(Reuters) - Shares of Israeli drugmaker Teva Pharmaceutical Industries rose over 5 percent in after-hours trading on Friday after the U.S. Food and Drug Administration (FDA) approved the company’s new migraine treatment, a drug Teva has been banking on to help revive its fortunes.

A man walks past the logo of Teva Pharmaceutical Industries at their plant in Jerusalem December 14, 2017. REUTERS/Ammar Awad/File Photo

The wholesale price of the drug, Ajovy, is $575 a month, the same as Aimovig, a similar monthly injection sold by Amgen Inc and Novartis AG that has been available in the United States since May.

Teva’s drug can also be given once every three months - in three consecutive injections - an option priced at $1,725.

“We felt that $575 was an appropriate price,” Brendan O’Grady, head of Teva’s North America commercial operations, told Reuters. He said Teva has been actively negotiating with health insurers and other payers for months on how best to allow patient access to the new drug.

Teva, the world’s largest generic drugmaker had hoped to receive approval for Ajovy, known generically as fremanezumab, by June.

Its release was delayed due to U.S. regulatory concerns about the manufacturing process at the South Korean plant of its development partner Celltrion.

Around 39 million Americans suffer from migraine headaches, according to the Migraine Research Foundation, making for a large market that has attracted several drugmakers.

Eli Lilly & Co is also developing a migraine treatment in the same new class of drugs, with the FDA expected to take action by Sept. 27.

Demand for Aimovig has been strong, buoyed in part by Amgen programs giving patients two months of free samples followed by up to a year’s supply of the drug for those having trouble with insurance coverage. Analysts, on average, have forecast annual Aimovig sales of nearly $1 billion by 2022, according to Thomson Reuters data.

Teva said it would offer an assistance program for commercially insured patients, bringing their out-of-pocket costs to as little as $0.

Deutsche Bank has forecast peak annual sales of fremanezumab of $500 million.

While Teva has an enormous portfolio of generic medicines, it has long been dependent on its top-selling branded multiple sclerosis drug Copaxone, now facing generic competition, which accounted for about 20 percent of total sales.

Ajovy, which will initially be available in a pre-filled syringe rather than a more sophisticated auto-injector device like Aimovig’s, is seen as crucial for Teva’s recovery.

Shares of Teva, which rose 2.9 percent to close at $22.85 in regular trading, were up another 5.4 percent at $24 after hours.

The company’s share price has been in freefall for most of the past three years, losing about two-thirds of its value as Teva struggled to bring new drugs to market and became saddled by debt from a $40.5 billion purchase of Allergan’s generic drug business in 2016.

In a bid to lower debt, Teva is in the process of cutting more than a quarter of its workforce and closing or selling 10 of its factories. Teva said last month its net debt had fallen to $28.4 billion from a peak of $35 billion.

In addition to the migraine drug, Teva is banking on Austedo, an experimental Huntington’s disease treatment, to help it return to growth.