Merck & Co has signed a licensing deal with Santen Pharmaceutical Co giving it extensive rights to the Japanese group’s glaucoma drug tafluprost.

Under the terms of the agreement, Merck will pay an undisclosed fee as well as milestones and royalty payments based on future sales of tafluprost, a treatment for glaucoma and ocular hypertension, in exchange for exclusive rights to the drug in Western Europe (excluding Germany), North and South America, plus Africa. Santen will retain commercial rights to tafluprost in most countries in Eastern and Northern Europe plus Asia Pacific, including Japan.

Merck added that it will provide promotion support to Santen in Germany and Poland and if tafluprost is approved in the USA, Santen has an option to co-promote it there. The treatment is a prostaglandin analogue co-developed with Asahi Glass Co which has been approved in 11 countries. It is currently marketed as Taflotan in Germany, Denmark, Finland, Sweden and Norway and in Japan as Tapros.

Licensing tafluprost “further expands Merck's strong portfolio of topical treatments in ophthalmology," said senior executive Vlad Hogenhuis. Santen chief executive Akira Kurokawa added that through the agreement, “we are well positioned to significantly expand our access to additional markets”.

Tafluprost, preserved and preservative-free formulations, belongs to the prostaglandin class for the reduction of elevated intraocular pressure (IOP) in open-angle glaucoma and ocular hypertension.