- Intravenous bolus dose(s) or infusion to combat vasoplegia-induced hypotension associated with anaesthesia
- Can be used by IM and SC routes too
- As an nasal decongestant (although evidence suggests oral consumption not really very effective)
- As a mydriatic agent
Phenylephrine
Phenylephrine
- Phenylephrine is a directly-acting sympathomimetic with potent alpha-agonist actions and no beta activity
Presentation
- Presents as a clear solution of 0.1 - 10mg/ml
- Stronger concentrations may be used by perfusionists during cardiopulmonary bypass
Absorption
- IV administration results in a rapid rise in BP that lasts 5-10mins
- IM or SC use takes 15 minutes to work but lasts up to 1hr
Metabolism
- Metabolised in the liver by MAO to unknown products
Cardiovascular
- Raised SVR and therefore BP
- May cause a reflex bradycardia (and therefore a drop in cardiac output)
- Not arrhythmogenic
Neurological
- Does not cross BBB
- Increases cerebral blood flow but cerebral tissue oxygen saturation falls (Anaesthesia, 2023)
Renal
- Reduction in renal blood flow due to vasoconstriction
Uteroplacental
- Preferred to ephedrine for maternal hypotension during LSCS as evidence suggests phenylephrine is associated with a more favourable cord gas profile