Thiamine is an essential vitamin meaning humans must consume thiamine from their diet in order to stay healthy. Low thiamine levels can lead to adverse events. Thiamine is absorbed in the intestine by a transporter protein. This is made by the SLC19A3 gene. The SLC19A3 gene provides instructions for making the thiamine transporter protein, which moves thiamine into cells. Certain drugs, like metformin and trimethoprim, have been shown to interrupt function of the SLC19A3 gene.~Metformin is a first-line therapy for patients with Type 2 diabetes and is associated with improvements in diabetic complications. Trimethoprim is an anti-bacterial drug that is often prescribed to treat infections such as urinary tract infections. At different phases of this study, participants will be administered thiamine, thiamine with metformin, and/or thiamine with trimethoprim to determine whether taking a drug and a vitamin together affects the body's ability to absorb, distribute, and eliminate thiamine. The levels of thiamine in the participants' blood and urine will be measured before and after taking thiamine or thiamine in combination with metformin and/or trimethoprim.
In Part 1, subjects will be administered thiamine, thiamine with metformin, and thiamine with trimethoprim. Part 2 will expand on Part 1 and subjects will be administered thiamine and thiamine with trimethoprim. The goal is to determine whether taking a drug and a vitamin together affects the body's ability to absorb, distribute, and eliminate thiamine (Vitamin B1).