Drug Interactions between Cr-GTF and thyrotropin alpha

ADJUST DOSING INTERVAL: Concurrent administration of chromium picolinate-containing oral products may decrease the oral bioavailability of levothyroxine in some patients. The exact mechanism has not been elucidated but may involve nonspecific adsorption of levothyroxine to polyvalent cations, resulting in an insoluble complex that that is poorly absorbed from the gastrointestinal tract. A study in seven healthy volunteers reported that, compared to administration alone, coadministration of 1 mg levothyroxine sodium with chromium picolinate 1 mg led to a 17% reduction in the serum levels of levothyroxine. However, the clinical significance of this reduction has not been established. It is not known whether this interaction occurs with other oral thyroid hormone preparations.

MANAGEMENT: Some experts recommend separating the times of administration of levothyroxine and chromium picolinate by either taking oral levothyroxine at least 30 minutes before or three to four hours after taking chromium picolinate-containing oral preparations. Monitoring of serum TSH levels is recommended. Patients with gastrointestinal or malabsorption disorders may be at a greater risk of developing clinical or subclinical hypothyroidism due to this interaction.