Long term treatment with stimulant laxatives - clinical evidence for effectiveness and safety?

Bisacodyl and sodium picosulfate are classified both as stimulant laxatives, approved for short-term treatment of constipation and sold without prescription (OTC). Stimulant laxatives are associated with harmful long-term colonic effects and possible carcinogenic risk - and evidence support that these agents are used for longer periods. We aimed to compile and review the clinical trial evidence describing the effectiveness and safety of long-term treatment (>14 continuous days) with stimulant laxatives. The PubMed database was searched for all randomised clinical trials (RCTs) examining the effect of bisacodyl or sodium picosulfate in adult patients diagnosed with constipation. Five RCTs (one open-label and four double-blinded) with intervention periods of four weeks duration were eligible. These included 1008 patients, whereof 26% dropped out. A positive global assessment of efficacy was obtained in 78-99% of the patients treated with bisacodyl or sodium picosulfate. Notably, the same global assessment was obtained in 46-54% of the placebo-treated patients. Compared to placebo, an improvement in stool consistency and a significant increase in number of bowel movements peer week were seen in favor of bisacodyl and sodium picosulfate. However, for pyridostigmine, a significant difference was seen compared to bisacodyl. AEs were generally mild, but frequent (up to 72%) mostly diarrhea and abdominal pain. The evidence base does not support use of stimulant laxatives for more than four weeks. Due to the substantial use of stimulant laxatives including sold OTC, longer term RCTs and epidemiological studies investigating effects and safety on the longer term are warranted.