rhGH Therapy on Hepatic Drug Metabolism

Children recently diagnosed with idiopathic GH deficiency who were candidates for rhGH therapy were eligible for enrollment. All subjects were recruited via informed parental consent and patient assent (for children > 7 years). The anticipated sample size was 12 children.

Inclusion Criteria:

• Children ages 4 to 14 years with a height less than the 5th percentile for age and sex or having a decelerated across two major percentiles (5th, 10th, 25th, 50th, 90th, and 95th) on standard pediatric growth curves, poor growth velocity (less than 5 centimeters/year), radiographic evidence of delayed bone age (i.e. greater than 1 SD below the mean for chronological age) and a documented diagnosis of idiopathic growth hormone deficiency [as determined by failure to raise serum GH concentrations 10 microgram/Liter following provocative testing with two growth hormone secretagogues(e.g. insulin, arginine, or clonidine)].
• All subjects will be prepubertal, as determined by Tanner staging.

Exclusion Criteria:

• Children receiving medications known to induce or inhibit hepatic CYP1A2, NAT-2, XO, CYP2D6 or CYP3A4 activity.
• Subjects with a history of smoking (including exposure to second hand smoke > 8 hours per day) or illicit drug use.
• Subjects with a history of hepatic, renal, cardiac or thyroid disorders. Presence of hepatic, renal, cardiac or thyroid disease will be established based on clinical history and results of recent laboratory tests conducted as part of the routine medical evaluation of children who are being considered for rhGH therapy.
• Children experiencing fever or acute viral illness
• Children who have a history of a hypersensitivity reaction to dextromethorphan or caffeine
• Children who have received prior treatment with rhGH
• Children who are receiving corticosteroids or thyroid hormone