The loading (40 mg) and daily maintenance (20 mg) doses will be reduced by 50% for patients: a) who have at least one parent of Asian descent (loading 20 mg and daily 10 mg), b) whose age < 18 years (loading 20 mg and daily 10 mg), c) whose serum creatinine concentration is greater than or equal to 248 umol/L (2.8 mg/dL) who are not on renal replacement therapy (loading 20 mg and daily 10 mg), and by 75% for patients: d) who have at least one parent of Asian descent and/or age < 18 years and serum creatinine is greater than or equal to 248 umol/L (2.8 mg/dL) (loading 10 mg and daily 5 mg).