United States of America - The Food and Drug Administration (FDA) has approved a new indication for somatropin, rDNA origin, for injection (Humatrope®), a brand of growth hormone, for the long-term treatment of children with idiopathic short stature, also called non-growth hormone deficient short stature.

“Short stature” has been defined by the American Association of Clinical Endocrinologists and the Growth Hormone Research Society as height more than 2 standard deviations (SD) below the mean for age and sex. This corresponds to the shortest 2.3 percent of children. This new indication restricts therapy to children who are even shorter, specifically more than 2.25 SD below the mean for age and sex, or the shortest 1.2% of children.

Approval was based on two randomized, multicentre trials, conducted in approximately 300 children with idiopathic short stature after excluding other causes, including growth hormone deficiency.

The pivotal trial was a randomized, double-blind study in 71 children aged 9-15 years. Patients received injections of either Humatrope® or placebo three times weekly until adult height was reached. Thirty-three patients contributed final height measurements after a mean treatment duration of 4.4 years. Mean final height of patients exceeded that of the placebo patients by approximately 1.5 inches.

In a second study, patients received one of three increasing doses in divided doses six times weekly. The average duration of treatment to final height was 6.5 years. Final height exceeded that predicted at the time of enrolment in the majority of patients, and by up to nearly four inches in some. In the high-dose group, mean final height exceeded mean height predicted at baseline by nearly three inches.

The safety profile in children with idiopathic short stature did not differ from that in children with other conditions for which growth hormone is indicated.

Various growth hormone products are currently indicated in children for short stature associated with growth hormone deficiency, chronic renal insufficiency, Turner syndrome, Prader-Willi syndrome, and in children born small for gestational age.

The manufacturer has advised FDA that it will not engage in direct-to-consumer advertising and will limit the marketing of this product for this new use to paediatric endocrinologists only to better ensure proper use in the indicated population. In addition, the manufacturer intends to tightly control distribution.

Reference: http://www.fda.gov/medwatch 30 May 2003.