The effect of antiepileptic drugs on thyroid hormonal function: causes and implications

Regarding the quality assessment, six out of seven studies were considered at low risk of bias,25–28,31,38 while one37 was considered at moderate risk because of measurement of outcomes. A detailed assessment of the systematic error risk of all included studies is presented in Supplementary Tables S2 and S3, and Supplementary Figures S1 and S2. The GRADE quality of evidence suggested that there was moderate quality of evidence in the included studies (Supplementary Table S4). The effectiveness of levothyroxine therapy is measured by monitoring your symptoms and by checking the amount of two main thyroid-related hormones—thyroid stimulating hormone and T4—in the blood. Levothyroxine is usually started at a low dose and slowly increased over time.

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Lamotrigine has not been shown to result in endocrine side effects. The newer AEDs have not yet been thoroughly studied, but case reports indicate that some of these drugs could also be suspected to cause such effects synthroid splitting if endocrine changes commence after treatment initiation. It is important to be aware of possible endocrine side effects of AEDs as they can have a major impact on quality of life, and are, at least partly, reversible after AED discontinuation.

EIAEDs increase sex hormone binding globulin (SHBG) concentrations in both men and women.
To clarify the effect of the concomitant ingestion of PPI and tablet LT4, we conducted a systematic review of interventional and observational studies in the literature aiming at determining serum TSH changes before and after the concomitant use of these two drugs.
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Levothyroxine is a man-made form of the human thyroid hormone called T4.

Can I take other medications with levothyroxine?

These findings are consistent with drug—drug interactions that reduce levothyroxine serum concentrations, leading to a compensatory increase in TSH level and the need to increase levothyroxine dosage. This study has the advantage of a large sample size, and it certainly suggests that these interacting drugs may have a clinically important effect on levothyroxine serum concentrations. Nonetheless, the effect of individual drugs on levothyroxine cannot be determined because so many different drugs were studied and the results were lumped together. Epilepsy is a chronic disease and its treatment is lifelong in one-third of patients. Data from cross-sectional and prospective studies have reviewed the influence of antiepileptic drugs (AEDs) on thyroid hormones.

Taking it on an empty stomach results in the best absorption of the drug from the intestine. You may be able to take other medications with levothyroxine, but some of them will have to be taken at a different time from when you take your levothyroxine. Horn and Hansten are both professors of pharmacy at the University of Washington School of Pharmacy. For an electronic version of this article, including references, if any, visit

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum. The study was supported by the Indian Council of Medical Research, New Delhi, India. There is 1 alcohol/food interaction with Keppra (levetiracetam). Some mixtures of medications can lead to serious and even fatal consequences. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Therefore, levothyroxine should be taken on a consistent schedule with regard to time of day and relation to meals to avoid large fluctuations in blood levels, which may alter its effects.
One factor that probably contributes to the variability of levothyroxine drug—drug interactions is that some individuals are completely dependent on exogenous levothyroxine (eg, following total thyroidectomy) while others have varying degrees of residual thyroid function.
This review focuses on the evidence, mechanisms of thyroid abnormalities with AEDs and their clinical implications.
The GRADE quality of evidence suggested that there was moderate quality of evidence in the included studies (Supplementary Table S4).
Completed the searching and screening of literature and data extraction.
Patient’s demographic data including age, sex, diagnosis, duration of treatment, other medications, and serum fT3, fT4, and TSH levels were monitored.

You should avoid or limit the use of alcohol while being treated with levETIRAcetam. Do not use more than the recommended dose of levETIRAcetam, and avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medication affects you. Talk to your doctor or pharmacist if you have any questions or concerns. The concomitant use of LT4 and PPI showed a significant increase in TSH concentration.

Ranjitha Arulmozhi contributed in study design, data gathering, data analysis and preparing first draft of the manuscript. If you are unsure whether one of your medicines interacts with levothyroxine, talk to your doctor or pharmacist. Make sure to always give all of your healthcare providers a full list of your medications (prescription and nonprescription) and any supplements you take.

Interactions between antiepileptic drugs and hormones

Patient’s demographic data including age, sex, diagnosis, duration of treatment, other medications, and serum fT3, fT4, and TSH levels were monitored. Fasting venous blood sample of 5 ml was collected from the patients and control subjects. Then, the blood was centrifuged and serum obtained was subjected to chemiluminescence autoanalyzer for assessing serum fT3, fT4, and TSH levels (Immulite-Siemens). The normal range of serum fT3 is 1.5–4.1 pg/ml, serum fT4 is 0.8–2.0 ng/dl, and serum TSH is 0.4–4 mIU/ml. The timing of meals relative to your oral levothyroxine dose can affect the absorption of the medication.

Automatically receive FDA alerts, drug interaction warnings, plus data on food, allergy & condition interactions. However, this does not necessarily mean no interactions exist. This section collects any data citations, data availability statements, or supplementary materials included in this article. Usually it should be taken at least 30 to 60 minutes before eating breakfast, or at bedtime (3 or more hours after the evening meal).

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Automatically receive FDA alerts, drug interaction warnings, plus data on food, allergy & condition interactions.
Well-designed large studies are needed in order to further better clarify the interfering role of PPI on LT4 intestinal absorption.
The timing of meals relative to your oral levothyroxine dose can affect the absorption of the medication.
All data analyzed during the study are included in this published version.

In the case of levothyroxine, you may need more frequent testing of thyroid stimulating hormone and T4 levels when other medications are added or removed from your treatment regimen. After another drug has been added to or removed from your regimen, you should report worsening of any disease symptoms or medication side effects to your doctor. The objective of the study was to evaluate and compare the effect of conventional and newer antiepileptic drugs (AEDs) on thyroid hormone levels in adult epileptic patients. The contradictory findings mentioned may result from the limited size of the cohorts analyzed as well as differences in subjects enrolled (patients vs. healthy volunteers). To clarify the effect of the concomitant ingestion of PPI and tablet LT4, we conducted a systematic review of interventional and observational studies in the literature aiming at determining serum TSH changes before and after the concomitant use of these two drugs.