Presentation

1 ml glass vial containing 10 mg. Dilution prior to administration is essential, which is most easily done by adding the contents of the vial to a 100 ml bag of normal saline, i.e. final concentration 100 μg/ml.

50-100 μg bolus doses are titrated to effect.

Phenylephrine acts directly on alpha-adrenoceptors. It has no actions on beta-adrenoceptors.

Stimulation of alpha-adrenoceptors causes vasoconstriction and an increase in systemic vascular resistance. As a result, there is reflex bradycardia, which may cause a fall in cardiac output if a large dose is given.

Severe hypotension associated with a normal or fast heart rate.