25th February 2025

Overview of biologics

Biological disease-modifying anti-rheumatic drugs are proteins which are derived from human genes and genetically engineered to inhibit specific parts of the immune system. There are four main inflammatory targets: tumour necrosis factor (TNF) inhibitors (most common), B cell inhibitors, interleukin inhibitors and T cell inhibitors.

They are more precise and rapid-acting than conventional DMARDs, which have a broad immune-suppressing effect. However, they are more expensive, so are only used after these (often 2 options) have failed to work and as per NICE criteria. They are often given with methotrexate to reduce loss of efficacy from anti-drug antibody formation.

As with conventional DMARDs, there are a variety of side effects. In general, these include: an increased risk of infection (active bacterial or severe viral infection is a contraindication), blood dyscrasia, gastrointestinal upset, fatigue, myalgia and headaches. There has been debate about risk of malignancy (current is a contraindication), but evidence only suggests an increased risk of skin cancers, particularly melanoma, with TNF inhibitors.