OBJECTIVE: Cases treated with
phenytoin 5% or 10% creams were gathered. The mean onset of
pain relief, the duration of effect, and reduction in
pain intensity measured on the 11-point numerical rating scale (NRS) were all studied. A single-blind response test with
phenytoin 10% and placebo creams was conducted on 12 patients in order to select responders prior to prescribing the active cream. Plasma
phenytoin concentrations were measured in 16 patients.
RESULTS: Nine patients applied
phenytoin 5% cream, and 61 patients used
phenytoin 10% cream. After grouping the effects of all of the patients, the mean onset of
pain relief was 16.3 min (SD: 14.8), the mean duration of
analgesia was 8.1 h (SD: 9.1), and the mean
pain reduction on the NRS was 61.2% (SD: 25.0). The mean
pain reduction on the NRS while using
phenytoin cream was statistically significant compared with the baseline, with a reduction of 4.5 (CI: 4.0 to 5.0, p < 0.01). The 12 patients on whom a single-blind response test was performed experienced a statistically significant reduction in
pain in the area where the
phenytoin 10% cream was applied in comparison to the area where the placebo cream was applied (p < 0.01). Thirty minutes after the test application, the mean
pain reduction on the NRS in the areas where the
phenytoin 10% cream and the placebo cream were applied was 3.3 (CI: 2.3 to 4.4, p < 0.01) and 1.1 (CI: 0.4 to 1.9, p < 0.05), respectively. In all 16 patients, the
phenytoin plasma levels were below the limit of detection. So far, no systemic side effects were reported. Two patients only reported local side effects: a transient burning aggravation and
skin rash.
CONCLUSION: