Two years after being labeled approvable by the FDA, Zelapar, a version of the Parkinson's disease drug selegiline designed using a fast-dissolving oral delivery system, finally was given the go-ahead to launch.

It's good news for Valeant Pharmaceuticals International Inc., which picked up Zelapar through its February 2004 acquisition of Amarin Pharmaceuticals Inc., the U.S. subsidiary of London-based Amarin Corp. The drug, originally developed by Elan Corp. plc, of Dublin, Ireland, and a division of Dublin, Ohio-based Cardinal Health Inc., received its first approvable letter in 2003.

After completing two additional safety studies, Valeant submitted a complete response in January 2005. That was followed by a second approvable letter in October requesting minor clarifications.

Valeant's acquisition of Amarin included an up-front cash payment of $38 million, plus an additional $8 million in regulatory milestones related to Zelapar, including $5 million to be paid upon FDA approval. The deal also included a $10 million payment from Valeant to Elan and Cardinal Health once drug sales reach specified thresholds. (See BioWorld Today, Feb. 13, 2004.)

Zelapar's launch is expected "sometime in the third quarter," said Jeff Misakian, vice president of investor relations for Costa Mesa, Calif.-based Valeant.

The drug, approved as an adjunct to levodopa or carbidopa therapy, is expected to capture a significant portion of the overall Parkinson's market, which is estimated at about $700 million in the U.S. Valeant has not disclosed pricing for Zelapar. Its active ingredient, selegiline, is a selective, irreversible monoamine oxidase-B inhibitor that has been approved in conventional tablet form to treat patients in the earlier stages of Parkinson's. Selegiline is designed to prevent the breakdown of dopamine, the neurotransmitter in the brain controlling movement.

"What's new about [Zelapar] is its delivery system," Misakian told BioWorld Today. Zelapar is delivered using the Zydis delivery system, a technology developed by Cardinal Health, which allows the orally disintegrating tablet to "dissolve within seconds in the mouth and delivers more of the active drug in a lower dose."

With conventional tablets, "you lose a lot of the drug in the gut," he added. "Zelapar bypasses the gut and the first-pass hepatic metabolism," and instead, enters systemic circulation via the oral mucosa.

Patients receiving Zelapar at doses of 1.25 mg and 2.2 mg over the course of 12-weeks demonstrated a significant reduction in "off" time - the period during which patients are not receiving symptomatic benefit despite treatment - compared to placebo. At the end of 12 weeks, Zelapar-treated patients had an average of 2.2 hours per day, less off time, compared to baseline vs. 0.6 hours per day in the placebo group.

"That's pretty significant for Parkinson's patients," Misakian said. "So what this does is provide patients with an alternative treatment."

Zelapar is Valeant's second marketed product for Parkinson's disease. The company acquired Tasmar (tolcapone) from F. Hoffmann-La Roche Ltd., of Basel, Switzerland, and re-launched the drug in the U.S. in 2004. Tasmar, a catechol-O-methyl transferase inhibitor, is indicated as an adjunct therapy in combination with levodopa and carbidopa for patients with severe Parkinson's disease who do not respond to those treatments alone or cannot take other adjunctive therapies.

Tasmar recorded sales of $1.2 million for the first quarter of 2006. In February, the FDA approved labeling changes to allow for less-restrictive patient monitoring.

Valeant's shares (NYSE:VRX) gained 12 cents Thursday to close at $17.56.