Teva Pharmaceutical Industries is banking on approval in early 2014 for a new thrice-weekly version of its multiple sclerosis treatment Copaxone to bolster sales ahead of a likely onslaught from copies of its best-selling drug.

Teva, itself the world's biggest maker of generic medicines, posted lower first-quarter profit as revenue in the United States was hurt by a drop in sales of a key branded product due to generic competition.

The company is five months into a sweeping reorganisation it promised would bring extra rewards for shareholders.

The Israeli company has grown rapidly in recent years through a series of multibillion-dollar acquisitions but its shares have badly underperformed its rivals in the past two years.

Among key challenges is the looming 2015 patent expiry of Copaxone, the world's top treatment for multiple sclerosis which accounts for about 20% of Teva's sales and 50% of its profit.

Chief Executive Jeremy Levin said Teva in late March filed for U.S. Food and Drug Administration approval for its three-times-a-week injectable dose of Copaxone, which currently is administered daily.

"We anticipate FDA action in the first quarter next year," Levin told a conference call of analysts on Thursday.

Copaxone posted a 17% rise in global sales in the first quarter to $1.1 billion. The drug faces competition from oral treatments that are already available or expected to hit the market in coming years.

"Global Copaxone sales were 10% above our estimate, driven by higher-than expected U.S. sales," Morgan Stanley analyst David Risinger said.

The upside on Copaxone helped partly offset lower-than-expected global generic sales of $2.3 billion, he said.

U.S. generic sales fell 27% as a few products faced increased competition. European generic sales rose 9% as Teva increased its penetration in France and Italy.

Teva earned $1.12 per diluted share excluding one-time items in the quarter, down from $1.47 a year earlier as revenue fell to $4.9 billion from $5.1 billion. It was forecast to earn $1.10 a share excluding items on revenue of $4.85 billion, according to Thomson Reuters I/B/E/S.

Teva's U.S. sales, which comprise 50% of group totals, fell 11% in the first quarter to $2.4 billion as sales of sleep disorder drug Provigil declined substantially due to generic competition that began in the second quarter of 2012.

Teva plans to focus on new therapeutic entities (NTEs), which could be new uses, formulations, delivery methods or combinations of existing products. So far 13 have been approved for development this year and Teva expects some of these to be launched in the next few years.

Teva reaffirmed its full year 2013 outlook for revenue of $19.5 billion to $20.5 billion and adjusted EPS of $4.85-$5.15.

Teva declared a quarterly dividend of 1.15 shekels (32 cents) a share, unchanged from the fourth quarter when it raised its payout by 15%.