AstraZeneca (AZN.L) took a major step to build up its respiratory medicine business on Wednesday by striking a deal worth up to $2.1 billion for the rights to Spanish group Almirall’s (ALM.MC) lung drugs. The British drugmaker, which resisted a $118 billion takeover attempt by Pfizer (PFE.N) in May, said it would pay an initial $875 million and up to $1.22 billion more if the drugs meet development and sales targets. The tie-up boosts a key therapeutic area for AstraZeneca, whose Chief Executive Pascal Soriot is determined to show his company has a strong independent future.