To the Editor: I was dismayed by the placebo-controlled
design of the study by Dr Backonja and colleagues1
that examined the effectiveness of gabapentin in patients with diabetic neuropathy.
As the authors clearly state, the use of tricyclic antidepressants is well
established and effective for the treatment of painful diabetic neuropathy.
The use of a placebo control for a condition for which there is an effective
treatment, even for the short duration of this trial, is in my opinion unethical.
Furthermore, a comparison of outcomes using a new treatment with an established
treatment is of considerably more clinical importance than comparison with
a placebo. Although tricyclic antidepressants may have adverse effects that
limit their tolerability for some patients, dizziness, somnolence, and confusion
were common adverse effects with gabapentin. The considerable cost differences
between gabapentin and tricyclic antidepressants make a direct comparison
of these treatments of paramount interest. The cost of a 30-day supply of
a 900-mg/d dose of gabapentin, which is one fourth of the maximum dose titration
in this study, is $93.2 In comparison, the
cost of a 30-day supply of generic formulations of amitriptyline and nortriptyline
is $3 and $12, respectively.3
Margolis K. Gabapentin for Painful Diabetic Neuropathy. JAMA. 1999;282(2):133-134. doi:10-1001/pubs.JAMA-ISSN-0098-7484-282-2-jbk0714