APG has optioned Jane Heller’s latest novel, “The Secret Ingredient,” for Jamie McGurk and Dey Young’s Off Balance Prods.Making her first foray into screenwriting, Heller will adapt the novel herself. “Ingredient” is the story of an unhappy L.A. woman who attempts to inject new life into her marriage by dosing her husband with a virility-enhancing elixir. APG chief exec Mark Canton will produce the pic with McGurk and Young. Steve Barnett will exec produce. “Ingredient,” Heller’s ninth novel, was published in February by St. Martin’s. It’s the second of Heller’s novels to be optioned by Off Balance Prods. McGurk and Young also are developing “Lucky Stars,” the Gersh-repped author’s unpublished 10th novel, along with Lakeshore Entertainment.