Golimumab

Golimumab is a fully human monoclonal IgG1 anti-TNF antibody with a monthly subcutaneous or every 8 week intravenous schedule, used in rheumatoid arthritis, psoriatic arthritis, axial spondyloarthritis, ulcerative colitis and polyarticular juvenile idiopathic arthritis.

Class. Anti-tumour necrosis factor monoclonal antibody.

Mechanism. Binds soluble and transmembrane TNF alpha with high affinity, neutralising its activity.

Pharmacokinetics. Subcutaneous bioavailability about 53 percent, half-life about 2 weeks. Clearance is higher in heavy patients and with antibodies; methotrexate lowers clearance.

Rheumatoid arthritis (with methotrexate). 50 mg subcutaneously once monthly on the same date. In patients over 100 kg with inadequate response after 3 to 4 doses, 100 mg monthly may be used. Intravenous alternative: 2 mg/kg over 30 minutes at weeks 0 and 4, then every 8 weeks.

Psoriatic arthritis and ankylosing spondylitis or non-radiographic axial spondyloarthritis. 50 mg subcutaneously once monthly. Intravenous: 2 mg/kg at weeks 0 and 4, then every 8 weeks (psoriatic arthritis and ankylosing spondylitis).

Ulcerative colitis. Loading dose 200 mg at week 0 and 100 mg at week 2, then 50 mg every 4 weeks for patients under 80 kg and 100 mg every 4 weeks for those of 80 kg or more.

Polyarticular juvenile idiopathic arthritis (2 years and over). 80 mg/m2 intravenously at weeks 0 and 4, then every 8 weeks.

Maximum dose. 100 mg subcutaneously monthly in selected adults; 2 mg/kg intravenously for each infusion.

Contraindications. Active tuberculosis or serious infection, moderate to severe heart failure, and hypersensitivity.

Boxed-warning-level risks. Serious infections and malignancy, including hepatosplenic T cell lymphoma and lymphoma in young patients.

Adverse effects. Common: upper respiratory infections, injection site reactions, raised liver enzymes. Serious: tuberculosis and hepatitis B reactivation, demyelination, lupus-like reactions, cytopenias, heart failure, hypersensitivity, new or worsening psoriasis.

Major interactions. Anakinra and abatacept (avoid), other biologics, live vaccines (avoid).

Common prescribing errors. Missing methotrexate co-therapy in rheumatoid arthritis; incorrect weight bands in ulcerative colitis; skipping screening.

Special groups.

• Pregnancy: limited data; use only if benefit outweighs risk, with stop in the third trimester where possible and delay of live vaccines in the infant for 6 months or more.

• Breastfeeding: limited data; likely low transfer into milk.

• Children: body surface area dosing for juvenile arthritis.

• Older adults: higher infection risk.

• Kidney impairment: no adjustment.

• Liver impairment: no adjustment; monitor enzymes.

• Region: screen for tuberculosis and hepatitis B; ensure refrigerated storage.

Formulations. 50 mg and 100 mg prefilled pens or syringes; 50 mg intravenous vial diluted in 0.9 percent sodium chloride and infused over 30 minutes through a low protein binding filter. Store at 2 to 8 degrees Celsius.

Baseline. Tuberculosis screen, hepatitis B and C and HIV serology, full blood count, liver enzymes, chest radiograph, vaccination update.

Monitoring. Disease activity and infection symptoms at each visit; blood count and liver enzymes periodically.

Stop or hold thresholds. Serious infection, demyelination, lupus-like syndrome, severe hypersensitivity, or malignancy.

Referral and escalation. Specialist initiated. Refer for non-response at 12 to 16 weeks.