 - pregnancy, lactation or lack of effective contraception in women of child-bearing potential e.g., not post menopausal for 2 years, or had tubal ligation; lack of effective contraception in men if the partner is of child-bearing potential; women must have been practicing an effective contraceptive method for at least three months prior to entry in to the trial hormonal contraception or intrauterine device in conjunction with a barrier method; men must use a condom or be surgically sterilized 