Calcium acetate and Euthyrox
Determining the interaction of Calcium acetate and Euthyrox 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:Using calcium acetate together with levothyroxine may decrease the effects of levothyroxine. You should separate the administration of levothyroxine and calcium acetate by at least 4 hours. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. 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 calcium-containing products may decrease the oral bioavailability of levothyroxine by one-third in some patients. Pharmacologic effects of levothyroxine may be reduced. The exact mechanism of interaction is unknown but may involve nonspecific adsorption of levothyroxine to calcium at acidic pH levels, resulting in an insoluble complex that is poorly absorbed from the gastrointestinal tract. In one study, 20 patients with hypothyroidism who were taking a stable long-term regimen of levothyroxine demonstrated modest but significant decreases in mean free and total thyroxine (T4) levels as well as a corresponding increase in mean thyrotropin (thyroid-stimulating hormone, or TSH) level following the addition of calcium carbonate (1200 mg/day of elemental calcium) for 3 months. Four patients had serum TSH levels that were higher than the normal range. Both T4 and TSH levels returned to near-baseline 2 months after discontinuation of calcium, which further supported the likelihood of an interaction. In addition, there have been case reports suggesting decreased efficacy of levothyroxine during calcium coadministration. 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 calcium-containing preparations by at least 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.
- Singh N, Singh PN, Hershman JM "Effect of calcium carbonate on the absorption of levothyroxine." JAMA 283 (2000): 2822-5
- Neafsey PJ "Levothyroxine and calcium interaction: timing is everything." Home Healthc Nurse 22 (2004): 338-9
- Csako G, McGriff NJ, Rotman-Pikielny P, Sarlis NJ, Pucino F "Exaggerated levothyroxine malabsorption due to calcium carbonate supplementation in gastrointestinal disorders." Ann Pharmacother 35 (2001): 1578-83
- Schneyer CR "Calcium carbonate and reduction of levothyroxine efficacy." JAMA 279 (1998): 750
Generic Name: calcium acetate
Brand name: Calphron, Eliphos, PhosLo Gelcap, Phoslyra, PhosLo
Synonyms: Calcium Acetate
Generic Name: levothyroxine
Brand name: Euthyrox, Levoxyl, Synthroid, Tirosint, Unithroid, Levothroid, Tirosint-Sol
Synonyms: n.a.
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.
- Calcium acetate-Evac-u-gen
- Calcium acetate-Evamist
- Calcium acetate-Evamist Transdermal
- Calcium acetate-Evekeo
- Calcium acetate-Evekeo ODT
- Calcium acetate-Evening Primrose
- Euthyrox-Calcium Acetate Capsules
- Euthyrox-Calcium Acetate Capsules and Tablets
- Euthyrox-Calcium Acetate Gelcaps
- Euthyrox-Calcium Acetate Oral Solution
- Euthyrox-Calcium Acetate Tablets
- Euthyrox-Calcium and Vitamin D Capsules and Tablets