Because poly(butyl a-cyanoacrylate) was less toxic than poly(isobutyl a-cyanoacrylate)and its nanocapsules could be orally absorbed via intestine wall

the polymeric nanocapsules as drug delivery system of peptides was prepared by the interracial polymerization of butyl a-cyanoacrylate other than isobutyl a-cyanoacrylate used previously．The aqueous phase contained a surfactant such as Tween 20 and polymericstabilizer such as dextrin T-70

dextrin T-40 as well as Poloxamer 188 And the organic phase composed of monomer butyl a-cyanoacrylate and a cosolvent such as glycerol trioleate or benzyl alcohol in bulky solvent ethanol or acetone．The nanocapsule sizes and their distribution were measured by laser scattering technique and transmission electron micrography．It was investigated the influence of the used surfactants

polymeric stabilizers

cosolvents

and temperature in vacuum evaporation on the nanocapsule sizes．The results show that dextrin T-70 is a better polymeric stabilizer than its low molecular weight analog dextrin T-40 and Poloxamer 188 for the monomer phase soluble in ethanol to be dispersed in aqueous phase with Tween 20 as a surfaetant The size of the polymeric nanocapsules decreased with increase of amounts of dextrin T-70 and Tween 20 dissolved in aqueous phase．Compared with glycerol trioleate

benzyl alcohol as cosolvent could made the nanocapsules larger and smoother because benzyl alcohol might make the immigration of the solvent

ethanol

in the monomer phase into aqueous phase more slowly．In addition

when the formed suspension of poly(butyl a-eyanoacrylate)nanocapsules was concentrated by evaporation in vacuum at 30℃ instead of 20℃

small nanocapsules would be aggregated into large particles．