In this article, originally published in 2004, Dr. Gareth Parry, Professor of Neurology at the University of Minnesota, outlines the categories of drug risk for patients with Charcot-Marie-Tooth disease (CMT, an inherited disorder that damages the peripheral nerves controlling movement and sensation). Understanding these distinctions can help patients have more informed conversations with their doctors and pharmacists.

Six Categories of Drug Risk in CMT

  1. Drugs proven to cause irreversible nerve damage in CMT patients. A small number of drugs have been shown to worsen CMT in ways that do not reverse after the drug is stopped. The clearest example is vincristine. These drugs should never be used unless there is absolutely no alternative.
  2. Drugs that cause clinically significant neuropathy and are likely to worsen CMT. These drugs have not always been tested specifically in CMT patients, but their known effects on nerves make them worth avoiding when possible. Most medications on standard CMT medication alert lists fall into this category.
  3. Drugs that possibly cause mild or clinically insignificant neuropathy. Dilantin (phenytoin) is one example. It can cause a neuropathy, but it is rarely significant. That said, Dr. Parry would not choose it as a first-line epilepsy treatment for a CMT patient. However, if it proved to be the most effective option for controlling seizures, the benefit would outweigh the remote risk of worsening CMT.
  4. Drugs that cause muscle damage rather than nerve damage. Statins such as Lipitor (atorvastatin) fall into this group. In rare cases they cause muscle breakdown, which could worsen a CMT patient’s condition through a different mechanism than nerve damage. Whether to use them depends on the individual risk balance. A patient with very high cholesterol faces serious risks from stroke or heart attack that statins can reduce. If cholesterol can be managed through diet and exercise, that is preferable, but statins remain a reasonable option when needed.
  5. Drugs that probably cause significant neuropathy, but only rarely and in certain individuals. Statins are again an example in this category for some patients.
  6. Drugs that act on the central nervous system and cause fatigue and a sense of weakness, without directly damaging nerves or muscle. These effects are almost always reversible and vary widely between individuals. Amitriptyline is a common example, frequently prescribed for neuropathic pain in CMT patients. Most people experience some tiredness; a smaller number feel so exhausted they cannot get out of bed. The fatigue usually improves over time. Because the effects are reversible, Dr. Parry does not avoid these drugs, but he makes sure patients understand the potential for significant fatigue.

General Principles

Dr. Parry offers the following guidance for CMT patients managing medications:

  • Do not take any medication unless you need it.
  • Never take a known neurotoxic drug unless there is absolutely no alternative.
  • Avoid drugs that cause weakness and fatigue when alternatives exist, even if they do not directly affect the nerves.
  • Always ask your doctor and pharmacist about potential adverse effects of any prescribed drug, particularly in relation to your CMT.

For a current list of medications flagged for people with CMT, visit our patient resources page.