Bristol-Myers Squibb Co. said it will increase its stock buyback program by $2 billion as rising sales of drugs and hair-care products boost its earnings and its shares trade near record levels. The addition raises the total buyback program to $8 billion. The New York-based maker of the cancer drug Taxol and Clairol beauty products said it's the second time the board has expanded the buyback program in the last two years. Like its rivals, Bristol-Myers is buying back shares as relatively new drugs to treat chronic conditions, such as high blood pressure and cholesterol levels, fuel profit. Bristol-Myers' earnings in 1997 rose 12% to $3.21 billion, or $3.14 a diluted share, spurred by rising sales of Taxol, the cholesterol reducer Pravachol, the diabetes treatment Glucophage and the AIDS drug Zerit. Bristol-Myers shares fell 81 cents to close at $108.50 on the New York Stock Exchange. The shares have risen 60% in the last year.