Medication-Related Neuropathy

Today's post from nytimes.com (see link below) is a general look at how neuropathy can be caused by certain drugs you are taking. We all underestimate the toxicity of drugs over the long term but some of the ones listed here may surprise you. That said, by no means all people who take these drugs as prescribed, get neuropathy - it's mostly the exception rather than the rule but if you and your doctor are searching for reasons why you have neuropathic problems, it may be worth while looking at your medications to see if there's a possible link there.

Neuropathy Secondary to Drugs Reference from A.D.A.M. New York Times Health

Neuropathy secondary to drugs is a loss of sensation or movement in a part of the body due to nerve damage from a certain medicine.

Causes

The damage is caused by the toxic effects of certain medications on the peripheral nerves (nerves that are not in the brain or spinal cord). There may be damage to the axon part of the nerve cell, which interferes with nerve signals.

Most commonly, many nerves are involved (polyneuropathy). This usually causes sensation changes that begin in the outside parts of the body (distal) and move toward the center of the body (proximal). There may also be changes in movement, such as weakness.

Many medications may affect the development of neuropathy, including:
 
Heart or blood pressure medications
Amiodarone
Hydralazine
Perhexiline
Drugs used to fight cancer
Cisplatin
Docetaxel
Paclitaxel
Suramin
Vincristine
Drugs used to fight infections
Chloroquine
Isoniazid (INH) -- used against tuberculosis
Metronidazole (Flagyl)
Nitrofurantoin
Thalidomide (used to fight leprosy)
Drugs used to treat autoimmune disease
Etanercept
Infliximab
Leflunomide
Drugs used to treat skin conditions (Dapsone)
Anticonvulsants (phenytoin)
Anti-alcohol drugs (disulfiram)
Drugs to fight HIV
Didanosine (Videx)
Stavudine (Zerit)
Zalcitabine (Hivid)
Arsenic
Colchicine
Gold

Symptoms
Numbness, loss of sensation
Tingling, abnormal sensations
Weakness

Sensation changes usually begin in the feet or hands and move inward.

Exams and Tests

A brain and nervous system examination will be done.

Other tests include:
Blood tests to check levels of the medication (even normal blood levels of certain drugs may be toxic in elderly or certain other persons)
EMG and nerve conduction test of the electrical activity of nerves and muscles

Treatment

Treatment is based on the symptoms and how severe they are. The medication causing the neuropathy may be stopped, reduced in dose, or changed to another medication. (Never change any medication without first talking to your health care provider).

The following medications may be used to control pain:
Over-the-counter pain relievers may be helpful for mild pain (neuralgia).
Phenytoin, carbamazepine, gabapentin, pregabalin, duloxetine, or tricyclic antidepressants such as nortriptyline may reduce the stabbing pains some people experience.
Opiate pain relievers, such as morphine or fentanyl, may be needed to control severe pain.

Whenever possible, avoid or reduce medication use to lessen the risk of side effects.

If you have lost sensation, you may need to take safety measures to avoid injury.

Outlook (Prognosis)

Many people can partially or fully return to their normal function. The disorder does not usually cause life-threatening complications, but it can be uncomfortable or disabling.

Possible Complications
Inability to function at work or home because of permanent loss of sensation
Pain with tingling in the area of the nerve injury
Permanent loss of sensation (or rarely, movement) in an area
When to Contact a Medical Professional

Call your health care provider if you have a loss of sensation or movement of any area of the body while taking any medication.
Prevention

Your health care provider will closely monitor your treatment with any medication that may cause neuropathy. The goal is to keep the proper blood level of medication needed to control the disease and its symptoms while preventing the medication from reaching toxic levels.

References
Katirji B, Koontz D. Disorders of peripheral nerves. In: Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC. Bradley’s Neurology in Clinical Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 76.

Weimer LH, Sachdev N. Update on medication-induced peripheral neuropathy. Curr Neurol Neurosci Rep. 2009;9(1):69-75.

http://www.nytimes.com/health/guides/disease/neuropathy-secondary-to-drugs/overview.html