QLT Inc announced results from phase-II clinical trials and a device study for the punctal plug delivery system (PPDS). These studies are part of a development programme that is being conducted by QLT's wholly-owned subsidiary, QLT Plug Delivery, Inc. QLT also announced its plans to expand the programme to evaluate a second drug for a new target indication.

Recent clinical data on the third-generation punctal plug designs demonstrate a retention rate of 81 per cent, based on available data from 185 eyes with 12 weeks of follow-up. Retention data are derived from a study of healthy volunteers testing several punctal plug prototype designs and from phase-II studies of the latanoprost punctal plug delivery system (L-PPDS) in patients with open-angle glaucoma (OAG) or ocular hypertension (OH), in which the third-generation prototypes were used. Punctal plug designs are continuing to be refined to maximize retention rates. The company will provide an update on retention rate results by year-end.

In parallel with the punctal plug device refinements, additional activities are focused on optimizing an insertion tool and development of a simple home-use detection system that would allow patients to confirm the presence of the punctal plugs.

"I am pleased with the improvements we have made in the punctal plug retention rate. We continue to work to maximize our retention rates and to explore what retention rate may be acceptable for a commercial product," said Bob Butchofsky, president and chief executive officer of QLT. "Although we did not see the dose response in our on-going L-PPDS studies, we now know that there are multiple factors that affect drug delivery from a punctal plug and our research efforts for the latanoprost PPDS will be focused on addressing those factors. Building on that knowledge, the next step for this platform technology will be a clinical trial with olopatadine, a compound which targets ocular tissue on the surface of the eye."

The L-PPDS is a novel, sustained and controlled release drug delivery system that utilizes the puncta to house a drug-eluting device.

Prostaglandins represent the largest segment of the US glaucoma market.

Olopatadine blocks the release of histamine from mast cells. Olopatadine is an active pharmaceutical ingredient that has been approved by the Food and Drug Administration for the treatment of the signs and symptoms of allergic conjunctivitis and is marketed under the trade names Pataday and Patanol in the US (Alcon).

QLT Inc is a pharmaceutical company dedicated to the development and commercialization of innovative therapies for the eye.