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TGA issues new warning of VTE risk with oral contraceptives containing dienogest, and updates contraception advice for tamoxifen

The Therapeutic Goods Administration has issued new advice regarding the risk of venous thromboembolism when using combined oral contraceptives containing dienogest.

Dienogest, a progestogen, is available in two combined oral contraceptives (COCs) in Australia. These are marketed by Bayer under the brand names Valette and Qlaira:

  • Valette (dienogest/ethinylestradiol) is indicated for oral contraception and treatment of mild-moderate acne in women wanting contraception
  • Qlaira (dienogest/estradiol valerate) is indicated for oral contraception and treatment of heavy or prolonged menstrual bleeding in women wanting contraception (with no organic pathology).

A review by the TGA in 2016 found that while the risk of venous thromboembolism (VTE)…. “is generally rare” and occurs in approximately 2 in 10,000 women, the risk is slightly increased in women using a COC containing ethinylestradiol and a progestogen.

At the time, the risk of developing VTE from a combined oral contraceptive containing dienogest was listed as ‘not yet known’.

Since 2016, a meta-analysis of four prospective cohort studies found the risk of VTE in women taking dienogest/ethinylestradiol was estimated to be 8–11/10,000 in a year compared to 5–7/10,000 for women taking levonorgestrel/ethinylestradiol.

The TGA is advising health professionals that, “in women who have been using a dienogest-containing contraceptive without a problem, there is no reason to stop taking it based on this updated information.

However, it is important that women are aware of the risk of VTE and its signs and symptoms such as pain or swelling in the legs, sudden unexplained breathlessness, rapid breathing or cough, and chest pain”.

“It is important to know the contraindications when prescribing oral contraceptives and consider a woman’s individual risk factors for thromboembolism, including smoking, obesity, increasing age, migraines and a family history of VTE”.

Meanwhile, the TGA has also issued a safety update that the “recommended duration of contraception after finishing tamoxifen treatment has been extended from two months to nine months”.

“This means women should continue their contraception and not become pregnant for at least nine months after tamoxifen therapy has ended,” the advice states.

The change is based on “US FDA guidance for genotoxic pharmaceuticals which recommends a minimum contraception period of six months plus five elimination half-lives after cessation of therapy,” the TGA said.

“Tamoxifen is contraindicated in pregnancy and the possibility of pregnancy should be excluded before treatment is started. Women of child-bearing potential should be advised to use barrier or other non-hormonal contraceptive methods if they are sexually active, both during treatment and for nine months after treatment has ended.

Women should be informed about the potential risks to the foetus, should they become pregnant while taking tamoxifen or within nine months of finishing treatment”.

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