Carbetocin is a drug used to control postpartum hemorrhage, bleeding after giving birth. It is an analogue of oxytocin, and its action is similar to that of oxytocin; it causes contraction of the uterus. Carbetocin binds to oxytocin receptors present on the smooth musculature of the uterus, resulting in rhythmic contractions of the uterus, increased frequency of existing contractions, and increased uterine tone. The oxytocin receptor content of the uterus is very low in the non-pregnant state, and increases during pregnancy, reaching a peak at the time of delivery.

Carbetocin is indicated for the prevention of uterine atony and postpartum haemorrhage (excessive bleeding) following delivery of the infant by elective caesarean section under epidural or spinal anaesthesia.

A single intravenous dose of 100 mcg of carbetocin injection is administered by bolus injection, slowly over 1 minute, only when infant delivery has been completed by caesarean section under epidural or spinal anaesthesia. carbetocin is to be used as a single dose only.

Because of its long duration of action relative to oxytocin, uterine contractions produced by carbetocin cannot be stopped by simply discontinuing the medication. Therefore, carbetocin should not be administered prior to delivery of the infant for any reason, including elective or medical induction of labour. Inappropriate use of carbetocin during pregnancy could theoretically mimic the symptoms of oxytocin overdosage, including hyperstimulation of the uterus with strong (hypertonic) or prolonged (tetanic) contractions, tumultuous labour, uterine rupture, cervical and vaginal lacerations, postpartum haemorrhage, utero-placental hypoperfusion and variable deceleration of foetal heart, foetal hypoxia, hypercapnia, or death. Carbetocin should not be used in patients with a history of hypersensitivity to oxytocin or carbetocin. Carbetocin should not be used in patients with cardio vascular disease, especially coronary artery disease, valvular heart disease, cardiomyopathy and heart failure. Carbetocin is not intended for use in children. 

10-40% of patients experienced nausea, vomiting, abdominal pain, itching skin, increased body temperature, trembling and weakness. Infrequent adverse events (1-5% of patients) included back pain, dizziness, metallic taste, anaemia, sweating, chest pain, dyspnoea, chills, tachycardia and anxiety.

Overdose Effects

Overdosage of carbetocin can be expected to produce enhanced pharmacological effects associated with uterine hyperactivity and pain. Treatment consists of symptomatic and supportive management.

• In patients who may not have an adequate uterine contraction after a single injection of carbetocin, more aggressive treatment with additional doses of oxytocin or ergometrine is warranted.
• As carbetocin is closely related in structure to oxytocin, hyponatraemia may occur.
• Carbetocin should be used cautiously in the presence of epilepsy, migraine, asthma or any state in which a rapid addition to extracellular water may produce hazard for an already overburdened system.
• Patients with eclampsia and pre-eclampsia should be monitored for changes in blood pressure.
• Carbetocin is not recommended for use in elderly patients.

Pregnancy & Lactation

Use of carbetocin injection is contraindicated during pregnancy. Small amounts of carbetocin has been shown to cross over from plasma into the breast milk of nursing women. The small amount of carbetocin ingested by infant would not be expected to present a significant safety concern.