OBJECTIVES : Humira (adalimumab) was the bestselling pharmaceutical product with global sales of 18.4 billion USD in 2017. Humira is a biological drug that cannot be produced chemically so biosimilars exists instead of classical generic drugs. In Denmark, adalimumab is provided free of charge to patients in out-patient clinics and bought through national tenders. There is no automated substitution to biosimilars, but the Danish Medicines Council makes treatment recommendations. Reduction of drug costs is possible by using biosimilars and carrying out non-medical shifts to biosimilars (i.e. switching a patient well treated on a bio-originator to its biosimilar). Adalimumab biosimilars became available in Denmark following the Humira patent expiration on 16 October 2018. The tendering resulted in 3 biosimilars; Amgevita for pediatric patients, and Hyrimoz (Western Denmark) and Imraldi (Eastern Denmark) for adult patients. The objective of this study was to describe the shift to adalimumab biosimilars in dermatology, gastroenterology and rheumatology and calculate the associated cost saving.

METHODS : Monthly data on drug sales to Danish Hospital departments were used to assess the biosimilar uptake proportion and subsequent changes in the cost.

RESULTS : The adalimumab biosimilars became available in November 2018. 104,592 Defined Daily Doses (DDDs) of adalimumab (bio-originator and biosimilars) were used in November 2018. The proportion of biosimilars was 63.2% in November 2018 and increased to 94.2% in December 2018. The total drug cost dropped from €4.4 million in September 2018 to €1.7 million in November and to €0.9 million in December 2018 (80.2% reduction).

The corresponding proportion of biosimilars in December 2018 was for pediatrics 80.5%, for Western Denmark 93.8%, and Eastern Denmark 97.2%. There were no differences between clinical specialties.

CONCLUSIONS : A rapid shift to adalimumab biosimilars from Humira was seen within 2 months from market entry in Denmark. This led to cost reductions to one-fifth despite the lack of automated substitution.