Levothyroxine (LT4) and proton pump inhibitors (PPI) are two of the most prescribed
drugs particularly in elderly population [
[1]
,
[2]
]. As they are frequently co-ingested, the effect on levothyroxine absorption is especially
relevant due to its narrow therapeutic index [
[1]
]. It is well established that an acid gastric pH is required to the dissolution of
LT4 before its absorption in the intestine. Accordingly, some in vitro studies illustrated
that an increase in the gastric pH affects the dissolution of the LT4 tablet [
[3]
]. As PPI act by blocking the secretion of gastric acid through covalent binding to
the H+/K+ATPase enzyme they have been included in the list of factors affecting gastrointestinal
absorption of levothyroxine with moderate clinical significance [
[1]
]. Regarding the appropriate timing of LT4 administration it has been widely recommended
for tablets to be taken during fasting before breakfast [
[4]
]. Similarly, PPI are usually ingested during the morning before breakfast and that
is one of the main reasons because the co-ingestion of these two drugs is a matter
of concern particularly for the clinicians who prescribed and follow-up the patients
due to the impact that PPI may have on LT4 treatment.To read this article in full you will need to make a payment
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References
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Article info
Publication history
Published online: February 21, 2020
Accepted:
February 16,
2020
Received:
February 6,
2020
Identification
Copyright
© 2020 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.
