METFORMIN – INDUCED DIARRHEA AS DELAYED ADVERSE REACTION AFTER MANY YEARS OF USE – CASE REPORT
Abstract
Background: Metformin is an oral antidiabetic drug from bigvanides group. It does not cause hypoglycemia, and therefore has found its place as a first-line therapy in type 2 diabetes. It is used both as mono-therapy and as adjunctive therapy with other anti-diabetics and insulin. Some of the most common adverse reactions of metformin are: gastrointestinal upset, diarrhea, nausea, flatulence and vomiting. Adverse reactions usually occur at the beginning of the therapy.
Aim: To show the potential of metformin to cause delayed adverse effects after years of use.
Case report: A sixty-four-year-old woman with type 2 diabetes was treated with metformin for ten years. Several months ago she started to have diarrhea with fluctuating character and intensity. She lost 20 pounds in weight without a special diet. Gastroenterologist and surgeon were consulted, but the cause of diarrhea was not established. A clinical pharmacologist was consulted next to evaluate possible relationship between diarrhea and medication. According to the relevant literature, metformin had the highest prevalence of diarrhea among the medication that was taken by the patient. Therefore, the strategy of discontinuation and then re-challenge by the drug was used. Two days after the metformin was discontinued the diarrhea stopped, and five days later, after the patient was re-challenged by the drug, diarrhea reappeared, with similar characteristics as before.
Conclusion: Metformin-induced diarrhea usually occurs at the beginning of the treatment. However, it could have delayed appearance, even after many years of continuous use of metformin.References
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