OXYTOCIN
Clinical safety rating
cautionComprehensive clinical and safety monograph for OXYTOCIN (OXYTOCIN).
Comprehensive clinical and safety monograph for OXYTOCIN (OXYTOCIN).
Induction of labor for medical necessityAugmentation of labor to enhance uterine contractionsPostpartum hemorrhage prevention and treatmentIncomplete abortion adjunct (off-label)Lactation support (off-label)
Oxytocin is a nonapeptide hormone that binds to oxytocin receptors on the myometrium, stimulating G-protein coupled receptor activation and increasing intracellular calcium, leading to uterine smooth muscle contraction. It also acts on mammary gland myoepithelial cells to induce milk ejection.
| Metabolism | Primarily metabolized by oxytocinase (leucyl-cystinyl aminopeptidase) in the liver and kidney, and by placental oxytocinase during pregnancy. Excreted renally. |
| Excretion | Renal: >99% as intact oxytocin and metabolites; biliary/fecal: negligible. |
| Half-life | Terminal elimination half-life: 1–6 minutes (intravenous); clinical context: rapid offset requires continuous infusion for sustained uterine contraction. |
| Protein binding | Negligible (<1%); does not bind significantly to plasma proteins. |
| Volume of Distribution | 0.04–0.06 L/kg; limited distribution, primarily in extracellular fluid. |
| Bioavailability | Intramuscular: approximately 80%; intranasal: highly variable (1–15%). |
| Onset of Action | Intravenous: 0.5–1 minute; intramuscular: 3–5 minutes; intranasal: within minutes (variable). |
| Duration of Action | Intravenous: 20–60 minutes (infusion-dependent); intramuscular: 2–3 hours; intranasal: 20–40 minutes. |
| Molecular Weight | 1007.19 |
For induction/augmentation of labor: IV infusion, initial 0.5-2 mU/min, increase by 1-2 mU/min every 30-60 min until desired contraction pattern; max 20 mU/min. For postpartum hemorrhage: IV bolus 3 units (slow push) or IV infusion 10-40 units in 1000 mL crystalloid, rate adjusted to control bleeding; alternatively IM 10 units after delivery of placenta.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for renal impairment; oxytocin is not significantly renally excreted. |
| Liver impairment | No specific dose adjustment guidelines for hepatic impairment; oxytocin is rapidly metabolized in plasma and liver, dose adjustment not required for Child-Pugh class A, B, or C. |
| Pediatric use | Not indicated for pediatric use; no weight-based dosing established. |
| Geriatric use | No specific elderly dose adjustment; use standard adult dosing with caution in elderly due to potential cardiovascular effects, monitor fluid balance closely. |
| 1st trimester | Oxytocin is not typically used in first trimester; limited data. No known teratogenicity in animal studies, but human data insufficient. |
| 2nd trimester | Use only if clearly needed; may cause uterine hyperstimulation. No known fetal abnormalities. |
| 3rd trimester | Approved for labor induction/augmentation; monitor for uterine hyperstimulation and fetal distress. |
Clinical note
Comprehensive clinical and safety monograph for OXYTOCIN (OXYTOCIN).
| Placental transfer | Not measurable as oxytocin is a peptide rapidly degraded by placental oxytocinase; does not cross placenta in significant amounts. |
| Breastfeeding | Oxytocin is a natural hormone excreted in breast milk in small amounts. It is rapidly degraded in the infant's gastrointestinal tract. Considered safe during breastfeeding; no adverse effects reported in nursing infants. |
| Lactation Rating | L1 - Safe |
| Teratogenic Risk | Oxytocin is not teratogenic in humans. First trimester: No increased risk of major malformations. Second and third trimesters: No evidence of teratogenicity; used therapeutically for induction/augmentation of labor. Risks are related to uterine hyperstimulation and fetal hypoxia, not structural anomalies. |
| Fetal Monitoring | Continuous fetal heart rate monitoring and uterine activity (tocography) required during administration. Monitor maternal vital signs, fluid balance (risk of water intoxication), and signs of uterine hyperstimulation or rupture. |
| Fertility Effects | No known adverse effects on fertility. Oxytocin is used therapeutically in labor and postpartum; does not impair conception or reproductive function. |
■ FDA Black Box Warning
WARNING: Oxytocin should be administered only by trained personnel in a hospital setting with immediate availability of a physician. Prolonged or high-dose use can cause uterine hyperstimulation, tetanic contractions, uterine rupture, postpartum hemorrhage, and water intoxication (hyponatremia). Fetal heart rate must be monitored continuously.
| Serious Effects |
Hypersensitivity to oxytocin or any componentSignificant cephalopelvic disproportionUnfavorable fetal positions or presentation (e.g., transverse lie)Fetal distress where delivery is not imminentUterine hypertonus or tetanic contractionsInability to achieve vaginal delivery (e.g., cord prolapse, placenta previa)Severe toxemia (pre-eclampsia/eclampsia) with high risk of uterine rupture
| Precautions | Uterine hyperstimulation may lead to fetal distress, uterine rupture, or amniotic fluid embolism. Water intoxication (hyponatremia) can occur with prolonged infusion and antidiuretic effect. Monitor uterine activity, fetal heart rate, and fluid balance. Use with caution in grand multiparity, cervical insufficiency, or prior uterine surgery. |
| Food/Dietary | No significant food interactions. Maintain normal hydration unless instructed otherwise. Avoid large meals immediately before administration to reduce risk of nausea/vomiting. |
| Clinical Pearls | Use undiluted 10 IU/mL solution for postpartum hemorrhage; administer slowly (0.5-1 mL/min) to avoid hypotension. Dilute in NS or LR for induction/augmentation. Do not use in patients with significant cephalopelvic disproportion or fetal distress. Monitor uterine activity and fetal heart rate continuously. Have magnesium sulfate and nifedipine available for hyperstimulation. Store at room temperature; do not freeze. |
| Patient Advice | This medication is used to start or strengthen labor contractions, or to control bleeding after childbirth. · You will receive this as an injection or through an IV line under close monitoring. · Common side effects include nausea, vomiting, and headache; report excessive pain or prolonged contractions. · Inform your healthcare provider if you have a history of heart disease, high blood pressure, or prior uterine surgery. · Avoid sudden movements if receiving IV; alert staff if you feel lightheaded or have chest pain. |
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