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Post-herpetic neuralgia
JEREMY ACKERMAN AND ADAM J. SINGER
n Agents
n Tricyclic antidepressants
n Anticonvulsants
n Opioids
n Local anesthetics
n Capsaicin
n Ketamine
n Evidence
Post-herpetic neuralgia (PHN) is one of the more commonly encountered
manifestations of neuropathic pain. Pharmacotherapy remains the mainstay
of PHN treatment, although other interventions (e.g. nerve stimulation,
biofeedback) may have utility outside the acute care environment. 1,2 It
should be emphasized that prompt treatment of acute herpes zoster
decreases the risk of PHN development (and reduces the severity of PHN
that does occur). 3
Post-herpetic neuralgia is one of the many neuropathies for which tricyclic
antidepressants (TCAs) are useful. At least three RCTs compare PHN pain
relief between placebo and TCAs (amitriptyline in two studies and desipramine
in the other). 4 Only two PHN patients need to be treated at least
to achieve 50% pain relief in at least one study. Though the clinical difference
is probably marginal, there is evidence to support selection of nortriptyline
over amitriptyline based on the former agent achieving equal efficacy with
fewer adverse effects. 5
A placebo-controlled trial testing the anticonvulsant gabapentin found
that one patient in three achieved significant pain relief. 6 Studies comparing
antidepressants with anticonvulsants demonstrate similar efficacies (i.e.
overlapping confidence intervals for pain relief measures). However, the