Levothyroxine drug interactions

What significant drug interactions are associated with the use of levothyroxine ... 

Drug interaction Warfarin and thyroxine are frequently taken togetirer especially in elderly patients. This combination is thought to be a source of adverse bleeding due to the thyroxine-dependent potentiation of warfarin effects. The results of a 16-year-population-based nested case-control study in which 10,532 patients hospitalised for haemorrhage were matched with 40,595 controls could not substantiate this interaction. There was no increased risk of haemorrhage in warfarin-treated patients receiving levothyroxine up to 30 days (odds ratio (OR) of 1.11,95% Cl of 0.67-1.86), 60 days (OR of 0.76) or 90 days (OR of 0.67) prior to hospitalisation [13 ]. 

Pincus D, Gomes T, HelHngs C, Zheng H, Paterson JM, Mamdani MM, et al. A population-based assessment of the drug interaction between levothyroxine and warfarin. Clin Pharmacol Ther 2012 92(6) 766-70. 

Patients with hypothyroidism and organic depression may need both levothyroxine and antidepressant drug therapy, in ievothyroxine-treated patients with hypothyroidism who were treated with sertraiine, there was an eievated serum thyrotropin concentration, indicative of a decrease in the efficacy of ievothyroxine. What is the possible mechanism of interaction between the two drugs ... 

There seem to be no reports of adverse effects in other patients given both drugs and the evidence for this interaction is by no means conclusive. Although rifampicin can affect thyroid hormones, it appears that healthy individuals can compensate for this. Since hypothyroid patients may not be able to compensate in the same way, bear this interaction in mind if rifampicin is given to a patient taking levothyroxine. 

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