 1. Pregnant or breast-feeding females are excluded due to potential risks of foetal and teratogenic adverse events of an investigational agent. Pregnancy tests must be obtained prior to enrolment on this study for girls of reproductive potential. The need to commence pregnancy testing will be at the discretion of the treating physician to facilitate taking in to account factors such as precocious puberty, endocrine status and medications which can affect pubertal status. Males or females of reproductive potential may not participate unless they have agreed to use an effective contraceptive method. Abstinence is an acceptable method of birth control. 