A look at medications for diabetic neuropathy

“You become responsible, forever, for what you have tamed.”  – The Little Prince, Antoine de Saint Exupery.

In the treatment of peripheral neuropathy, Partnership HealthPlan of California’s formulary has step requirements. It begins with tricyclic antidepressants (amitriptyline or nortriptyline) and moves through gabapentin and then on to pregabalin (Lyrica) and duloxetine (Cymbalta). Lest we be drawn to the new, bright and shiny objects sometimes presented to us, there is reason to remain with the slightly tarnished objects of old (I like to think of them as having a fine patina).

A recently published study compared three drugs in the treatment of painful diabetic neuropathy: amitriptyline, duloxetine, and pregablin at doses of 75 mg, 120 mg, and 600 mg total daily doses respectively. These last two doses are twice what the FDA has approved for peripheral neuropathy but are commonly used. To my surprise (not really), the mean pain scores at four weeks had improved in all three groups with no significant difference among the three medications. Duloxetine reduced sleep time but improved sensory motor performance. Pregabalin caused more fatigue, dizziness, and somnolence although continuity of sleep was improved. Pregabalin caused significantly more adverse events than the other two medications.

A logical extension of the study’s findings would have me consider using nortriptyline in place of the less-well-tolerated amitriptyline and would also have me use the chemical doppelganger gabapentin instead of pregabalin.

Our not-for-profit philosophy looks to reduce wasteful costs so that funds can be redistributed to service, member benefits, and reimbursement to our splendid network of physicians and providers. It is important to be aware of the cost of the aforementioned medications. (Thanks to Dr. Ominder Mehta, one of our PHC pharmacists, for looking these up.)

Amitriptyline 75 mg / day             $3.30 / month

Nortriptyline 75 mg/day                $12.60 /month

Gabapentin 1800 mg/day             $76.00 / month (as 600 mg caps); $34/month (as 300 mg caps)

Lyrica 600 mg/ day                       $190 / month (as 300mg caps); $280 /month (as 200 mg caps)

Cymbalta 120 mg/ day                 $380 / month

Eye opening! A more than 100-fold difference. Should we keep the funds within the community or send them off to Eli Lilly (Cymbalta) or Pfizer (Lyrica)?

Marshall Kubota, MD

Boyle J et al. “Randomized, placebo-controlled comparison of amitriptyline, duloxetine, and pregabalin in patients with chronic diabetic peripheral neuropathic pain:  Impact on pain, polysomnographic sleep, daytime functioning, and quality of life.” Diabetes Care 2012 Dec; 35-2451. (http://dx.doi.org/10.2337/dc12-0656)

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>