OPKO Health Inc said its experimental drug for growth hormone deficiency (GHD) in adults failed to provide a statistically significant benefit over a placebo in a late-stage study, sending its shares down about 17 percent on Friday.

Miami-based OPKO, which is developing the drug, hGH-CTP, with Pfizer Inc, said on Friday it had identified one or more outliers that may have affected the trial, in which patients were given the drug once a week.

GHD is a rare disorder characterized by the inadequate secretion of the growth hormone from the pituitary gland, an organ responsible for the production of multiple hormones.

The disorder can be hereditary, can be acquired as a result of trauma, infection, radiation therapy or brain tumor growth, and can even emerge without a diagnosable cause.

OPKO said it had also started another pediatric late-stage study to evaluate the drug against the standard-of-care hormone replacement therapy genotropin, which was originally developed by Pfizer.

An approval for pediatric GHD - which accounts for about 50 percent of the total GHD market - is substantially more valuable for OPKO, given that it makes them eligible to receive double-digit royalty payments from Pfizer, Laidlaw & Co analyst Yale Jen had said in a client note in September.

If approved, Jen expects the drug to generate $1 billion in peak sales by 2026, he told Reuters on Friday.

Up to Thursday's close of $11.46, shares of OPKO, which also focuses on diagnostics, had gained about 14 percent this year.

Pfizer's shares were down 0.15 percent at $32.54. (Reporting by Divya Grover in Bengaluru; Editing by Ted Kerr and Shounak Dasgupta)