X0306 4 2016-10-05 0 0001396814 Pacira Pharmaceuticals, Inc. PCRX 0001204788 STACK DAVID M C/O PACIRA PHARMACEUTICALS, INC. 5 SYLVAN WAY, SUITE 300 PARSIPPANY NJ 07054 1 1 0 0 CEO and Chairman Common Stock 2016-10-05 4 M 0 30000 1.61 A 63637 D Common Stock 18596 I By Stack Schroon Mohawk FLP Common Stock 1208 I By LCK Investment LLC Stock Option (Right to Buy) 1.61 2016-10-05 4 M 0 30000 0.00 D 2020-09-02 Common Stock 30000 40695 D The option exercise reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan previously adopted by the reporting person in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934. Mr. Stack is the general partner of Stack Schroon Mohawk FLP. Mr. Stack and his wife are the owners of LCK Investment LLC. The option vested as to 50% of the option shares on February 2, 2011, 19,377 option shares vested on February 3, 2011, and the remaining option shares vested in successive equal monthly installments for the subsequent 19 months. /s/ James Scibetta, Attorney-in-Fact 2016-10-07