Enriched enrollment randomized double-blind placebo-controlled cross-over trial with phenytoin cream in painful chronic idiopathic axonal polyneuropathy (EPHENE): a study protocol

Drug release profile of phenytoin-loaded starch-based biomaterials incorporating hierarchical microparticles with photothermal effects

This study aimed to synthesize phenytoin (PHT)-loaded water chestnut starch-based biomaterials and evaluate their drug release kinetics for use in transdermal drug delivery systems for antiepileptic therapy. Hierarchical microparticles (HMPs) extracted from human hair were also used to improve the PHT release efficiency. The physicochemical characteristics of PHT, HMPs, and the prepared biomaterials were evaluated by physical properties, antimicrobial activities, FE-SEM, FT-IR, XRD, 1H NMR, and 13C CPMAS solid-state NMR. The photothermal effect and the PHT release profile were confirmed through 808 nm NIR laser irradiation. After 30 min of the laser exposure, the temperature of the HMP-added biomaterials increased by 1.50-1.59 times compared to that of without the HMPs. PHT release in buffers and artificial skin test under NIR laser irradiation enhanced by 1.20-1.85 times owing to the photothermal effect. The release kinetics in pH buffer and artificial skin were determined using the Fickian diffusion and Korsmeyer-Peppas models. Additionally, to verify the transdermal penetration of PHT, drug-release simulations were conducted using rhodamine B in agar blocks and pig ears. The results implied that the photothermal effect of the HMPs enhanced the penetration of the drug.

Is the Capsaicin 179 mg (8% w/w) Cutaneous Patch an Appropriate Treatment Option for Older Patients with Peripheral Neuropathic Pain?

Introduction

Capsaicin 179 mg (8% weight per weight) cutaneous patch ("capsaicin patch") is a recommended topical treatment for peripheral neuropathic pain (PNP). In older patients, topical treatments may be preferred over systemic treatments, but data specific to the older population are scarce.

Methods

We conducted pooled analyses of multiple clinical trials to evaluate efficacy and safety of capsaicin patch in older patients. The analysis of efficacy included four randomized, double-blind, 12-week studies with similar trial design comparing a single treatment of capsaicin 179 mg cutaneous patch vs low-dose control patch in post-herpetic neuralgia. For the safety evaluation, data were pooled from 18 interventional studies in which capsaicin patch was used in PNP with varying etiologies.

Results

Capsaicin patch had similar analgesic efficacy in elderly (n=582) and non-elderly patients (n=545) in terms of change from baseline to 2-12 weeks in the 11-point numeric pain rating scale (NPRS) score for average pain over the previous 24 hours. In both age groups, decrease in NPRS score was significantly greater with capsaicin patch vs control. Older patients treated with capsaicin patch were significantly more likely than those in the control group to achieve responder status (ie mean decrease in NPRS score from baseline to week 2-12 of at least 30% or ≥2 points): 36.1% vs 27.1% (odds ratio [OR] [95% CI] 1.52 [1.06, 2.18]; P=0.0231) and 33.1% vs 20.9% (OR [95% CI] 1.90 [1.30, 2.78]; P=0.0009) for active treatment vs control group, respectively. Similar proportions of non-elderly patients (n=2,311) and elderly patients (n=537) treated with capsaicin patch experienced treatment-emergent adverse events (TEAEs) (81.6% and 78.1%, respectively) and serious TEAEs (8.2% and 7.2%), with application-site reactions the most common TEAEs in both groups.

Conclusion

The capsaicin patch was equally efficacious and well tolerated in older patients as in younger patients.