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Opioid doses in NP may be relatively higher than customary for non-NP
indications, and in fact varying types of NP (as outlined in specific chapters)
may warrant different opioid dosages. 4,5,7 While there is probably not too
much difference between the various opioids in terms of efficacy for NP,
efficacy and side effects in individual patients tend to vary between different
agents. Some longer-acting opioids not traditionally used in the ED may be
useful in NP. For instance, the long-acting agent levorphanol (in either low
dose of 2.7 mg QD, or at a high daily dose of 8.9 mg) has been found effective
in a wide variety of NP disorders. 8
The clinical model upon which NP treatment with opioids is based is the use
of this class for cancer pain. Some components of the cancer pain treatment
approach are worth reiterating. First, sustained-release opioids are administered
on a scheduled (rather than an as-needed) basis. This approach minimizes drugrelated
complications, since such problems are often a function of high peak
opioid levels. 2 Second, the same opioid that is prescribed in sustained-release
form should be prescribed in a shorter-acting form for relief of breakthrough
pain. A recommended starting dose for rescue drug therapy is approximately 10–
15% of the total daily opioid dose, administered every 3–4 h as needed.
If the patient can tolerate oral medications, the PO route for opioids is
preferred since these formulations are easily administered, cost effective, and
may be available in several preparations (e.g. liquid as well as pill form). In
patients unable to tolerate oral medications, there are other choices (e.g.
sublingual, transdermal).
Although it has mu receptor activity, and is associated with some abuse
potential, tramadol is not a pure opioid. It is likely that tramadol’s inhibition
of monoamine reuptake contributes to its uility in NP. For generalized
polyneuropathy, and for specific NP indications as outlined in other chapters,
tramadol (up to 200 mg PO BID for polyneuropathy) can be quite useful. 9
ANTIDEPRESSANTS
Neuropathy – overview 291
Antidepressants are of substantial clinical utility in NP. The main subgroups
used are the tricyclic drugs (TCAs), the SSRIs,andtheserotonin–norepinephrine
reuptake inhibitors (SNRIs).