Prolonged labour is associated with higher infection rates, greater use of antibiotics, increased maternal distress, more use of oxytocin, and more demands on staff and hospital resources. The time to delivery is important to women undergoing induction of labour, as are other outcomes such as the time to active labour, the rate of caesarean delivery and other adverse events (Shetty et al. 2005).
The misoprostol controlled-release vaginal insert offers advantages over the dinoprostone controlled-release vaginal insert in terms of substantially reduced time to vaginal or any delivery, and reduced need for oxytocin. However, the rate of uterine hyperstimulation was about 3 times higher with misoprostol vaginal inserts compared with dinoprostone vaginal inserts. The study authors note that use of the misoprostol vaginal insert therefore requires careful monitoring with timely recognition of tachysystole affecting the fetus and implementation of appropriate interventions, which may include caesarean delivery.
The misoprostol vaginal insert is expected to cost about £93. This is more than the dinoprostone vaginal gel, tablet and controlled-release inserts, which range in cost from £13.28 to £30.00. Although there is evidence that misoprostol reduces the median time to delivery compared with dinoprostone, it is not known whether this will confer economic benefits for obstetric units in terms of a reduction in the use of resources (for example, staffing) and the total cost of inducing labour, compared with current management. Health economic analyses of the misoprostol vaginal insert are expected to be published later in 2014.
Note that licensed indications for products vary. For example, the dinoprostone controlled-release vaginal insert is licensed for the induction of labour from 38 weeks' gestation, whereas the misoprostol vaginal insert is licensed from 36 weeks' gestation. Dinoprostone may be used in women with a favourable or unfavourable cervix; misoprostol is indicated only in women with an unfavourable cervix.
The 2008 NICE clinical guideline on induction of labour states that misoprostol (a prostaglandin E1) should only be offered as a method of induction of labour to women who have had an intrauterine fetal death or in the context of a clinical trial. If induction of labour is clinically justified, NICE states that vaginal prostaglandin E2 (dinoprostone gel, tablet or controlled-release insert) is the preferred method, unless there are specific clinical reasons for not using it (in particular the risk of uterine hyperstimulation). The results of EXPEDITE suggest that the risk of uterine hyperstimulation is higher with the misoprostol vaginal insert than with the dinoprostone vaginal insert.
It is difficult to provide estimated usage based on the available data.
According to NHS maternity statistics, 671,255 babies were delivered in NHS hospitals in England, 2012−2013. When the method of onset of labour was known, 64% of deliveries were spontaneous onset; 12.8% were medically induced; 12.7% were caesarean onset; 5.5% were medically and surgically induced; and 5.0% were surgically induced (Health and Social Care Information Centre 2013).
Currently, vaginal prostaglandin E2 is the preferred method of induction of labour unless there are specific clinical reasons for not using it (Induction of labour, NICE clinical guideline 70). The manufacturer of the misoprostol vaginal insert, Ferring Pharmaceuticals, estimates that two-thirds of the 23.3% of inductions (medical and/or surgical) are eligible for medical induction with vaginal prostaglandin E2, suggesting that the estimated patient population for medical induction of labour in England is about 100,000 women per year.
It is unclear how many of these women might receive the misoprostol vaginal insert rather than vaginal prostaglandin E2, particularly because the contraindications for the 2 drugs are similar.