Relief of stent related symptoms: review of engineering and pharmacological solutions.

ABSTRACT

PURPOSE: We review the recent publications on developing engineering and pharmaceutical agents to alleviate stent related symptoms, and examine basic science studies that may support a particular approach. MATERIALS AND METHODS: Data on randomized controlled trials for relief of stent related symptoms were analyzed. Studies involving engineering and pharmacological agents to resolve stent related morbidity were assessed separately. RESULTS: A variety of physical characteristics of stents, including materials, diameter, length and shape, have been modified to reduce stent related symptoms. Numerous studies have been conducted to engineer the ideal stent without clear and definite conclusions. There are mixed results with materials and negative results with shape. Appropriate stent length appears to be important but decreased diameter has not been shown to help. A recent study using a ketorolac eluting stent showed no significant benefit. Even with the best material and length it appears that patients still have significant stent related symptoms. To relieve stent related symptoms several classes of oral medications have been proposed for off-label use based on intuition or experience. Recently prospective, randomized, placebo controlled trials have been performed, along with basic science studies regarding the pharmacology of the ureter. They showed a clear and consistent beneficial effect of alpha1-blockers in patients with indwelling ureteral stents. CONCLUSIONS: Although there have been many advances in stent composition, construction geometry and design, the ideal stent has yet to be engineered. By contrast, the oral administration of alpha-blockers has shown the greatest reduction in stent morbidity.