Introduction Calcium oxalate is the predominant component of most renal stones; they occur in 10% of patients with bile salt and/or fatty acid malabsorption due to enteric hyperoxaluria¹. Patients who have undergone extensive ileal resection, jejuno-ileal bypass surgery or a Roux-en-Y gastric bypass, whose colon remains in continuity, are at a greater risk of developing enteric hyperoxaluria. It is managed by dietary restriction of oxalate and fat, a high calcium intake, and increasing water intake to ensure a daily urine volume of more than 3 litres. The latter is difficult to achieve in patients with short bowel syndrome.

Ox-Absorb^® is an organic marine hydrocolloid derived from plants and seaweed and was first described in the 1980’s as a promising new treatment for enteric hyperoxaluria. It was also noted that it thickened stools and reduced stool frequency. Ox-Absorb^®is unlicensed in the UK and imported on a named patient basis from the USA. When it was used by the renal physicians at North Bristol NHS Trust to reduce oxalate stone formation, patients reported beneficial effect on stool frequency and consistency.

Method We conducted a retrospective case note review of all patients prescribed Ox-Absorb® in North Bristol NHS Trust. Drug history, weight, change in stool consistency and urinary oxalate levels were documented. Net reduction in tablet burden and a cost analysis of the use of Ox-Absorb^®were calculated.

Results 8 patients were prescribed Ox-Absorb^®. 7/8 patients reported thicker stools and reduced stool frequency and there was a reduction in tablet burden (mean 8.6 tablets; range 2 to 22; median 7). Mean net reduction of tablets was 22% (median 29%). There was a cost reduction in 3/8 patients, all of whom were taking higher doses of loperamide, codeine phosphate and Creon^®(£1.09, £0.57 and £0.15 per day). 3/8 patients had to stop the drug due to supply problems and all noted worsening in diarrhoea symptoms which improved on restarting the drug. Urinary oxalate was reduced in only 2/8 patients.

Conclusion In this small cohort, patients who were prescribed Ox-Absorb^® reported thicker stools and were able to reduce their net anti-diarrhoeal tablet burden. This was cost effective in patients taking higher doses of loperamide, codeine and Creon^®. We believe a larger study of this drug relative to standard treatments is justified.

Disclosure of interest None Declared.