Possible Effects of Medications on Vitamin Absorption or Metabolism
Medications | Effects |
|---|---|
Ethanol Ethanol | Impairs thiamin utilization |
Isoniazid Isoniazid | Interferes with niacin and pyridoxine metabolismand pyridoxine metabolism |
Ethanol and oral contraceptivesEthanol and oral contraceptives | Inhibit folate absorption |
Phenytoin, phenobarbital, primidone, or phenothiazines Phenytoin, phenobarbital, primidone, or phenothiazines | In most patients, cause folate (folic acid) deficiency*, probably because hepatic microsomal drug-metabolizing enzymes are affectedIn most patients, cause folate (folic acid) deficiency*, probably because hepatic microsomal drug-metabolizing enzymes are affected |
Antiseizure drugs (eg, carbamazepine, phenobarbital, phenytoin) Antiseizure drugs (eg, carbamazepine, phenobarbital, phenytoin) | Can decrease vitamin D metabolismCan decrease vitamin D metabolism |
Aminosalicylic acid, slow-release potassium iodide, colchicine, trifluoperazine, metformin, ethanol, and oral contraceptives Aminosalicylic acid, slow-release potassium iodide, colchicine, trifluoperazine, metformin, ethanol, and oral contraceptives | Interfere with absorption of vitamin B12 |
Proton pump inhibitors | Can decrease absorption of vitamin B12, vitamin C, iron, calcium, and magnesium |
* Folate supplements may make phenytoin less effective.* Folate supplements may make phenytoin less effective. | |