1 EXHIBIT 10.6(a) WATSON PHARMACEUTICALS, INC. AMENDMENT TO THE 1991 STOCK OPTION PLAN Section 2 of the 1991 Stock Option plan was amended as follows: "The phrase '5,700,000 (determined as of May 5, 1997)' is substituted for the phrase '4,700,000 (determined as of May 10, 1996)' where it appears in Paragraph 2 of the 1991 Plan."