Bowel preparation with bisacodyl and 2 liters of polyethylene glycol is more acceptable to patients than a 4-liter regimen and is equally effective in cleansing the colon.

The effect of histamine and cimetidine on the growth of four human colon cancer cell lines was studied. Histamine significantly stimulated the uptake of tritiated thymidine in vitro in a dose dependent manner, to a maximum of 120% and 116% of controls for C170 and LIM2412, respectively. This effect was antagonised by cimetidine, but not diphenhydramine.

Summary Histamine has recently been shown to be a growth factor for some gastric and colorectal cancer cells. Previous studies have shown that cimetidine blocks in vitro and in vivo histamine-stimulated growth and cAMP release from the human colonic cancer cell line, C170. In this study, ranitidine, another H2 receptor antagonist, did not affect either basal or histamine-stimulated in vitro proliferation of C170, and failed to prevent cAMP release in vitro. Ranitidine did not inhibit in vivo growth of C170 at a dose of 1, 10, 25, 50 or 100 mg kg-', in contrast to 50 mg kg -day-' cimetidine, which produced 39.3% inhibition of tumour volume (P<0.01) after 23 days' treatment. Ranitidine did not inhibit in vivo histamine-stimulated growth of C170 cells.LIM2412, another colonic cancer cell line, was significantly stimulated by both cimetidine and ranitidine in vivo. Ranitidine had no effect on in vitro cell proliferation.

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