Assessing the Efficacy of Monthly 308 nm Excimer Lamp Double-Stacked Pulse Adjusted Therapy for Alopecia Areata

Introduction

Alopecia areata (AA) is an autoimmune disease characterized by T cell-mediated attack on the hair follicle. Although there are a wide range of therapies, the majority of them are not satisfactory due to side effects, pain due to intralesional injections or limited efficacy. In this study, we sought to evaluate the efficacy, influence factors, and safety of 308 nm excimer lamp used in a monthly basis in a double-stacked pulse manner for the treatment of AA.

Methods

This was a prospective study, using 308 nm excimer lamp in a double-stacked pulse therapy for AA. The primary endpoint was the improvement in SALT score.

Results

A total of 40 patients with AA were enrolled in this study. Forty (100%) patients achieved clinical response. Hyperpigmentation and erythema occurred on the treated alopecic areas of all patients but they were considered tolerable. Patients of younger age or with a smaller area of affection had a better overall treatment response.

Conclusion

308 nm excimer lamp therapy is an excellent option for single or multiple AA because it achieves a good clinical response with less adverse effects than other therapies. This therapy may be useful for low-income countries where new JAK inhibitors are not available, however, for patients with extensive hair loss, it is not as effective and thus, it may be unfit for patients with alopecia totalis and alopecia universals.

Photochemical removal of acetaldehyde using 172 nm vacuum ultraviolet excimer lamp in N2 or air at atmospheric pressure

The photochemical removal of acetaldehyde was studied in N₂ or air (O₂ 1-20%) at atmospheric pressure using side-on and head-on types of 172 nm Xe₂ excimer lamps. When CH₃CHO was decomposed in N₂ using the head-on lamp (HL), CH₄, CO, and CO₂ were observed as products in FTIR spectra. The initial removal rate of CH₃CHO in N₂ was ascertained as 0.37 min^-1. In air (1-20% O₂), HCHO, HCOOH, CO, and CO₂ were observed as products in FTIR spectra. The removal rate of CH₃CHO in air using the side-on lamp (SL) increased from 3.2 to 18.6 min^-1 with decreasing O₂ concentration from 20 to 1%. It also increased from 2.5 to 3.7 min^-1 with increasing CH₃CHO concentration from 150 to 1000 ppm at 20% O₂. The best energy efficiency of the CH₃CHO removal using the SL in a flow system was 2.8 g/kWh at 1% O₂. Results show that the contribution of O(₁D) and O₃ is insignificant in the initial decomposition of CH₃CHO. It was inferred that CH₃CHO is initially decomposed by the O(₃P) + CH₃CHO reaction at 5-20% O₂, whereas the contribution of direct vacuum ultraviolet (VUV) photolysis increases concomitantly with decreasing O₂ pressure at < 5% O₂. After initial decomposition of CH₃CHO, it was oxidized further by reactions of O(₃P), OH, and O₃ with various intermediates such as HCHO, HCOOH, and CO, leading to CO₂ as a final product.

Efficient removal of benzene in air at atmospheric pressure using a side-on type 172 nm Xe2 excimer lamp

The photochemical removal of benzene was studied in air at atmospheric pressure using a side-on type 172 nm Xe₂ excimer lamp with a wide irradiation area. After 1.5 min photoirradiation, C₆H₆ (1000 ppm) in air was completely converted to HCOOH, CO, and CO₂ at a total flow rate of 1000 mL/min. The initial decomposition rate of C₆H₆ was determined to be 1.18 min^-1. By using a flow system, C₆H₆ (200 ppm) was completely removed at a total flow rate of 250 mL/min. The conversion of C₆H₆ and the energy efficiency in the removal of C₆H₆ changed in the 31-100% and 0.48-1.2 g/kWh range, respectively, depending on the flow rate, the O₂ concentration, and the chamber volume. On the basis of kinetic model simulation, dominant reaction pathways were discussed. Results show that the O(³P) + C₆H₆ reaction plays a significant role in the initial stage of the C₆H₆ decomposition. Important experimental parameters required for further improvement of the C₆H₆ removal apparatus using a 172 excimer lamp were discussed based on model calculations.