Pfizer has revised a research and development deal with drug delivery group pSivida, under which the latter could gain up to $168.8 million if the drug giant elects to take charge of an implant for glaucoma.

The new deal focuses solely on the development of a long-term, sustained-release implant - based on a bioerodible version of pSivida's Durasert technology system - that delivers Pfizer's latanoprost drug into the subconjunctival space of the eye in patients with ocular hypertension and glaucoma. 

Under the terms of the new deal, pSivida will get an initial fee of $2.3 million to develop the product through Phase II clinical trials, after which Pfizer has the option of snapping up an exclusive, worldwide license for its further development and commercialisation.

In this case, pSivida stands to receive a $20-million payment, double-digit sales-based royalties and additional development, regulatory and sales performance milestone payments of up to $146.5 million. 

However, should Pfizer decide not to exercise its option, then pSivida retains the rights to develop the product further either with a partner or on its own.

"If successfully developed and approved by regulatory authorities, using pSivida’s unique drug-delivery technology to deliver latanoprost could play a significant role in addressing compliance issues associated with a daily eye drop regimen for the treatment of glaucoma," said Yvonne Greenstreet, Senior Vice President and Head of the Medicines Development Group for Pfizer’s Specialty Care Business Unit, explaining the firm's interest in the deal.