Study on Encapsulation of Diethyl Phenyl Acetamide in Calcium-Alginate Microsphere for Enhanced Repellent Efficacy

Biopolymeric and lipid-based nanotechnological strategies for the design and development of novel mosquito repellent systems: recent advances

Mosquitoes are the most medically important arthropod vectors of several human diseases. These diseases are known to severely incapacitate and debilitate millions of people, resulting in countless loss of lives. Over the years, several measures have been put in place to control the transmission of mosquito-borne diseases, one of which is using repellents. Repellents are one of the most effective personal protective measures against mosquito-borne diseases. However, conventional delivery systems of repellents (e.g., creams, gels, and sprays) are plagued with toxicity and short-term efficacy issues. The application of biopolymeric and lipid-based systems has been explored over the years to develop better delivery systems for active pharmaceutical ingredients including mosquito repellents. These delivery systems (e.g., solid lipid micro/nanoparticles, micro/nanoemulsions, or liposomes) possess desirable properties such as high biocompatibility, versatility, and controlled/sustained drug delivery, and thus are very important in tackling the clinical challenges of conventional repellent systems. Their capability for controlled/sustained drug release has improved patient compliance as it removes the need for consistent reapplication of repellents. They can also be engineered to reduce repellents' skin permeation, consequently improving their safety. However, despite the benefits that these systems offer very few of them have been successfully translated to the global market for commercial use, a vital challenge that previous reports have not thoroughly examined. The issue of limited clinical translation of novel repellent systems is a vital aspect to consider, as the ultimate goal is to move these systems from bench to bedside. As such, this study seeks to highlight the recent advances in the use of biopolymeric and lipid-based systems for the development of novel mosquito-repellent systems and also analyze the challenges that have limited the clinical translation of these systems while proposing possible strategies to overcome these challenges.

Trends in insect repellent formulations: A review

The use of natural and synthetic repellents, marketed in different pharmaceutical forms, is growing in the world due to the emerging vector-borne viral diseases as Dengue, Zika, Chikungunya, Yellow Fever and Malaria. The choice of the ideal formulation will depend on a series of factors to be analyzed: type of repellent active (natural or synthetic), pharmaceutical forms (spray, lotion, cream, gel), action time duration (short or long), environment of exposure and the user (adult, pregnant women, children, newborn). The most used repellents are DEET, IR3535 (Ethyl Butylacetylaminopropionate) (EB), Icaridin (Picaridin) and essential oils, each of them presenting advantages and disadvantages. DEET is the oldest and the most powerful repellent available in the market, thus being the reference standard. For this reason, there are many classic formulations available in the market containing the chemical component DEET in spray forms and lotions. However, due to its toxicity, DEET is not recommended for children up to 6 months and pregnant women. DEET has been an option along with other market-shared products as IR3535 and Icaridin (Picaridin), which present less toxicity in their composition. IR3535 is the less toxic and may be prescribed for children over 6 months of age and pregnant women so that they have been the best option because of the lower toxicity levels presented. IR3535 is the one that has the lowest toxicity level among the three options and may be prescribed for children above 6 months of age and pregnant women. Icaridin is as potent as DEET, but less toxic, and has the advantage of having the long-lasting action among the aforementioned repellents. The new formulations have been based on controlled release systems (CRS). The CRSs for repellents comprise polymer micro/nanocapsules, micro/solid lipid nanoparticles, nanoemulsions/microemulsions, liposomes/niosomes, nanostructured hydrogels and cyclodextrins. There are many formulations based on micro and nanocapsules containing DEET and essential oils to increase repellent action time duration and decrease permeation and consequently, systemic toxicity. The development of new formulations for the IR3535 and Icaridin is a research field yet to be explored. The current trend is the use of natural repellent actives such as essential oils, which present low toxicity, do not harm the environment, but present reduced repellent action time due to rapid evaporation after skin application. CRSs have been used as vehicle of natural repellents to improve long-lasting repellent action, reduce skin permeation and systemic effects.