Vitamin B2

Riboflavin/Nutrient Depletion:

  • AntibioticsAntibiotics: According to secondary sources, long-term use of antibiotics may deplete vitamin B levels, including riboflavin.
  • AnticholinergicsAnticholinergics: The effect of an anticholinergic agent on riboflavin absorption in humans has been discussed (203). Further information is lacking.
  • AnticonvulsantsAnticonvulsants: In human research, patients on various antiepileptic agents had decreased riboflavin status (204). Supplementation with riboflavin in patients with low riboflavin status and on antiepileptic drugs did not improve the thyroid function (205).
  • AntimalarialsAntimalarials: Low riboflavin levels have been associated with use of antimalarial agents (207; 208; 209).
  • Boric acidBoric acid: According to a review, boric acid forms a complex with the polyhydroxyl ribitol side chain of riboflavin and increased its water solubility, resulting in increased excretion of riboflavin within the first 24-48 hours (227).
  • ContraceptivesContraceptives: According to reviews, riboflavin levels in plasma and erythrocytes may decrease with high-dose oral contraceptive use, resulting in increased requirement (228; 229; 230; 231; 232). Joshi et al. determined that riboflavin levels were not further decreased in riboflavin-deficient women using oral contraceptives, but were in women with adequate status (236). The physiological significance of these studies is unclear.
  • Diuretics, thiazideDiuretics, thiazide: In human research, use of diuretics increased riboflavin excretion (237).
  • FolateFolate: In human research, folic acid 400mcg daily appeared to exacerbate a tendency toward riboflavin deficiency (225).
  • PhenothiazinesPhenothiazines: In rat tissues, chlorpromazines inhibited flavokinase, the enzyme that transforms riboflavin into its functionally active cofactor form (248). In a review, chlorpromazine increased riboflavin excretion in the urine (227).
  • ProbenecidProbenecid: Probenecid altered the renal clearance of riboflavin, in human research (249; 250).
  • Thyroid agentsThyroid agents: In human research, use of antithyroid therapy resulted in decreased riboflavin status (220).
  • Tricyclic antidepressantsTricyclic antidepressants: In rat tissues, amitriptyline and imipramine inhibited flavokinase, the enzyme that transforms riboflavin into its functionally active cofactor form (248). In human research, riboflavin, in combination with other B vitamins, increased the antidepressant effect of tricyclic antidepressant treatment (252). According to secondary sources, riboflavin deficiency has occurred following use of amitriptyline.