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Phenformin is an antidiabetic drug from the biguanide class. It was marketed as DBI by Ciba-Geigy, but was withdrawn from most markets in the late 1970s due to a high risk of lactic acidosis, which was fatal in 50% of cases. Phenformin was discovered in 1957 by Ungar, Freedman and Seymour Shapiro, working for the US Vitamin Corporation. Clinical trials begun in 1958 showed it to be effective, but with gastrointestinal side effects. ==Toxicity== Phenformin sales began to decline in the US from 1973 due to negative trial studies and reports of lactic acidosis. By October 1976, the FDA Endocrinology and Metabolism Advisory Committee recommended phenformin be removed from the market. The FDA began formal proceedings in May 1977, leading to its eventual withdrawal on November 15, 1978. In 1977, 385,000 patients with early-stage diabetes were taking phenformin in the US. Ralph Nader's Health Research Group put the US government under pressure to ban the drug. Ciba-Geigy Corp resisted, claiming there was no satisfactory alternative for many patients. However, in July the FDA declared the drug an "imminent hazard to the public health" and gave doctors 90 days to switch to an alternative treatment (such as insulin, dietary restrictions or other drugs). As of 2008, phenformin was still legally available in Italy, Brazil, Uruguay, China, Poland, Greece and Portugal. Cases of phenformin-induced lactic acidosis continue to be reported worldwide. In Hong Kong, where phenformin is banned, cases of phenformin-induced lactic acidosis have occurred after taking Chinese proprietary medicines, claiming to be herbal, which were adulterated with phenformin. In the US, the FDA has recalled Chinese "herbal products" containing phenformin. The related drug metformin is considerably safer than phenformin, with three cases of lactic acidosis per 100,000 patient-years compared to 64 cases per 100,000 patient-years, and those are mostly confined to patients with impaired renal function. Cimetidine may reduce renal clearance of phenformin and increase lactic acidosis risk. There is also increased risk of lactic acidosis with alcohol, nephrotoxic drugs. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Phenformin」の詳細全文を読む スポンサード リンク
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