Epidural administration of local anesthetic and methylprednisolone is significantly more effective in preventing PHN at 12 months compared to intravenous acyclovir and prednisolone.

The analgesic efficacy and toxicity of oral diclofenac sodium 50 mg (q.i.d.) vs. nefopam 60 mg (q.i.d.) and a combination of 640 mg ASA and 40 mg codeine (q.i.d.) in cancer patients with moderate to severe chronic pain has been evaluated in a randomized double-blind study. Planned duration of treatment was 10 days. Pain intensity was evaluated by a visual analog scale. The length of patient participation in the trial, the patient's final global evaluation and the incidence of side effects were also evaluated. Ninety-nine patients were enrolled in the study. All treatments produced a statistically significant pain relief (P less than 0.01) without differences among groups but only 26 of 99 patients (26.3%) completed the planned treatment period. Mean time in the study was 4.65 days. Inefficacy and side effects were the main reasons for premature treatment interruption. Patients treated with nefopam had a significantly shorter period in the study than patients treated with the other 2 treatments. Adverse effects were slightly more frequent with the nefopam and ASA + codeine regimens. The 3 therapeutic regimens appear to be similar as to analgesic efficacy, but diclofenac presents the advantage of a slightly better safety profile than nefopam and the ASA + codeine combination.

Twelve patients with intense or very intense pain of the non-incident type, secondary to neoplasia, were divided at random into two groups and treated with an epidural dose of 3 mg of morphine in 10 ml of glucose solution (6 patients = group M) or with 0.3 mg of buprenorphine in the same vehicle (6 patients = group B). None of the patients had previously been treated with opioids by any route. After first determining basal values, the following assessments were carried out: (1) evaluation of the analgesic effect of the drugs with checks at 30 min and at 1, 2, 3, 4, 6 and 18 h after administration, using a visual analogue scale, a numerical rating scale and a simple descriptive scale; and (2) evaluation of effects on respiration by means of checks at 30 and 90 min and at 6 and 18 h, on control of breathing indices (P0.1; VE; VA; Ti/Ttot; VT/Ti; RR), gas exchange indices (delta(A-a)O2; VD/VT; pAO2; R) and blood gas and acid-base indices (paO2; paCO2; pH; HCO3-). The data obtained were analyzed statistically using analysis of variance and Student's t test. The study results showed very similar analgesic efficacy for both treatments at a single dosage level of morphine (3 mg) compared to buprenorphine (0.3 mg), which was approximately 3 times greater than an equivalent parenteral dose of morphine (10 mg). Analysis of the results revealed statistically, though not clinically, significant changes in respiratory function indices, only in the buprenorphine-treated group. The effects of buprenorphine on respiratory function, when administered epidurally at the above dosage, are less favourable than those of morphine in the early measurements, probably because of its greater systemic absorption; nevertheless, the risk of delayed respiratory depression appears to be less after buprenorphine than after morphine.

The effect of vincristine (Vin, a fast axonal transport blocker) to prevent any alteration in the excitability of dorsal horn neurons, following peripheral nerve injury, was investigated on 31 rats: 20 with chronic constriction injury (CCI) of the sciatic nerve and 11 sham preparations. In 15 of the 20 CCI rats, a small piece of gelfoam soaked with Vin was applied to the sciatic nerve before ligation (Vin+); in the remaining 5 rats the nerve was ligated without Vin (Vin-). The 11 sham rats were 7 Vin+ and 4 Vin-. The dorsal horn neuronal activity was recorded after 2-3 postoperative (PO) weeks. In the CCI Vin- rats, the neurons showed increased spontaneous activity and hyperresponsiveness to noxious stimulus with prolonged afterdischarges, events considered to signal central neuron sensitization. In the CCI Vin+ rats, the neuronal spontaneous and stimulated activity values were significantly lower (p < 0.001) than in the CCI Vin- rats being comparable to normal values. In sham Vin+ and Vin- rats, the neuronal activities had normal values. Given the crucial role attributed to central neuron sensitization for the development of neuropathic pain, the possibility that vincristine, by blocking the axonal transport, exerts a preventive action on this syndrome is discussed.

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