Observational studyClinical drug investigation2015
Drug interactions with levothyroxine therapy in patients with hypothyroidism: observational study in general practice.
Observational study in Clinical drug investigation, 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 18 papers.
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The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
18 citing papers in PubMed, 40 citations in OpenAlex.
- Phase 1 Study Evaluating the Pharmacokinetics, Dose Proportionality, Bioavailability, and Tolerability of Subcutaneous Levothyroxine Sodium (XP-8121).Clinical and translational science · 2025Trial
- Evaluation of the clinical pharmacist's effect on achieving treatment goals in patients with hypothyroidism: a randomized controlled trial.BMC endocrine disorders · 2025Trial
- Targeting Oxidative Stress and Apoptosis with Levothyroxine in Experimental Parkinson's Disease in Rats.Neurochemical research · 2026Article
- Association of pharmacogenomic, clinical and behavioural factors with oral levothyroxine (LT-4) dose of hypothyroid patients in Sri Lanka: a matched case control study.BMC medical genomics · 2024Article
- Efficacy of Levothyroxine Sodium Soft Gelatin Capsules in Thyroidectomized Patients Taking Proton Pump Inhibitors: An Open-Label Study.Thyroid : official journal of the American Thyroid Association · 2023Article
- Effect of morning versus night-time administration of proton pump inhibitor (pantoprazole) on thyroid function test in levothyroxine-treated primary hypothyroidism: a prospective cross-over study.Thyroid research · 2023Article
- Medications and Food Interfering with the Bioavailability of Levothyroxine: A Systematic Review.Therapeutics and clinical risk management · 2023Review
- Factors influencing the levothyroxine dose in the hormone replacement therapy of primary hypothyroidism in adults.Reviews in endocrine & metabolic disorders · 2022Review
- Liquid levothyroxine formulations in patients taking drugs interfering with L-T4 absorption.Frontiers in endocrinology · 2022Review
- Daily requirement of softgel thyroxine is independent from gastric juice pH.Frontiers in endocrinology · 2022Article
- Managing symptoms in hypothyroid patients on adequate levothyroxine: a narrative review.Endocrine connections · 2020Review
- Diagnosis and Management of Hypothyroidism in Gulf Cooperation Council (GCC) Countries.Advances in therapy · 2020Review
- L-T4 Therapy in the Presence of Pharmacological Interferents.Frontiers in endocrinology · 2020Review
- Improvement in the management of chronic obstructive pulmonary disease following a clinical educational program: results from a prospective cohort study in the Sicilian general practice setting.NPJ primary care respiratory medicine · 2018Article
- Drug interactions in users of tablet vs. oral liquid levothyroxine formulations: a real-world evidence study in primary care.Endocrine · 2018Article
- Diagnosis and management of treatment-refractory hypothyroidism: an expert consensus report.Journal of endocrinological investigation · 2017Review
- Article
- Concomitant use of levothyroxine and interacting medications in U.S. ambulatory care visits.Journal of the American Pharmacists Association : JAPhAArticle
Corrections and comments
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Authors and funding
11 authors at 3 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
BACKGROUND AND
objectivesSeveral drugs may interact with levothyroxine and reduce its bioavailability. The aim of this study was to analyse the Italian general practice patients with hypothyroidism from 2002-2011, in terms of variation of thyroid-stimulating hormone (TSH) levels, number of levothyroxine prescriptions and dose of levothyroxine before and during potential drug-drug interactions (DDIs).
methodsData were extracted from the Italian general practice Health Search CSD Longitudinal Patient Database (HSD). Analysis was limited to individuals aged 18 years and older with at least one levothyroxine prescription from 2002 to 2011 and at least one year of clinical history recorded in HSD. A quasi-experimental pre-post analysis was carried out using a self-controlled study design, on an intention-to-treat basis.
resultsOverall, 5,426 levothyroxine users (7.5 % of population in HSD) were included in the study. The incidence rate ratio comparing the TSH trend before and during the period of exposure to potential DDI showed a significant increase of TSH levels during initial exposure to potential DDI, which decreased over time. The number of prescriptions and dose of levothyroxine decreased before the potential DDI and increased symmetrically during the period of exposure to potential DDI.
conclusionsThe co-prescription of levothyroxine and potentially interacting drugs results in an increased use of levothyroxine. Clinicians should carefully consider adjusting levothyroxine therapy in presence of concomitant drugs, such as proton-pump inhibitors, which may reduce levothyroxine bioavailability.
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