SPERMICIDAL ACTIVITY-STRUCTURE RELATIONSHIP OF NONOXYNOL OLIGOMERS - PHYSICOCHEMICAL BASIS

Oligomers of nonoxynol-9 were isolated and purified using a preparativ e HPLC technique. The various oligomers obtained possess the same nony lphenol base, but vary in the length of poly(ethylene oxide) chain and thus have different physicochemical characteristics. The partitioning of these oligomers into human sperm and vaginal mucosa was performed. While the partitioning of the oligomers into human sperm was observed to follow a bell-shaped pattern, the vaginal mucosa partitioning show ed a dome-shaped pattern. The permeation across the vaginal mucosa exc ised from the sheep was also studied for selected oligomers and the ra te of vaginal permeation was found to follow zero-order kinetics, whic h varied with the number of ethylene oxide units in the oligomers stud ied. The vaginal permeabilities calculated for all the oligomers studi ed were observed to be a linear function of their partition coefficien ts. It is interesting to note that as the number of ethylene oxide uni ts increased, both the spermicidal activity and the vaginal permeabili ty increased proportionally, reaching a peak with a poly(ethylene oxid e) chain having 8-10 ethylene oxide units, and then decreased as the c hain length increased further. The observations substantiate the role of hydrophilic-lipophilic balance in the activity-structure relationsh ip of nonoxynol-9 oligomers.