Vitamin B1 (Thiamine)
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Scopolamine-containing Medications
Tetracycline-containing Medications
Tricyclic Antidepressants (TCAs)
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Interactions with Vitamin B1 (Thiamine)

Supplementation with vitamins B1, B2, and B6 (10 mg each) at the start of tricyclic antidepressant therapy improved cognitive functioning and depression ratings in 14 geriatric patients undergoing treatment with nortriptyline titrated to doses yielding blood levels between 50 to 150 ng/mL (Bell et al. 1992). B vitamins may augment the treatment of depression in elderly patients.


In a randomized, double-blind, placebo-controlled, double-crossover clinical trial with 13 healthy subjects, coadministration of thiamine (5 g po) countered the cognitive side effects associated with scopolamine treatment (0.007 mg/kg IM) as compared to placebo (Meador et al. 1993).


In one study, the bioavailability of tetracycline hydrochloride was reduced significantly by concomitant administration of vitamin B complex to healthy subjects (Omray 1981). Patients should be cautioned to take vitamin B complex supplements at different times from tetracycline.


Bell I, Edman J, Morrow F, et al. Brief communication. Vitamin B1, B2, and B6 augmentation of tricyclic antidepressant treatment in geriatric depression with cognitive dysfunction. J Am Coll Nutr. 1992;11:159-163.

Meador KJ, Nichols ME, Franke P, et al. Evidence for a central cholinergic effect of high-dose thiamine. Ann Neurol. 1993;34:724-726.

Omray A. Evaluation of pharmacokinetic parameters of tetracycline hydrochloride upon oral administration with vitamin C and vitamin B complex. Hindustan Antibiot Bull. 1981;23(VI):33-37.

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