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Euthyrox and Kaitlib FE

Determining the interaction of Euthyrox and Kaitlib FE and the possibility of their joint administration.

Check result:
Euthyrox <> Kaitlib FE
Relevance: 24.04.2023 Reviewer: Shkutko P.M., M.D., in

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:

Before taking ethinyl estradiol, tell your doctor if you also use levothyroxine. You may need dose adjustments or special tests in order to safely take both medications together. If you are already taking ethinyl estradiol and levothyroxine, your thyroid levels may need to be measured if your dose of ethinyl estradiol is changed or stopped. You should notify your doctor if you have symptoms of low thyroid such as tiredness, feeling cold, constipation, unexplained weight gain, depression, joint or muscle pain, thinning hair or hair loss, dry skin, hoarseness, and abnormal menstrual periods. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using your medications without first talking to your doctor first.

Professional:

MONITOR: Estrogens may increase serum thyrotropin concentration, which could be harmful in patients with thyroid cancer receiving thyroxine for thyrotropin suppression or increase dosage requirements in patients with hypothyroidism receiving thyroxine for replacement therapy. Estrogens are known to increase serum thyroid-binding globulin concentration in a dose-dependent manner. Consequently, there may be a reduction in unbound, or free, thyroxine available for hormone activity, which, in turn, leads to an increase in serum thyrotropin concentration. Normally, thyroxine secretion can increase to compensate for this effect, but patients with hypothyroidism lack the mechanism to adapt. Limited evidence suggests that transdermal estrogen therapy may not affect thyroid-binding globulin concentrations; however, more data are required to confirm that.

MANAGEMENT: In patients treated with thyroxine, serum thyrotropin should be measured approximately 12 weeks after estrogen therapy is initiated, changed or discontinued, and the thyroxine dosage adjusted accordingly. Patients should be advised to contact their physician if clinical manifestations of hypothyroidism occur, such as fatigue, cold intolerance, constipation, unexplained weight gain, depression, joint or muscle pain, thinning hair or hair loss, dry skin, hoarseness, and abnormal menstrual periods.

References
  • Chetkowski RJ, Meldrum DR, Steingold KA, et al. "Biologic effects of transdermal estradiol." N Engl J Med 314 (1986): 1615-20
  • Utiger RD "Estrogen, thyroxine binding in serum, and thyroxine therapy." N Engl J Med 344 (2001): 1784-5
  • Arafah BM "Increased need for thyroxine in women with hypothyroidism during estrogen therapy." N Engl J Med 344 (2001): 1743-9
  • "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical, Abbott Park, IL.
Euthyrox

Generic Name: levothyroxine

Brand name: Euthyrox, Levoxyl, Synthroid, Tirosint, Unithroid, Levothroid, Tirosint-Sol

Synonyms: n.a.

Kaitlib FE

Generic Name: ethinyl estradiol / norethindrone

Brand name: Blisovi 24 Fe, Estrostep Fe, Femcon Fe, Kaitlib FE, Lo Minastrin Fe, Microgestin 24 Fe, Norinyl 1+35, Ortho-Novum 7/7/7, Taytulla, Tri-Norinyl, Zenchent, Blisovi 24 Fe, Blisovi Fe 15/30, Blisovi Fe 1/20, Gildess 24 Fe, Gildess Fe 15/30, Gildess Fe 1/20, Junel Fe 15/30, Junel Fe 1/20, Junel Fe 24, Larin 24 Fe, Larin Fe 15/30, Larin Fe 1/20, Lo Loestrin Fe, Loestrin 24 Fe, Loestrin Fe 15/30, Loestrin Fe 1/20, Lomedia 24 Fe, Microgestin 24 Fe, Microgestin Fe 15/30, Microgestin Fe 1/20, Tarina Fe 1/20, Tilia Fe, Tri-Legest Fe, femhrt 05 mg/25 mcg, Fyavolv, Jevantique Lo, Jinteli, Femcon Fe, Generess FE, Loestrin 1/20, Ovcon 35, Brevicon

Synonyms: Kaitlib FE (birth control), Kaitlib Fe

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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