Nektar stock drops after Pfizer pulls plug on drug

BOSTON, Oct. 18 (Reuters) - Shares of Nektar Therapeutics (NKTR.O) fell 22 percent on Thursday in premarket trading after its partner Pfizer Inc. (PFE.N) returned the rights to their inhaled diabetes drug Exubera amid sluggish sales.

Exubera, which was developed by Nektar and Pfizer, was approved by U.S. regulators in January 2006. The hope was that diabetics who require insulin would prefer to inhale it than inject it.

"Despite our best efforts, Exubera has failed to gain the acceptance of patients and physicians," Pfizer Chief Executive Jeff Kindler said in a statement. "We have therefore concluded that further investment in this product is unwarranted."

Nektar's shares fell to $6.30 in electronic trading before the market opened from a close of $8.08 on Wednesday on Nasdaq. (Reporting by Toni Clarke)