Biomedical Engineering Reference
In-Depth Information
and emotional problems for some people of short stature, the
consequences were not life-threatening. The older treatment for
growth hormone deficiency was dangerous. Human growth
hormone from cadavers could be contaminated with a mysterious
infectious protein that led to dementia and death.
The development and approval of the recombinant versions of
these drugs was the culmination of years of work by scientists. It also
presented a problem for the FDA. How would the agency review
applications for approval of drugs produced using recombinant
DNA methods? The FDA recognized that, though the method of
production of the new recombinant drugs might be different, the
agency's focus needed to stay on the product, rather than on the way
it was produced. The key questions for the reviewers were 1) whether
the product was safe and effective, 2) whether it could be manu-
factured so that it would be consistently pure, and 3) whether the
manufacturer had provided satisfactory written evidence for these
facts. The FDA's decision to focus on product rather than source
allowed the field of recombinant medicines to move forward more
rapidly than other applications of biotechnology.
REPLACING MISSING PROTEINS
Several recombinant drugs treat inherited conditions by replacing
missing or malfunctioning proteins. Several of these are enzymes,
proteins that drive biochemical reactions. The body has many
different enzyme proteins, each of which performs a specific job
in the construction or breakdown of chemicals. Some inherited
conditions are caused by a destructive buildup of substances, a
buildup that occurs because of an error in the gene for a particular
enzyme that breaks down that chemical.
One example is an enzyme replacement drug used to treat a
form of
Gaucher disease
, which is caused by an inherited error in
the gene coding for the enzyme that breaks down the fatty sub-
stance
cerebroside
. In Gaucher disease, certain immune system cells
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