Development & evaluation of controlled release formulations of DEPA, an insect repellent.

Three controlled release formulations of the insect repellent DEPA (N, N-Diethyl phenylacetamide), Depa-A, Depa-B and Depa-C have been developed and tested on human subjects against Aedes aegypti adult mosquitoes for repellency and the results were compared to those of a solution of DEPA (Depa-0). The increase in the protection time of the formulations, as compared to Depa-0 was compared. Depa-B was found to be effective with a protection time of 7.13 and 6.15 h and percentage increase in protection time of 44.5 and 38.2 at the two application rates of 0.5 and 0.25 mg/cm2 of the repellent. This observation agreed with the studies carried out on the evaporation of the repellent formulations on two models, on adsorbing and nonadsorbing surfaces for the relative adsorption and evaporation by analysing the repellent concentrations, using an infrared spectrophotometer.