The Food and Drug Administration on Friday approved Allergan Inc.’s Latisse, a beauty treatment that increases the length, thickness and darkness of eyelashes by using the same ingredient found in another drug of the company used to treat glaucoma, Lumigan.

Patients treated with Lumigan found a side effect of the drug to be eyelash growth, prompting Allergan to study it for the new use. Latisse is applied to the base of the upper eyelash with a sterile, single-use-per-eye disposable applicator. Allergan said Latisse's retail price will be $120 for a 30-day supply bottle for both eyes.

Allergan states that “Latisse users can expect to experience longer, fuller, and darker eyelashes in as little as eight weeks, with full results in 16 weeks.”

Once treatment is stopped, eyelashes will gradually return to where they were prior to treatment.

The drug will be available by prescription starting in the first quarter of 2009. The company said it estimates global sales could top $500 million a year.

“We would agree based on the high level of enthusiasm for this product among our industry contacts. However, we think the initial uptake will be muted due to the economic situation,” Wachovia Capital Markets Inc. analyst Larry Biegelsen wrote in a research note. He also added that Latisse will be included in Allergan’s discount program to physicians who use large volumes of its products, including notably the antiwrinkle drug Botox.

Side effects of Latisse include darkening of the eyelid skin, which may be reversible and it may also cause increased pigmentation of the colored part of the eye, which is likely to be permanent.