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.
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.
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.
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