OXYTOCIN 5 USP UNITS IN DEXTROSE 5%
Clinical safety rating: caution
Comprehensive clinical and safety monograph for OXYTOCIN 5 USP UNITS IN DEXTROSE 5% (OXYTOCIN 5 USP UNITS IN DEXTROSE 5%).
Oxytocin is a nonapeptide hormone that binds to oxytocin receptors on the myometrium, increasing intracellular calcium and stimulating uterine smooth muscle contraction. It also acts on mammary gland myoepithelial cells to promote milk ejection.
| Metabolism | Rapidly metabolized in the liver and kidneys by oxytocinase (cystinyl aminopeptidase) and other peptidases. Small amounts are excreted unchanged in urine. |
| Excretion | Renal (primarily); >99% of infused oxytocin is excreted unchanged in urine; negligible biliary/fecal elimination. |
| Half-life | Terminal elimination half-life: 1–6 minutes (intravenous); 2–5 minutes (intramuscular); short half-life requires continuous infusion for sustained effect. |
| Protein binding | Low; approximately 30% bound to plasma proteins (no specific carrier protein identified). |
| Volume of Distribution | 0.2–0.3 L/kg; small Vd consistent with distribution primarily in extracellular fluid; does not readily cross placenta. |
| Bioavailability | Intravenous: 100%; Intramuscular: approximately 50% (due to first-pass hepatic metabolism after absorption). |
| Onset of Action | Intravenous: 30–60 seconds (uterine contraction); Intramuscular: 3–5 minutes; Subcutaneous: 3–5 minutes. |
| Duration of Action | Continuous infusion required for sustained uterine tone; single IV dose effect lasts 20–30 minutes; IM dose effect lasts 30–60 minutes. |
Induction or augmentation of labor: IV infusion, initial rate 0.5-2 mU/min, increased by 1-2 mU/min every 15-30 min until adequate contractions; max 20 mU/min. Postpartum hemorrhage: IV infusion 10-40 units in 1000 mL D5W or NS, rate adjusted to control bleeding.
| Dosage form | INJECTABLE |
| Renal impairment | No dosage adjustment required for renal impairment. Oxytocin is extensively metabolized and renal excretion of unchanged drug is minimal. |
| Liver impairment | No dosage adjustment required for hepatic impairment. Oxytocin metabolism by liver is not significantly altered in liver disease. |
| Pediatric use | Not indicated for pediatric use. Oxytocin is only used in obstetrics for labor induction or postpartum hemorrhage in adults. |
| Geriatric use | Not indicated for geriatric use. Oxytocin is exclusively used in women of childbearing age for obstetrical indications. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for OXYTOCIN 5 USP UNITS IN DEXTROSE 5% (OXYTOCIN 5 USP UNITS IN DEXTROSE 5%).
| Breastfeeding | Limited data; M/P ratio not established. Oxytocin is rapidly metabolized and excreted in breast milk in negligible amounts. Endogenous oxytocin is normally present in milk. Exogenous use during lactation is unlikely to affect the infant due to rapid plasma clearance (half-life 3-5 minutes). Caution advised if used postpartum for hemorrhage. |
| Teratogenic Risk | FDA Pregnancy Category C. Oxytocin is not expected to increase the risk of major birth defects when used as indicated for labor induction/augmentation. However, high doses may cause uterine hyperstimulation leading to fetal distress, hypoxia, or neonatal morbidity. First trimester exposure is minimal as use is typically restricted to labor. No teratogenicity observed in animal studies but fetal risks are primarily related to uterotonic effects. |
■ FDA Black Box Warning
WARNING: UTERINE RUPTURE AND FETAL INJURY. To be used only under close medical supervision. High doses or prolonged use may lead to uterine hyperstimulation, tetanic contractions, and uterine rupture. Fetal heart rate must be monitored continuously.
| Serious Effects |
Significant cephalopelvic disproportion, unfavorable fetal position, fetal distress, preterm labor (unless tocolysis is desired), uterine scarring (e.g., previous Cesarean section), invasive cervical carcinoma, hypertonic uterine patterns, allergy to oxytocin, and cases where vaginal delivery is contraindicated.
| Precautions | Risk of uterine hyperstimulation, fetal distress, uterine rupture, water intoxication (especially when administered with large volumes of electrolyte-free solutions), severe hypotension, and anaphylaxis. Monitor uterine activity, fetal heart rate, and fluid balance. |
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| Fetal Monitoring | Continuous electronic fetal heart rate monitoring and uterine activity monitoring (tocodynamometry or intrauterine pressure catheter) are mandatory. Assess maternal vital signs (blood pressure, heart rate) and fluid balance due to risk of water intoxication with prolonged high-dose infusion. Monitor for signs of uterine hyperstimulation (tachysystole, hypertonus) or rupture. |
| Fertility Effects | No direct adverse effects on fertility. Oxytocin is used exogenously for labor induction and does not affect gametogenesis, implantation, or early pregnancy maintenance. Endogenous oxytocin plays a role in parturition and lactation but supplemental use does not impair reproductive potential. |