Advancements in the treatment of hypothyroidism with L-T4 liquid formulation or soft gel capsule: an update

Abstract

The most recent advance concerning levothyroxine (L-T4) therapy is the development of novel oral formulations: the liquid preparation, and the soft gel capsule. Areas covered: This review evaluates the most recent clinical studies about these new formulations. The liquid formulation has been shown to overcome: the food and beverages intereference with L-T4 tablets absorption, caused by food or coffee at breakfast; malabsorption induced by the increased gastric pH, resulting from atrophic gastritis, or due to proton-pump inhibitors; and malabsorption after bariatric surgery. The use of liquid L-T4 has been studied also in pregnancy, newborns and infants, suggesting a better bioequivalence than tablets. Finally, liquid L-T4 is more active than tablets in the control of thyroid-stimulating hormone (TSH) in hypothyroid patients without malabsorption, drug interference, or gastric disorders, leading to a hypothesized higher absorption of liquid L-T4 also in these patients. Few studies have evaluated soft gel L-T4 with promising results in patients with malabsorption related to coffee or gastritis. Expert opinion: Liquid L-T4 (and soft gel capsules) are more active than the tablet L-T4 in the control of TSH in hypothyroid patients with gastric disorders, malabsorption, or drug interference, but also in patients without absorption disorders.

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

“…Considering that the drug dosage was the same between both groups, we suppose that the different TSH level could be associated with a higher absorption of L‐T4 in the liquid formulation; the underlying mechanisms is not well‐known yet …”

“…Considering that the drug dosage was the same between both groups, we suppose that the different TSH level could be associated with a higher absorption of L-T4 in the liquid formulation; the underlying mechanisms is not well-known yet. 11 The low pH value of the gastric environment is mandatory for the correct melting of L-T4 tablets and its solubility could be impaired by several factors. 19,20,24,25 Therefore, we have recruited patients without malabsorption or gastric diseases, nor drug interference.…”

“…Several studies have demonstrated that we could reach, in both adults and children, a higher percent of L‐T4 absorption when it is given in liquid solution rather than in solid tablet …”

“…Several studies have demonstrated that we could reach, in both adults and children, a higher percent of L-T4 absorption when it is given in liquid solution rather than in solid tablet. 11 Physicians usually attempt to achieve the desired thyroid-stimulating hormone (TSH) range by increasing the L-T4 daily prescription, even in those patients with concomitant factors (drugs, bariatric surgery or coffee consumption) that can alter the L-T4 tablets absorption. In vivo studies have proved how L-T4 oral solution can overcome this malabsorption issue.…”

Relational Stability in the Expression of Normality, Variation, and Control of Thyroid Function

“…Ingestion of a T4 load unaccompanied by the production of a physiologically appropriate T3-fraction may drive the system attempting regulatory balance into non-optimum positions (101). While LT4 dose escalation or the use of liquid formulations effectively control elevated TSH levels in various conditions including gastric problems, intestinal malabsorption, or drug interference (103, 104), this situation is different, as low FT3 concentrations persist in these patients despite suppressed TSH levels and elevated FT4 concentrations (102). Apparently, a minority of patients on LT4 still fail to concomitantly raise their serum FT3 concentrations as the T4 excess itself impairs T3–T4 conversion (102, 105).…”