Core pharmacology

Class Group

ADRENERGIC

Legacy Cicm Level

Level 2

Introduction

synthetic noncatecholamine with both direct and indirect
sympathomimetic actions.

Indications Uses

short term correction of BP in the setting of regional anaesthesia and off label for short term BP correction

Presentation

clear solution 10mg/mL in one mL vials and usually diluted to
10mg in 10ml or 20ml

Main Action

both direct and indirect
sympathomimetic actions. It acts mainly via alpha1/2 adrenoceptors to cause
vasoconstriction but also has some minor beta activity.

Mechanism of action

through ↑TPR
May be transient bradycardia due to baroreceptor feedback upon infusion initiation.
↑Pulmonary vascular resistance. ↑coronary artery flow by an indirect mechanism (stimulates NA release)

Physiological effects

CVS:
- Increased SVR leading to an increase in diastolic and systolic BP
- Reflex bradycardia may occur despite B1 effects
- It has positive inotropic effects but cardiac output is more likely to decrease as a result of increased afterload
- Coronary artery blood flow increases as an indirect mechanism
- Increased PVR

CNS:
- Doesn’t cross BBB
- Causes cerebral vasoconstriction but increases CPP

Renal/GU
- Renal vasoconstriction but re-established renal perfusion pressure in hypotension
- Uterine contraction and reduces uterine blood flow

Metabolic
- Inhibits insulin release and increases lipolysis
- May increase VO2

Adverse Effects Toxicity

Caution should be exercised in patients with pulmonary hypertension. May cause
severe hypertension in some patients

Absorption

IV. BA 100%
0.1-0.2mg boluses titrated to BP
onset / dur imm / up to 20 mins

Distribution

limited data on pharmacokinetics

Metabolism

Hepatic

Excretion

Unknown

Half-life

short

Route And Dose

IV boluses or infusion