Integra (Ferrous Fumarate, Polysaccharide Iron Complex, Vitamin C, and Vitamin B3) and Levothyroxine Oral Solution
Determining the interaction of Integra (Ferrous Fumarate, Polysaccharide Iron Complex, Vitamin C, and Vitamin B3) and Levothyroxine Oral Solution and the possibility of their joint administration.
In the database of official manuals used in the service creation an interaction registered by statistical results of studies was found, which can either lead to negative consequences for the patient health or strengthen a mutual positive effect. A doctor should be consulted to address the issue of joint drug administration.
Consumer:Levothyroxine and multivitamin with iron should not be taken orally at the same time. Products that contain iron may interfere with the absorption of levothyroxine and reduce its effectiveness. You should separate the dosing of these medications by at least 2 to 4 hours if possible. Contact your doctor if your condition changes or you experience symptoms of hypothyroidism such as dry skin, weight gain, cold intolerance, weakness, muscle cramps or stiffness, slow pulse, or constipation. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.
Professional:ADJUST DOSING INTERVAL: Concurrent administration of iron-containing products may decrease the oral bioavailability and pharmacologic effects of levothyroxine. The exact mechanism of interaction is unknown, but in vitro data suggest it may involve nonspecific adsorption of levothyroxine to iron at acidic pH levels, resulting in an insoluble complex that is poorly absorbed from the gastrointestinal tract. In one study, 14 patients with hypothyroidism who were taking a stable long-term regimen of levothyroxine demonstrated an increase in mean serum thyrotropin (thyroid-stimulating hormone, or TSH) level from 1.6 to 5.4 mU/L following the addition of ferrous sulfate (300 mg administered simultaneously with levothyroxine 30 to 60 minutes before breakfast) for 3 months. A total of 11 patients had increases in serum TSH at week 12 compared to baseline, including two that had levels above the upper limit of normal for the assay, indicating the presence of hypothyroidism. Nine of the eleven also had an increase in signs and symptoms of hypothyroidism based on subjective evaluation using a clinical score. It is not known whether this interaction occurs with other thyroid hormone preparations.
MANAGEMENT: Some experts recommend separating the times of administration of levothyroxine and iron-containing preparations by at least 2 to 4 hours. 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.
- Campbell NR, Hasinoff BB, Stalts H, Rao B, Wong NC "Ferrous sulfate reduces thyroxine efficacy in patients with hypothyroidism." Ann Intern Med 117 (1992): 1010-3
Generic Name: multivitamin with iron
Brand name: Integra, Fero-Folic 500, Theragran Hematinic, Ultra Enerforce
Synonyms: n.a.
Generic Name: levothyroxine
Brand name: Levoxyl, Synthroid, Tirosint, Unithroid, Euthyrox, Levothroid, Tirosint-Sol
Synonyms: Levothyroxine
In the course of checking the drug compatibility and interactions, data from the following reference sources was used: Drugs.com, Rxlist.com, Webmd.com, Medscape.com.
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