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Drug Interactions between liothyronine and Protonix IV

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

liothyronine pantoprazole

Applies to: liothyronine and Protonix IV (pantoprazole)

MONITOR: Concurrent administration of proton pump inhibitors (PPI) may decrease the oral bioavailability of levothyroxine. Pharmacologic effects of levothyroxine may be reduced. The mechanism of interaction is suspected to be PPI induced hypochlorhydria leading to reduced levothyroxine absorption since gastric acidity is an essential requirement for levothyroxine absorption. However, the PPIs pantoprazole, omeprazole and lansoprazole did not affect the absorption of oral levothyroxine in some studies. It is not known whether this interaction occurs with other thyroid hormone preparations. This interaction may extend to potassium-competitive acid blockers (PCAB), as they also cause potent acid suppression.

MANAGEMENT: Caution is advised if levothyroxine is used concomitantly with PPI or PCAB. Consider the alteration in gastric pH caused by the PPI and PCAB. Some authorities recommend separating administration of PPI and levothyroxine by several hours, however there are no studies showing improved absorption when PPIs are administered separately from levothyroxine. If concomitant administration is necessary, consider monitoring TSH level and watching for clinical evidence of reduced levothyroxine effects. Patients should be advised to contact their physician if they experience symptoms of hypothyroidism, such as fatigue, cold intolerance, constipation, unexplained weight gain, depression, joint or muscle pain, thinning hair or hair loss, dry skin, hoarseness, and abnormal menstrual periods.

References (9)
  1. (2002) "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical
  2. (2024) "Product Information. Levothyroxine Sodium (levothyroxine)." Lannett Company Inc
  3. (2023) "Product Information. Levothyroxine Sodium (levothyroxine)." Zentiva Pharma UK Ltd
  4. (2023) "Product Information. Levothyroxine (Sandoz) (levothyroxine sodium)." Sandoz Pty Ltd
  5. JW Dietrich, K Gieselbrecht, RW Holl, BO Boehm (2006) "Absorption Kinetics of Levothyroxine Is Not Altered by Proton-pump Inhibitor Therapy" Horm Metab Res, 38, p. 57-59
  6. Ananthakrishnan S, Braverman LE, levin rm, Magnani B, Pearce EN (2008) "The effect of famotidine, esomeprazole, and ezetimibe on levothyroxine absorption" National Library of Medicine, 18, p. 493-498
  7. (2024) "Product Information. Eltroxin (levothyroxine)." Shire US Inc
  8. Raquel de Carvalho Abi-Abib, Mário Vaisman (2014) "Is it necessary to increase the dose of levothyroxine in patients with hypothyroidism who use omeprazole?" Arq Bras Endocrinol Metabol, 58(7), p. 731-6
  9. Issac Sachmechi, David M. Reich, Michael Aninyei, Francisca Wibowo, Garima Gupta, Paul J. Kim (2007) "Effect of Proton Pump Inhibitors on Serum Thyroid-Stimulating Hormone Level in Euthyroid Patients Treated with Levothyroxine for Hypothyroidism" Endocr Pract, 13, p. 345-349

Drug and food interactions

Moderate

liothyronine food

Applies to: liothyronine

ADJUST DOSING INTERVAL: Concurrent administration of calcium-containing products may decrease the oral bioavailability of levothyroxine by one-third in some patients. Pharmacologic effects of levothyroxine may be reduced. The exact mechanism of interaction is unknown but may involve nonspecific adsorption of levothyroxine to calcium at acidic pH levels, resulting in an insoluble complex that is poorly absorbed from the gastrointestinal tract. In one study, 20 patients with hypothyroidism who were taking a stable long-term regimen of levothyroxine demonstrated modest but significant decreases in mean free and total thyroxine (T4) levels as well as a corresponding increase in mean thyrotropin (thyroid-stimulating hormone, or TSH) level following the addition of calcium carbonate (1200 mg/day of elemental calcium) for 3 months. Four patients had serum TSH levels that were higher than the normal range. Both T4 and TSH levels returned to near-baseline 2 months after discontinuation of calcium, which further supported the likelihood of an interaction. In addition, there have been case reports suggesting decreased efficacy of levothyroxine during calcium coadministration. It is not known whether this interaction occurs with other thyroid hormone preparations.

MANAGEMENT: Some experts recommend separating the times of administration of levothyroxine and calcium-containing preparations by at least 4 hours. Monitoring of serum TSH levels is recommended. Patients with gastrointestinal or malabsorption disorders may be at a greater risk of developing clinical or subclinical hypothyroidism due to this interaction.

References (4)
  1. Schneyer CR (1998) "Calcium carbonate and reduction of levothyroxine efficacy." JAMA, 279, p. 750
  2. Singh N, Singh PN, Hershman JM (2000) "Effect of calcium carbonate on the absorption of levothyroxine." JAMA, 283, p. 2822-5
  3. Csako G, McGriff NJ, Rotman-Pikielny P, Sarlis NJ, Pucino F (2001) "Exaggerated levothyroxine malabsorption due to calcium carbonate supplementation in gastrointestinal disorders." Ann Pharmacother, 35, p. 1578-83
  4. Neafsey PJ (2004) "Levothyroxine and calcium interaction: timing is everything." Home Healthc Nurse, 22, p. 338-9

Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

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