MAIN CHANGES IN THE 2019 UPDATE   Prescrire updates its review of drugs to avoid every year. As a result, some drugs are added to the list, while others are removed pending the outcome of our reassessment of their harm-benefit balance, or because the pharmaceutical company or a health authority decided to withdraw them from the market, or because new data show that their harm-benefit balance is no longer clearly unfavourable in all their indications. (See  > A reliable, rigorous and independent methodology)

Market withdrawal. One drug included in Prescrire's 2018 review of drugs to avoid is no longer marketed: telithromycin, a macrolide antibiotic, which was withdrawn worldwide in early 2018 by the company (Prescrire Int n° 196).

Harm-benefit balance under review. Oral selexipag, a prostacyclin receptor agonist authorised for pulmonary arterial hypertension, has been dropped from this year's list while Prescrire reassesses its harm-benefit balance in light of new published data.

Removed from the list in light of new data: olaparib, omalizumab, panitumumab and varenicline. Several drugs that previously featured in Prescrire's list of drugs to avoid have been removed from the list, because new data showed that their harm-benefit balance is not clearly unfavourable, or that they are useful options in rare situations.

• In patients with relapsed platinum-sensitive ovarian cancer with a BRCA gene mutation, olaparib prolongs the median time before exposure to another cytotoxic drug by a little over a year, but without prolonging survival. This benefit came at the cost of immediate exposure to olaparib's adverse effects, which are common, and serious in about 10% of patients (Prescrire Int n° 200).
   
• Omalizumab, an anti-IgE monoclonal antibody, is an option for patients with severe asthma in the rare cases in which the symptoms remain unbearable despite high doses of corticosteroids, or when the adverse effects of corticosteroid therapy are intolerable. It has serious adverse effects, including anaphylactic reactions, infections, arterial, cardiac and cerebral thromboembolic events, and severe thrombocytopenia (Prescrire Int n° 199).
   
• Mepolizumab, an anti-interleukin-5 monoclonal antibody, was also removed from the list of drugs to avoid despite an inadequate assessment and an uncertain role, because it has some efficacy in this setting and similar adverse effects to omalizumab.
   
• In patients with metastatic colorectal cancer without a RAS mutation, the anti-EGFR monoclonal antibody panitumumab is an option. But it exposes about 25% of patients to serious and sometimes fatal adverse effects (Prescrire Int n° 198).
   
• According to our review of the data available in 2018 on varenicline, its harm-benefit balance is not clearly unfavourable, although it is less favourable than that of nicotine replacement therapy. The adverse effects of varenicline are mainly neuropsychiatric disorders in patients with a history of mental illness, as well as serious cardiac disorders. In light of these data, it would appear preferable to make repeated smoking cessation attempts with nicotine-containing products rather than resorting to varenicline (Prescrire Int n° 196).

Additions to this year's review of drugs to avoid: ulipristal 5 mg, mephenesin, oxomemazine.

• Ulipristal 5 mg is best avoided by patients with uterine fibroids in light of the serious hepatic adverse effects reported in this clinical situation since its market introduction (Prescrire Int n° 198; Rev Prescrire n° 418).
   
• Four other drugs were added because their adverse effects are disproportionate in all their authorised indications:
  • mephenesin, a "muscle relaxant";
  • oxomemazine, a sedating antihistamine with antimuscarinic activity and neuroleptic properties, authorised as a cough suppressant;
  • topical glyceryl trinitrate, a nitrate used for anal fissure;
  • obeticholic acid, a bile acid derivative authorised for primary biliary cholangitis. 
• Cimetidine should be avoided because it has far more drug interactions than other H2-receptor antagonists. These drug interactions can cause serious adverse effects, yet cimetidine has no advantages over other H2-receptor antagonists.