Eisai and Pfizer have won approval in the USA to extend the labelling for their Alzheimer’s disease treatment Aricept to include patients with severe forms of the disease.

The approval makes Aricept (donepezil HCl) the only prescription drug on the US market that is registered for use in the full range of Alzheimer’s, from those with mild symptoms right through to patients in the later, severe stages of the disease.

This ability to provide continuity of treatment using one drug could give Aricept a lift over its rivals in the Alzheimer’s treatment sector, such as fellow cholinesterase inhibitors Novartis’ Exelon (rivastigmine) and Johnson & Johnson’s Razadyne (galantamine) – and also drugs reserved for use in severe cases, notably Forest Laboratories’ NMDA receptor antagonist Namenda (memantine).

The approval is based on the results of a six-month Swedish trial involving 248 nursing home patients with severe Alzheimer’s disease which were published in The Lancet in March. Patients treated with Aricept in the study had statistically significant benefit compared to those taking placebo in both cognition and function/activities of daily living scales.

An application for the indication of severe AD has also been submitted in Japan and in Europe.

Pfizer reported sales of $170 million for Aricept in the first half of the year – in line with the same period of 2005 – while Eisai said it made $444 million from the drug worldwide in the second quarter.