The effects of the suppository vehicle, drug concentration, and nonionic surfactants on in uitro benzocaine dialysis through a cellulose membrane and on rectal absorption in rats of total radioactivity following administration of 3H-benzocaine were investigated. In uitro dialysis correlatea quite well with in uiuo absorption, and drug release was greater from water-soluble vehicles than from oleaginous vehicles. Inclusion of a nonionic hydrophilic or lipophilic surfactant in cocoa butter resulted in a statistically significant increase for in uitro drug release, while a lipophilic surfactant showed little effect in uiuo and a hydrophilic surfactant depressed release in uiuo. Both types of surfactant had small effects on release from polyethylene glycol. In uitro release of benzocaine from some commercially available suppositories was compared with experimental preparations. Variation in blood radioactivity following administration of the same concentration of 3H-benzocaine in the same dosage form in male and female rats is reported.
Keyphrases Absorption-benzocaine from suppositories, effect of vehicle, drug concentration, and nonionic surfactants, rats Distribution-benzocaine from suppositories, effect of vehicle, drug concentration, and nonionic surfactants, rats Benzocaine-absorption and distribution from suppositories, rats [II Suppositoriesabsorption and distribution of benzocaine, rats 0 Dosage formssuppositories, absorption and distribution of henzocaine, rats ~~ 8 -a Average weight of' 1 0 suppositories. b Avcra e weight o f six o r niorc suppositories. CPolyethylenc glycol vehicle consisted of polycthylenc glycol 1000 (75%) and polyethylcnc glycol 4000 (25'%,) d Hcrshcy's. e Coninicrcially available product.. P Also cont.iins hcxachlorophcnc, cplicdrinc sulfate, and bismuth subgallatc. R Also contains osyquinolinc sulfate, zinc oxide, nienthol, and balsaln peru. *Also contains ephedrine sulfate, oxyquinoline sulfate, zinc oxide, bisniuth subgallate, a n d balsam peru.