Secukinumab (trade name Cosentyx) is a type of drug known as an interleukin-17A (IL-17A) inhibitor. IL-17A is an immune molecule found in our blood. In people with psoriatic arthritis and ankylosing spondylitis, IL-17A is overproduced in the body causing inflammation and joint damage. This can result in stiff and painful joints and restricted movement as seen in people with psoriatic arthritis and ankylosing spondylitis. Secukinumab binds to IL-17A and blocks its effect, helping to improve these symptoms.