Flexion Therapeutics Inc., of Burlington, Mass., reported net sales of non-opioid pain drug Zilretta (triamcinolone acetonide extended-release injectable suspension) totaling $7 million for the third quarter, up 84 percent over the second quarter. The drug gained approval late last year for treating knee osteoarthritis. The company's net loss for the quarter was $43.6 million, or $1.15 per share. As of Sept. 30, its cash, equivalents and marketable securities totaled $302.9 million. Shares of Flexion (NASDAQ:FLXN) gained $2.72, or 19 percent to close Thursday at $16.99.