What does this research mean for the field?

Acute differences in hemodynamic and neuroendocrine responses to prazosin and phenoxybenzamine converge during chronic therapy, suggesting these differences stem from onset rapidity rather than receptor selectivity, and that prejunctional alpha-2 receptors lack functional significance in essential hypertension. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To evaluate the relevance of selective alpha 1-adrenergic receptor blockade to blood pressure reduction by comparing hemodynamic and neuroendocrine responses to prazosin and phenoxybenzamine.

February 1, 1983Circulation

Hemodynamic and neuroendocrine responses to acute and chronic alpha-adrenergic blockade with prazosin and phenoxybenzamine.

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Why the study?

Does prazosin compared to phenoxybenzamine alter hemodynamic and neuroendocrine responses in patients with essential hypertension?

Population

11 patients with essential hypertension

Comparison

Prazosin (acute and chronic oral administration) vs Phenoxybenzamine and placebo

Design

RCT, randomized, double-blind, placebo-controlled

Follow-up

acute and chronic

Authors

JMJulia Mulvihill-WilsonSociedad Española de Cardiología FGF. Andrew GaffneyKarolinska Institutet WPW. A. PettingerCreighton University

Discussion

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Implication

Acute differences in alpha-blockade hemodynamics equalize chronically; challenges functional role of prejunctional alpha2-receptors in essential hypertension.

Key Points

To evaluate the relevance of selective alpha 1-adrenergic receptor blockade to blood pressure reduction by comparing hemodynamic and neuroendocrine responses to prazosin and phenoxybenzamine.
Randomized, double-blind, placebo-controlled, crossover trial in N=11 patients with essential hypertension.
Evaluated acute and chronic oral administration of prazosin and phenoxybenzamine under baseline conditions, lower body negative pressure, and dynamic bicycle exercise.
In acute administration, prazosin lowered arterial blood pressure by reducing total peripheral resistance (p < 0.05), whereas phenoxybenzamine produced an 8% reduction in cardiac output (p < 0.05) with minimal peripheral resistance changes.
Plasma norepinephrine concentrations and heart rate increased significantly more with prazosin than with phenoxybenzamine (p < 0.02), particularly during lower body negative pressure and exercise.
During chronic treatment, circulatory responses adapted such that both drugs produced similar hemodynamic and neuroendocrine profiles.

Structured PICO

Does prazosin compared to phenoxybenzamine alter hemodynamic and neuroendocrine responses in patients with essential hypertension?

Population

11 patients with essential hypertension

Intervention

Prazosin (acute and chronic oral administration)

Comparator

Phenoxybenzamine (acute and chronic oral administration) and placebo

Outcome

Hemodynamic and neuroendocrine responses (arterial blood pressure, total peripheral resistance, cardiac output, forearm vascular resistance, forearm blood flow, heart rate, plasma norepinephrine concentration)surrogate

Acute administration of prazosin and phenoxybenzamine produces different hemodynamic and neuroendocrine responses in essential hypertension, but chronic therapy results in similar profiles, suggesting prejunctional alpha 2-receptors have no functional significance in these patients.

Cite This Study

Mulvihill-Wilson et al. (1983) studied this question.

synapsesocial.com/papers/6a126719ea48cb855a34c36a https://doi.org/10.1161/01.cir.67.2.383

Topics

Hypertension management

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Implication

Acute differences in alpha-blockade hemodynamics equalize chronically; challenges functional role of prejunctional alpha2-receptors in essential hypertension.

Hemodynamic and neuroendocrine responses to acute and chronic alpha-adrenergic blockade with prazosin and phenoxybenzamine.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Topics

Hemodynamic and neuroendocrine responses to acute and chronic alpha-adrenergic blockade with prazosin and phenoxybenzamine.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Topics

Also Consider