OXYTOCIN – PITOCIN
OXYTOCIN – Stimulates uterine smooth muscle contractions.
Increases excitability of muscle cells.
Increases strength of muscle contractions.
Supports the propagation of the contraction.
HALF LIFE – Circulatory half-life is 3 – 5 minutes.
Takes approximately 40 minutes to reach a steady-state plasma concentration.
USES:
Induction & Augmentation.
Fourth stage to stimulate uterine contractions & control uterine atony.
Not thought to cross placenta barrier because of molecular weight and oxytocinase in placenta.
ROUTE/DOSAGE
IM/IV
Start induction at 0.5 – 1 mu/min until good contractions are achieved.
MAXIMUM recommended dose usually = 10 mu/min (120ml/hr)
Decrease oxytocin by similar increments when labor is well established & dilation has progressed to 5 – 6
cm.
CONTRAINDICATIONS – same as for induction
MATERNAL SIDE EFFECTS
1. CARDIOVASCULAR RESPONSEInitial decrease in BP, with prolonged administration 30% increase over baseline B/P may occur.
Cardiac output and stroke volume increased.
In doses > 20 mu/min, antidiuretic effect results in a decrease free water exchange in kidney &
decrease UO.
2. HYPERSTIMULATION results in HYPERCONTRACTILITY, which may cause:
a. abruption placenta
b. impaired uterine blood flow
c. rapid labor & birth – cervical, vaginal, or perineal lacerations, uterine atony. Fetal trauma.
d. uterine rupture.
e. H2O intoxication (n/ v, hypotension, tachycardia, cardiac arrhythmias) if given in an electrolyte –
free solution or at a rate over 20 mu/ml (120ml/hr).
f. hypotension with rapid IV bolus administered postpartially.
FETAL/NEONATAL EFFECTS
1. Maternal hypercontractility causes a decreased oxygen supply to the fetus, which is reflected by
irregularities and/or decreased FHR.
2. Hyperbilirubinemia
3. Trauma for rapid birth.
AUGMENTATION – Prepare and administer as for induction.
Flow rate is gradually increased at no less than every 30 minutes to a maximum of 10mu/min.
FOURTH STAGE USE: One dose of 10 units Pitocin IM or added to IV fluids for continuous infusion.
N/ADN/Spring 09/RNSG Oxytocin Pitocin
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Revised 11/08