2 Clinical Trials for Various Conditions
Metformin is a safe and effective first-line drug for type 2 diabetes that is also widely recommended for weight loss and diabetes prevention. But, metformin is associated with gastrointestinal and other side effects which prevent its use in 10-20% of patients and appear to limit the usable dose in others. This study is an N-of-1 trial design that will recruit 20 previously metformin-intolerant patients for re-challenge with metformin in a double-blind scenario. In this setting, 'intolerant' means either unable to take metformin at all, or unable to increase the dose past 1,000 mg despite the treating physician's recommendation to do so. Patients will be assigned to take their baseline medication regimen plus 2 weeks of 250 mg per day of metformin extended release, followed by 500 mg metformin XR, 750 mg, and 1,000 mg metformin XR with each treatment period separated by a 2-week course of placebo. Initial treatment, placebo or metformin XR, will be decided randomly. At the end of each two-week treatment period, participants will complete questionnaires assessing overall satisfaction with the medication, gastrointestinal symptoms, and adherence. Six months after the conclusion of the intervention, patients will be asked if they are continuing metformin at a higher dose than upon entry to the trial. This trial has two aims. First, to test the hypothesis that medication satisfaction will be the same during periods of placebo treatment and during periods of treatment with the active drug. The second aim is to test the hypothesis that \> 30% of metformin-intolerant patients in an N of 1 crossover trial are able to tolerate higher-dose metformin at 6-months.
Metformin is associated with a high degree of gastrointestinal intolerance, which limits the effective use of the medication. It is proposed to be an inhibitor of liver mitochondrial glycerophosphate dehydrogenase which results in partial blockade of mitochondrial complex 1 and inhibition of metabolism of lactate to pyruvate. There is also evidence that it is accumulated in gastrointestinal cells, and that there are certain genotypes associated with inclusion or lack of exclusion of the metformin from these cells. To validate this hypothesis investigators propose to give metformin after a standard meal test to see if there is the accumulation of lactic acid in those with gastrointestinal intolerance to metformin, compared to those without intolerance, and to determine if these elevations of lactic acid and GI symptoms are associated with genetic predispositions. Aims: 1. To determine if the GI intolerance to metformin is associated with post meal elevations of lactic acid. a. The test will measure the inhibition of mitochondrial complex 1 levels of lactate to pyruvate compared with non- intolerant subjects. 2. To determine if individuals with gastrointestinal symptoms and elevated lactate/pyruvate ratios have genetic variation in the organic cation transporters.