Positive Control(s) in Polyurethane Condom-Lubricant Compatibility Testing

Abstract

Abstract Despite the proliferation of over-the-counter (OTC) personal lubricants (PLs) in the last two decades, to date, no known positive control has been identified to assess the compatibility of these PLs with polyurethane (PU) condoms. In the absence of suitable positive controls, PU condom compatibility with OTC PLs is assessed using a method built for testing compatibility of latex condoms with PLs. Herein, we attempt to identify a safe-to-handle positive control(s) for determining PU condom-lubricant compatibility. At room temperature (RmT), swelling of and induced stress in PU condom sample coupons were studied at various strain rates after discrete applications of a few ingredients common in commercial PLs. Additionally, stress reduction at a constant stretch was measured at 37°C. At low strain rates, changes in the induced stress and stress-to-strain ratio were detectable because of ingredients, e.g., hydroxy-terminated poly(dimethyl siloxane) of viscosity 25 cSt that caused substantial swelling of the condom materials at RmT, indicating prospective positive controls. At 37 °C, the percent stress reduction in PU samples under constant stretch was significant, with a few PL ingredients that did not significantly swell the PU material at RmT. Ingredients that enable significant stress reduction can serve as positive controls in PU condom-lubricant compatibility testing using the tensile method, provided the strain rate is comparable to the rate of condom-lubricant interaction, as evidenced by swelling study. At RmT, absence of swelling and insignificant changes in tensile properties at high strain rates do not guarantee the absence of interactions. Instead of testing mineral oil on latex condoms, manufacturers may now use a PU condom-specific positive control, when testing compatibility of PU condoms with OTC PLs.