Correspondence

Treatment of Postherpetic Neuralgia

N Engl J Med 1996; 335:1768-1769December 5, 1996

Article

To the Editor:

In their review of postherpetic neuralgia Drs. Kost and Straus (July 4 issue) 1 suggest that narcotic analgesic drugs be given before antidepressant drugs (or carbamazepine) in patients with this disorder. The use of opioid narcotic drugs for the treatment of chronic pain not caused by cancer is controversial, and it has been suggested that such treatment should be considered only if “all other reasonable attempts at analgesia have failed.” 2 The recommendation of a trial of opioid therapy before tricyclic antidepressant therapy disregards this guideline as well as the evidence of the efficacy of antidepressant drugs in patients with postherpetic neuralgia.

We also disagree with the recommendation that opioid therapy be discontinued if relief of pain is incomplete with small doses given for one to two days. If readers accept this recommendation, hardly any patients will receive an adequate trial. To us, a finding of incomplete relief suggests that the pain will respond if the dose is increased, and in addition, treatment for only one or two days cannot be considered an adequate trial. In our experience, the dose-adjustment phase of opioid therapy takes two to three weeks.3 Fear of sedation and dependence should not deter the use of these drugs. Sedation — if it occurs at all — is temporary, and the risk of dependence is negligible if opioid drugs are administered in appropriate doses and if the patient has no history of substance abuse.2

Thorsten Zenz
Michael Zenz, M.D., Ph.D.
Michael Tryba, M.D., Ph.D.
University Hospital Bergmannshiel, 44789 Bochum, Germany

3 References

1
Kost RG, Straus SE. Postherpetic neuralgia -- pathogenesis, treatment, and prevention. N Engl J Med 1996;335:32-42
Full Text | Web of Science | Medline

2
Reidenberg MM, Portenoy RK. The need for an open mind about the treatment of chronic nonmalignant pain. Clin Pharmacol Ther 1994;55:367-369
CrossRef | Web of Science | Medline

3
Zenz M, Strumpf M, Tryba M. Long-term oral opioid therapy in patients with chronic nonmalignant pain. J Pain Symptom Manage 1992;7:69-77
CrossRef | Web of Science | Medline

To the Editor:

Drs. Kost and Straus gave practical guidelines for the prevention and treatment of postherpetic neuralgia, but they failed to mention amantadine. Originally developed as an antiviral drug, amantadine is an antagonist at the N-methyl-d-aspartic acid–glutamate receptor. It reduces calcium influx into the cell, thereby reducing excitability. In prospective studies in patients with herpes zoster, amantadine reduced the duration of zoster-associated pain and prevented postherpetic neuralgia.1,2

Alexander Rösler, M.D.
Frank Schnorpfeil, M.D.
Christoph Fritz, M.D.
Marburg University Hospital, 35033 Marburg, Germany

2 References

1
Galbraith AW. Treatment of acute herpes zoster with amantadine hydrochloride (Symmetrel). BMJ 1973;4:693-695
CrossRef | Web of Science | Medline

2
Barolin GS, Saurugg D, Zechner G. Verbesserung der Zostere Therapie unter Adamantin. Munch Med Wochenschr 1978;120:757-760

Author/Editor Response

The authors reply:

To the Editor: Zenz et al. touch on a controversial topic. We noted that “some pain-management specialists believe that a tricyclic antidepressant drug should be tried before a narcotic drug.” The problem involves balancing the need for rapid pain relief, which a narcotic drug may provide in a subgroup of patients, against the probable greater benefit of a tricyclic antidepressant drug after some weeks of dose adjustment. The rationale for our recommendation that a narcotic be given before an antidepressant is to provide prompt relief to the subgroup that will respond quickly to tolerable doses of a narcotic but to avoid delaying the initiation of therapy with an antidepressant for those who do not respond to the narcotic. We agree that a trial of a narcotic involving weeks of dose escalation should be reserved for patients whose condition has not improved during treatment with tricyclic antidepressant and anticonvulsant drugs; such patients are perhaps best treated by pain specialists.

Rösler et al. refer to two controlled trials of amantadine therapy during acute herpes zoster for the prevention of postherpetic neuralgia.1,2 The finding of reduced postherpetic neuralgia among patients who received amantadine in the study by Galbraith1 is provocative, but it is undermined by the inclusion of over 66 physician–observers for the 100 patients enrolled, the absence of criteria for pain measurement, the different median ages of the patients in the amantadine and placebo groups (50 vs. 60 years), and other methodologic flaws. We omitted it from our analysis and did not recommend amantadine for these reasons. We thank the authors for bringing the other study to our attention.2

We would also like to comment on two other aspects of the treatment algorithm in Figure 4 of our article. First, the structure of the right-hand portion of the algorithm was influenced by an algorithm originally devised by Galer and Portenoy.3 Second, we recommended a dosage of 750 mg of famciclovir three times daily for the treatment of patients with acute zoster. Although that dosage proved effective in the studies cited in our article, the dosage now approved by the Food and Drug Administration is 500 mg three times daily.

Rhonda G. Kost, M.D.
Stephen E. Straus, M.D.
National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892

3 References

1
Galbraith AW. Treatment of acute herpes zoster with amantadine hydrochloride (Symmetrel). BMJ 1973;4:693-695
CrossRef | Web of Science | Medline

2
Barolin GS, Saurugg D, Zechner G. Verbesserung der Zostere Therapie unter Adamantin. Munch Med Wochenschr 1978;120:757-760

3
Galer BS, Portenoy RK. Acute herpetic and postherpetic neuralgia: clinical features and management. Mt Sinai J Med 1991;58:257-266
Web of Science | Medline

Citing Articles (1)