Oxytocin augmentation of dysfunctional labor. IV. Oxytocin pharmacokinetics.
Plasma oxytocin levels ([OT[p) were measured every 20 minutes during infusions of oxytocin. The initial dose of 1 mU/min was incremented, if necessary, by 1 mU/min at 40-minute intervals until sufficient contractility was obtained to effect cervical dilatation. The results demonstrated: the [OT]p rises linearly with each dose for the first 40 minutes of the infusion; there is no difference between the 40- and 60-minute sample values, suggesting that the peak [OT]p of each dose is achieved in 40 minutes; the increment in [OT]p required to produce effective contractility varies widely from 0.58 to 5.09 microU/ml; the plasma clearance rate varied from 11.2 to 32.5 ml/kg/min. Approximately 40 minutes is required for any particular dose of oxytocin to reach a "steady-state" [OT]p and the maximal uterine contractile response. The design of regimens for the augmentation or induction of labor should be based on this knowledge.
D002584:Cervix Uteri / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007700:Kinetics; D007743:Labor, Obstetric / Q000187:drug effects*; D007744:Obstetric Labor Complications / Q000503:physiopathology; D010121:Oxytocin / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D011247:Pregnancy; D013997:Time Factors; D014590:Uterine Contraction / Q000187:drug effects
D010121:Oxytocin