When Neurotoxic Medications Cause Peripheral Neuropathy

Forty million people in the U.S. suffer from some form of peripheral neuropathy.¹ The causes of peripheral neuropathy stem from systemic diseases such as diabetes mellitus, autoimmune disorders, side effects from medications, toxic exposures, infections, and hereditary diseases.^2-3 Each different condition can also result in damage specifically to sensory, motor or autonomic nerve fibers, or a combination of these nerve fibers.³

Let's discuss several classes of medications that can cause peripheral neuropathy. The prevalence of peripheral neuropathy increases as patients age; in fact, 8 percent of patients 55 years and older have been diagnosed with neuropathic pain.⁴ If your patient has been told they have peripheral neuropathy and their physician has ruled out systemic diseases, toxic exposures, infections and hereditary disorders, then consider the medications the patient is taking as a potential cause.

Statins

Many Americans take statins, lipid-lowering agents such as lovastatin and simvastatin. Published research is now identifying that hyperlipidemia is the single largest contributing factor to developing neuropathy, largely because most of those patients are put on statins.^5-6

It has been determined that patients on long-term statin medication may substantially increase their risk of developing polyneuropathy.⁷ Statins have been found to primarily cause sensory neuropathy, which means patients taking these medications can have loss of sensation, loss of balance and pain.²

Antidysrhythmics

Antidysrhythmics are another class of medications many older adults are taking. These medicines are used to suppress abnormal rhythms of the heart. Digoxin, amiodarone, phenytoin or dilantin, and procainamide have all been identified to cause peripheral neuropathy.²

These cardiac medications have been found to cause sensory neuropathy only or sensorimotor neuropathy with axonal-damage neuropathies, meaning patients taking these medications can experience loss of sensation, loss of balance, pain and weakness.²

Antibiotics

Certain antibiotics are the next class of medications that have the potential to cause peripheral neuropathy. Nitrofurantoin (Macrobid) is an antibiotic used to treat and prevent urinary tract infections, and this medication can cause sensorimotor neuropathy.²

Fluoroquinolones are broad-spectrum antibiotics commonly prescribed to treat respiratory and urinary infections. Common brands names of fluoroquinolones include Cipro, Levaquin, Avelox, Noroxin and Floxin. Many of the newer fluoroquinolones have been found to be linked to serious nerve damage, and the FDA is strengthening its warnings regarding these medications.⁸

Mainstream medical treatment for neuropathy has two overall goals. The first is to control underlying disease processes, such as managing systemic diseases like diabetes, hypothyroidism, vitamin deficiencies, renal disease and chronic liver disease; and identifying and eliminating toxins such as alcohol and treating infections that can lead to neuropathy.

The second goal is to control symptoms with medications including gabapentin or neurontin, Lyrica and antidepressants. These medications all affect the central nervous system and cause drowsiness, fatigue, dizziness and difficulty walking.

It is clear that the medications discussed above can lead to neuropathy, and the medications used to treat neuropathic pain can be unpleasant for patients to be on long term. Being cognizant of medication side effects and carrying out a drug interaction check greatly improves the management of your patient (whether they have neuropathy or not). Checking drug interactions between the patient's medications and supplements should also be the standard of care, and you can direct the patient to consult with their prescribing physician if significant interactions are found.

References

1. Hovaguimian A, Gibbons CH. Diagnosis and treatment of pain in small-fiber neuropathy. Curr Pain Headache Rep, 2011 Jun;15(3):193-200.
2. Azhary H, Farooq MU, Bhanushali M, et al. Peripheral neuropathy: differential diagnosis and management. Am Fam Physician, 2010 Apr 1;81(7):887-92.
3. Levine T. Small fiber neuropathy: disease classification beyond pain and burning. J Cent Nerv Syst Dis, 2018 Apr 18;10: 1179573518771703.
4. Martyn CN, Hughes RA. Epidemiology of peripheral neuropathy. J Neurol Neurosurg Psychiatry, 1997 Apr;62(4):310-8.
5. Vincent AM, Hinder LM, Pop-Busui R, et al. Hyperlipidemia: a new therapeutic target for diabetic neuropathy. J Peripher Nerv Syst, 2009 Dec;14(4):257-67.
6. Wiggin TD, Sullivan KA, Pop-Busui R, et al. Elevated triglycerides correlate with progression of diabetic neuropathy. Diabetes, 2009 Jul;58(7):1634-40.
7. Gaist D, Jeppesen U, Andersen M, et al. Statins and risk of polyneuropathy: a case-control study. Neurology, 2002 May 14;58(9):1333-7.
8. Cofano G, Hennings M, Sergent A. Vertigo secondary to fluoroquinolone neuropathy: a case report. Ann Vertebral Sublux Res, 2016 May;(9):29-31.