Rifaximin in the management of colonic diverticular disease.

Rifaximin is a rifamycin derivative that acts by inhibiting bacterial RNA synthesis. Since it is virtually unabsorbed after oral administration, its bioavailability within the GI tract is high, with intraluminal and fecal drug concentrations largely exceeding the minimum inhibitory concentration values observed in vitro against a broad spectrum of bacteria, including Gram-positive and Gram-negative bacteria, both aerobes and anaerobes. The GI tract, therefore, represents the primary therapeutic target and the disorders in which intestinal bacteria have a pathogenic role represent the main indication. This is the case with colonic diverticular disease. As a consequence, the broad antibacterial activity of rifaximin appears to be of value in the treatment of this clinical condition. Clinical trials have provided evidence of the substantial benefit of rifaximin in diverticular disease. Indeed, available data show the efficacy of the drug in achieving symptomatic relief in patients with uncomplicated disease. A therapeutic gain of approximately 30%, compared with fiber supplementation only, can be expected after cyclic administration of rifaximin for 12 months. However, its value in the prevention of inflammatory complications of the disease needs to be further explored. Recent studies have shown some evidence of synergy between rifaximin and mesalazine and suggest that a combined treatment could be worthwhile in selected subsets of patients with diverticular disease.