Adalimumab

Adalimumab belongs to the class of biological response modifiers called tumour necrosis factor (TNF) blockers. It is currently approved for the treatment of psoriasis, psoriatic arthritis, rheumatoid arthritis and Crohn disease. In New Zealand, in August 2009, PHARMAC approved funding for severe treatment-resistant psoriasis on Special Authority application.

Adalimumab has the trade name Humira®

How does it work?

Adalimumab is a recombinant monoclonal antibody containing only human peptides. It works by directly binding to TNF molecules in the blood and diseased tissue. TNF bound to adalimumab is prevented from causing the inflammation that results in psoriasis plaques.

How is it given?

Adalimumab is administered by subcutaneous injection once every two weeks. It is available as a pre-prepared syringe or pen. After initial counselling and training, patients can usually self-inject into the thigh or abdomen. A different site should be used at each injection to reduce soreness and prevent the skin from becoming tender, red, bruised or hard.

The recommended dose for treating psoriasis is 80mg then 40 mg a week later, followed by 40mg every fortnight as a single dose.

Other medications including methotrexate and acitretin can usually be continued during treatment with adalimumab.

Pretreatment tests

Dermatologists are likely to request routine blood count, liver and renal function, fasting lipids and antinuclear antibody before starting adalimumab. In females, a pregnancy test may be appropriate.

Patients should be tested for tuberculosis (TB) and active or latent viral hepatitis. If present, these infections should be treated before starting adalimumab.

Precautions

Because adalimumab works by selectively targeting TNF, theoretically it should not have much effect on the rest of the body's immune system. However, caution must be taken when considering its use in patients prone to infections or in those with chronic or recurrent infections. It is wise to avoid concurrent treatment with ciclosporin as the combination increases the risk of infection.

As they may induce illness in immunodeficient individuals, live vaccines should not be used during treatment with adalimumab. Currently available live attenuated viral vaccines include measles, mumps, rubella, varicella, yellow fever, influenza (intranasal) and oral polio vaccine. Live attenuated bacterial vaccines include BCG and oral typhoid vaccine.

Adalimumab should also be used with caution in the following situations:

• Congestive heart failure: it should not be used by patients with moderate or severe heart failure
• Pre-existing or recent-onset CNS demyelinating disorders (e.g., multiple sclerosis)
• Patients with skin cancer or at high risk of skin cancer

Patients on anakinra, a drug used in rheumatoid arthritis, should not be prescribed adalimumab.

The safety of adalimumab during pregnancy and breastfeeding is unknown. It is therefore not recommended. Where possible, the drug should be discontinued several months before conception.

Adverse effects

Adalimumab appears to be well tolerated. Mild to moderate injection site reactions (redness, swelling, itching, pain) appear to be the most common side effect, occurring in 20% of patients.

Severe cutaneous reactions have rarely been reported, including worsening psoriasis, vasculitis, anaphylaxis, Stevens Johnson syndrome and toxic epidermal necrolysis.

A full list of reported adverse effects is described in the manufacturer's datasheet for Humira.