IN PATIENTS WITH SUBCLINICAL HYPOTHYROIDISM WHILE IN THERAPY WITH TABLET L-T4, THE LIQUID L-T4 FORMULATION IS MORE EFFECTIVE IN RESTORING EUTHYROIDISM

Hypothyroidism and metabolic cardiovascular disease

Cardiovascular disease (CVD) remains the leading cause of death worldwide, representing a major health issue of social and economic relevance. Both hyperthyroidism and hypothyroidism are very common in the adult population, and both disorders may contribute to the onset and progression of CVD. After a brief description of the role of thyroid hormones (THs) on the physiology of the cardiovascular system and the potential mechanism that links THs alterations with changes in cardiac function, blood pressure, endothelial function, and lipid levels, we review updated data about the clinical impact of overt hypothyroidism (OH) and subclinical hypothyroidism (SCH) on CV risk, CVD, and mortality. Furthermore, we summarize the current evidence for treating SCH with levothyroxine (L-T4). Several guidelines of distinguished endocrine societies recommend treatment for SCH with TSH higher than 10 mIU/L, where the benefit of L-T4 therapy is more evident for younger people, but still controversial in those aged over 65 years. Based on current knowledge, more research efforts are needed to better address the clinical management of CV risk and CVD in the elderly affected by SCH.

The interplay of oxidative stress and immune dysfunction in Hashimoto's thyroiditis and polycystic ovary syndrome: a comprehensive review

In recent years, there has been a significant increase in the concomitant incidence of Hashimoto's thyroiditis (HT) and polycystic ovary syndrome (PCOS), both in terms of incidence, etiology, and clinical consequences. PCOS patients suffering from autoimmune thyroid diseases show insulin resistance, impaired glucose tolerance, weight gain, and metabolic and reproductive complications. Studies have shown that chronic stress and its consequence, i.e. oxidative stress, play an important role in the pathomechanism of both disorders. It has also been shown that long-term exposure to stress triggers biological mechanisms, in particular related to the regulation of the inflammatory cascade, which plays a key role in autoimmune diseases. The paper is a review of the literature on the role of chronic stress, oxidative stress, and immune processes in the pathogenesis of HT and PCOS. In addition, the review is a source of knowledge about the treatment of these diseases, and in particular the use of antioxidants in therapeutic management.

Therapeutic Equivalence of a New Preparation of Liquid Levothyroxine with Tablets in Patients with Overt Primary Hypothyroidism

BACKGROUND

A new liquid levothyroxine (LT4) dissolved in glycerol and water has recently been developed by a Greek pharmaceutical company (Uni-Pharma, Athens, Greece).

OBJECTIVES

To evaluate the therapeutic equivalence of this new liquid LT4 preparation versus the already existing tablet formulation of the same manufacturer, in order to obtain approval by the Greek National Organization for Medicines.

METHODS

This was a prospective, randomized, cross-over phase III study. The study included 50 patients (9 men and 41 non-pregnant women, with a mean age of 42.5 ± 12.5 years), with documented overt primary hypothyroidism. All subjects were well controlled on substitution therapy with various LT4 formulations. None of the patients had known LT4 malabsorption. The patients were randomized into 2 groups (A and B). The individuals of group A initially received T4® tablets for 10 ± 2 weeks and subsequently switched to T4® drops (100 μg/mL solution) at the same dose for another 10 ± 2 weeks. In group B, the reverse procedure was followed. Total T3 (T3), free T4 (fT4), and TSH were measured in all participants at enrollment and at the end of each 10 ± 2-week trial period.

RESULTS

Out of the 50 recruited patients, 6 were lost to follow-up and 5 were excluded due to non-compliance with the study protocol. In the 39 patients who completed the study, the serum TSH levels after 10 ± 2 weeks of treatment either with T4® tablets or with T4® drops did not differ (1.759 ± 1.104 vs. 2.076 ± 1.334 mIU/L, mean ± SD).

CONCLUSIONS

In hypothyroid patients, the new liquid LT4 preparation (T4® drops) is therapeutically equivalent to the tablet form (T4® tablets).

New Formulations of Levothyroxine in the Treatment of Hypothyroidism: Trick or Treat?

Background: Levothyroxine (LT4) as a medication is used by up to 5.3% of the adult population. For optimal efficacy, the traditional tablet formulation (LT4tab) requires that patients avoid concomitant ingestion with food, drinks, and certain medications, as well as excellent patient compliance. Some comorbidities influence bioavailability of LT4 and may mandate repeated dose adjustments. Summary: New LT4 formulations (soft gel [LT4soft] and liquid [LT4liq]) containing predissolved LT4 are claimed to improve bioavailability, presumably by facilitating absorption. Thus, these formulations may well be more suitable than LT4tab for patients whose daily requirements are subjected to variations in bioavailability. Here, we review the evidence and indications for use of new LT4 formulations and highlight areas of uncertainty that are worthy of further investigation. While bioequivalence is established for LT4soft and LT4liq administered to healthy volunteers compared with LT4tab in pharmacokinetic (PK) studies, therapeutic equivalence of the new formulations seems to be different in several clinical settings. Some evidence suggests that new formulations of LT4 may mitigate against the strict requirements relating to concomitant ingestion with food, drinks, and certain medications, which apply to traditional LT4 tablets. The principal indication is in selected patients with disease fluctuations and intermittent therapies with interfering medications, where the need for frequent dose adjustments and office visits may be diminished. Whether the use of LT4soft or LT4liq in patients with impaired gastric acid secretion results in better control of hypothyroidism than LT4tab remains unclear. Conclusions: The evidence in favor of using LT4soft and LT4liq in clinical practice over LT4tab is weak, and the underlying putative PK mechanisms unclear. Additional studies to investigate these potential benefits, define the cost-effectiveness, and understand the PK mechanisms involved with new LT4 formulations are needed.

The Stability of TSH, and Thyroid Hormones, in Patients Treated With Tablet, or Liquid Levo-Thyroxine

Approximately, 5% of the population is affected by hypothyroidism, mainly women and persons aged more than 60 years. After the diagnosis of hypothyroidism the usual therapy is tablet levothyroxine (L-T4), with a monitoring of the thyroid-stimulating hormone (TSH) level in primary hypothyroidism every 6-8 weeks and L-T4 is adjusted as necessary to reach an euthyroid state. Once TSH is stabilized in the normal range, it is recommended to conduct annual testing in the treated subjects to warrant suitable replacement. More recently advances regarding L-T4 treatment are the introduction of new oral formulations: the liquid solution, and soft gel capsule. The soft gel capsule permits a quick dissolution in the acid gastric pH. The liquid preparation does not require an acid gastric environment. Many pharmacokinetic studies demonstrated a more rapid absorption for the liquid L-T4, or capsule, than with tablet. Many studies have shown that the liquid, or capsule, formulations can overcome the interaction with foods, drugs or malabsorptive conditions, that are able to impair the tablet L-T4 absorption. Lately studies have suggested that liquid L-T4 can permit to maintain more efficiently normal TSH levels in hypothyroid patients in the long-term follow-up, than tablet L-T4, both in patients with malabsorptive states, and in those without malabsorption. Further large, prospective, longitudinal studies are needed to evaluate the stability of TSH, in hypothyroid patients treated with different L-T4 formulations.

L-T4 Therapy in Enteric Malabsorptive Disorders

Levothyroxine (L-T4) absorption can be impaired by various causes: a) L-T4 ingestion during breakfast, or with food; b) conditions of reduced gastric acidity; c) intestinal procedures and diseases such as bariatric surgery, lactose intolerance (LI), celiac disease (CD), inflammatory bowel disease; d) drugs that alter L-T4 absorption, increasing the gastric pH, or preventing the dissolution of tablets. The development of new oral formulations, i.e. the liquid preparation and the soft gel capsule, represents the most recent advance regarding L-T4 therapy. Treating hypothyroidism with L-T4 tablets can lead to an improper control of thyroid-stimulating hormone (TSH) in ~10%-15% of patients. The improperly elevated TSH is usually managed by increasing the L-T4 daily dose, and revaluating TSH upon 2-6 months. The increase of the L-T4 dosage may cause iatrogenic hyperthyroidism, especially when the underlying disorders are cured. Liquid L-T4 can be administered in patients unable to swallow capsules or tablets, and this is one of its major benefits. Liquid L-T4 can: 1- overcome food and beverages interference; 2- bypass the malabsorption associated with an increased gastric pH; 3- circumvent the issue of malabsorption in patients who underwent bariatric surgery; 4-maintain TSH values under control better than L-T4 tablets in hypothyroid patients with typical or atypical CD, or in patients with LI. Few clinical studies evaluated soft gel L-T4 with encouraging findings in patients with gastric- or coffee-related malabsorption, or hypothyroid patients without malabsorption. Additional research is necessary to investigate liquid L-T4, or soft gel capsule, in other conditions of altered L-T4 absorption.

The exploration of Hashimoto's Thyroiditis related miscarriage for better treatment modalities

Hashimoto's thyroiditis (HT) is the most prevalent autoimmune thyroid disease (ATD) worldwide and is strongly associated with miscarriage and even recurrent miscarriage (RM). Moreover, with a deepening understanding, emerging evidence has shown that immune dysfunctions caused by HT conditions, including imbalanced subsets of CD4+ T-helper cells, B regulatory (Breg) cells, high expression levels of CD56dim natural killer (NK) cells, and cytokines, possibly play an important role in impairing maternal tolerance to the fetus. In recent years, unprecedented progress has been made in recognizing the specific changes in immune cells and molecules in patients with HT, which will be helpful in exploring the mechanism of HT-related miscarriage. Based on these findings, research investigating some potentially more effective treatments, such as selenium (Se), vitamin D3, and intravenous immunoglobulin (IVIG), has been well developed over the past few years. In this review, we highlight some of the latest advances in the possible immunological pathogenesis of HT-related miscarriage and focus on the efficacies of treatments that have been widely introduced to clinical trials or practice described in the most recent literature.

Liquid and softgel capsules of l-thyroxine results lower serum thyrotropin levels more than tablet formulations in hypothyroid patients

Objective

Evidence indicates that L-T4 in liquid and softgel capsule are absorbed better than tablets in hypothyroid patients, even when patients are under medications that impair the intestinal absorption of L-T4. However, no study has evaluated all three L-T4 formulations in the same hypothyroid patients. This study aims to fill this gap. The outcome was the degree of TSH change in the liquid and softgel formulations, using tablet L-T4 as the reference, regardless of sequence of formulation and regardless of whether patients were co-ingesting with interfering medications.

Methods

We recorded serum TSH levels in two groups of L-T4 replaced patients with primary hypothyroidism (23 subjects who did not co-ingest interfering medications, and 20 subjects who did). Either group of patients took one formulation of L-T4 at a time with variable sequences. In the first group, the median durations of exposure to tablet, liquid or softgel L-T4 were 14, 9 and 10 months, respectively. In the second group the corresponding durations were 13, 11 and 10 months, during which patients co-ingested interfering medications.

Results

In the 23 patients, there were 78, 74 or 101 TSH determinations during liquid, softgel capsule or tablet L-T4 regimens. Serum TSH levels associated with liquid, capsule or tablet L-T4 were 1.62 ± 0.51, 1.77 ± 0.44 mU/L (P = 0.049 vs liquid) or 2.38 ± 0.69 mU/L (P < 0.0001 vs liquid or capsule). Rates of TSH ≤ 2.50 mU/L were 97.4% (liquid), 95.9% (softgel) or 64.4% (tablet, P < 0.0001 vs liquid or capsule). Rates of TSH ≤ 4.12 mU/L were 100%, 100% or 98.0%.

In the 20 patients, the corresponding TSH determinations were 56, 57 and 41, and corresponding TSH levels were 2.74 ± 0.98, 2.70 ± 0.79 or 7.53 ± 2.82 mU/L. Rates of TSH ≤ 2.50 mU/L were 51.8% (liquid), 47.4% (capsule, P = 0.64) or 2.4% (tablet, P < 0.0001 vs liquid or capsule). Rates of TSH ≤ 4.12 mU/L were 92.8% (liquid), 94.7% (capsule, P = 0.68) or 12.2% (tablet, P < 0.0001 vs liquid or capsule).

Conclusions

L-T4 ingested as liquid solution or softgel capsule is more bioavailable compared to L-T4 ingested as tablet, and it is slightly superior to capsule L-T4 only in the absence of co-ingestion of interfering medications.

Hashimotos' thyroiditis: Epidemiology, pathogenesis, clinic and therapy

Hashimoto's thyroiditis (HT), the most frequent autoimmune thyroid disorders (AITDs), is the leading cause of hypothyroidism in the iodine-sufficient areas of the world. About 20-30% of patients suffers from HT, whose cause is thought to be a combination of genetic susceptibility and environmental factors that causes the loss of immunological tolerance, with a consequent autoimmune attack to the thyroid tissue and appearance of the disease. The pathologic features of lymphocytic infiltration, especially of T cells, and follicular destruction are the histological hallmark of autoimmune thyroiditis (AIT), that lead to gradual atrophy and fibrosis. An important role in the immune-pathogenesis of AITDs is due to chemokines and cytokines. In about 20% of patients, AITDs are associated with other organ specific/systemic autoimmune disorders. Many studies have demonstrated the relationship between papillary thyroid cancer and AITD. The treatment of hypothyroidism, as result of AIT, consists in daily assumption of synthetic levothyroxine.

Novel thyroxine formulations: a further step toward precision medicine

Levothyroxine (T4) is a critical-dose drug, because little variations in the blood concentration may cause treatment failure as well as iatrogenic thyrotoxicosis. Despite the dose response of this drug being more carefully titrated nowadays, several papers still report that a significant fraction of patients treated with levothyroxine demonstrate a TSH which is not on target. Moreover, some widespread gastrointestinal disorders as well as interfering drugs and foods may cause the "refractoriness" of a significant number of patients to an expected dose of thyroxine. The increasing awareness of the mechanisms interfering with the oral thyroid hormone bioavailability and the body of evidence regarding the complexity of treatment in certain classes of patients prompted pharmaceutical research to identify new hormonal formulations to optimize the performance of this drug. In this brief review, the progression of the scientific knowledge of novel T4 formulations use has been analyzed.

Levothyroxine Formulations: Pharmacological and Clinical Implications of Generic Substitution

Oral levothyroxine (LT4) is the standard therapy for patients with hypothyroidism. Oral LT4 is available in several formulations, including tablets, soft gel capsules and oral solution. Multiple brand-name and generic LT4 tablets are available. In the US, the Food and Drug Administration (FDA) has developed a protocol for establishing bioequivalence of LT4 formulations based on serum thyroxine (T4) levels after a single oral dose administered to healthy volunteers. This protocol has been criticized by professional endocrinology associations for using healthy individuals and ignoring serum thyroid-stimulating hormone (TSH) levels. In addition, the protocol did not initially correct for baseline T4 levels, although this was changed in a later version. There are concerns that the FDA's protocol could allow products with clinically significant differences in bioavailability to be declared therapeutically equivalent and interchangeable. Once a generic LT4 has been shown to be bioequivalent to a brand-name LT4, it may be substituted for that brand-name LT4 with no need for dose adjustment or follow-up therapeutic monitoring. Often, the substitution is made by the pharmacy without the physician's knowledge. Even small differences between LT4 formulations can cause significant changes in TSH levels. This may be a particular concern in vulnerable populations, including elderly, pregnant, and pediatric patients. Problems that can be encountered when switching between formulations or when original products are reformulated are discussed in this review. These problems include altered efficacy and adverse events, some of which can be caused by excipients. Patients should be maintained on the same LT4 preparation if possible. If the LT4 preparation is changed, TSH levels should be evaluated and, if necessary, the dose of LT4 adjusted.Funding: Merck.Plain Language Summary: Plain language summary available for this article.

Oral L-thyroxine liquid versus tablet in patients submitted to total thyroidectomy for thyroid cancer (without malabsorption): A prospective study

Objective

No consistent data are present in literature about the effectiveness of Levothyroxine (L‐T4) liquid formulation in patients without malabsorption after thyroidectomy. The aim of this study is to compare the effectiveness of L‐T4 liquid formulation, with L‐T4 tablets, in thyroid cancer patients after thyroidectomy (without malabsorption or drug interference).

Methods

One hundred five patients were recruited; 52 patients were treated with liquid L‐T4 formulation, while 53 with L‐T4 tablets, at the same dosage (1.5 mcg/kg/day). Patients started to assume the drug the day after surgery, 30 min before breakfast. In both groups circulating levels of thyrotropic hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) were dosed at week 6 (first control), and then at week 12 (second control).

Results

We obtained significantly lower TSH values in the liquid L‐T4 group patients, compared to the tablet L‐T4 group, at the first control (P < .05), and at the second control (P < .01), while FT4 and FT3 levels were not significantly different. Hypothyroid range (TSH > 3.6 mcU/mL) was significantly more prevalent in the patients treated with L‐T4 tablet.

Conclusions

A better control of TSH was observed in thyroidectomized patients (without malabsorption, gastric disorders, or drug interference) with liquid L‐T4 regimen.

Level of Evidence

2c–Outcomes Research

Liquid L-thyroxine versus tablet L-thyroxine in patients on L- thyroxine replacement or suppressive therapy: a meta-analysis

PURPOSE

To compare the effectiveness of liquid L-T4 (L-thyroxine) and tablet L-T4 in patients on L-T4 replacement or suppressive therapy.

METHODS

The Cochrane Library, PubMed, Embase, and Web of Science databases were searched to identify relevant articles. All prospective or randomized controlled studies (RCTs) comparing liquid L-T4 and tablet L-T4 in patients on L-T4 replacement or suppressive therapy were included in the analysis.

RESULTS

Overall, the initial search of the four databases identified 1278 published studies; of these, eight studies were ultimately included in the meta-analysis. TSH (thyroid stimulating hormone) levels were significantly suppressed in patients on liquid L-T4 compared with those on tablet L-T4, in patients on L-T4 suppressive therapy with L-T4 malabsorption (Mean Difference (MD) = -2.26, 95% Confidence Interval (CI): -3.59, -0.93; P = 0.0009)). However, liquid L-T4 and tablet L-T4 did not show a statistically significant difference in patients on L-T4 suppressive therapy without malabsorption (MD = 0.08, 95% CI: -0.31, 0.47; P = 0.69). TSH levels were significantly normalized in patients on liquid L-T4 compared with those on tablet L-T4, in Patients on L-T4 replacement therapy with L-T4 malabsorption (MD = -3.20, 95% CI: -5.08, -1.32; P = 0.0009). However, liquid L-T4 and tablet L-T4 did not show a statistically significant difference in patients on L-T4 replacement therapy without malabsorption (MD = 0.91, 95% CI: -0.03, 1.86; P = 0.06).

CONCLUSION

Liquid L-T4 is more efficient than tablet L-T4 in patients on L-T4 replacement or suppressive therapy with malabsorption. No significant differences were observed in patients without malabsorption. Further studies should be conducted to verify these findings.

Drug interactions in users of tablet vs. oral liquid levothyroxine formulations: a real-world evidence study in primary care

PURPOSE

Several medications may interact with levothyroxine (LT4) intestinal absorption or metabolism, thus reducing its bioavailability. We investigated the variability of thyroid stimulating hormone (TSH) levels and prescribed daily dosages (PDDs) of LT4 before and during potential drug-drug interactions (DDIs) in users of tablets vs. oral liquid LT4 formulations.

METHODS

By using the Italian general practice Health Search Database (HSD), we retrospectively selected adult patients with at least one LT4 prescription from 2012 to 2015 and at least 1 year of clinical history recorded. The incident prescription of interacting medications (e.g., proton pump inhibitors, calcium or iron salts) was the index date. Analysis was carried out using a self-controlled study design.

RESULTS

Overall, 3965 users of LT4 formed the study cohort (84.1% women, mean age 56 ± 16.5 years). TSH variability on the entry date was greater among liquid LT4 users than in those prescribed with tablets as shown by the difference between 75th and 25th centile, which were 3.01 and 3.8, respectively. The incidence rate ratio (IRR) for TSH variability did not differ between groups, before and during exposure to DDIs. In contrast, PDDs less likely increased during the exposure to DDI with oral liquid LT4 compared with tablets (IRR = 0.84; 95% CI: 0.77-0.92), especially in patients with post-surgical hypothyroidism (IRR = 0.75; 95% CI: 0.64-0.85).

CONCLUSIONS

In clinical practice, the use of oral liquid LT4 is not associated with increased PDDs, compared with tablets formulation, during exposure to DDIs. These results support the need for individualizing LT4 formulation to prescribe, especially in patients with various comorbidities and complex therapeutic regimens.

Increased Requirement of Replacement Doses of Levothyroxine Caused by Liver Cirrhosis

BACKGROUND

Since hypothyroidism is a fairly common dysfunction, levothyroxine (L-T4) is one of the most prescribed medications. Approximately 70% of the administered L-T4 dose is absorbed. The absorption process takes place in the small intestine. Some disorders of the digestive system and some medicines, supplements, and drinks cause L-T4 malabsorption, resulting in failure of serum TSH to be normal. Only rarely liver cirrhosis is mentioned as causing L-T4 malabsorption.

CASE REPORT

In this study, we report increased requirement of daily doses of l-thyroxine in two patients with the atrophic variant of Hashimoto's thyroiditis and liver cirrhosis. In one patient, this increased requirement could have been contributed by the increased serum levels of the estrogen-dependent thyroxine-binding globulin (TBG), which is the major plasma carrier of thyroid hormones. In the other patient, we switched from tablet L-T4 to liquid L-T4 at the same daily dose. Normalization of TSH levels was achieved, but TSH increased again when she returned to tablet L-T4.

CONCLUSION

Liver cirrhosis can cause increased L-T4 requirements. In addition to impaired bile secretion, the mechanism could be increased serum TBG. A similar increased requirement of L-T4 is observed in other situations characterized by elevation of serum TBG. Because of better intestinal absorption, L-T4 oral liquid formulation is able to circumvent the increased need of L-T4 in these patients.

Thyroxine Treatment With Softgel Capsule Formulation: Usefulness in Hypothyroid Patients Without Malabsorption

BACKGROUND

Levothyroxine sodium (LT4) is the therapy of choice for hypothyroidism. In the last decade, new LT4 formulations, such as liquid and softgel capsules, became available. Even if some evidence has been reached in the efficacy of liquid LT4 in patients with suboptimal TSH on tablet LT4, the usefulness of softgel LT4 has been rarely studied. This study aimed at evaluating the effect of switching from tablet to softgel LT4 patients without increased need for LT4. TSH was used as proxy of LT4 bioavailability and effectiveness.

METHODS

During the period from April to August 2017, 19 patients on tablet LT4 treatment for hypothyroidism, mostly due to autoimmune thyroiditis, were enrolled. Subjects with causes of malabsorption or increased requirement of LT4 were previously excluded. Patients finally included were asked to switch from tablet to softgel LT4 formulation at unchanged dose and ingestion fashion (30 min before breakfast). TSH was measured with chemiluminescence immunoassays.

RESULTS

According to exclusion and inclusion criteria, 19 patients were finally selected. One of these had headache 4 days later and come back to tablet LT4, and 18 of them (16W/2M; mean age = 55 years; BMI 22.7 kg/m²) completed the study. They were treated with a median LT4 dose of 88 μg/day and showed a median TSH value of 3.33 mIU/L. The rate of cases with TSH ≤ 4.0 mIU/L was 61.1% (11/18 cases). When patients were re-evaluated after 3 months of softgel LT4, we observed that TSH reached levels under 4.0 mIU/L in 16/18 (88.9%) patients, TSH was lower in 11 cases, and in 6 out of 7 patients with pre-switch TSH values over the normal range. Overall, TSH values on softgel LT4 (median 1.90 mIU/L) was significantly lower from that observed during tablet LT4 (p = 0.0039).

CONCLUSION

These data show that hypothyroid patients with no proven malabsorption may have an improved TSH following 3 months from the switch from tablet to softgel LT4 preparation at unchanged dose.

Adherence to Levothyroxine Treatment Among Patients With Hypothyroidism: A Northeastern Italian Survey

Background: A significant number of patients show sub-optimal adherence to levothyroxine (LT4) therapy, mainly because they have to postpone their breakfast by at least 30 min. The aim of this observational cross-sectional study was to assess the therapeutic compliance of patients on LT4 treatment and to verify the preference of a lifetime treatment in tablet or liquid form. Patients and Methods: Ambulatory care patients aged 18 years or older, affected by hypothyroidism and on LT4 treatment (in tablet or liquid form) were administered the eight-item Morisky Medication Adherence Scale (MMAS-8). The MMAS-8 questionnaire was supplemented with 3 further items to specifically evaluate preference between tablet and liquid forms of LT4 for lifetime treatment. Results: A total of 320 patients (272 female), median age 47.9 ± 15.6 years (range, 20-78 years), completed the MMAS-8 questionnaire. Eighty-seven percent of the participants were adhering to their treatment for both tablet and liquid LT4 formulations, although significant differences emerged. Patients on LT4 tablets forgot to take their medication more frequently (p < 0.001), felt hassled about sticking to their treatment plan (p < 0.001), and had difficulty remembering to take all their medication(s) (p < 0.001) than those on liquid LT4 treatment. Conclusions: Adherence to LT4 treatment was high for both tablet and liquid formulations. Taking LT4 at breakfast was the most convenient option for most patients.

Levothyroxine Therapy: Changes of TSH Levels by Switching Patients from Tablet to Liquid Formulation. A Systematic Review and Meta-Analysis

BACKGROUND

In the last years, levothyroxine (LT4) has been commercialized also in liquid formulation, which is less sensitive to the factors known to reduce the absorption of tablet LT4. To date, there is no robust information that liquid LT4 can improve pharmacologic thyroid homeostasis of patients with reduced efficacy of tablet LT4. This analysis aimed at achieving solid evidence that switching thyroxine treatment from tablet to liquid preparation improves patients' TSH levels.

METHODS

The search was performed in PubMed/MEDLINE and Scopus database based on the terms "thyroid," "levothyroxine," and "liquid," and updated until September 25, 2017. Studies were included only if they described patients with suboptimal TSH on tablet LT4, subsequently switched to liquid LT4.

RESULTS

The literature search retrieved 462 articles and six were finally included. The pooled mean difference of TSH value between tablet and liquid LT4 was 4.23 mIU/L (95% CI from 3.69 to 4.77). Mild heterogeneity was found (I₂ 60%). Overall mean difference of TSH was significant (p < 0.0001).

CONCLUSION

The present meta-analysis showed that patients with suboptimal TSH on tablet LT4 can have a significantly improved TSH by switching to liquid LT4 formulation at unchanged dose.

Treatment pattern and frequency of serum TSH measurement in users of different levothyroxine formulations: a population-based study during the years 2009-2015

BACKGROUND

Several conditions can modify the intestinal absorption of levothyroxine tablets, with potential consequences on their therapeutic effect. Pre-dosed ampoules and oral drops have been recently made available to overcome this limitation.

AIMS

To describe the pattern of use of different formulations of levothyroxine in a general population of Southern Italy and to perform an exploratory analysis investigating the effect of switching from levothyroxine tablets to oral liquid formulations.

METHODS

Data were extracted from the Caserta Local Health Unit database. All patients receiving at least one levothyroxine prescription during the years 2009-2015 were identified. 1-year incidence of use of formulation-specific levothyroxine was calculated. Switchers between levothyroxine tablets and oral liquid formulations were identified and the frequency of thyroid-stimulating hormone measurement within 2 years prior and after the switch date was explored.

RESULTS

Overall, 56,354 levothyroxine users were included in the study. Of these, 55,147 patients received at least one prescription for tablets (97.9%), 1867 pre-dosed ampoules (3.3%) and 1550 oral drops (2.8%). The proportion of levothyroxine users receiving oral liquid formulations slightly increased over time. Patients switching from tablets to oral liquid formulations showed a statistically significant reduction in the number of thyroid-stimulating hormone measurements after switching from tablets, especially in presence of drugs interacting with levothyroxine potentially altering its absorption.

CONCLUSIONS

Use of levothyroxine oral liquid formulations is increasing over time even though their use is still limited in a general population of Southern Italy. Our exploratory analysis showed that the frequency of thyroid-stimulating hormone measurement was reduced in patients switching from levothyroxine tablet to new formulations.

l-Thyroxine in an Oral Liquid or Softgel Formulation Ensures More Normal Serum Levels of Free T4 in Patients with Central Hypothyroidism

CONTEXT

l-Thyroxine (l-T4) therapy of central hypothyroidism (CH) is guided by measurements of serum free thyroxine (FT4), which should be above the midnormal range value (MNRV). In some countries, novel formulations of oral l-T4 (liquid or softgel) are available further to the classic tablets. The intestinal absorption of either novel formulation is greater than tablets in patients with primary hypothyroidism.

OBJECTIVE

To evaluate whether new oral formulations of l-T4 could be considered optimal in patients with CH who do not reach the FT4 target using tablet l-T4.

DESIGN

Our observation of six patients with isolated CH and serum FT4 below MNRV under stable adequate doses of tablet l-T4 (median 1.51 μg/kg bw/day), prompted us to switch them to liquid (n = 4) or softgel (n = 3) l-T4 at the same dose, and verify whether FT4 increased above MNRV. A seventh patient with FT4 above MNRV was enrolled because she wanted a "more modern formulation." Postswitch FT4 was measured at least twice with the same kit as preswitch FT4.

RESULTS

In the first six patients, postswitch FT4 averaged 13.0 ± 1.6 pg/ml compared to 10.4 ± 1.8 preswitch FT4 (P = 0.00026), with 11/13 (85%) measurements above MNRV compared to 0/20. In the liquid or softgel l-T4 group, postswitch FT4 averaged 13.1 ± 1.6 vs. 10.6 ± 0.9 pg/ml preswitch (P = 0.0004) or 12.9 ± 2.1 vs. 10.3 ± 2.4 (P = 0.048), respectively. In the seventh patient (switched to liquid l-T4), averages were 18.3 vs. 15.2 pg/ml, and proportions 4/4 vs. 2/2.

CONCLUSION

In CH patients, oral liquid or softgel l-T4 administered at the same doses as tablet l-T4 ensures target serum FT4 levels above MNRV that tablet l-T4 may miss. In turn, this performance suggests the more favorable pharmacokinetics profile of either novel formulation compared with the tablet formulation.

Severe Hypothyroidism due to the Loss of Therapeutic Efficacy of l-Thyroxine in a Patient with Esophageal Complication Associated with Systemic Sclerosis

BACKGROUND

Thyroid function abnormalities and thyroid autoantibodies have been frequently described in patients with systemic autoimmune diseases as systemic sclerosis (SSc). Serum TSH levels are higher in SSc patients with more severe skin diseases and a worse modified Rodnan skin score. Asymptomatic esophageal involvement due to SSc has never been described as a cause of severe hypothyroidism due to l-thyroxine (l-T4) malabsorption in patients with Hashimoto's thyroiditis (HT) and SSc.

CASE REPORT

Here, we report a case of a 56-year-old female affected by both SSc and HT who developed severe hypothyroidism due to the loss of therapeutic efficacy of l-T4. Therapeutic failure resulted from the altered l-T4 absorption because of SSc esophageal complications. Clinical findings improved after the administration of oral liquid l-T4. Thyroid function completely normalized with a full clinical recovery, the disappearance of the pericardial effusion and the improvement of the pulmonary pressure.

CONCLUSION

A recognition of a poor absorption is crucial in patients with hypothyroidism and SSc to reduce the risk of the subsequent adverse events. This case suggests the importance of clinical and laboratory surveillance in patients with SSc and HT because the systemic complications of these dysfunctions may worsen the prognosis of hypothyroid SSc/HT patients.