Failure of l-T4 treatment to reach target serum thyroid-stimulating hormone levels generally prompts the physicians to increase l-T4 daily dose. In vitro studies have shown that the soft gel capsule releases the active ingredient more consistently at varying pH than the tablet. In addition, in vivo studies have confirmed the in vitro data and have demonstrated that both the soft gel capsule and the liquid formulation are capable to solve tablet l-T4 malabsorption caused by certain drugs, bariatric surgery or coffee. These new formulations may be attractive also for patients who cannot/do not want to change their (improper) habits of l-T4 ingestion. Finally, the oral solution l-T4 could be suitable for patients who cannot swallow the solid formulations.
The number of thyroid cancers is increasing. Standard treatment usually includes primary surgery, thyroid-stimulating hormone suppressive therapy, and ablation of the thyroid remnant with radioactive iodine (RAI). Despite the generally good prognosis of thyroid carcinoma, about 5% of patients will develop metastatic disease, which fails to respond to RAI, exhibiting a more aggressive behavior. The lack of specific, effective and well-tolerated drugs, the scarcity of data about the association of multi-targeting drugs, and the limited role of radioiodine for dedifferentiated thyroid cancer, call for further efforts in the field of new drugs development. Rearranged during transfection (RET)/papillary thyroid carcinoma gene rearrangements, BRAF (B-RAF proto-oncogene, serine/threonine kinase) gene mutations, RAS (rat sarcoma) mutations, and vascular endothelial growth factor receptor 2 angiogenesis pathways are some of the known pathways playing a crucial role in the development of thyroid cancer. Targeted novel compounds have been demonstrated to induce clinical responses and stabilization of disease. Sorafenib has been approved for differentiated thyroid cancer refractory to RAI.
These results first show that liquid L-T4 could prevent the problem of malabsorption in patients with BPD and confirm those of previous studies in patients submitted to RYGB, suggesting that the L-T4 oral liquid formulation could circumvent malabsorption after bariatric surgery.
The purpose of this work is to evaluate if the coffee-associated malabsorption of tablet levothyroxine (L-T4) is reduced by soft gel capsule. We recruited 8 patients with coffee-associated L-T4 malabsorption including one hypothyroid patient. For 6 months, the patients were switched to the capsule maintaining the L-T4 daily dose. Patients took the capsule with water, having coffee 1 h later (proper habit, PH) on days 1-90, or with coffee ≤ 5 min later (improper habit, IH) on days 91-180. After 6 months, 2 patients volunteered for an acute loading test of 600 μg L-T4 (capsule) ingested with water (PH) or with coffee (IH). In the single hypothyroid patient, the post-switch TSH ranged 0.06-0.16 mU/L (PH) versus 5.8-22.4 mU/L pre-switch (PH) and 0.025-0.29 mU/L (IH) versus 26-34 mU/L pre-switch (IH). In the other 7 patients, post-switch TSH was 0.41 ± 0.46 (PH) versus 0.28 ± 0.20 pre-switch (PH) (P = 0.61) and 0.34 ± 0.30 (IH) versus 1.23 ± 1.47 pre-switch (IH) (P < 0.001). Importantly, TSH levels in PH versus IH habit did not differ post-switch (P = 0.90), but they did pre-switch (P < 0.0001). The proportions of post-switch TSH levels <0.10 mU/L with PH (33.3 %) or with IH (33.3 %) were borderline significantly greater than the corresponding pre-switch levels with PH (10.3 %) (P = 0.088) or with IH (0 %) (P = 0.0096). In the two volunteers, the L-T4 loading test showed that coffee influenced L-T4 pharmacokinetics minimally. Soft gel capsules can be used in patients who are unable/unwilling to change their IH of taking L-T4.
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