BioMed Research International / 2018 / Article / Tab 4 / Review Article
The Efficacy and Safety of Norepinephrine and Its Feasibility as a Replacement for Phenylephrine to Manage Maternal Hypotension during Elective Cesarean Delivery under Spinal Anesthesia Table 4 Pharmacology of phenylephrine and norepinephrine.
Phenylephrine Norepinephrine Pharmacology α 1, α 2α 1, α 2, β 1>>β 2Onset time 60 s < 60s Half time 5 min 1-2 min Molecular structure Molecular weight 167 g/mol 169 g/mol Metabolism Deamination, glucuronidation, sulfation COMT+MAO to VMA Relative potency 1× 13× Placental transfer Minimal Likely minimal too Fetal metabolism stimulation Lower than ephedrine Lower than phenylephrine MAP ↑ ↑ HR Dose dependently ↓ ± or ↓ SV ± ± or ↑ CO Dose dependently ↓ ± or ↑ SVR ↑ ↑ Venous resistance ↑ ± Venous return ± ± Myocardial contractility ± or ↓ ↑
COMT: catechol-O-methyltransferase; MAO: monoamine oxidase; VMA: vanillylmandelic acid; MAP: mean arterial pressure; HR: heart rate; SV: stroke volume; CO: cardiac output; SVR: systemic vascular resistance; ± indicates neutral effect.
