Some of the views expressed in the following notes on newly approved products should be regarded as tentative, as there may have been limited published data and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. As a result of fuller experience, initial comments may need to be modified. The Committee is prepared to do this. Before new drugs are prescribed, the Committee believes it is important that full information is obtained either from the manufacturer's approved product information, a drug information centre or some other appropriate source.
Duratocin (Ferring)
ampoules containing 100 microgram/mL
Approved indication: prevention of uterine atony after Caesarian section
Australian Medicines Handbook section 17.7.1
Oxytocin is a hormone released from the posterior pituitary. As it stimulates rhythmic contractions of uterine smooth muscle, synthetic preparations can be used to induce or augment labour. Oxytocin can also be used to prevent postpartum haemorrhage.
Carbetocin is a synthetic analogue of oxytocin, with a longer half-life (41 minutes after intravenous injection vs 1–5 minutes). It stimulates a prolonged uterine response lasting about an hour.
The approved indications reflect the largest published trial of carbetocin. This involved 694 women who were having elective Caesarian sections under regional anaesthesia. The women were randomised to receive, after delivery, a bolus dose of oxytocin followed by an infusion, or a bolus dose of carbetocin followed by an infusion of placebo. In the oxytocin group, 10% of the women needed additional treatment to maintain the uterine contraction in the 48 hours after delivery. Only 6.3% of the women given carbetocin needed additional treatment.1
The adverse effects of carbetocin resemble those of oxytocin. They include abdominal pain, nausea, flushing and headache. Nearly half the patients may complain of itching.
While a single dose of carbetocin may be preferable to an infusion of oxytocin, after Caesarian section, it may not reduce blood loss more than oxytocin. In the main trial, the fall in postoperative haemoglobin was similar in both groups. Two women in each group had a postpartum haemorrhage.1
Carbetocin has not been studied after vaginal delivery or in women with a high risk of postpartum haemorrhage after Caesarian section. More research, including patient safety and economic evaluations, will therefore be needed before it can replace oxytocin as the first drug to use in the active management of the third stage of labour.
manufacturer provided all requested data
Reference
1. Dansereau J, Joshi AK, Helewa ME, Doran TA, Lange IR, Luther ER, et al. Double-blind comparison of carbetocin versus oxytocin in prevention of uterine atony after cesarean section. Am J Obstet Gynecol 1999;180:670-6.
The T-score ( 
) is explained in 'Two-way
transparency', Aust Prescr 2005;28:103.
