How is levothyroxine supplied
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Levothyroxine Supply: Conventional and Novel Formulations
Introduction to Levothyroxine Supply
Levothyroxine, a synthetic form of the thyroid hormone thyroxine (T4), is widely prescribed for the treatment of hypothyroidism. Despite its common use, the bioavailability of levothyroxine can be affected by various factors, including food, other medications, and certain medical conditions. To address these challenges, several formulations and delivery methods have been developed to improve the efficacy and patient compliance of levothyroxine therapy.
Conventional Levothyroxine Tablets
Bioavailability Challenges
The traditional form of levothyroxine is the oral tablet. However, its absorption can be significantly impaired by food, especially those rich in soy, iodine, and fiber, as well as by certain medications and gastrointestinal disorders1 2. This necessitates taking the medication on an empty stomach, typically 30-60 minutes before breakfast, which can be inconvenient for many patients4.
Novel Levothyroxine Formulations
Liquid Solutions and Soft Gel Capsules
To overcome the limitations of tablet formulations, liquid solutions and soft gel capsules have been developed. These alternatives bypass the gastric dissolution phase, leading to more consistent absorption and potentially reducing the impact of food on drug efficacy1 3. Studies have shown that these formulations are particularly beneficial for patients with gastrointestinal disorders, those on multiple medications, and those who have undergone bariatric surgery3.
Bioavailability of Liquid Solutions
Recent research has demonstrated that liquid levothyroxine solutions, such as ThyquidityTM, maintain bioequivalence to traditional tablets even when taken closer to meal times. A study found that administering the liquid solution 10 or 30 minutes before a high-fat, high-calorie breakfast did not significantly affect the drug's absorption, offering greater dosing flexibility for patients4.
Alternative Delivery Routes
Injections, Suppositories, and Sprays
In addition to oral formulations, other delivery routes have been explored to address specific patient needs. These include injections, suppositories, nasal sprays, and sublingual and transdermal administrations. These methods can be particularly useful in thyroid emergencies or for patients with swallowing difficulties (dysphagia)1.
Nanomaterial-Based Delivery Systems
Innovative approaches using nanomaterials have also been investigated to create sustained-release formulations of levothyroxine. These systems aim to improve patient compliance by reducing the frequency of dosing and potentially lowering treatment costs1.
Conclusion
Levothyroxine is available in various formulations to address the challenges associated with its bioavailability and patient compliance. While conventional tablets remain widely used, novel formulations such as liquid solutions and soft gel capsules offer significant advantages, particularly for patients with specific medical conditions or those requiring more flexible dosing schedules. Additionally, alternative delivery routes and nanomaterial-based systems hold promise for further enhancing the efficacy and convenience of levothyroxine therapy.
Sources and full results
Most relevant research papers on this topic
Levothyroxine: Conventional and Novel Drug Delivery Formulations
Novel formulations and delivery routes for levothyroxine can improve bioavailability, reduce side effects, and enhance patient compliance.
Levothyroxine Interactions with Food and Dietary Supplements–A Systematic Review
Levothyroxine ingestion in the morning and at bedtime is equally effective, but interactions with coffee, soy products, fiber, calcium, or iron supplements can decrease its absorption.
Systematic ReviewLiquid and softgel levothyroxine use in clinical practice: state of the art
Softgel and liquid levothyroxine formulations show promising results in improving individual tailored treatment for hypothyroidism in selected patient categories.
Systematic Review
Rigorous JournalRF23 | PSAT258 Comparable Bioavailability of a Novel Levothyroxine Solution taken 10 or 30 minutes prior to a High-Fat, High-Calorie Breakfast
ThyquidityTM oral solution shows bioequivalence to Synthroid® when administered 10 or 30 minutes before a high-calorie, high-fat breakfast, making it a convenient option for patients.
RCTRigorous JournalMedications and Food Interfering with the Bioavailability of Levothyroxine: A Systematic Review
Many medications and foods can impair the bioavailability of levothyroxine, requiring awareness and dose adjustment for optimal treatment.
Systematic ReviewA Novel Levothyroxine Solution Results in Similar Bioavailability Whether Taken 30 or Just 15 Minutes Before a High-Fat High-Calorie Meal
A novel levothyroxine solution (Tirosint®-SOL) shows no significant difference in bioavailability when taken 15 minutes before a high-fat, high-calorie meal compared to the recommended 30-minute interval.
RCTRigorous JournalOral levothyroxine therapy postbariatric surgery: Biopharmaceutical aspects and clinical effects.
Bariatric surgery may compromise levothyroxine absorption or decrease dose requirements, requiring close monitoring of thyroid hormone levels.
Systematic ReviewREVIEW: Treatment of hypothyroidism with combinations of levothyroxine plus liothyronine.
Levothyroxine alone remains the treatment of choice for hypothyroidism replacement therapy until clear advantages of levothyroxine plus liothyronine are demonstrated.
Systematic Review
Highly CitedEffect of levothyroxine supplementation on pregnancy outcomes in women with subclinical hypothyroidism and thyroid autoimmuneity undergoing in vitro fertilization/intracytoplasmic sperm injection: an updated meta-analysis of randomized controlled trials
Levothyroxine supplementation may reduce miscarriage rates in infertile women with subclinical hypothyroidism and thyroid autoimmuneity undergoing IVF/ICSI, but more population-based RCTs are needed to confirm this recommendation.
Meta-AnalysisRigorous JournalLevothyroxine Therapy: Changes of TSH Levels by Switching Patients from Tablet to Liquid Formulation. A Systematic Review and Meta-Analysis
Switching from tablet to liquid levothyroxine significantly improves TSH levels in patients with suboptimal TSH on tablet LT4, at unchanged dose.
Meta-Analysis