Melanosis coli

Aloe, senna, and cascara occur naturally in plants. These laxatives are poorly absorbed and after hydrolysis in the colon, produce a bowel movement in 6-12 hours when given orally and within 2 hours when given rectally. Chronic use leads to a characteristic brown pigmentation of the colon known as melanosis coli. There has been some concern that these agents may be carcinogenic, but epidemiologic studies do not suggest a relation to colorectal cancer. 

Senna may cause abdominal cramps and diarrhoea. Prolonged use of senna may produce watery diarrhoea with excessive loss of fluid and electrolytes, particularly potassium, muscular weakness and weight loss. Changes in the intestinal musculature associated with malabsorption and dilation of the bowel, similar to ulcerative colitis and to megacolon, may also occur. Cardiac and renal symptoms have been reported. Melanosis coli and a red or yellow discoloration of the urine and faeces may also occur. 

Melanosis coli occurred in a 39-year-old liver transplant patient who took an over-the-counter product containing aloe, rheum, and frangula (4). The typical brownish pigmentation of the colonic mucosa developed over 10 months. The medication was withdrawn and follow-up colonoscopy 1 year later showed normal looking mucosa. However, a sessile polypoid lesion was found in the transverse colon. Histology showed tubulovillous adenoma with extensive low-grade dysplasia. 

Willems M, van Butrren HR, de Krijger R. Anthranoid self-medication catrsing rapid development of melanosis coli. Neth J Med 2003 61(l) 22-4. 

The safety and efficacy of senna have been reviewed (4). Its rhein-anthrone-induced laxative effects occur through two distinct mechanisms, an increase in intestinal fluid transport, which causes accumulation of fluid intralumm-ally, and an increase in intestinal motihty. Senna can cause mild abdominal complaints, such as cramps or pain. Other adverse effects are discoloration of the urine and hemorrhoidal congestion. Prolonged use and overdose can result in diarrhea, extreme loss of electrolytes, especially potassium, damage to the surface epithelium, and impairment of bowel function by damage to autonomic nerves. Abuse of senna has also been associated with melanosis coli, but resolution occurs 8-11 months after withdrawal. Tolerance and genotoxicity do not seem to be problems associated with senna, especially when used periodically in therapeutic doses. 

Weiss SH, Wands JR, Yardley JH. 1973. Demonstration by electron defraction of black mercuric sulfide (b-HgS) in a case of "melanosis coli and black kidneys" caused by chronic inorganic mercury poisoning. Lab Invest 401-402. 

Most of the concerns with the use of diphenylmethane derivatives apply to the anthraquinone derivatives. In addition, the anthraquinone derivatives may cause melanosis coli, an accumulation of dark pigment, mainly in the cecum and rectum, that is evident after 4 to 13 months of use. A pathologic effect of melanosis coli has not been demonstrated, and it appears to be reversible after anthraquinones have been discontinued for 3 to 6 months. 

A cohort study also aimed to clarify whether laxative use and melanosis coli (a blackish-brown discoloration of the colonic mucosa caused by longterm use of anthranoid-containing laxatives) are risk factors for colorectal can-... 

Melanosis coli is observed in 12-31% of unselected constipated patients. A causal relationship between melanosis coli and use of anthraquinone laxatives has been shown in animals and humans. Sennosides produce melanosis coli after 4—13 mo of use, which disappears 5-11 mo after cessation of sennoside use. Melanosis coli begins abruptly at the ileocolonic junction and may extend to the dentate line. The intensity is highest in the cecum and becomes less intense in the aboral direction, and may increase again in the rectum, with a prevalence of 1-8% on proctoscopy. The pigment has not been definitively identified, but it is probably lipofuscin. Even if melanosis coli cannot be seen... 

Nusko G, Schneider B, Muiller G, Kusche J, Hahn EG. Retrospective study on laxative use and melanosis coli as risk factors for colorectal neoplasma. Pharmacology 1993 47(Suppl 1) 234—41. 

Excessive apoptosis Melanosis coli, Shigella flexneri dysentery, graft versus host disease, AIDS, inflammatory bowel disease. 

Internal use of aloe latex is contraindicated in persons with the following conditions intestinal obstruction, abdominal pain of unknown origin, or any inflammatory condition of the intestines (i.e., appendicitis, colitis, Crohn s disease, irritable bowel syndrome) (Bensky et al. 2004 Bradley 1992 Chadha 1988 Roth et al. 1984 Weiss and Meuss 2001 Wichtl 2004) melanosis coli hemorrhoids (Bradley 1992 Felter and Lloyd 1898 List and Horhammer 1973 Roth et al. 1984) liver... 

A prospective cohort study of the risk of anthraquinone laxatives use for the development of colorectal neoplasms indicated no statistically significant risk of anthranoid use for the development of colorectal adenomas or carcinomas. Macroscopic and high-grade microscopic melanosis coli were not significant risk factors for the development of adenomas or carcinomas (Nusko et al. 2000). 

In a retrospective study of 2277 patients who underwent colonoscopy, the correlation between patients laxative use or melanosis coli and colorectal neoplasms was examined. Increases in colorectal adenomas were observed in patients with melanosis coli and in patients with a history of laxative use (Nusko et al. 1993). 

Gastrointestinal A 74-year-old woman developed severe melanosis coli of the whole colon after using anthraquinone laxatives over many decades [72 ]. Endoscopy showed marked black pigmentation of the colonic mucosa, which was confirmed by histology as widespread lipofuscin granulation. Several adenomatous lesions were found, although no colorectal cancer was detected. 

Abendroth A, Klein R, Schlaak J, Metz KA, Dobos GJ, Langhorst J. Impressive picture of a melanosis coli after chronic anthraquinone laxative use—is there an increased risk for colorectal cancer Z Gastroenterol 2009 47 579-82. 

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