Studies With Prazosin—a New Effective Hypotensive Agent. Ii

Hua, A. S. P.; Macdonald, Ileene M.; Myers, Jonny; Fang, Peter; Kincaid‐Smith, Priscilla

doi:10.5694/j.1326-5377.1977.tb98989.x

Cited by 17 publications

(4 citation statements)

References 4 publications

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“…The liberation of renin and activation of angiotensin instantly augments the direct vasoconstrictor influences of sympathetic stimulation of peripheral resistance vessels and venous capacitance vessels so that (0) given double-blind in random order to 16 patients with essential hypertension pretreated with a diuretic (cyclopenthiazide) and P-blocking drug (propranolol). (Hua, Myers & Kincaid-Smith, 1978 \H I I PULMONARY DECREASED INCREASED HYPERLIPIDAEMIA CHANGES BLOOD PRESSURE INTRACARDIAC I INCREASED PRESSURES | INCREASED AFTER-LOAD * HYPOINSULINAEMIA INCREASED SYMPATHETIC DRIVE I ACIDAEMIA |_ I Figure 13 Flow diagram of the pathophysiological events accompanying the onset of left ventricular failure which may constitute a self-sustaining cycle. Solid lines indicate events for which there is firm evidence; broken lines indicate more speculative relationships.…”

Section: Resultsmentioning

confidence: 99%

“…In contrast, there are relatively few valid studies comparing the antihypertensve efficacy of these two different classes of peripheral vasodilators. The earliest, and perhaps still the most valid, clinical trial comparing hydralazine, a 'non-specific' vasodilator, with prazosin, a competitive a,-adrenoceptor antagonist, is that reported by Hua, Myers & Kincaid-Smith (1978); they demonstrated comparable reductions in the resting blood pressure with equivalent doses of 20 mg and 1 mg of each drug respectively (Figures 11 and 12). Taken together these various reports indicate that in the resting state, with a relatively low level of sympathetic a-adrenoceptor stimulation, reduction of the blood pressure can probably be as effectively achieved by drugs with generalized.vasodilator properties as those with specific a,-adrenoceptor blocking activity.…”

Section: Evolution Of the Haemodynamic Profilementioning

confidence: 98%

“…of changes in erect diastolic blood pressure by hydralazine (-) and prazosin (0) given double-blind in random order to 16 patients with essential hypertension pretreated with a diuretic (cyclopenthiazide) and 1-blocking drug (propranolol) (Hua, Myers & Kincaid-Smith, 1978.). …”

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Vasodilators and Α‐adrenoceptor Antagonists in Hypertension and Heart Failure

1981

Brit J Clinical Pharma

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The mechanism of the increase in arteriolar resistance in hypertension and heart failure is differently derived. In hypertension, venous compliance is normal and the concentric narrowing of the arteriolar resistance vessels is ‘anatomical’; it is not due to increased stimulation or enhanced sensitivity of the vascular smooth muscle. In heart failure narrowing of both the arteriolar resistance and venous capacitance vessels derives predominantly from increased sympathoadrenal stimulation of α1‐adrenoceptors in the vascular smooth muscle. Vasodilator drugs which relax vascular smooth muscle differ widely in their site of activity. None are entirely specific for arteries, arterioles or veins, but they may be grouped for therapeutic convenience into those predominantly acting on arterioles (for example hydralazine) and those acting on veins (for example nitrates). Control of the resting blood pressure in stable essential hypertension appears to be equally well achieved with non‐specific arteriolar dilators (for example hydralazine, minoxidil, calcium antagonists) as those with specific α1‐adrenoceptor blocking properties (for example prazosin, indoramin). Pressure surges due to dynamic exercise and mental stress are little influenced by either category of drug. In contrast, α‐adrenoceptor antagonists appear to be capable of partly suppressing increase in ambulatory pressure and the pressor responses to isometric exercise and cold, particularly in patients pre‐treated with β‐blocking drugs. In acute heart failure, non‐selective α‐blocking drugs (for example phentolamine) produce an equal reduction in left ventricular filling pressure but greater increase in cardiac output than vasodilator drugs with a more balanced relaxing effect on arterioles and venules. In chronic heart failure, the little information available indicates that non‐selective arteriolar dilatation is probably associated with a greater increase in cardiac output but lesser reduction in left ventricular filling pressure than with specific α1‐adrenoceptor blocking drugs. Attenuation of the initial haemodynamic benefits during extended treatment is common to all vasodilators, including α‐adrenoceptor antagonists. α‐Adrenoceptor antagonists have yet to be convincingly shown to be haemodynamically superior to drugs with less specific vasodilator activity in the treatment of hypertension and heart failure.

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Section: Resultsmentioning

confidence: 99%

Section: Evolution Of the Haemodynamic Profilementioning

confidence: 98%

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Vasodilators and Α‐adrenoceptor Antagonists in Hypertension and Heart Failure

1981

Brit J Clinical Pharma

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“…Many observers have demonstrated that prazosin is an effective anti-hypertensive agent when given alone or in combination with a diuretic and,8-adrenoceptor blockade (Marshall et al, 1977). In cross-over studies it appears to be as effective as hydralazine in combination therapy (Hua et al, 1977). Consequently one must question whether good blood pressure control could have been obtained merely by substituting prazosin completely for hydralazine.…”

Section: Discussionmentioning

confidence: 99%

The addition of prazosin to standard triple therapy in the treatment of severe hypertension.

Heagerty¹,

Russell²,

Bing³

et al. 1982

Brit J Clinical Pharma

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1 A small dose of prazosin was added to the treatment regime of sixteen hypertensive patients poorly controlled on a combination of bendrofluazide, hydralazine and propranolol. 2 There was a significant improvement in blood pressure control in all patients at 1 month (P less than 0.01) and this was maintained at 9 months (P less than 0.02). Tolerance to prazosin was not a problem. 3 The addition of prazosin to conventional triple drug therapy produces a further useful fall in blood pressure.

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Antihypertensives

Scriabine

Taylor

2000

Ullmann's Encyclopedia of Industrial Chemistry

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Studies With Prazosin—a New Effective Hypotensive Agent. Ii

Cited by 17 publications

References 4 publications

Vasodilators and Α‐adrenoceptor Antagonists in Hypertension and Heart Failure

Vasodilators and Α‐adrenoceptor Antagonists in Hypertension and Heart Failure

The addition of prazosin to standard triple therapy in the treatment of severe hypertension.

Antihypertensives

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