Core pharmacology

Class Group

Direct Vasodilator

Legacy Cicm Level

-

Introduction

direct vasodilator whose mechanism of action is poorly understood.

Indications Uses

It is used primarily in severe refractory hypertension in combination with other antihypertensives
Topical to treat baldness

Presentation

10mg tablets
Topical

Mechanism of action

Poorly understood. May be potassium channel activator)

↑hair production

Onset Peak Duration

PO. doses 10-40mg PO daily

Physiological effects

Arteriole vasodilation with preserved venous tone, and minimal effect on epicardial vasculature. Reflex ↑ in HR, CO and activation of the RAAS → peripheral oedema.

Adverse Effects Toxicity

activation of the RAAS and the increase in HR and CO make this drug less
efficacious. Because of this reason it is almost always given in combination with a
thiazide or betablocker. It is contraindicated in phaechromocytoma and may
precipitate pericardial eff¬usion and worsen angina.

Absorption

PO. BA up to 90%

Protein binding

None

Metabolism

Hepatic primarily via glucuronidation

Excretion

Urine (12% as unchanged drug)

Half-life

4 hours

Route And Dose

PO. doses 10-40mg PO daily