OXYTOCIN 20 USP UNITS IN DEXTROSE 5%
Clinical safety rating: caution
Comprehensive clinical and safety monograph for OXYTOCIN 20 USP UNITS IN DEXTROSE 5% (OXYTOCIN 20 USP UNITS IN DEXTROSE 5%).
Oxytocin is a nonapeptide hormone that acts on oxytocin receptors (OXTR) in uterine myometrium and mammary gland epithelium, leading to Gq/11-coupled phospholipase C activation, increasing intracellular Ca2+ and promoting uterine smooth muscle contractions. It also stimulates milk ejection by contracting myoepithelial cells.
| Metabolism | Oxytocin is rapidly metabolized in the liver and kidneys by aminopeptidases (oxytocinase). Small amounts are also metabolized in the mammary gland and other tissues. Half-life is approximately 3-5 minutes. |
| Excretion | Primarily renal (>99% as intact peptide, small amount as metabolites). Biliary/fecal excretion negligible. |
| Half-life | Terminal elimination half-life: 1–6 minutes (IV), with a slower second phase of 12–20 minutes. Clinical context: Rapid clearance necessitates continuous IV infusion for sustained uterotonic effect. |
| Protein binding | 30% (primarily albumin; no specific binding protein identified). |
| Volume of Distribution | 0.1–0.3 L/kg (low Vd, reflecting limited extravascular distribution, primarily in extracellular fluid). |
| Bioavailability | Oral: <1% (degraded by gastrointestinal peptidases). IM: 70–80%. Intranasal: 10–20%. IV: 100%. |
| Onset of Action | IV: ≤1 minute. IM: 3–5 minutes. Intranasal: 5–10 minutes. |
| Duration of Action | IV: 20–60 minutes (infusion-dependent). IM: 2–3 hours. Intranasal: 2–4 hours. Note: Tachyphylaxis may reduce effect with prolonged use. |
Initial infusion at 0.5-2 mU/min, increased by 1-2 mU/min every 15-30 min until desired uterine activity, then taper. Maximum dose typically 20 mU/min.
| Dosage form | INJECTABLE |
| Renal impairment | No specific GFR-based dose adjustment required; use with caution in severe renal impairment due to fluid overload risk from dextrose 5%. |
| Liver impairment | No specific Child-Pugh based adjustment required; oxytocin is metabolized primarily in liver, but no dose modification guidelines exist for hepatic impairment. |
| Pediatric use | Not indicated; use only for labor induction/augmentation in pregnant adolescents. No weight-based dosing for other indications. |
| Geriatric use | Not indicated in elderly; contraindicated for non-obstetric uses in postmenopausal women. No specific geriatric dose recommendations. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for OXYTOCIN 20 USP UNITS IN DEXTROSE 5% (OXYTOCIN 20 USP UNITS IN DEXTROSE 5%).
| Breastfeeding | Oxytocin is metabolized rapidly in plasma and gastrointestinal tract, with negligible oral bioavailability. No M/P ratio is established due to rapid degradation. Endogenous oxytocin is essential for milk let-down; exogenous oxytocin may be used therapeutically for lactation disorders. Excretion into breast milk is minimal and not clinically significant. Considered compatible with breastfeeding. |
| Teratogenic Risk | Oxytocin is not a known human teratogen. In the first trimester, exposure is primarily from endogenous oxytocin; exogenous oxytocin for induction/augmentation is given in late pregnancy. No increased risk of structural anomalies has been documented. Second and third trimester use is for labor induction/augmentation and postpartum hemorrhage; risks are related to uterine hyperstimulation, fetal distress, and neonatal jaundice, not direct teratogenicity. |
■ FDA Black Box Warning
Oxytocin should be used only for medical indications and not for elective induction of labor. Proper dosing and monitoring are essential to avoid uterine hyperstimulation, which can lead to fetal hypoxia, uterine rupture, or maternal death. Continuous fetal monitoring and qualified personnel must be available.
| Serious Effects |
["Hypersensitivity to oxytocin or any component","Significant cephalopelvic disproportion","Unfavorable fetal position or presentation that prevents vaginal delivery","Fetal distress where immediate delivery is not advisable","Uterine hypertonicity or tetanic contractions","Placenta previa or vasa previa","Active genital herpes infection","When vaginal delivery is contraindicated (e.g., previous classical cesarean section, invasive cervical cancer)"]
| Precautions | ["Uterine hyperstimulation leading to fetal distress, uterine rupture, or maternal injury","Water intoxication due to antidiuretic effect of oxytocin, especially with high doses and prolonged infusion","Fetal bradycardia and other adverse fetal effects","Monitor uterine activity, fetal heart rate, and maternal vital signs closely","Use caution in severe hypertension, cardiovascular disease, or grand multiparity"] |
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| Fetal Monitoring | Continuous electronic fetal heart rate monitoring and uterine activity monitoring (tocodynamometry) required during oxytocin infusion. Maternal vital signs, fluid balance, and signs of uterine hyperstimulation or tetanic contractions must be assessed frequently. Monitor for water intoxication (hyponatremia) due to antidiuretic effect, especially with high doses or prolonged infusion. Serum electrolytes may be checked if indicated. |
| Fertility Effects | No known adverse effects on fertility. Oxytocin is used therapeutically for induction of labor and does not impair future fertility. Endogenous oxytocin plays a role in parturition and lactation but not in ovulation or implantation. |