration (PAC) were measured before and after captopril administration. The mean (+/- SEM) maximal decline in BP was 38/18 +/- 3/2, 34/18 +/- 4/2, and 25/17 +/- 3/2 mm Hg and occurred within 70 minutes of each of the three doses. In contrast, the duration of a 10 mm Hg or greater decrease in BP was prolonged markedly (103 +/- 5, 175 +/- 15, and 287 +/- 10 minutes) after each dose increment. After captopril, mean PRA levels increased while PAC levels fell. Transient dizziness on standing occurred in two patients, but captopril was otherwise well tolerated. Evaluation of the response to initial doses of captopril appears to be helpful in predicting maintenance requirements.
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PMID:Captopril in diuretic-treated hypertensive patients. 700 Oct 71

Patients with mild to moderate essential hypertension were treated with guanabenz plus placebo (26 patients) or guanabenz plus hydrochlorothiazide (26 patients) for one year. Ambulatory plasma renin activity was determined during placebo treatment, after four weeks and one year of treatment with the study drugs, and one month after discontinuation of guanabenz while continuing the same hydrochlorothiazide dosage. Treatment with guanabenz plus hydrochlorothiazide proved more satisfactory than treatment with guanabenz plus placebo in that fewer patients were treatment failures, a smaller dosage of guanabenz was required, better control of supine blood pressure was achieved, and no increase in guanabenz dosage was needed to maintain chronic blood pressure control. Drowsiness, dry mouth, and dizziness were the side effects noted most commonly. Plasma renin activity was not significantly suppressed by chronic guanabenz therapy. Thus, guanabenz is an effective new antihypertensive that provides optimal blood pressure control when used with a diuretic.
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PMID:Effect of guanabenz and hydrochlorothiazide on blood pressure and plasma renin activity. 701 28


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