The MHRA and CHM publish the monthly newsletter Drug Safety Update, highlighting important information and advice to support the safer use of medicines. To subscribe to Drug Safety Update email alerts, please visit this link to register.
The MHRA has provided the following synopsis of key drug safety issues from the September to November 2016 issues of Drug Safety Update.
Levonorgestrel-containing emergency hormonal contraception: advice on interactions with hepatic enzyme inducers and contraceptive efficacy
Medicines or herbal remedies that induce cytochrome P450 3A4 (CYP3A4) enzymes reduce blood levels of levonorgestrel, which may affect emergency contraceptive efficacy.
Women seeking emergency contraception who have used CYP3A4 enzyme inducers within the last 4 weeks should preferably use a non-hormonal emergency contraceptive; for example, a copper intrauterine device. If this is not an option, the woman should take double the usual dose of levonorgestrel, increasing from 1.5 milligrams to 3 milligrams (2 packs)1.
Posaconazole (Noxafil): tablets and oral suspension are not directly interchangeable
Posaconazole tablets and oral suspension are not directly interchangeable: switching from oral suspension to tablets can lead to overdosing and serious adverse drug reactions, whereas switching from tablets to oral suspension can lead to underdosing and lack of efficacy. Prescribers should specify the dosage form for posaconazole on every prescription. Pharmacists should ensure that the correct oral form is dispensed2.
Idelalisib (Zydelig▼): updated indications and advice on minimising the risk of infection
The MHRA has updated its advice for healthcare professionals, following a review of the safety of idelalisib, including the risk of infection3. Please see Drug Safety Update for details.
Etoricoxib (Arcoxia): revised dose recommendation for rheumatoid arthritis and ankylosing spondylitis
The MHRA has updated its prescribing information to introduce a lower recommended dose of etoricoxib of 60 mg daily for people with rheumatoid arthritis or ankylosing spondylitis. In people with insufficient relief from symptoms, an increased dose of 90 mg once daily may improve efficacy4.
Brimonidine gel (Mirvaso): risk of exacerbation of rosacea symptoms
Some people may have exacerbation of rosacea symptoms when treated with brimonidine gel. Treatment should be started with a small amount of gel (less than the maximum dose of 1 gram gel total weight, about 5 pea-sized amounts) for at least 1 week and the dose should be increased gradually, based on tolerability and response to treatment5.
Recent safety letters to healthcare professionals
Of the safety letters published recently, the MHRA would particularly like to draw healthcare professionals’ attention to the following 2:
- Retigabine (Trobalt) will be withdrawn from the market in June 2017; healthcare providers should begin seeking alternative treatment for affected people, and treatment should be withdrawn with a gradual dose reduction over at least 3 weeks. Retigabine treatment should not be started in anyone new6
- Levothyroxine has been reintroduced to the market by Teva and new tablet strengths are now available7.
- Drug Safety Update Vol 10 issue 2 September 2016: 1
- Drug Safety Update Vol 10 Issue 2 September 2016: 2
- Drug Safety Update Vol 10 issue 2 September 2016: 3
- Drug Safety Update Vol 10 issue 3 October 2016: 1
- Drug Safety Update Vol 10 issue 4 November 2016: 1
- Drug Safety Update Vol 10 issue 3 October 2016: 2
- Drug Safety Update Vol 10 issue 4 November 2016: 3