Ellen Burstyn has joined the cast of “Possible Side Effects,” Showtime’s drama pilot set inside the world of the pharmaceutical industry.

Burstyn will play the matriarch of the Hunt family, a powerful but dysfunctional brood that runs a drug company that gets into a heap of trouble. Josh Lucas is already attached to star, as is Tim Blake Nelson.

Tim Robbins is writing and directing “Possible Side Effects,” and exec producing with Elaine Goldsmith-Thomas and Daniel Thomas.

Burstyn will next be seen in the feature “W.” as Barbara Bush. Her recent TV credits include the telepics “For One More Day” and “Mrs. Harris.” She also appeared in the series “Big Love,” “Book of Daniel” and “That’s Life.”