Design of a simulated urethra model for the quantitative assessment of urinary catheter lubricity

Catheters designed for intermittent urological catheterization should posse ss appropriate lubricity and mechanical properties to ensure optimal clinic al performance. However, the lack of a reproducible in vitro method that si mulates clinical use makes it difficult to evaluate the lubricity of urinar y catheters and other devices for urethral insertion. Therefore, this study describes a suitable method based on use of a Texture Analyzer to characte rize the lubricity of such devices. The novel method was susequently applie d to the evaluation of commercially-available intermittent urinary catheter s. In addition, other important physicochemical properties of these cathete rs were examined, namely Young's modulus, degree of hydration and morpholog y. Catheter lubricity was quantified, using a Texture Analyzer, by measurem ent of the forces required for insertion and removal of the device from two model substrates, agar and mucin-coated silicone tubing. Significant diffe rences in lubricity were identified between the commercially-available cath eters, with Aquacath and Lofric exhibiting the lowest forces of insertion a nd removal. There were no significant differences between the extent of hyd ration between the catheters, with the exception of Uro-flo which exhibited the lowest hydration. Therefore, the differences in lubricity were not dir ectly related to the extent of hydration. The forces required for insertion /removal of all catheters were markedly greater in the simulated mucin mode l than in the agar substrate and the former, simulated urethra model, was a ccepted to mimic more accurately, the in vivo situation. Significant differ ences were observed between the Young's Moduli of the catheter biomaterials , with Aquacath possessing the largest value. In conclusion, this study has described the use of a texture analyzer and polymeric substrates for the e valuation of biomaterial lubricity. Using these methods, Aquacath and Lofri c catheters exhibited greatest lubricity. However, following additional con sideration of the mechanical properties of these biomaterials, Aquacath pos sessed the most appropriate physicochemical properties for use in intermitt ent catheterization. (C) 2001 Kluwer Academic Publishers.