Digoxin Aminosalicylic acid

Aminosalicylic acid may affect isoniazid, digoxin, and vitamin B- 2-Adverse Reactions... 

Another patient taking digoxin, potassium chloride, docusate, diazepam and warfarin 2.5 mg daily, was also given aminosalicylic acid 12 g, isoniazid 300 mg and pyridoxine 100 mg daily, and at the same time the warfarin dose was doubled to 5 mg daily. His prothrombin time increased from 18 to 130 seconds over 20 days but no signs of haemorrhage were... 

Aminosalicylic acid causes a small reduction in digoxin levels in healthy subjects but the importance of this in patients is uncertain. 

In one study in 10 healthy subjects, the bioavailability of a single 750-microgram dose of digoxin, using urinary excretion as a measure, was reduced by 20% by aminosalicylic acid 2 g four times daily for 2 weeks. This seems to be just another aspect of the general malabsorption caused by aminosalicylic acid. The importance of this interaction in patients is not known (it is probably small) but it would be prudent to monitor concurrent use. 

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