Is cysteamine use effective in the treatment of melasma? A systematic review and meta-analysis.

Melasma is a recurrent hypermelanosis disorder characterized by the appearance of brownish and symmetrical spots on the skin. It affects the quality of life and is resistant to available treatment approaches. Cysteamine has been reported as a promising depigmenting agent for melasma treatment and following formulation enhancement, its use is being reported. This review aimed to evaluate the efficacy of the use of depigmenting formulations containing 5% cysteamine in the treatment of patients with melasma. A systematic search was performed in PubMed, Science Direct, and Scielo databases until December 27, 2021, based on criteria selected by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Statistical analysis was performed with Review Manager 5.4 software. The risk of bias was assessed using the Cochrane Risk of Bias Tool for Randomized Trials. A total of six studies containing 120 melasma patients treated with 5% cysteamine were included in this meta-analysis. The meta-analysis demonstrated that 5% cysteamine is effective for the treatment of patients with melasma (MD 6.26 [95% CI 3.68-8.83], p < 0.0001, I2  = 86%). In this review, through meta-analysis allows concluding that 5% cysteamine is effective in the treatment of melasma and presents a low probability of side or adverse effects.

Sub-lethal effects of essential oil of Lippia sidoides on drywood termite Cryptotermes brevis (Blattodea: Termitoidea).

The drywood termite Cryptotermes brevis (Walker, 1853) (Kalotermitidae) is one of the most important wood structural pest in the world. Substances from the secondary metabolism of plants (e.g., essential oils) have been considered an environmentally safer form of control for urban pests, such as termites. In the present study, we analyzed the lethal and sub-lethal effects of essential oil of Lippia sidoides and its major components on C. brevis pseudergates in two routes of exposure (contact and fumigation). The essential oil of L. sidoides and thymol were more toxic to C. brevis pseudergates when applied by contact (LD50 = 9.33 and 8.20µgmg-1, respectively) and by fumigation (LC50 = 9.10 and 23.6µLL-1, respectively). In general, treatments changed the individual and collective behaviors of C. brevis pseudergates, as well as the displacement and walking speed. The essential oil of L. sidoides and its major components showed a high potential to control C. brevis pseudergates, due to the bioactivity in the two routes of exposure and the sub-lethal effects on the behavior and walking, important activities for the cohesion of C. brevis colonies.