Levothyroxine - Uses, Mechanism Of Action, Pharmacology, Side Effects, And Contraindications

Video transcript:-
Levothyroxine is a synthetic form of thyroxine hormone.
It is structurally identical to the endogenous T4 hormone produced by the thyroid gland
Major indications of levothyroxine include the following.
Primary hypothyroidism, including Hashimoto's thyroiditis.
Secondary or tertiary hypothyroidism due to pituitary or hypothalamic disease.
Post-thyroidectomy hormone replacement.
And for thyroid-stimulating hormone suppression in thyroid cancers.
Following administration, Levothyroxine is converted to T3, which is the active form of thyroxine hormones, in the peripheral tissues.
T3 binds to the thyroid hormone receptors in cell nucleus and alters gene expression.
By doing so, it modulates metabolism, protein synthesis, and growth in virtually all tissues.
This leads to normalization of the metabolic rate, thermoregulation, and sympathetic activity.
The drug is absorbed into the body mainly by the ileum and jejunum of the small intestine.
It has an oral bioavailability of approximately 70%.
The excess drug is metabolized in the liver and excreted in bile and urine.
The adverse effects are usually dose-related and occur with over-replacement.
Some common ones include Palpitations, tachycardia, and arrhythmias.
Anxiety, tremor, and insomnia.
Weight loss, heat intolerance, and sweating.
Diarrhea.
Osteoporosis, usually with long-term overuse.
And menstrual irregularities.
Absolute contraindications for the use of levothyroxine include, Untreated adrenal insufficiency, which may precipitate adrenal crisis.
Thyrotoxicosis.
And known hypersensitivity to levothyroxine or any of its components.
Relative contraindications include cardiovascular disease such as angina, and arrhythmias.
Elderly patients.
And Diabetes mellitus.

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