T4 50μg/tab 100tabs

Levothyroxine Sodium (T4) is a synthetic form of thyroxine, a hormone naturally produced by the thyroid gland. In the body, T4 is converted into its active form, L-triiodothyronine (T3), which plays a critical role in regulating metabolism, energy production, and protein synthesis.

Both T4 and T3 bind to thyroid hormone receptors in the cell nucleus, influencing DNA transcription and protein synthesis, thereby controlling metabolic activity throughout the body. Levothyroxine is chemically identical to endogenous thyroxine and is produced in the biologically active L-form.

Form: Oral (tablets)
Drug class: Thyroid hormone (thyroid replacement therapy)

Medical Purpose of Levothyroxine

Levothyroxine is primarily prescribed to treat hypothyroidism, a condition in which the thyroid gland does not produce sufficient hormones. Low thyroid hormone levels may occur due to:

• Autoimmune thyroid disease

• Thyroid surgery

• Radiation therapy

• Certain medications

Levothyroxine replaces or supplements the body’s natural thyroid hormones, restoring normal metabolic function. It is also known as L-thyroxine or T4.

Effects on Metabolism and Performance

Metabolic Regulation

By restoring normal thyroid hormone levels, levothyroxine helps maintain a healthy metabolic rate, which is essential for energy balance, fat utilization, and overall physiological function.

Energy and Endurance

Proper thyroid function supports stable energy levels, helping reduce fatigue and improve endurance during physically demanding activities.

Muscle Recovery and Protein Synthesis

Balanced thyroid hormones support protein synthesis and tissue repair, which are critical during muscle recovery phases.

Weight Management

By regulating metabolism, levothyroxine assists in maintaining healthy body weight when used appropriately under medical supervision.

Consistent Physical and Mental Performance

Stable thyroid levels contribute to consistent cognitive and physical performance, particularly important for individuals with high training demands.

Use with Growth Hormone

Individuals receiving Human Growth Hormone (HGH) therapy may require T4 supplementation. Growth hormone increases the conversion of T4 to T3, which can lead to a functional T4 deficiency if not properly supported.

Dosage and Administration

Levothyroxine should be taken:

• On an empty stomach

• 30–60 minutes before meals

• With a full glass of water

Dosage depends on age, body weight, medical condition, and response to therapy. While maximum doses of 300–400 μg per day are rarely required, most individuals should begin with a low dose and adjust gradually under medical guidance.

Typical Use Pattern (Non-medical Context)

• Starting dose: 25–50 μg per day

• Increase by 25–50 μg every 5–6 days

• Average dose: 100–200 μg per day

• Maximum duration: 5–7 weeks

• Rest period: At least 6 weeks between cycles

Gradual dose escalation and proper breaks help restore natural thyroid function after use.

⚠️ Levothyroxine is sometimes combined with clenbuterol to enhance metabolic effects; this significantly increases physiological stress and should be approached with caution.

Pharmacokinetics

• Oral absorption: 40–80%

• Absorption site: Jejunum and upper ileum

• Absorption increases with fasting and decreases with certain foods, medications, and age

Elimination Half-Life

• Normal thyroid function: 6–7 days

• Hypothyroidism: 9–10 days

• Hyperthyroidism: 3–4 days

Approximately 80% is eliminated via the kidneys, with the remainder excreted in stool.

Primary Effects

• Regulates metabolic rate

• Supports fat utilization

• Enhances anabolic processes

• Stimulates the central nervous system

Side Effects

Adverse effects are usually dose-related and associated with excessive intake.

Common symptoms of overdose:

• Heat intolerance

• Excessive sweating

• Anxiety or nervousness

• Insomnia

• Tremors

• Rapid or irregular heartbeat

• Unintended weight loss

Seek immediate medical attention if experiencing:

• Chest pain or tightness

• Difficulty breathing or swallowing

• Fainting

• Severe fatigue

• Heart rhythm disturbances

Acute overdose can be life-threatening and may require beta-blockers and supportive care.

Precautions

Prolonged use of high doses may suppress natural thyroid hormone production. Studies indicate up to a 20% reduction after several weeks of use. When used correctly, normal thyroid function typically recovers within 3–4 weeks after discontinuation.

Levothyroxine has stimulant-like effects (increased heart rate, nervousness), which may be mitigated with beta-blockers under medical supervision.

Contraindications

Levothyroxine should not be used in individuals with:

• Hypersensitivity to levothyroxine sodium

• Acute myocardial infarction

• Thyrotoxicosis of any cause

• Untreated adrenal insufficiency

Drug and Food Interactions

Reduced absorption:

• Calcium or iron supplements (avoid within 4 hours)

• Soy products (avoid within 3 hours)

• Aluminum or magnesium antacids

• Sucralfate, simethicone

• Cholestyramine, colestipol

Significant interactions:

• Ketamine (hypertension, tachycardia)

• Tricyclic and tetracyclic antidepressants (increased toxicity)

• Lithium (interferes with thyroid hormone metabolism)

Special Warnings

• Introduce levothyroxine gradually in individuals over 50 years old

• Use caution in patients with cardiovascular disease

• Monitor closely in patients with diabetes or adrenal disorders

• Excessive dosing may contribute to bone loss and osteoporosis

Storage Instructions

• Store at room temperature

• Keep in a cool, dry place away from direct sunlight

• Keep out of reach of children

• Do not use after the expiration date