Effectiveness of prostaglandin E1 for the treatment of patients with neuropathic pain following herpes zoster

Objective. Postherpetic neuralgia (PHN) is one of the most painful neuropathic conditions, the mechanism of which remains unclear. There is no universally accepted treatment. The pain in PHN is often relieved by bathing, heating, or sympathetic blockade, suggesting a circulation-dependent property of the pain. Therefore, we examined the effectiveness of prostaglandin E₁ (PGE₁), which has an analgesic effect via improvement of peripheral blood circulation, for patients with PHN. Design. A total of 27 patients with PHN underwent intravenous administration of 60 μg of PGE₁ dissolved in 100 mL of physiological saline and 5 mL of 8.4% sodium bicarbonate solution at an infusion rate of 0.02 μg/kg/min. Oral administration of PGE₁, limaprost alfadex, was followed at doses of 30 μg/day for 2 weeks. Pain at rest and tactile allodynia before and after the treatment was evaluated with visual analog scale (VAS). Results. Intravenous PGE₁ significantly decreased VAS in rest pain and tactile allodynia without severe adverse effects. The analgesic effect of PGE₁ continued during the 2 weeks of oral administration of PGE₁. Oral PGE₁ caused nausea in seven cases, diarrhea in three, and abdominal distention in one subject. All subjects, except for two cases of nausea, continued the treatment until the end of the study, although some required a decrease in the dose to 15 μg/day. During the 2-week oral administration, the VAS did not change remarkably in the three patients whose VAS were not decreased by at least 80% during the initial infusion. Conclusions. The results of the present study indicate that oral PGE₁ following the intravenous administration produces prompt and continuous analgesia in patients with PHN. Moreover, the intravenous treatment using PGE₁ appears useful for predicting the analgesic effect of PGE₁ in the patients.