Background: Despite being widely prescribed, relatively few controlled trials have been
conducted on the class of neurotrophic/antinociceptive nutraceuticals. While performing a search in
the literature, we came across an old registration study on micronized palmitoylethanolamide in patients
with low back pain – sciatica by Guida and colleagues.
Methods: We contacted the authors of the article and obtained all the original material, which allowed
us to reanalyze the study. We assessed its clinical relevance by calculating the numbers needed to treat
for pain (visual analog scale) and function (Roland-Morris Questionnaire). After excluding patients for
whom the information available was insufficient, we assigned each patient to one of the five categories
of increasing probability of neuropathic pain: pure lumbago, lumbago with projecting pain to surrounding
regions (e.g. gluteus or groin), lumbago with projecting pain to the thigh or leg, pure sciatica
and radiculopathy, and investigated any correlations (Spearman) between the improvement in pain and
function with these five classes.
Results: Compared with placebo, palmitoylethanolamide 600 mg/die yielded a number needed to treat
of 1.7 (95% confidence interval: 1.4-2) for pain, and 1.5 (95% confidence interval: 1.4-1.7) for function.
The correlation between the five categories was highly significant for pain relief (P <0.0001),
though not significant for reduced dysfunction.
Conclusion: Palmitoylethanolamide was extremely effective on pain and function in a large cohort of
patients with low back pain – sciatica. Although the multiple mechanisms of action of palmitoylethanolamide
are ideal for mixed pain conditions such as low back pain – sciatica, the correlation between
pain relief and the likelihood of neuropathic pain suggests that this drug exerts a predominant action
on the neuropathic pain component.