Inclusion complexation of carbaryl and  -cyclodextrin in solution and in the solid state

This study was carried out with the aim of investigating the interactions between beta-cyclodextrin and carbaryl, a carbamate pesticide, and their effect on some physico-chem. properties of carbaryl, such as aq. soly. and lipophilicity. The interactions between carbaryl and beta-cyclodextrin were thoroughly investigated both in soln. and in the solid state. The effect of beta-cyclodextrin on the aq. soly. of carbaryl was evaluated by the phase soly. method. The amt. of carbaryl dissolved increased linearly with the addn. of beta-cyclodextrin according to an AL type plot and without pptn. of the complex. The apparent stability const. of the complex was 289 +/- 21 M-1, assuming a 1:1 stoichiometry; this value was confirmed by a method based on CD measurements. Equimolar carbaryl/beta-cyclodextrin solid systems were prepd. by phys.-mixing and freeze-drying, and fully characterized by Differential Scanning Calorimetry, X-ray powder diffractometry and Fourier Transform Infra-Red anal. The results of the solid state study demonstrated that the freeze-drying method yields a system with a high degree of amorphization and yields an inclusion complex. The dissoln. profile of the pesticide was affected by the physico-chem. properties of each solid system, the freeze-dried form dissolving more rapidly. However, the phys. assocn. of beta-cyclodextrin and carbaryl enhanced the aq. soly. of the insecticide as well.