LIPID LOWERING
AGENTS
The first line of therapy
are diet, weight loss and
exercise. Where drug therapy
is indicated, the following
points should be considered
DRUGS FOR GENERAL USE: THOUGHT
TO BE SAFE
Probucol,
cholestyramine and colestipol
are safe and may be used.
FIBRATES
The fibrates
are a class of drug particularly
useful for reducing triglyceride
levels. Most appear to be
safe. We suggest that clofibrate,
fenofibrate, bezafibrate,
and gemfibrozil may be used
with caution, but this suggestion
is tentative and care must
be exercised.
STATINS
These drugs
are very useful for reducing
cholesterol levels. Most of
these are metabolised by the
cytochrome P450 system ( a
marker of potential porphyrinogenicity),
but recent evidence suggests
that some may not however
induce this enzyme system
(which is a good thing, and
will lead to increased safety
in porphyria). Furthermore,
there have as yet been no
actual reports of adverse
consequences in porphyria,
despite their use in patients.
We suggest that in each patient
the potential benefits are
weighed against the risk of
aggravating porphyria and
an individualised decision
made. Experimental evidence
suggests that rosuvastatin
may be the safest, since only
10% is metabolised in the
liver, the rest is excreted
unchanged, followed by pravastatin
(though it is metabolised
by cytochrome P450, 50% is
excreted unchanged in the
urine, and it does not however
appear to induce cytochrome
P450. Some of the others,
notably simvastatin, atorvastatin,
fluvastatin and cerivastatin
do appear to induce cytochrome
P450 and may theoretically
be less safe.
NO DATA
There is no
information on acipimox, and
it is best avoided at present.
PRECAUTIONS TO FOLLOW WHEN
INTRODUCING DRUGS OF UNPROVEN
SAFETY
Particularly
with reference to the statins,
the doctor should::
- Introduce agents one
at a time.
- Warn the patient that
the agent is not guaranteed
safe; obtain their consent
for its use; warn them to
cease medication and report
back to him or her immediately
in the event that they develop
abdominal pain.
- Take particular care in
patients with AIP and in
those with a history of
more severe porphyria, especially
those who have suffered
acute attacks within the
past few years
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