Intended for healthcare professionals


Prescribing biosimilars

BMJ 2018; 362 doi: (Published 24 July 2018) Cite this as: BMJ 2018;362:k3141
  1. Jeffrey K Aronson, clinical pharmacologist1 2,
  2. Ben Goldacre, senior clinical research fellow 1,
  3. Robin E Ferner, honorary professor of clinical pharmacology2 3
  1. 1Centre for Evidence Based Medicine, Nuffield Department of Primary Care Health Sciences, Oxford, UK
  2. 2West Midlands Centre for Adverse Drug Reactions, City Hospital, Birmingham, UK
  3. 3Institute of Clinical Sciences, University of Birmingham, UK
  1. Correspondence to: J K Aronson jeffrey.aronson{at}

Slow adoption is costly

Generic formulations of small molecules are usually as effective as originators, have similar harms, and are cheaper to prescribe. The same should be true of biosimilars, which are generic equivalents of originator biological medicines (biologics).1

Two years ago2 we cited an article in the Financial Times,3 the author of which claimed that the UK had been slow to adopt biosimilars. Here we provide evidence that that is so, based on the limited publicly available information on NHS prescribing of biosimilars.

Biosimilars are biological medicines that are highly similar to other already approved drugs and are themselves approved according to the same standards of pharmaceutical quality, safety, and efficacy.4 They are not necessarily identical. Consider, for example, monoclonal antibodies. Although a biosimilar is likely to preserve the primary amino acid sequence of the originator, differences in glycosylation, deamination, oxidation, or three dimensional structure can occur. These can affect interactions with target molecules, which could lead to differences in benefits, harms, or both, between biosimilars and the corresponding originators. This may be the case, for example, with epoetins.56

Clinicians face two problems: choosing between an originator …

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