SAN DIEGO — Patients who consume a liquid formulation of thyroxine (L-T4) with breakfast in the treatment of hypothyroidism show no significant differences in thyroid-hormone levels compared to those taking the therapy 30 minutes or more prior to a meal, as is typically recommended, according to new research.
"Our results confirm for the first time, in a double-blind, randomized placebo-controlled study, that liquid L-T4 formulation can be consumed at breakfast," lead author Dr Carlo Cappelli (University of Brescia, Italy) told Medscape Medical News.
The preliminary findings, from the first 44 patients out of a target of 80 to 100, suggest the possibility of eliminating one of the most challenging causes of noncompliance in hypothyroidism treatment: the requirement that patients take their medication 30 minutes to 1 hour prior to breakfast, because absorption is maximal when administered on an empty stomach.
While no liquid L-T4 formulations for oral use are currently available in the United States, soft-gel capsules containing liquid are available, said Dr Bryan R Haugen (University of Colorado School of Medicine, Denver), who was not involved in the study.
"The study has not completed enrollment, so it may be premature to make conclusions. I can't tell by this if dose adjustments were needed when switching from before meals to with meals," for example, Dr Haugen said.
But if further work shows "that these more liquid preparations of levothyroxine are not affected by food, but the solid forms are, it would definitely help our patients with compliance," he added. However, he noted one downside: the gel capsules are significantly more expensive than other solid levothyroxine preparations (like Synthroid [AbbVie] or Levoxyl [Pfizer]).
Chance Observation Led to Trial
Dr Cappelli described the impetus for the research — the chance observation of a patient whose thyroid levels inexplicably did not appear to be adversely affected despite his confessing to consuming liquid L-T4, against instructions, with coffee.
"We fortuitously identified a euthyroid patient who wrongly consumed liquid L-T4 with coffee at breakfast. After changing the time of consumption to 30 minutes before breakfast, no change in [thyroid-stimulating hormone] TSH, free T4, and free T3 concentrations were observed."
The Italian researchers sought to further probe the issue, conducting a phone survey of their patients and identifying 54 patients who also reported taking liquid L-T4 at breakfast.
After having the patients adjust their consumption of the treatment to 30 minutes before breakfast, the authors evaluated levels of TSH, free T4, and free T3 and found no significant differences after 3 and 6 months.
Dr Cappelli and colleagues then decided to conduct their trial, named TICO; Dr Cappelli reported data on the first 36 females and eight male patients, who had a mean age of 48.4 and who were beginning treatment with L-T4 for hypothyroidism, at the recent 2014 Annual Meeting of the American Thyroid Association.
Patients were instructed to consume liquid from two undistinguishable vials daily — one, from vial A, to be taken 30 minutes prior to breakfast and the other, from vial B, during breakfast. One of the vials contained liquid L-T4 (Tirosint fiala monouso, IBSA Farmaceutici Italia, Akrimax Pharmaceuticals/IBSA) at a dosage of 1.6 µg/kg, and the other contained a placebo.
After 40 days, patients were tested for levels of TSH, free T4, and free T3 to ensure they had achieved normal thyroid-hormone levels.
Participants then had the order of their vial consumption switched, so that those receiving the liquid L-T4 30 minutes prior to the meal would now be taking it during the meal, and vice versa.
Overall, patients received a mean dose of L-T4 of 64.71 µg/day.
No Difference in Thyroid Hormone Levels According to T4 Formulation
After the second 40 days with the switched treatment-placebo order, no significant differences in thyroid levels were seen in patients before and after switching the order of vial consumption, including in TSH (2.32 vs 2.94 mlU/L after the switch, P = 0.129); free T4 (10.51 vs 10.60 pg/mL, P = 0.774) and free T3 (2.70 vs. 2.72 pg/mL, P = 0.774).
"[The findings show that] liquid L-T4 formulation can be consumed at breakfast, improving the compliance of hypothyroid patients who have to start L-T4 replacement therapy," Dr Cappelli said.
"Oral liquid L-T4 formulations could diminish the problem of L-T4 malabsorption caused by coffee when using traditional tablet formulations."
In addition, "the oral solution L-T4 could be suitable for patients who cannot swallow the solid formulations," he said.
However, Dr Haugen pointed out that this is a moot point in the United States, because anyone unable to swallow tablets wouldn't be able to take a gel cap either, and no purely liquid form of T4 is available there.
"I would also like to see a study where Tirosint was compared directly with a solid formulation (like Synthroid or Levoxyl) for effects of food," Dr Haugen concluded.
The study received no commercial funding, and the authors have reported they have no relevant financial relationships.
2014 Annual Meeting of the American Thyroid Association; October 30, 2014; San Diego, CA. Abstract 28
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Cite this: Liquid Thyroxine Could Be Taken With Meals, Aid Compliance - Medscape - Nov 13, 2014.