Endo International is looking to acquire Auxilium Pharmaceuticals in a deal worth $2.2 billion.

Its offer of $28.10 per share in cash and stock represents a premium of 31% to Auxilium's closing price yesterday (September 16), though the latter’s shares shot up 37% to over $29.50 in after-hours trading.

The chief attraction of Auxilium is Xiaflex (collagenase clostridium histolyticum) which is approved in the USA for Dupuytren's contracture, which affects the connective tissue beneath the skin in the palm of the hand, and Peyronie's disease, which causes a bothersome curvature of the penis during sex. It has a total of 12 Food and Drug Administration-approved products in urology, orthopaedic and other areas, including Stendra (avanafil), an oral erectile dysfunction drug, which are “natural complements to the men's health and pain products in Endo's pharmaceuticals portfolio”, the latter firm claims.

Rajiv De Silva, Endo chief executive, said the proposal would provide Auxilium shareholders “a substantial premium and immediate cash value for their investment…as well as the opportunity to participate in the upside potential of a leading global specialty healthcare company”. He added that Endo “stands ready to engage immediately with Auxilium, complete our confirmatory diligence, negotiate a definitive agreement and complete this exciting transaction”.

Auxilium is saying nothing for the moment about the Endo bid but just a week ago announced it was reducing its headcount by 30% in a bid to reduce operating expenses by more than $75 million. It is also in the process of acquiring Canadian biotech QLT.