ISSN 2398-2985      

Levothyroxine

Jreptile

Synonym(s): T4, L-thyroxine


Introduction

Name

  • Levothyroxine.
  • Levothyroxine sodium.

Class of drug

  • Synthetic hormone.

Description

Chemical name

  • (S)-2-Amino-3-[4-(4-hydroxy-3,5-diiodophenoxy)-3,5-diiodophenyl]propanoic acid.

Molecular formula

  • C15H11I4NO4.

Molecular weight

  • 776.87.

Physical properties

  • Odorless, light yellow to buff-colored, tasteless, hygroscopic powder that is very slightly soluble in water and slightly soluble in alcohol.
  • Levothyroxine sodium is unstable in aqueous solutions. If using a commercial liquid preparations, it is suggested to obtain validated stability data for the product. 

Storage requirements

  • Store at room temperature in tight, light-resistant containers.
  • The injectable product should be reconstituted immediately before use and any unused product  should be discarded after reconstitution.

Uses

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Indications

  • Used to treat hypothyroidism, either primary or secondary: iatrogenic hypothyroidism may occur after thyroid gland removal.
  • Anecdotal reports of its use to treat hepatic lipidosis.

Administration

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Pharmacokinetics

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Precautions

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Interactions

with other drugs

Catecholamines
  • Epinephrine Epinephrine, norepinephrine.
  • Effects are enhanced by thyroxine.
Sympathomimetics
  • Effects are enhanced by thyroxine.
Warfarin
  • Potentiate the anticoagulant effects of warfarin by increasing the catabolism of vitamin K-dependent clotting factors.
Insulin
  • Diabetic patients may have altered insulin requirements - monitor carefully during the initiation of therapy.
Estrogens
  • May increase thyroid requirements by increasing TBg Estradiol.
Digoxin, digitoxin
  • The therapeutic effect may be reduced by thyroid hormones.
Ketamine
  • Increased risk of tachycardia and hypertension Ketamine.

With diagnostic tests

  • Many drugs (in humans) may have effects on thyroid function tests, including anabolic steroids, antithyroid drugs, barbiturates, corticosteroids, diazepam, fluorouracil, heparin, insulin, mitotane (op-DDD), nitroprusside, oestrogens, phenylbutazone, phenytoin, propranolol, salicylates and thiazides.

Adverse Reactions

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Hadfield C A, Clayton L A, Clancy M M et al (2012) Proliferative thyroid lesions in three diplodactylid geckos: Nephrurus amyae, Nephrurus levis and Oedura marmorata. J Zoo Wildl Med 43 (1), 131-140 PubMed.

Other sources of information

  • Plumb D C (2015) Plumb's Veterinary Drug Handbook. 8th edn. Wiley-Blackwell, USA. pp 1296.
  • McArthur S, Wilkinson R & Meyer J (2004) Medicine and Surgery of Tortoises and Turtles. Blackwell Publishing, UK. pp 579.
  • Girling S J & Raiti P (2004) BSAVA Manual of Reptiles. BSAVA, UK. pp 383.
  • Tennant B (1999) Small Animal Formulary. 3rd edn. BSAVA, UK.

Organisation(s)

  • National Office of Animal Health (NOAH) Compendium of Data Sheets for Animal Medicines. Website: www.noahcompendium.co.uk.
MEMBER BENEFIT

Can’t find what you’re looking for?

We have an ever growing content library on Vetlexicon so if you ever find we haven't covered something that you need please fill in the form below and let us know!

 
 
 
 

To show you are not a Bot please can you enter the number showing adjacent to this field

 Security code