{Ob/Gyn Meds}

OXYTOCIN

Adult Dosing

• Postpartum Hemorrhage: 10 U IV at 20-40 mU/min (mU=milliunits)
  • May be given IM
• Labor Induction: 0.5-1 mU/min IV, titrate 1-2 mU/min q15-60min until contraction pattern established similar to normal labor
• Monitor: intrauterine pressure, fetal heart rate

Pediatric Dosing

• Not applicable

Contraindications and Cautions

• Contraindications
  • Significant cephalopelvic disproportion
  • Unfavorable fetal positions or presentations, eg, transverse lies, which are undeliverable without conversion prior to delivery
  • Obstetric emergencies that favor surgery
  • Fetal distress where delivery is not imminent
  • Where adequate uterine activity fails to achieve satisfactory progress
  • Hyperactive or hypertonic uterus
  • When vaginal delivery is contraindicated, eg, invasive cervical carcinoma, active herpes genitalis, total placenta previa, vasa previa, & cord presentation or prolapse of cord
  • Hypersensitivity
  • Relative: fetal distress, polyhydramnios, partial placenta previa, prematurity, borderline cephalopelvic disproportion, previous major surgery of cervix or uterus (incl C-section), overdistension of uterus, grand multiparity, invasive cervical carcinoma, history of uterine sepsis or traumatic delivery
  • Not indicated for elective labor induction
• Cautions
  • If uterine hyperactivity occurs, discontinue immediately
  • Risk of severe water intoxication on prolonged administration
  • Restricting fluid intake may be warranted
  • IM not recommended for labor induction/augmentation

Indications & Uses

• Induction of labor, control of postpartum hemorrhage (Go to Evidence-Based Inquiry)

Mechanism of Action

• Uterine stimulant, vasopressive, & antidiuretic effects

Adverse Drug Reactions

• Hyperstimulation of the uterus, with strong (hypertonic) &/or prolonged (tetanic) contractions, or a resting uterine tone of 15-20 mm H2O between contractions may occur, possibly resulting in uterine rupture, cervical & vaginal lacerations, postpartum hemorrhage, abruptio placentae, impaired uterine blood flow, amniotic fluid embolism, & fetal trauma including intracranial hemorrhage
• Sinus bradycardia, tachycardia, premature ventricular complexes & other arrhythmias, permanent CNS or brain damage, and death secondary to asphyxia
• Uteroplacental hypoperfusion & variable deceleration of fetal heart rate, fetal hypoxia, perinatal hepatic necrosis, and fetal hypercapnia
• Severe decreases in maternal systolic & diastolic blood pressure, increases in heart rate, systemic venous return & cardiac output, & arrhythmia

Pregnancy and Lactation

• Pregnancy Category: X
• Lactation: may be distributed milk; commencement of nursing should be delayed for at least 1 day when discontinued

Kinetics/Dynamics

• Half-Life: 3-5 min
• Duration:
  • IM: 2-3 hr
  • IV: 1 hr
• Vd: 0.3 L/kg
• Protein Bound: none
• Metabolism: rapidly destroyed in the liver and kidneys
• Excretion: small amounts in urine, unchanged

Overdose Management

• Restrict fluids, promote diuresis, correct electrolyte imbalances
• Barbiturate if convulsions

Interactions

• Go to Drug Interactions [DI]

Trade Names

• Dosing Strengths: (inj soln) 10 U/mL

• United States: Pitocin; Syntocinon*
• Canada: Syntocinon*; Toesen*

* = Discontinued

IV/IM Info

• IV Incompatibilities
  • Additive: fibrinolysin
• IV Compatibilities
  • Solution: compatible w/ most common solvents
  • Additive: chloramphenicol sodium succinate, metaraminol, netilmicin, sodium bicarbonate, thiopental, verapamil
  • Y-site: heparin, hydrocortisone sodium succinate, insulin, meperidine, morphine sulfate, KCl, vitamin B/C, warfarin
• IV Preparation
  • Dilute to 10 mU/mL by adding 10 U (1 mL) to 1000 mL of D5W, LR, or NS
• IV/IM Administration
  • Administer by IV infusion using infusion control device, or
  • By IM injection (not recommended in most cases)
• Storage
  • Store at room temperature (15-25°C)
  • Do not freeze
  • Do not use solution if discolored or contains precipitate

Other Information

• Class: Ob/Gyn Meds
• Requires prescription
• ATC Code: H01BB02
• US Cost Info: Generic ($$) | Brand ($$$$)
• Medicare Part D: N/A

Evidence-Based Practice

1. In patients undergoing induction for a second-trimester fetal demise, does the use of high-dose oxytocin reduce the incidence of retained placenta?
2. In pregnant women with an unfavorable cervix who have a Foley balloon placed, is adding oxytocin an effective strategy?

References

1. ASHP Drug Compendium (Oxytocin (Systemic); Oxytocics)
2. FDA Monograph http://www.accessdata.fda.gov/drugsatfda_docs/label/2007/018261s028lbl.pdf (Accessed July, 2014)
3. Colaianni G, Tamma R, Di Benedetto A, et al. The oxytocin-bone axis. J Neuroendocrinol. 2013.
4. Israel S, Hart E, Winter E. Oxytocin Decreases Accuracy in the Perception of Social Deception. Psychol Sci. 2013.
5. Kanat M, Heinrichs M, Domes G. Oxytocin and the social brain: Neural mechanisms and perspectives in human research. Brain Res. 2013.
6. Klein BY, Tamir H, Hirschberg DL, Glickstein SB, Ludwig RJ, Welch MG. Oxytocin modulates markers of the unfolded protein response in Caco2BB gut cells. Cell Stress Chaperones. 2013.
7. Mlynarczuk J, Wrobel MH, Ziolkowska A, Kotwica J. Involvement of the orphan nuclear receptor SF-1 in the effect of PCBs, DDT and DDE on the secretion of steroid hormones and oxytocin from bovine granulosa cells. Anim Reprod Sci. 2013.
8. Poutahidis T, Kearney SM, Levkovich T, et al. Microbial Symbionts Accelerate Wound Healing via the Neuropeptide Hormone Oxytocin. PLoS One. 2013;8(10):e78898.
9. Tabak BA. Oxytocin and social salience: a call for gene-environment interaction research. Front Neurosci. 2013;7:199.
10. van Roekel E, Verhagen M, Scholte RH, Kleinjan M, Goossens L, Engels RC. The Oxytocin Receptor Gene (OXTR) in Relation to State Levels of Loneliness in Adolescence: Evidence for Micro-Level Gene-Environment Interactions. PLoS One. 2013;8(11):e77689.
11. Weisman O, Delaherche E, Rondeau M, Chetouani M, Cohen D, Feldman R. Oxytocin shapes parental motion during father-infant interaction. Biol Lett. 2013;9(6):20130828.

Updated/Reviewed: July, 2014