Search Results (12)

Background/Objectives: Levothyroxine (L-T4) replacement therapy is essential following total thyroidectomy. While liquid L-T4 formulations exhibit superior pharmacokinetic properties compared to tablets, their specific metabolic impact—particularly on insulin resistance—remains unclear. The aim of this study was to compare the short-term effects of liquid versus tablet L-T4 replacement therapy on insulin resistance indices in recently thyroidectomized women and to identify baseline predictors of metabolic response. Methods: A post hoc analysis included 130 women randomized to receive either liquid or tablet L-T4 after total thyroidectomy. Metabolic parameters—including the homeostatic model assessment for insulin resistance (HOMA-IR), triglycerides-glucose (TyG) index, and triglycerides-to-HDL cholesterol (TG/HDL-C) ratio—were assessed at baseline and after two months. Results: Both L-T4 formulations significantly improved insulin resistance indices over two months. Liquid L-T4 induced a more pronounced reduction in HOMA-IR (treatment effect p = 0.022) and fasting insulin levels (treatment effect p = 0.017) compared to the tablet formulation. No significant between-group differences were observed for TyG index or TG/HDL-C ratio. Changes in insulin resistance markers were independent of body mass index variations and were predicted by baseline metabolic parameters including insulin, glucose, and lipid levels. Conclusions: L-T4 replacement therapy improves insulin resistance markers shortly after thyroidectomy, with the liquid formulation exerting a greater effect on hepatic insulin sensitivity. These findings support the individualized selection of L-T4 formulations to optimize both endocrine and metabolic outcomes post-thyroidectomy. Full article

Background/Objectives: Levothyroxine (L-T4) is available for use in congenital hypothyroidism (CH) in three formulations: tablets, drops, and oral solution. This study aims to compare the efficacy and safety of all three L-T4 formulations. Methods: We enrolled 63 children born between January 2019 and April 2023 in the Emilia-Romagna Region (Italy) and diagnosed with CH by newborn screening. They were divided according to the L-T4 formulation used: drops (Group D), oral solution (Group S), and tablets (Group T). Clinical and laboratory data were collected up to 3 years after the start of replacement therapy. Results: Serum-free thyroxine (sFT4) and thyroid stimulating hormone (sTSH) normalization occurred within the first month of treatment in most patients of all groups. No negative effects on growth and cognitive development were observed. At 7–15 days we found higher median sTSH levels (p = 0.031) and a greater percentage of patients with sTSH > 5 µU/mL (p = 0.011) in Group S than in Group T, but comparable sFT4 levels. At 12 months, a greater percentage of patients of Group D showed sFT4 values below the normal range than Group S (p = 0.011) and Group T (p = 0.038); Conclusions: Overall, our study reported an equal efficacy of the L-T4 oral solution compared to drops and tablets in CH treatment. A larger series of patients and a long-term follow-up are needed. Full article

Levothyroxine tablets, although highly prescribed in the United States, have been one of the most frequently recalled products. Because of the importance of the medication, several efforts have been put in place by the United States Food and Drug Administration (US FDA) to control the quality of levothyroxine tablets available to patients using the drug. The choice of excipients used in the formulation has been shown to impact the hygroscopicity and microenvironment, and ultimately the stability of the levothyroxine tablets formulations. Based on information generated from the US FDA Enforcement Report database, one of the main reasons for recalls is the low potency of different batches of the product. The yearly product recall trends for levothyroxine formulations were determined using the FDA Enforcement Report database. Three brands of levothyroxine tablets were selected with excipient lists similar to those products that have been historically recalled. The samples were placed at ambient (~23 °C), accelerated stability (40 °C/75% RH), and stress (50 °C/75% RH) conditions for up to 6 months. Sample potencies were determined at 0, 1.5, 3, and 6 months using the methods for assay and impurities in the United States Pharmacopeia (USP) monograph for levothyroxine tablets. Additional sample monitoring was conducted by overlaying the initial powder X-ray diffractograms (PXRD) of the samples from 0 months with the patterns generated thereafter. There has been a decline in the number of levothyroxine tablets recalled over the years. The highest numbers of recalls were recorded in the years 2013 [33] and 2020 [23]; no recalls occurred in the years 2019 and 2022. All of the brands evaluated met the USP 95.0–105.0% assay requirements at 1.5 months under accelerated conditions; only one of the brands complied at 3 months. Under ambient conditions, two brands were stable at 6 months, with borderline assay results. For stability, levothyroxine was found in microgram quantities in the formulations and PXRD could not detect changes at these low levels. However, we found some distinguishing data for samples under stress conditions. Full article

The present study aimed to evaluate the stability of active pharmaceutical ingredients (APIs) from different pharmacological classes in a compounded oral suspending vehicle. Oral suspensions of amoxicillin trihydrate (50 mg/mL), clozapine (25 mg/mL), indomethacin (5.0 mg/mL), levodopa/carbidopa (10.0/2.5 mg/mL), levothyroxine sodium (T4, 25 µg/mL), lomustine (4.0 and 10.0 mg/mL), methyldopa (25 mg/mL) and procarbazine (10.0 mg/mL) were formulated in SyrSpend^® SF PH4 and the stability was monitored for up to 90 days, except for amoxicillin trihydrate, which was evaluated for 30 days only. The APIs’ stability was determined by measuring percent recovery using stability-indicating high-performance liquid chromatography (HPLC or UHPLC) or titration (amoxicillin trihydrate only). The stability of amoxicillin trihydrate, clozapine, indomethacin and levodopa/carbidopa were studied at both refrigerated (2–8 °C) and room temperature (20–25 °C). Lomustine, procarbazine, and methyldopa were studied at refrigerated temperature only. Our data demonstrated promising stability for the compounded suspensions containing various APIs, investigated in SyrSpend^® SF PH4, as all APIs exhibited stability throughout the study duration and met content uniformity criteria. These findings lead to the conclusion that the tested compounded oral suspensions present a viable approach for creating personalized, age-appropriate formulations. The capacity to ensure dose consistency and stability using APIs from diverse pharmacological classes renders them suitable choices for both pediatric and geriatric patients. Full article

Thyroid diseases affect a considerable portion of the population, with hypothyroidism being one of the most commonly reported thyroid diseases. Levothyroxine (T4) is clinically used to treat hypothyroidism and suppress thyroid stimulating hormone secretion in other thyroid diseases. In this work, an attempt to improve T4 solubility is made through the synthesis of ionic liquids (ILs) based on this drug. In this context, [Na][T4] was combined with choline [Ch]⁺ and 1-(2-hydroxyethyl)-3-methylimidazolium [C₂OHMiM]⁺ cations in order to prepare the desired T4-ILs. All compounds were characterized by NMR, ATR-FTIR, elemental analysis, and DSC, aiming to check their chemical structure, purities, and thermal properties. The serum, water, and PBS solubilities of the T4-ILs were compared to [Na][T4], as well as the permeability assays. It is important to note an improved adsorption capacity, in which no significant cytotoxicity was observed against L929 cells. [C₂OHMiM][T4] seems to be a good alternative to the commercial levothyroxine sodium salt with promising bioavailability. Full article

(1) Background: We evaluated the long term adherence to two distinct formulations of levothyroxine (L-T4), liquid or solid, which are differently influenced by concomitant food ingestion. (2) Methods: A total of 106 thyroidectomized patients (82 female, mean age 58.2 ± 13.3 years) on L-T4 replacement therapy in either liquid (n = 52) or solid formulation (n = 54) were administered the four-item Medication Adherence Questionnaire (MAQ). (3) Results: The study population had 59.4% adherers and 40.6% non-adherers. The global MAQ score was significantly better in patients under liquid L-T4 in comparison to those under solid L-T4 (0.42 ± 0.82 vs. 0.83 ± 0.95, respectively, p = 0.0085). The patients on tablet L-T4 forgot to take their medication more frequently than those on liquid LT4 treatment (p = 0.0159) and were more often careless at times about taking their medication (p = 0.007), whilst about one in two thyroidectomized patients preferred tablets for lifetime medication therapy. The global MAQ score was directly correlated with the circulating TSH levels in the whole study population (0.700, p < 0.0001) and inversely correlated with both the FT3 (−0.220, p = 0.0232) and FT4 (−0.327, p = 0.0006) serum concentrations. (4) Conclusions: Long-term adherence to L-T4 treatment was globally satisfactory although it was better for the liquid formulation, which appears to represent an easier-to-manage L-T4 replacement therapy for most thyroidectomized patients, particularly for those with difficulties in taking L-T4 while fasting. Full article

Background: Increased knowledge of the pharmacokinetic characteristics of orally administered levothyroxine (L-T₄) has improved individualization of dosing regimens. However, up to 40–45% of patients, depending on the leading cause of hypothyroidism, are still over- or, more often, undertreated. Unintentional non-adherence to L-T₄ replacement therapy includes all situations of unintended drug–drug and drug–food interactions as well as fasting conditions that are not necessarily respected by patients. Results: In this specific context, the overall information concerning those factors with the potential to affect L-T₄ absorption refers only to tablet formulation. Indeed, this is the reason why new non-tablet formulations of L-T₄ were introduced some years ago. In this regard, the current literature review was designed to summarize pharmacokinetic, drug and food interactions and clinical data focusing on two new oral L-T₄ formulations, i.e., liquid and soft-gel capsule in healthy volunteers and patients with primary hypothyroidism. The non-tablet L-T₄ soft-gel capsules and solution have proven bioequivalence with the usual L-T₄ tablet Princeps and generic formulations. Clinical studies have suggested higher performance of non-tablet formulations than tablet in those patients with suboptimal adherence. The impact of gastrointestinal conditions and variation of gastric pH was lower with either soft gel/solution than with tablets. In addition, the extent of drug–drug and drug–food interactions remains low and of uncertain clinical relevance. Conclusions: Pending further studies allowing one to extend the use of soft-gel/solution preparations in unselected patients, non-tablet L-T₄ formulations should be considered as a first-line choice, especially in those patients with moderate-to-high potential of suboptimal tablet performance. Full article

Levothyroxine (l-thyroxine, l-T4) is a drug of choice for treating congenital and primary hypothyroidism. Although clinically significant interactions between l-T4 and food can alter the safety and efficacy of the treatment, they still seem to be generally underestimated by patients, physicians and pharmacists. This review aimed to investigate the effects of meals, beverages, and dietary supplements consumption on l-T4 pharmacokinetics and pharmacodynamics, to identify the most evident interactions, and to perform the recommendations for safe co-administering of l-T4 and food. A total of 121 studies were identified following a systematic literature search adhering to PRISMA guidelines. After full-text evaluation, 63 studies were included. The results proved that l-T4 ingestion in the morning and at bedtime are equally effective, and also that the co-administration of l-T4 with food depends on the drug formulation. We found limited evidence for l-T4 interactions with coffee, soy products, fiber, calcium or iron supplements, and enteral nutrition but interestingly they all resulted in decreased l-T4 absorption. The altered l-T4 efficacy when ingested with milk, juices, papaya, aluminium-containing preparations, and chromium supplements, as well as observed enhancement effect of vitamin C on l-T4 absorption, shall be further investigated in larger, well-designed studies. Novel formulations are likely to solve the problem of coffee, calcium and iron induced malabsorption of l-T4. Maintaining a proper time interval between l-T4 and food intake, especially for coffee and calcium, or iron supplements, provides another effective method of eliminating such interactions. Full article

Background and objectives: It is unclear why many patients with hypothyroidism prefer the use of desiccated thyroid extract (DTE) as a thyroid hormone replacement formulation over levothyroxine (LT4) treatment, as recommended by clinical practice guidelines. We analyzed patient-reported information from patient online forums to better understand patient preferences for and attitudes toward the use of DTE to treat hypothyroidism. Materials and Methods: We conducted a mixed-methods study by evaluating the content of online posts from three popular hypothyroidism forums from patients currently taking DTE (n = 673). From these posts, we extracted descriptive information on patient demographics and clinical characteristics and qualitatively analyzed posts’ content to explore patient perceptions on DTE and other therapies further. Results: Nearly half (46%) of the patients reported that a clinician initially drove their interest in trying DTE. Patients described many reasons for switching from a previous therapeutic approach to DTE, including lack of improvement in hypothyroidism-related symptoms (58%) and the development of side effects (22%). The majority of patients described DTE as moderately to majorly effective overall (81%) and more effective than the previous therapy (77%). The most frequently described benefits associated with DTE use were an improvement in symptoms (56%) and a change in overall well-being (34%). One-fifth of patients described side effects related to the use of DTE. Qualitative analysis of posts’ content supported these findings and raised additional issues around the need for individualizing therapy approaches for hypothyroidism (e.g., a sense of each patient has different needs), as well as difficulties obtaining DTE (e.g., issues with pharmacy availability). Conclusions: Lack of individualized treatment and a feeling of not been listened to were recurrent themes among DTE users. A subset of patients may prefer DTE to LT4 for many reasons, including perceived better effectiveness and improved overall well-being, despite the risks associated with DTE. Full article

The influence of excipients on the stability of sodium levothyroxine pentahydrate (LTSS) under ambient conditions and thermal stress was evaluated. Since LTSS is a synthetic hormone with a narrow therapeutic index, the interactions of LTSS with excipients can lead to a drastic diminution of therapeutic activity. Ten commonly used pharmaceutical excipients with different roles in solid formulations were chosen as components for binary mixtures containing LTSS, namely, starch, anhydrous lactose, D-mannitol, D-sorbitol, gelatin, calcium lactate pentahydrate, magnesium stearate, methyl 2-hydroxyethyl cellulose (Tylose), colloidal SiO₂ (Aerosil) and talc. As investigational tools, universal attenuated total reflectance- Fourier transform infrared spectroscopy UATR-FTIR spectroscopy and thermal analysis were chosen and used as follows: UATR-FTIR spectra were drawn up for samples kept under ambient conditions, while thermoanalytical tools (TG/DTG/HF data) were chosen to evaluate the inducing of interactions during thermal stress. The corroboration of instrumental results led to the conclusion that LTSS is incompatible with lactose, mannitol and sorbitol, and these excipients should not be considered in the development of new generic solid formulations. Full article

Patients on treatment with levothyroxine (T4) are informed to take this drug in the morning, at least 30 min before having breakfast. A significant decrease of T4 absorption was reported, in fact, when T4 solid formulations are taken with food or coffee. According to preliminary clinical study reports, administration of T4 oral solution appears to be less sensitive to the effect of breakfast beverages on oral bioavailability. In the present study, stability of T4 oral solution added to breakfast beverages was investigated. A 1 mL ampoule of single-dose Tirosint^® oral solution (IBSA Farmaceutici Italia, Lodi, Italy) was poured into defined volumes of milk, tea, coffee, and coffee with milk warmed at 50 °C, as well as in orange juice at room temperature. Samples were sequentially collected up to 20 min and analyzed by validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. The results of the study demonstrated that T4 is stable in all beverages after 20 min incubation. Demonstration of T4 stability is a prerequisite for a thorough evaluation of the effect of breakfast beverages on the bioavailability of T4 given as oral solution and for a better understanding of the reasons underlying a decreased T4 bioavailability administered as solid formulations. Full article