Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, 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. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.

Nomegestrol/oestradiol

Zoely (Merck Sharp and Dohme)
24 white active tablets and 4 yellow placebo tablets
Approved indication: contraception
Australian Medicines Handbook section 7.1.1

This new oral contraceptive contains the progestogen nomegestrol (2.5 mg) combined with the endogenous oestrogen 17β-oestradiol (1.5 mg). Nomegestrol is similar to endogenous progesterone and has a strong affinity for the human progesterone receptor. It also has strong anti-gonadotropic activity and moderate antiandrogenic activity.

The contraceptive efficacy of this new combination has been compared to drospirenone 3 mg/ethinyloestradiol 30 microgram (21 active and 7 placebo tablets) for 13 menstrual cycles in women aged 18–50 years.1 In this open-label trial, there were 4 pregnancies in the 1587 women who took the nomegestrol combination pill and 3 pregnancies in the 534 women who took the comparator pill (estimated Pearl Index in women aged ≤35 years = 0.38 vs 0.81). Most pregnancies were thought to be related to missed pills or conditions that affect contraceptive efficacy, such as diarrhoea or vomiting. However the reason for contraceptive failure was not identified for one pregnancy in the nomegestrol/oestradiol group. There were no pregnancies in women aged 36 and over.

The incidence of breakthrough bleeding or spotting in the trial was slightly higher with the nomegestrol combination pill than with the comparator during most cycles (14–20% vs 11–17%). However, this decreased over time in both groups. Periods were shorter and lighter with nomegestrol/oestradiol and missed periods were more common. This may have been because there were only four placebo pills with nomegestrol/oestradiol compared to seven with the comparator. One-third of women had acne at baseline. By cycle 13, this had decreased to 24% in the nomegestrol/oestradiol group and 16% in the comparator group.1

The contraindications and precautions for nomegestrol/ oestradiol are similar to other combined pills, as are the adverse effects. Acne (15.3% vs 7.1%), irregular withdrawal bleeding (11.7% vs 0.4%), weight gain (7.9% vs 6.2%) and headache (6.6% vs 6.2%) were more common with nomegestrol/oestradiol than with drospirenone/ethinyloestradiol. These events led to discontinuation in some women. There were three serious adverse events possibly related to treatment. These were menorrhagia in the nomegestrol/oestradiol group, and deep vein thrombosis and systemic lupus erythematosus in the comparator group.1

The combination of nomegestrol and oestradiol proved to be an effective contraceptive compared with drospirenone/ ethinyloestradiol. It is unclear if it will have any advantages over currently approved contraceptive pills, however periods may be shorter and lighter.

Read about The Transparency Score manufacturer provided additional useful information

The Transparency Score () is explained in New drugs: transparency, Vol 37 No 1, Aust Prescr 2014;37:27.

Note on references

At the time the comment was prepared, information about this drug was available on the website of the Therapeutic Goods Administration (www.tga.gov.au/industry/pm-auspar.htm).