Drugs and Chemicals of
Concern > HUMAN GROWTH HORMONE
HUMAN GROWTH HORMONE
(Trade Names: Genotropin®, Humatrope®, Norditropin®,
Nutropin®, Saizen®, Serostim®)
August 2007 DEA/OD/ODE
Introduction:
Human growth hormone (hGH) is a
naturally occurring polypeptide hormone secreted by the pituitary gland
and is essential for body growth. Daily secretion of hGH increases
throughout childhood, peaking during adolescence, and steadily declining
thereafter. In 1985, synthetic hGH was developed and approved by the
Food and Drug Administration (FDA) for specific uses. However, it is
commonly abused by athletes, bodybuilders, and aging adults for its
ability increase muscle mass and decrease body fat, as well as its
purported potential to improve athletic performance and reverse the
effects of aging.
Licit Uses:
Several FDA-approved injectable
hGH preparations are available by prescription from a supervising
physician for clearly and narrowly defined indications. In children, hGH
is approved for the treatment of poor growth due to Turner’s syndrome,
Prader-Willi syndrome, and chronic renal insufficiency, hGH
insufficiency/deficiency, for children born small for gestational age,
and for idiopathic short stature. Accepted medical uses in adults
include the treatment of the wasting syndrome of AIDS and hGH
deficiency. The recommended dosage is 40 m g/kg/day for children and
25 m g/kg/day for adults. The FDA-approved injectable formulations
are available as liquid preparations, or as powder with a diluent for
reconstitution.
Chemistry and Pharmacology:
Using recombinant DNA technology,
two forms of synthetic hGH were developed, somatropin and somatrem.
Somatropin is identical to the endogenous pituitary-derived hGH, whereas
somatrem has an extra amino acid on the N-terminus. Both synthetic forms
have similar biological actions and potencies as the endogenous hGH
polypeptide. Synthetic hGH also is chemically indistinguishable from the
naturally occurring hormone in blood and urine tests.
hGH binds to growth hormone
receptors present on cells throughout the body. hGH functions to
regulate body composition, fluid homeostasis, glucose and lipid
metabolism, skeletal muscle and bone growth, and possibly cardiac
functioning. Sleep, exercise, and stress all increase the secretion of
hGH.
The use of hGH is associated with
several adverse effects including edema, carpal tunnel syndrome, joint
pain, muscle pain, and abnormal skin sensations (e.g., numbness and
tingling). It may also increase the growth of pre-existing malignant
cells, and increase the possibility of developing diabetes.
hGH is administered by
subcutaneous or intramuscular injection. The circulating half-life of
hGH is relatively short (20-30 minutes), while its biological half-life
is much longer (9-17 hours) due to its indirect effects.
Illicit Uses:
Human growth hormone is illicitly
used as an anti-aging agent, to improve athletic performance, and for
bodybuilding purposes. It is marketed, distributed, and illegally
prescribed off-label to aging adults to replenish declining hGH levels
and reverse age-related bodily deterioration. It is also abused for its
ability to alter body composition by reducing body fat and increasing
skeletal muscle mass. It is often used in combination with other
performance enhancing drugs, such as anabolic steroids. Athletes also
use it to improve their athletic performance, although the ability of
hGH to increase athletic performance is debatable.
Abuser Population:
Athletes, bodybuilders, and aging
adults are the primary abusers of hGH. Because the illicit use of
synthetic hGH is difficult to detect, its use in sports is believed to
be widespread. Over the past few years, numerous professional athletes
have admitted to using hGH. Bodybuilders, as well as celebrities, also
purportedly use it for its ability to alter body composition. Aging
adults looking to reverse the effects of aging are increasingly using
synthetic hGH.
Illicit Distribution:
The illicit distribution of hGH
occurs as the result of physicians illegally prescribing it for
off-label uses, and for the treatment of FDA-approved medical conditions
without examination and supervision. Illicit distribution also involves
diverted hGH obtained through theft, smuggled hGH illegally imported
from other countries, distribution of injectable synthetic and
counterfeit hGH.
The illicit hGH formulations is
thought to be primarily through Internet pharmacies, wellness and
anti-aging clinics, and websites. Internet pharmacies are often
partnered with a physician willing to write prescriptions for a fee and
no physical examination. Individuals may also obtain hGH without a
prescription through the black market. hGH is often marketed with other
performance enhancing drugs (e.g., anabolic steroids).
Various oral preparations (e.g.,
sprays and pills) purported to contain hGH are marketed and distributed.
However, hGH is only bioavailable in the injectable form. The hGH
molecule is too large for absorption across the lining of the oral
mucosa and the hormone is digested by the stomach before absorption can
occur.
Control Status:
hGH is not controlled under the
Controlled Substances Act (CSA). However, as part of the 1990 Anabolic
Steroids Control Act, the distribution and possession, with the intent
to distribute, of hGH "for any use…other than the treatment of a
disease or other recognized medical condition, where such use has been
authorized by the Secretary of Health and Human Services…and pursuant
to the order of a physician…" was criminalized as a 5-year felony
under the penalties chapter of the Food, Drug, and Cosmetics Act of the
FDA. In March 2007, a bill was introduced into the U.S. Senate to amend
the CSA and to add hGH to schedule III.
hGH is listed by the World
Anti-Doping Agency and the International Olympic Committee as a
performance enhancing drug barring athletes from using it.
Comments and additional information are welcomed by the
Drug and Chemical Evaluation Section, FAX 202-353-1263 or
telephone 202-307-7183.
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