Shares in UCB are on the rise this morning after US regulators gave the green light to the Belgian company’s Cimzia for the treatment of rheumatoid arthritis.

The US Food and Drug Administration has approved Cimzia (certolizumab pegol), the only PEGylated anti-tumor necrosis factor agent, for the treatment of adults with moderately to severely active rheumatoid arthritis. The injectable is already available for Crohn's disease, but this latest approval should be a far more lucrative one.

The FDA’s approval is based on four studies involving more than 2,300 patients which demonstrated that Cimzia, together with methotrexate, significantly reduced the signs and symptoms of RA after six months. Data also shows that the combo inhibited the progression of joint damage.

Cimzia will now battle for market share with the three anti-TNF blockbusters – Johnson & Johnson/Schering-Plough's Remicade (infliximab), Abbott Laboratories' Humira (adalimumab) and Amgen and Wyeth's Enbrel (etanercept). It will also compete with J&J/S-P’s Simponi (golimumab), which was approved by the FDA last month.

UCB is hoping that it will be able to steal a march on the competition through what it calls its “exclusively designed prefilled syringe” to deliver Cimzia, which has been developed with the direct input of RA patients

The innovative design, which saw UCB team with the “celebrated consumer products company” OXO, takes into account “some of the challenges many RA patients face when self-administrating their medicine”, the company says. In particular, the syringe was designed for use by patients with different grip styles and strengths, and patients worked with the relevant design and engineering teams.

The approval is great news for UCB as it will help the Brussels-based firm plug the gap in sales resulting from the loss of patent protection on its biggest earners – the allergy drug Zyrtec (cetirizine) and the antiepileptic Keppra (levetiracetam). The drug is also undergoing a review by European regulators for the treatment of RA.

Investors are extremely pleased this morning and UCB shares were up 19.5% to 23.16 euros at 11.00 UK time.