Drug treatment of overactive bladder: efficacy, cost and quality-of-life considerations

Abstract

Overactive bladder (OAB) syndrome has been recognised by the International Continence Society as an important symptom syndrome that affects millions of people worldwide. Quality of life is affected in most people with OAB; however, the aetiology is unknown. Some researchers suggest that it is because of a damage to central inhibitory pathways or sensitisation of peripheral afferent terminals in the bladder, others suggest that it is a bladder muscle problem; the reality is probably a spectrum encompassing these two main explanations. Therefore, treatment is difficult and is aimed at alleviating symptoms (being those of urgency, with or without urge incontinence, usually with frequency and nocturia) rather than treating the cause. A thorough patient history and physical examination are required to establish a possible diagnosis. Frequency/volume charts form an important aid to the diagnosis. Once a presumptive diagnosis is made, conservative management forms the first line of treatment and includes lifestyle modifications, bladder training and pelvic floor exercises. If this fails, pharmacotherapy, in the form of anticholinergic drugs, is initiated. There are many antimuscarinic drugs, for example oxybutynin, tolterodine and trospium chloride. Each has a different specificity to bladder muscarinic receptors, thus producing different adverse effect profiles (e.g. dry mouth, blurred vision and constipation). Different individuals experience these adverse effects to different extents. New anticholinergic drugs, that have undergone phase III trials and are more specific to the muscarinic M3 human bladder receptor, are being introduced to the market in 2004 (e.g. solifenacin succinate and darifenacin). In addition to adverse effect profile, cost and improvement in quality of life are important factors in choosing treatment. Further research is being conducted on other types of drugs and different administration modalities, for example intravesical botulinum toxin A. Sacral nerve neuromodulation is emerging as a potential treatment, but if all treatments fail then surgery is the last resort.