PITOCIN
Clinical safety rating
cautionComprehensive clinical and safety monograph for PITOCIN (PITOCIN).
Comprehensive clinical and safety monograph for PITOCIN (PITOCIN).
Induction of laborAugmentation of laborPostpartum hemorrhageIncomplete abortionUterine atony
Oxytocin receptor agonist; stimulates uterine smooth muscle contractions and myoepithelial cell contraction in the mammary gland.
| Metabolism | Primarily metabolized in the liver and kidneys by oxytocinase; also degraded in the gastrointestinal tract and by the lungs. |
| Excretion | Primarily renal: 90-95% of the dose is excreted in urine as intact peptide and metabolites; <1% excreted in feces via bile. |
| Half-life | Terminal elimination half-life is 3-5 minutes (plasma) with a terminal half-life of 1-6 minutes for exogenously administered oxytocin; clinical effects persist 20-30 minutes due to receptor binding. |
| Protein binding | Approximately 30%, bound primarily to serum albumin and oxytocin-specific binding proteins. |
| Volume of Distribution | 0.3 L/kg (total body water distribution; higher in pregnancy). Clinical meaning: reflects distribution to peripheral tissues and uterus. |
| Bioavailability | Intramuscular: approximately 50-80% due to first-pass metabolism; Intravenous: 100%; Oral: negligible (<1%) due to rapid peptidase degradation. |
| Onset of Action | Intravenous: 0.5-1 minute; Intramuscular: 2-5 minutes. |
| Duration of Action | Intravenous: 15-30 minutes (tonic uterine contraction); Intramuscular: 30-60 minutes. |
| Molecular Weight | 1007.19 |
IV infusion: 0.5-2 mU/min, increase by 1-2 mU/min every 15-60 minutes until contractions are established; maximum 20 mU/min.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment required; monitor for fluid overload. |
| Liver impairment | No specific dose adjustment required. |
| Pediatric use | Not indicated for pediatric use. |
| Geriatric use | Use lowest effective dose; monitor for fluid overload and hypertension. |
| 1st trimester | No known teratogenic effects; used for pregnancy termination or induction in specific circumstances. |
| 2nd trimester | May be used for induction of labor; risk of uterine hyperstimulation and fetal distress. |
| 3rd trimester | Standard use for induction of labor; monitor for uterine hyperstimulation and fetal heart rate abnormalities. |
Clinical note
Comprehensive clinical and safety monograph for PITOCIN (PITOCIN).
| Placental transfer | Does cross the placenta; used therapeutically to stimulate uterine contractions. |
| Breastfeeding | Excreted into breast milk in minimal amounts; not expected to cause adverse effects in breastfed infants. Use with caution. |
| Lactation Rating | L2 (Probably Compatible) |
| Teratogenic Risk | Pitocin (oxytocin) is not associated with structural teratogenicity when used at therapeutic doses. However, prolonged high-dose exposure during labor may cause fetal distress, neonatal hyperbilirubinemia, and transient hyponatremia. In first trimester, no evidence of increased malformation risk. In second and third trimesters, use may induce uterine hyperstimulation leading to fetal hypoxia or uterine rupture. Risk is dose- and duration-dependent. |
| Fetal Monitoring | Continuous fetal heart rate monitoring (cardiotocography) and maternal uterine activity monitoring (tocodynamometry) are required during infusion. Assess maternal blood pressure (risk of hypotension with rapid IV bolus) and fluid balance (risk of water intoxication). Monitor for signs of uterine hyperstimulation or tetanic contractions. Postpartum, monitor for retained placenta and neonatal Apgar scores. |
| Fertility Effects | No known adverse effects on fertility. Oxytocin is not used for fertility treatment; high doses may disrupt implantation if used during luteal phase, but not relevant in clinical use for labor induction/augmentation. |
■ FDA Black Box Warning
Only for use in hospital settings with adequate personnel and equipment. High doses or prolonged use may cause uterine hyperstimulation, tetanic contractions, or uterine rupture. Risk of water intoxication and hyponatremia due to antidiuretic effect.
| Serious Effects |
Hypersensitivity to oxytocin or any componentSignificant cephalopelvic disproportionUnfavorable fetal positions or presentationFetal distress before labor onsetUterine hyperactivity or tetanic contractionsInvasive cervical cancerObstructed laborPrior uterine scar from classical cesarean section
| Precautions | Monitor uterine activity and fetal heart rate continuously. Use cautiously in grand multiparity, cervical trauma, or overdistended uterus. Avoid simultaneous IV administration of fluids containing electrolytes in large volumes to minimize water intoxication. |
| Food/Dietary | No known food interactions. Maintain hydration and light diet as tolerated during labor. |
| Clinical Pearls | Pitocin (oxytocin) is used for induction/augmentation of labor. Must be administered via IV infusion with strict monitoring of uterine activity and fetal heart rate. Titrate dose every 30-60 minutes. Maximum dose is typically 20 mU/min; higher doses increase risk of uterine hyperstimulation. Have terbutaline or magnesium sulfate available for tocolysis if needed. Avoid in cases of placental previa, vasa previa, or fetal distress. Use with caution in grand multiparity (≥5) due to risk of uterine rupture. |
| Patient Advice | This medication induces contractions to start or strengthen labor. · You will be closely monitored throughout infusion for your and your baby's safety. · Report any severe or continuous abdominal pain, changes in fetal movement, or excessive bleeding. · You may feel stronger, more frequent contractions than natural labor. · Inform your healthcare provider of any allergies or previous uterine surgery. |
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