US-based Acorda Therapeutics has acquired privately held Civitas Therapeutics for $525 million to gain access to a Parkinson's disease drug in late-stage development.

With the buy, the biotechnology firm has secured global rights for Civitas' experimental drug, CVT-30, used as an additional therapy where symptoms such as inability to move and muscle stiffness reappear in some Parkinson's patients during treatment.

Acorda said it expects to conduct only one late-stage study for the drug.

Positive results from the trial and existing mid-stage study data are expected to hasten the regulatory approval process as CVT-301 is an inhaled dry powder formulation of the current standard oral treatment, levodopa, the company said.

Acorda assumes that the deal, expected to be completed in the fourth quarter of 2014, will become "very accretive" within the first year of the drug's launch, despite higher research costs. The company said the enrollment for a late-stage trial of the drug was expected to begin in early 2015 and it would file for regulatory approval by the end of 2016.