atosiban

Action and Spectrum

Actions and spectrum:

atosiban is a synthetic nonapeptide analogue of oxytocin, which acts as an antagonist of oxytocin receptors. It has a specific action on the uterus and is used to prevent preterm labor. atosiban selectively blocks oxytocin receptors, resulting in inhibition of oxytocin-induced contractions of the uterus.

This effect is achieved by blocking the G-protein-coupled receptors that are found on the myometrial cells of the uterus. Atosiban also inhibits the release of prostaglandins, which are known to cause contractions in the uterus. The spectrum of atosiban is limited to the inhibition of preterm labor and is not effective for any other indications.

Drug Interaction

Adverse Reaction

Frequency undefined:

Nausea and vomiting

Dizziness

Hypotension

Hypersensitivity reactions

Headache

Flushing

Tachycardia

Abdominal pain

Diarrhea

Urticaria

Back pain

Dyspnea

Rash

Black Box Warning

Contraindication / Caution

Contraindication/Caution

Contraindication

• Hypersensitivity to atosiban or any component of the formulation.
• Known fetal distress.
• Pre-eclampsia with severe hypertension or HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count).
• Major obstetric haemorrhage or conditions with an increased risk of haemorrhage.
• Cervical dilation of more than 6 cm or cervical effacement of more than 80%. 

Caution

• Hypersensitivity: atosiban is contraindicated in individuals with a history of severe hypersensitivity reactions to atosiban or any of its components.
• Hepatic Impairment: The safety and efficacy are not established. Hence, caution is recommended when administering atosiban to such individuals.
• Cardiovascular disorders: atosiban should be used with caution in individuals with cardiovascular disorders, including cardiac disease, hypertension, and heart failure, as it can cause a transient decrease in blood pressure, heart rate, and myocardial contractility.
• Asthma: atosiban can cause bronchospasm in individuals with a history of asthma or other respiratory diseases. Hence, caution is recommended when administering atosiban to such individuals.
• Pregnancy and lactation: atosiban should be used during pregnancy only if clearly needed, and caution should be exercised when administering atosiban to nursing mothers.
• Renal impairment: The safety and efficacy are not established. Hence, caution is recommended when administering atosiban to such individuals

Comorbidities

• Fetal distress: atosiban may not be appropriate if there is fetal distress, as delivery may need to be expedited in such cases.
• Preeclampsia: atosiban may not be appropriate in cases of severe preeclampsia or eclampsia, as delivery may be the only option.
• Intrauterine infection: Infection of the uterus can be a contraindication to the use of atosiban.
• Bleeding disorders: atosiban may increase the risk of bleeding, and therefore, caution may be needed in patients with bleeding disorders.
• Maternal heart disease: atosiban can cause cardiovascular effects, and therefore, caution may be needed in women with pre-existing heart disease.

Pregnancy / Lactation

Pregnancy consideration: pregnancy Category B

Lactation: safety and efficacy are not established 

Pregnancy category:

• Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester.
• Category B: There is no evidence of risk to the fetus found in animal reproduction studies and there are not enough studies on pregnant women.
• Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for an effect in humans, care must be taken for potential risks in pregnant women
• Category D: There is adequate data available with sufficient evidence of human fetal risk from various platforms, but despite potential risks may be used only in emergency cases for potential benefits.
• Category X: Drugs listed in this category outweigh risks over benefits These category drugs should be prohibited for pregnant women.
• Category N: There is no data available for the drug under this category.

Pharmacology

Pharmacology

atosiban is a competitive antagonist of the hormone oxytocin. It exerts its action by binding to the oxytocin receptors, which are present on the smooth muscle cells of the uterus. By doing so, it inhibits the uterine contractions that occur during labor. atosiban has a short half-life and is rapidly cleared from the body. It is not metabolized by the liver and is eliminated by the kidneys.

Pharmacodynamics

atosiban is a synthetic nonapeptide analogue of oxytocin, which is an endogenous hormone. Atosiban acts as a competitive antagonist of oxytocin receptors, which are found on the smooth muscles of the uterus. By blocking the binding of oxytocin to its receptors, atosiban can inhibit the contractions of the uterus and delay the onset of preterm labor.

In addition to its antagonism of oxytocin receptors, atosiban may also have other effects on the uterus, including a direct relaxing effect on the uterine smooth muscles and an inhibition of the release of inflammatory mediators that can contribute to the onset of preterm labor. atosiban has a short half-life and is rapidly metabolized in the body, primarily by peptidases in the liver and kidneys. The drug is excreted primarily in the urine, with a small amount eliminated in the feces.

pharmacokinetics

atosiban is administered as an intravenous infusion. The pharmacokinetics of atosiban are best described by a two-compartment model, where the drug is initially distributed rapidly into the central compartment and then more slowly into the peripheral compartment. Atosiban has a short half-life of approximately 30 minutes and is primarily cleared by hepatic metabolism, with a small amount excreted unchanged in the urine. The elimination half-life is 2-3 hours. The pharmacokinetics of atosiban are not affected by age or gender, but hepatic and renal dysfunction may affect its clearance.

Adminstartion

Administration

atosiban is administered as an intravenous infusion. The recommended dose is an initial bolus injection of 6.75 mg over one minute, followed by a continuous infusion of 18 mg/hour for up to 72 hours. The infusion rate may be increased or decreased by 3 mg/hour increments to achieve the desired effect while monitoring the patient’s uterine contractions and fetal status.

Atosiban should only be administered by a healthcare professional experienced in the use of uterine relaxants and in the management of preterm labor.

Patient Information Leaflet

Patient information leaflet

Generic Name: atosiban 

Pronounced: (a-toh-si-ban)

Why do we use atosiban?

atosiban is primarily used to delay preterm labor in pregnant women around 24 – 33 weeks of gestation. It is used to prevent premature delivery of the baby and to allow time for the administration of glucocorticoids to enhance fetal lung maturation. Atosiban may also be used for cervical ripening and induction of labor in certain situations.