Levothyroxine is a Medicine belongs to Thyroid agent group whose information about Brand can be referenced from   Book : Martindale    Page : 2374   Edition : 37      Page :   Edition :   

  ►   Brandname : Eutroxsig, Oroxine, Berlthyrox, Eferox, Euthyrox, Thyradin-S, Eltroxin, Evotrox, Levothroid, Levoxyl, Novothyrox, Eltroxin, Thyronorm, Uthyrox
  ►  Strength : Tablet with 25 mcg.  Tablet with 50 mcg.  Tablet with 75 mcg.  Tablet with 88 mcg.  Tablet with 100 mcg.  Tablet with 112 mcg.  Tablet with 125 mcg.  Tablet with 137 mcg.  Tablet with 150 mcg.  Tablet with 175 mcg.  Tablet with 200 mcg.  Tablet with 300 mcg.  Capsule with 13 mcg.  Capsule with 25 mcg.  Capsule with 50 mcg.  Capsule with 75 mcg.  Capsule with 88 mcg.  Capsule with 100 mcg.  Capsule with 112 mcg.  Capsule with 125 mcg.  Capsule with 137 mcg.  Capsule with 150 mcg.  Injection with 200 mcg/vial.  Injection with 500 mcg/vial. 

Reference of this Medicine for its Strength can be taken from   Book : Basic & Clinical pharmacology    Page : 695   Edition : 12  
A Route of administration in pharmacology and toxicology is the path by which a drug, fluid, poison, or other substance is taken into the body. Routes of administration are generally classified by the location at which the substance is applied. Common examples include oral and intravenous administration.

  ►  Route of administration : Oral, IV, IM
Reference :-   Book : Martindale    Page : 2374   Edition : 37  

Dosing of Medicine differ in Adult & Pediatrics ↓

Adult Dose

S.No Ailment   Route   Dose Min   Dose Max   Unit   Dosage Form   Frequency   Additional Info
1 Hypothyroidism Oral 50 100 micrograms Tablet Dose: Given daily may be increased by 25 to 50 micrograms at intervals of about 4 weeks until the thyroid deficiency is corrected and a maintenance dose is established
2 Oral 12.5 50 micrograms Tablet Dose: For elderly patients, in those with cardiovascular disorders, or in those with severe hypothyroidism of long standing: given daily increased by increments of 12.5 to 25 micrograms at intervals of about 4 weeks may be appropriate.
3 Myxedema (hypothyroid) coma IV 200 500 micrograms Injection A further dose of 100 to 300 micrograms is given on the second day if no improvement is evident, and followed by daily supplements of about 100 to 200 micrograms until the patient is euthyroid and can tolerate oral doses

Ref :-  Book : Martindale    Page : 2374   Edition : 37  

Pediatric Dose

S.No Ailment   Age Min   Age Max   Weight ( Kg ) Route   Dose Min   Dose Max   Unit   Dosage Form   Frequency  Additional Info  
1 Hypothyroidism Oral 10 15 micrograms/kg Tablet o.d.
2 Hypothyroidism 1 Month 2 Year Oral 5 micrograms/kg Tablet o.d.
3 Hypothyroidism 2 Year 12 Year Oral 50 micrograms Tablet o.d.
4 Hypothyroidism 12 Year 18 Year Oral 50 micrograms Tablet o.d.

Ref :- Book : Martindale    Page : 2374   Edition : 37  
►  Side Effect : Tachycardia, palpitations, Cardiac arrhythmias, Increase in blood pressure, Anginal pain, Headache, Restlessness, Excitability, Insomnia, Tremors, Muscle weakness, Muscle cramps, Heat intolerance, Sweating, Flushing, Fever, Weight loss, Menstrual irregularities, Diarrhoea, Vomiting, Thyroid storm, Convulsions, Heart failure, Death
Ref :-   Book : Martindale    Page : 2372   Edition : 37.  

►  Drug Interaction : Drug interaction of Levothyroxine is with , Barbiturates , ,  Oestrogen, Lovastatin , Ferrous Sulphate , Ketamine , Sucralfate , Digoxin , Propranolol , Proguanil , Chloroquine , Phenytoin , Carbamazapine , Rifampicin , Amiodarone
Ref :-   Book : Martindale    Page : 2372-2373   Edition : 37.  

  ►    Mechanism of Drug Drug Interaction :  Amiodarone may inhibit the de-iodination of thyroxine to tri-iodothyronine resulting in a decreased concentration of tri-iodothyronine with a rise in the concentration of inactive reverse tri-iodothyronine. Enzyme induction by rifampicin enhances thyroid hormone metabolism resulting in reduced serum concentrations of thyroid hormones. Thyroid hormones enhance the effects of oral. Patients on anticoagulant therapy therefore require careful monitoring. Some drugs such as lithium act directly on the thyroid gland and inhibit the release of thyroid hormones leading to clinical hypothyroidism. As thyroid status influences metabolic activity and most body systems, correction of hypothyroidism may affect other disease states and dosage of any drug treatment. In hypothyroid diabetics for instance, starting thyroid replacement therapy may increase their insulin or oral hypoglycaemic requirements. Enzyme induction by drugs such as carbamazepine, phenytoin, or barbiturates enhances thyroid hormone metabolism resulting in reduced serum concentrations of thyroid hormones. Increased thyroid-stimulating hormone concentration has been noted after the use of chloroquine with proguanil for malaria prophylaxis in a patient stabilised on levothyroxine. Studies have indicated that plasma concentrations of propranolol are reduced in hyperthyroidism compared with the euthyroid state, probably due to increased clearance. Serum-digoxin concentrations appear to be lower in hyperthyroidism and higher in hypothyroidism, which may contribute in part to the observed insensitivity of hyperthyroid patients to digoxin therapy. Sucralfate reduces absorption of levothyroxine from the gastrointestinal tract as does aluminium hydroxide, and calcium carbonate. Severe hypertension and tachycardia have been reported when ketamine was used in patients taking levothyroxine. Colestyramine significantly reduces the absorption of levothyroxine by binding with thyroid hormones in the gastrointestinal tract. Ferrous sulfate reduces absorption of levothyroxine from the gastrointestinal tract. Both decreased efficacy and increased efficacy of levothyroxine have been reported in individual patients given lovastatin. Falsely low concentrations of levothyroxine (T4) or tri-iodothyronine (T3) have been reported during treatment with some anti-inflammatory drugs. Oestrogen therapy increases serum concentrations of thyroxine-binding globulin.
Ref :-   Book : Martindale    Page : 2372-2373   Edition : 37.  

►  Contraindication : Levothyroxine is contra-indicated in untreated hyperthyroidism. It has a narrow therapeutic index and should be used with extreme caution in patients with cardiovascular disorders including angina, heart failure, myocardial infarction, and hypertension, It should not be given to patients with adrenal insufficiency without adequate corticosteroid cover otherwise the thyroid replacement therapy might precipitate an acute adrenal crisis
Ref :-   Book : Martindale    Page : 2372   Edition : 37.  
  ►  Mechanism of Action :   Activation of nuclear receptor results in gene expression with RNA formation and protein synthesis
Ref :-   Book : Basic & Clinical pharmacology    Page : 695   Edition : 12.  

Pathway of DIETARY Product

​   ► Act.Comp / Nutrient / Food / Herb as follows :- Selenium with Another pathway.   Zinc with Another pathway.   Forskolin with Another pathway.  

  ►  Pathway with its reference as follows :-
  • stimulate thyroid gland --- (25. Binitha, M., Sarita, S., & Betsy, A. (2013). Zinc deficiency associated with hypothyroidism: An overlooked cause of severe alopecia. Int J Trichol, 5(1), 40. )
  • Thyroid stimulating nutrient --- (Eldelberg, D. The New Age of nutritional and herbal remedies. New Zealand )
  • Thyroid Stimulating Substances --- (PDR for Herbal medicines. (2000) (4th ed.). U.S. )

  •   ►  URL --
  • https://books.google.co.in/books?id=WZhj8EO9N3sC&pg=PA49&lpg=PA49&dq=The+New+Age+of+nutritional+and+herbal+remedies.++book&source=bl&ots=UVld-vNZL0&sig=5KwkKUUvW45p0TkfVUCtMZxnbow&hl=en&sa=X&ved=0ahUKEwiajLCNocrOAhVMto8KHfD2D-4Q6AEIMDAE#v=onepage&q=The%20 .
  • http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3746228/ .
  • http://www.vitorrentz.in/search/Text+Book+Of+Pharmacognosy .
  • +C.+K.+Kokate .
  • +A.P.+Purohit .
  • +S.B.+Gokhale .

  • DIETARY Substance Interactions

    ​   ► This Medicine interact with :- SOYA with Dietary Substance is Drug Enhancer.  

      ►  Reference :-
  • Driver, S. (2009). Stockleys Herbal Medicines Interactions. Royal pharmaceutical Society of Great Britain: Pharmaceutical press.

  •   ►  URL -- https://www.stonybrookmedicine.edu/sites/default/files/herbal_medicines_interactions-1.pdf

    ContraIndication DIETARY Substance

    ​   ► This Medicine contraindicate with :- BUGLEWEED with Interact with action of thyroid hormone .   LEMON BALM with Interact with action of thyroid hormone.  

      ►  Reference :-
  • Eldelberg, D. The New Age of nutritional and herbal remedies. New Zealand

  •   ►  URL -- https://books.google.co.in/books?id=WZhj8EO9N3sC&pg=PA49&lpg=PA49&dq=The+New+Age+of+nutritional+and+herbal+remedies.++book&source=bl&ots=UVld-vNZL0&sig=5KwkKUUvW45p0TkfVUCtMZxnbow&hl=en&sa=X&ved=0ahUKEwiajLCNocrOAhVMto8KHfD2D-4Q6AEIMDAE#v=onepage&q=The%20

    ►   Route of Elimination :   Hepatic (Metabolism), Faecal
    Ref :-   Book : Martindale    Page : 2373   Edition : 37.  

    ►    Plasma Half-life :   Min value :-   NA    Max value :-   NA

    ►    Peak Plasma Concentration :   Min value :-   NA    Max value :-   NA