Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Latina, Italy.
Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy.
Front Endocrinol (Lausanne). 2021 Jan 28;11:621616. doi: 10.3389/fendo.2020.621616. eCollection 2020.
Oral levothyroxine sodium is absorbed in the small intestine, mainly in the jejunum and the ileum being lower the absorption rate at duodenal level. The time interval between the ingestion of oral thyroxine and its appearance in the plasma renders unlike a gastric absorption of the hormone. However, several evidence confirm the key role of the stomach as a prerequisite for an efficient absorption of oral levothyroxine. In the stomach, in fact, occur key steps leading to the dissolution of thyroxine from the solid form, the process bringing the active ingredient from the pharmaceutical preparation to the aqueous solution. In particular, gastric juice pH, volume, viscosity, as well as gastric emptying time seem to be the most important limiting factors. These hypotheses are confirmed by the detection of an increased need for levothyroxine in patients with infection, chronic atrophic gastritis, gastroparesis, or in simultaneous treatment with drugs interfering with gastric acidic output. The aim of the present article is to focus on the knowledge of pathophysiologic events that determine the absorptive fate of traditional (tablet) and alternative thyroxine preparations (softgel capsule and liquid solution) in patients bearing gastric disorders.
口服左甲状腺素钠在小肠中被吸收，主要在空肠和回肠，十二指肠水平的吸收速率较低。口服甲状腺素与血浆中出现之间的时间间隔表明激素不是胃吸收的。然而，有几项证据证实胃是口服左甲状腺素有效吸收的前提。事实上，在胃中，发生了关键步骤，导致甲状腺素从固体形式中溶解，将有效成分从药物制剂带到水溶液中。特别是，胃液 pH 值、体积、粘度以及胃排空时间似乎是最重要的限制因素。这些假设通过检测到感染、慢性萎缩性胃炎、胃轻瘫或同时与干扰胃酸分泌的药物治疗的患者中左甲状腺素的需求增加得到证实。本文的目的是关注决定传统（片剂）和替代甲状腺素制剂（软胶囊和液体溶液）在患有胃疾病的患者中的吸收命运的病理生理事件的知识。
