3. Pregnancy, lactation or lack of effective contraception in women of child-bearing potential; lack of effective contraception in men if the partner is of child-bearing potential; women must have been practising 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 OR surgically sterilised). Men must use a condom or be surgically sterilised.