Spanish pharmaceutical firm Almirall has come to an agreement to buy U.S. dermatological company Aqua Pharmaceuticals for $327.6 million.

The purchase - according to what the company told the National Securities Market Commission, or CNMV, the Spanish government agency responsible for the financial regulation of the securities markets in Spain - represents a substantial geographic and business diversification and gives Almirall access to the world's largest dermatological market, which should provide the firm with an estimated 30 percent more income in 2014.

The initial payment for the transaction, which will be financed through debt, will amount to $305 million, to which must be added an additional payment of $22.6 million linked to the amortization of certain long-term tax assets.

If the firm reaches specific regulatory and commercial objectives, there could be additional payments of up to $75 million in 2014-2015.

The acquisition will be completed by Dec. 31, 2013, once the appropriate authorities give it the OK.

Almirall says that dermatology is a basic growth platform for the firm and continues to be a key engine for future growth.

Aqua Pharmaceuticals is one of the 10 largest U.S. companies in prescription dermatology and its current catalog of products includes treatments for skin conditions such as acne, atopic dermatitis and actinic keratosis, among others. The firm has 122 employees and in 2013 is expected to earn some $127 million.

The Spanish company stressed that it is not assuming any of Aqua Pharmaceuticals' pending debt - which is owed largely to RoundTable Healthcare, a U.S. risk capital firm - as part of the transaction. EFE