Rifaximin is an oral rifamycin antibiotic that is poorly absorbed by the gastrointestinal system (less than 1%). It has wide antibacterial action against most Gram-positive and Gram-negative aerobic and anaerobic bacteria associated with gastrointestinal infection.
Two licensed products are available, with marketing authorisation held by Norgine:
Targaxan 550 mg film-coated tablets are licensed for the reduction in recurrence of episodes of overt hepatic encephalopathy in people aged 18 years and older at a dose of 550 mg twice daily. The summary of product characteristics notes that clinical benefit in this indication was established from a controlled study in which participants in the study were treated for 6 months.
Xifaxanta 200 mg film-coated tablets are licensed for treating travellers' diarrhoea that is not associated with fever, bloody diarrhoea, 8 or more unformed stools in the previous 24 hours or occult blood or leucocytes in the stool. For this indication, rifaximin is given at a dose of 200 mg every 8 hours for a total of 9 doses. It is not recommended in people aged younger than 18 years.
Rifaximin is not licensed for the treatment of pouchitis and its use for this indication is off-label.
Management of some colorectal diseases may sometimes necessitate removal of the entire colon and rectum (proctocolectomy). This procedure is most commonly performed in people with ulcerative colitis; other indications include colorectal cancer and familial adenomatous polyposis. A pouch may be formed from the terminal ileum, which is attached to the anus so as to maintain normal passage of stool through the anus rather than through a permanent external ileostomy. This is called ileal pouch-anal anastomosis (IPAA).
Pouchitis is defined in the European Crohn's and Colitis Organisation (ECCO) publication European evidence-based consensus on the management of ulcerative colitis: special situations as non-specific inflammation of the ileal reservoir (pouch). It is reported to affect up to 50% of people in the 10-year period after IPAA for ulcerative colitis, although the cumulative incidence of pouchitis in people with an IPAA for familial adenomatous polyposis is much lower.
The ECCO consensus document states that symptoms of pouchitis include pelvic discomfort, abdominal cramps and urgency, tenesmus (a feeling of needing to evacuate the bowels), increased stool frequency and liquidity, and faecal incontinence. There may also be rectal bleeding, fever or other systemic symptoms. Diagnosis of pouchitis relies on evaluation of symptoms and endoscopy ('pouchoscopy') with biopsy of the pouch mucosa. The Pouchitis Disease Activity Index (PDAI), which incorporates symptoms, endoscopy and histological findings, has been developed to standardise diagnostic criteria and assess severity. The range of possible scores is 0–18, with higher scores indicating worse disease. Pouchitis is termed 'active' when symptoms, endoscopy and histological findings are present, and is indicated by a total PDAI score of 7 or more. Active pouchitis is further divided into acute or chronic, depending on the duration of symptoms. The ECCO consensus document defines chronic pouchitis as symptom duration of more than 4 weeks. Up to 10% of people will develop chronic pouchitis needing long-term treatment.
The ECCO consensus document states that pouchitis recurs in more than 50% of people who have experienced it and can comprise infrequent episodes (less than once a year), a relapsing course (1–3 episodes a year) or a continuous course. Complications of pouchitis include abscesses, fistulae, stenosis of the pouch–anal anastomosis and, rarely, adenocarcinoma of the pouch.
The ECCO consensus document states that the optimum treatment of acute pouchitis is not clearly defined and that the evidence base is limited. Antibiotics are the mainstay of treatment, and pouchitis responds to metronidazole or ciprofloxacin in most people. Single antibiotic treatment with either drug is normally the first-line treatment of choice. If pouchitis becomes chronic, combined antibiotic treatment can be effective. Other possible treatments include oral or topical budesonide or infliximab. None of these drugs is licensed specifically for treating pouchitis.
The ECCO consensus document states that, once antibiotic-induced remission has been achieved, a highly concentrated probiotic food supplement (VSL#3) can be effective for maintaining remission. It can also be effective in preventing pouchitis within the first year after surgery. Surgery can be considered as a last resort for people whose pouchitis does not respond to other treatment options.