Atosiban: Effects, Uses & Risks

Atosiban belongs to the group of tocolytics. As an oxytocin antagonist, it inhibits labor and is prescribed to avert preterm birth. The prescription drug is given as an injection and as an intravenous infusion.

What is atosiban?

Atosiban belongs to the group of tocolytics. As an oxytocin antagonist, it inhibits labor and is prescribed to avert preterm birth. The labor inhibitor atosiban is used in obstetric medicine and is intended to help avert a threatened premature birth during pregnancy. It is an ocytoxin antagonist from the group of tocolytics, which inhibits the effect of the two hormones oxytocin and vasopressin. The colorless, clear liquid is administered as a solution for injection and intravenous infusion. One vial of atosiban contains 5 ml of solution. Clearly, certain conditions must be met for atosiban to be administered. The prescription drug should be used only under the supervision of healthcare professionals.

Pharmacological action

Atosiban is a synthetic structural analog of the neuropeptide oxytocin present in the organism. As a competitive oxytocin antagonist, the drug acts at oxytocin receptors in the myometrium. It also binds to the vasopressin V1a receptor, inhibiting the action of vasopressin. Here, inhibition of Ca2+ ion release from intracellular stores in the sarcoplasmic reticulum occurs. Blocking the influx of Ca2+ ions into the myometrial cell inhibits the intracellular increase in Ca2+ required for uterine contraction. The magnitude of inhibition of uterine contractions depends on the dose of atosiban administered. Consequently, after the atosiban binds as described and its labor inhibitory effect, the contraction frequency and the tone of the uterine muscles decrease, and the uterus is immobilized. The recommended dose of atosiban can achieve up to twelve hours of uterine immobilization.

Medical use and application

Approximately two-thirds of all preterm births are caused by preterm labor, premature rupture of the membranes, or cervical insufficiency. Atosiban is used to treat preterm labor. Certain criteria must be present for the administration of atosiban, namely:

Regular contractions of the uterus lasting at least 30 seconds and with a frequency of more than four contractions within 30 minutes; opened cervix to a width of one to three centimeters (zero to three centimeters in primiparous women); cervical engorgement of more than 50 percent

Within the 24th to 33rd completed week of pregnancy; pregnant women over 18 years of age; fetus with regular heart rate. Atosiban is available by prescription and is administered in the hospital by a physician, midwife, or other healthcare professional. The doctor determines the dose. The drug is given intravenously in three consecutive steps:

The first injection is given slowly into the vein over a period of more than one minute. The recommended dose is 6.75 mg in 0.9 ml. Subsequently, the drug runs as a continuous infusion via a drip for over three hours. The recommended hourly dose is 18 mg. A reduced dose of atosiban of recommended 6 mg hourly follows for a maximum of 45 hours or until uterine contractions subside. There should be no more than three treatment repetitions per pregnancy. Atosiban is contraindicated in certain diseases or conditions, as seen in this review:

Allergy to drug ingredients; outside the 24th to 33rd week of pregnancy; rupture of the amniotic sac; irregular fetal heart rate; vaginal bleeding; eclampsia or severe preeclampsia; uterine infection; dislodged placenta or placenta covering the birth canal; deceased fetus; risky continuation of pregnancy.

Risks and side effects

Several side effects may occur with the use of atosiban. Occasional disturbances of well-being such as dizziness, nausea, vomiting, headache, and flushing have been observed. In addition, an increased heart rate, lowered blood pressure, increased blood sugar levels and reactions at the injection site could occur. Occasionally, rash, itching, fever, or insomnia occurred. Atosiban should be used only after a detailed medical consultation.