Oxytocin (Solution) Instructions for Use

ATC Code

H01BB02 (Oxytocin)

Active Substance

Oxytocin (Rec.INN registered by WHO)

Clinical-Pharmacological Group

A drug that increases the tone and contractile activity of the myometrium

Pharmacotherapeutic Group

Hypothalamic and pituitary hormones and their analogues; posterior pituitary lobe hormones; oxytocin and its analogues

Pharmacological Action

A synthetic hormonal agent, whose pharmacological action is similar to endogenous oxytocin.

It has a uterotonic, labor-stimulating, and lactotropic action. It has a stimulating effect on the smooth muscles of the uterus, increases the contractile activity of the myometrium and, to a lesser extent, the tone (especially in late pregnancy, during labor, and directly during delivery).

Under the influence of oxytocin, the permeability of cell membranes to calcium ions Ca²⁺ increases, the resting potential decreases and their excitability increases (a decrease in the membrane potential leads to an increase in the frequency, intensity, and duration of contractions).

In small doses, Oxytocin increases the frequency and amplitude of uterine contractions; in large doses or with repeated administration, it promotes an increase in uterine tone, frequency, and intensity of its contractions (up to tetanic).

It contracts the myoepithelial cells around the alveoli of the mammary gland, stimulates the flow of milk into the large ducts or sinuses, thereby enhancing milk secretion.

It is practically devoid of vasoconstrictor and antidiuretic action (manifests them only in high doses), does not cause contraction of the muscles of the bladder and intestines.

Pharmacokinetics

Plasma protein binding is low (30%). Similar to vasopressin, Oxytocin is distributed throughout the extracellular space. A small amount of oxytocin penetrates the placenta into the fetal circulatory system. Most of the oxytocin is rapidly metabolized in the liver and kidneys. During enzymatic hydrolysis, Oxytocin is inactivated, primarily under the action of tissue oxytocinase, the concentration of which in plasma, target organs, and placenta increases during pregnancy. It is excreted mainly by the kidneys unchanged. T_1/2 is 1-6 min (decreases in late pregnancy and during lactation).

Indications

For induction and stimulation of labor (primary and secondary uterine inertia, the need for premature delivery due to preeclampsia, Rh conflict, intrauterine fetal death; post-term pregnancy, premature rupture of amniotic fluid, management of labor in breech presentation).

For the prevention and treatment of hypotonic uterine bleeding after medical or spontaneous abortion in the first trimester, or termination of pregnancy in the second trimester, in the early postpartum period and to accelerate postpartum uterine involution; to enhance uterine contractility during cesarean section (after removal of the placenta).

ICD codes

Dosage Regimen

Administer the dosage individually based on indication, parity, and uterine response. Continuously monitor uterine activity, fetal heart rate, and maternal blood pressure and pulse. Discontinue infusion immediately upon signs of uterine hyperstimulation or fetal distress.

For induction or stimulation of labor, use intravenous infusion only. Dilute 5-10 IU in 500-1000 mL of an isotonic electrolyte solution, typically 0.9% sodium chloride. Initiate infusion at a rate of 0.5-4 mIU/min. Increase the rate in increments of 1-2 mIU/min at 30-60 minute intervals until a satisfactory contraction pattern is established, typically 3-5 contractions per 10 minutes. The maximum dose rarely exceeds 20 mIU/min. Do not use bolus intravenous administration for labor induction.

For control of postpartum uterine bleeding, administer 10-40 IU by intravenous infusion in 500-1000 mL of a non-hydrating diluent. Alternatively, administer 10 IU by intramuscular injection after delivery of the placenta. For treatment of incomplete or inevitable abortion, administer 10 IU by intravenous infusion at a rate of 20-40 drops per minute.

For adjunctive use during cesarean section, administer 5-10 IU by slow intravenous injection after placental delivery to produce uterine contraction. For intramuscular use, the typical single dose ranges from 2 to 10 IU. Adjust all doses carefully in patients with cardiovascular disorders and avoid fluid overload.

Adverse Reactions

Allergic reactions anaphylaxis and other allergic reactions; with too rapid administration – bronchospasm; rarely – fatal outcome.

From metabolism severe hyperhydration with prolonged IV administration with a large volume of fluid (antidiuretic effect of oxytocin), may be accompanied by convulsions and coma; rarely – fatal outcome.

From the cardiovascular system: severe arterial hypertension (in case of using vasopressor drugs), arterial hypotension (with simultaneous use with cyclopropane), shock; when used in high doses – arrhythmia, ventricular extrasystole, reflex tachycardia; with too rapid administration – bradycardia; myocardial ischemia, QT interval prolongation; subarachnoid hemorrhage; in rare cases – development of DIC syndrome.

From the respiratory system acute pulmonary edema without hyponatremia.

From the digestive system: nausea, vomiting.

From the reproductive system when used in large doses or with increased sensitivity – uterine hypertonus, cervical spasm, tetany, uterine rupture; increased bleeding in the postpartum period as a result of oxytocin-induced thrombocytopenia, afibrinogenemia, and hypoprothrombinemia, sometimes – hemorrhage into the pelvic organs; ruptures of the soft tissues of the birth canal.

From laboratory parameters hyponatremia.

In the fetus or newborn: as a consequence of oxytocin administration to the mother – within 5 minutes low Apgar score, neonatal hyperbilirubinemia, hyponatremia; with too rapid administration – decreased blood fibrinogen concentration, retinal hemorrhage; as a consequence of uterine contractile activity – sinus bradycardia, tachycardia, ventricular extrasystole and other arrhythmias; CNS damage; fetal death due to asphyxia.

Contraindications

Hypersensitivity to oxytocin; narrow pelvis (anatomical and clinical), transverse and oblique position of the fetus, face presentation of the fetus, premature birth, threatened uterine rupture, uterine scars (after previous cesarean section, uterine surgery), immature cervix; tendency to tetanic uterine contractions; risk of uterine rupture due to overdistension in polyhydramnios, multiple pregnancy, in multiparous women (more than 4 births in history), especially of advanced age; partial placenta previa or vasa previa, premature placental abruption, uterine sepsis, invasive cervical carcinoma, uterine hypertonus (not occurring during labor), signs of fetal distress, acute fetal hypoxia, severe second-half preeclampsia (preeclampsia, eclampsia), presentation or prolapse of the umbilical cord; severe cardiovascular diseases, chronic renal failure. Administration of oxytocin within 6 hours after intravaginal administration of prostaglandins is contraindicated. Long-term administration is contraindicated in the uterus inert to oxytocin administration.

With caution in women over 35 years of age; with second-half preeclampsia not classified as contraindications; administration of oxytocin to patients receiving hypotensive drugs and drugs causing QT interval prolongation; against the background of using inhalation anesthetics (cyclopropane, halothane, sevoflurane, desflurane), sympathomimetics and vasoconstrictors; simultaneous use with methylergometrine preparations.

Use in Pregnancy and Lactation

Oxytocin is used during pregnancy according to indications with mandatory consideration of contraindications. In the first trimester of pregnancy, Oxytocin is used only for spontaneous or medical abortion.

During breastfeeding, it should be used only in cases where the expected benefit to the mother outweighs the potential risk to the infant.

Use in Renal Impairment

Contraindicated for use in chronic renal failure.

Special Precautions

Administration of oxytocin should be carried out only in a specialized medical inpatient setting under strict medical supervision.

Oxytocin should not be used to stimulate labor until the fetal head is engaged in the pelvic inlet.

To avoid complications during the use of oxytocin for labor induction, it is necessary to constantly monitor the frequency of uterine contractions, the strength of uterine contractions, the cardiac activity of the mother and fetus, and the mother’s blood pressure.

If signs of uterine hyperactivity appear, the administration of oxytocin should be stopped immediately, as a result of which the uterine contractions caused by oxytocin usually soon stop. With adequate use, Oxytocin causes uterine contractions similar to spontaneous labor. Excessive stimulation of the uterus with improper use of oxytocin is dangerous for both the mother and the fetus. Even with adequate use of oxytocin and appropriate monitoring, hypertonic uterine contractions occur with increased uterine sensitivity to oxytocin.

The risk of developing afibrinogenemia and increased blood loss should be considered.

There are known cases of maternal death due to hypersensitivity reactions, subarachnoid hemorrhage, uterine rupture, and fetal death for various reasons associated with the parenteral administration of oxytocin for labor induction and stimulation in the first and second stages of labor.

As a result of the antidiuretic effect of oxytocin, hyperhydration may develop, especially with the use of constant oxytocin infusion and oral fluid intake.

Drug Interactions

Oxytocin enhances the pressor effect of sympathomimetic agents.

With simultaneous use of oxytocin with MAO inhibitors, the risk of increased blood pressure increases.

With cyclopropane, halothane anesthesia, the effect of oxytocin on the cardiovascular system may change with the unforeseen development of arterial hypotension, sinus bradycardia, and AV conduction disturbance in the mother during anesthesia.

Storage Conditions

Store at 2°C (36°F) to 8°C (46°F). Keep in original packaging, protected from light. Keep out of reach of children.

Dispensing Status

Rx Only

Important Safety Information

This information is for educational purposes only and does not replace professional medical advice. Always consult your doctor before use. Dosage and side effects may vary. Use only as prescribed.