[Long-term effectiveness of topical analgesics]. / Langzeiteffektivität topisch applizierter Analgetika.

ABSTRACT

BACKGROUND: Neuropathic pain consistently presents a significant therapeutic challenge. Topically applied analgesics have the advantage of showing low systemic side effects, but data on long-term effectiveness are lacking. Consequently, interviews were carried out with all patients being treated with topical analgesics in hospital. METHODS: Ethics 16-5690, German Clinical Trials Register (DRKS) 00011877. Between 2008 and 2017 a total of 265 patients were treated at least once with either capsaicin 8% (C), lidocaine 5% (L) and/or perineural botulinum toxin type A (B). From this sample, 205 patients (77%) were interviewed by telephone for feedback on pain reduction (first/last treatment low/moderate/very good), the possible reduction of analgesic prescription and if applicable the reasons for discontinuation of use (time of interview C 26 ± 19 months, L 61 ± 23 months, B 11 ± 6 months after start). Further pretreatment data and diagnoses were obtained from the in-house documentation system. Responders or long-term responders were defined as patients with at least one moderate pain reduction after the first or last treatment, as long as the effect was adequately maintained. RESULTS: In all treatment groups (56 ± 13 years, 62% male, C 80, L 84, B 58 patients) patients with a long history of pain (C 60 ± 73 months, L 59 ± 66 months, B 67 ± 71 months) and high pain intensity (numeric rating scale, NRS, C 7 ± 2, L 7 ± 2, B 6 ± 2), were predominant. The highest primary and long-term responder rates were exhibited by L (57%/60%, B 52%/37%, C 23%/15%). With B, long-term responders were most frequently able to reduce analgesic use (74%, C 58%, L 38%). DISCUSSION: Despite the long duration of the disease, the most used off-label topical drugs L and B demonstrated a high primary response rate (in contrast to C), with most benefiting from long-term treatment.