Declining sales of its now off-patent drug Adderall XR continue to weigh on Shire, the speciality pharmaceutical group, although strong growth in sales of new drugs are poised to compensate for the lost revenue.

Attention-deficit drug Adderall has faced generic competition since April and as a result Shire’s sales of the drug fell 74 per cent, or $198m (£120m), to $71m in the third quarter.