Levothyroxine 200mcg/5ml Inj, 5ml

Levothyroxine (T4) is a synthetic thyroid hormone that is chemically identical to the naturally occurring hormone. It is converted to its active metabolite, liothyronine (T3), in peripheral tissues. T3 then enters the cell nucleus and binds to thyroid hormone receptors, which regulate gene expression, influencing protein synthesis and metabolic processes throughout the body. Thyroid hormones are essential for normal metabolism, growth, and development.

Serious Side Effects: Seek Medical Help Right Away

Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:

Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of high blood pressure, including:
+ Severe headache or dizziness
+ Passing out
+ Changes in eyesight
Chest pain or pressure
Fast or abnormal heartbeat
Shortness of breath
Sudden weight gain or swelling in the arms or legs
Headache
Feeling tired or weak
Changes in appetite
Unintentional weight changes
Diarrhea, stomach cramps, or vomiting
Mood changes, such as feeling irritable, nervous, excitable, anxious, or restless
Shakiness
Trouble sleeping
Sensitivity to heat
Excessive sweating
Fever
Muscle cramps
Muscle weakness
Flushing
Bone pain
Changes in menstrual periods (in women)
In children: hip or knee pain, or a limp
In infants: changes in the shape of the head and face

Other Possible Side Effects

Like all medications, this drug can cause side effects. Many people experience no side effects or only mild ones. If you notice any of the following side effects or any other unusual symptoms, contact your doctor for advice:

* Hair loss (usually temporary and resolves on its own within the first few months of treatment)

Reporting Side Effects

This is not a comprehensive list of all possible side effects. If you have questions or concerns about side effects, talk to your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.

Before Taking This Medication: Important Information to Share with Your Doctor

It is essential to inform your doctor about the following:

Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
Certain health conditions, including:
+ Overactive thyroid gland (hyperthyroidism)
+ Weak adrenal gland (adrenal insufficiency)

This list is not exhaustive, and it is crucial to discuss all your health problems and medications with your doctor.

To ensure your safety, provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Natural products and vitamins you are using
* Any health problems you have

Carefully review your medications and health conditions with your doctor to confirm that it is safe to take this medication. Never start, stop, or change the dose of any medication without first consulting your doctor.

Important Information for All Patients Taking This Medication

It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. To ensure uninterrupted treatment, do not run out of this medication, as it may take several weeks to experience its full effects.

Special Considerations

If you have diabetes (high blood sugar), consult with your doctor, as this medication may affect blood sugar control. Your doctor may need to adjust your diabetes medications. Be sure to monitor your blood sugar levels as directed by your doctor and undergo regular blood tests as recommended.

When taking biotin or products containing biotin, stop using them at least 2 days before having your thyroid levels checked to ensure accurate test results.

Potential Risks and Side Effects

High doses of this medication may increase the risk of osteoporosis (weak bones), particularly after menopause. Discuss your individual risk factors with your doctor, who can help determine if you are at a higher risk of developing osteoporosis.

This medication may also affect fertility, potentially leading to difficulties in getting pregnant or fathering a child. If you plan to conceive, consult with your doctor before starting treatment.

Age-Related Considerations

If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.

Pregnancy and Breastfeeding

Inform your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. Your doctor will discuss the benefits and risks of this medication to you and your baby.

Pediatric Patients

If your child is taking this medication and experiences any weight changes, consult with your doctor, as their dose may need to be adjusted. Never give your child more of this medication than prescribed, as this can increase the risk of severe side effects.

In some cases, this medication may affect growth in children and teenagers. Regular growth checks may be necessary, so be sure to discuss this with your doctor.

• Amiodarone (can cause hypo- or hyperthyroidism, alters T4 to T3 conversion)
• Anticoagulants (e.g., Warfarin - increased anticoagulant effect)
• Antidiabetic agents (insulin, oral hypoglycemics - increased blood glucose, require dose adjustment)
• Cardiac glycosides (e.g., Digoxin - decreased therapeutic effect of digoxin)
• Sympathomimetics (e.g., Epinephrine - increased risk of coronary insufficiency in patients with CAD)
• Tyrosine kinase inhibitors (e.g., Sunitinib, Imatinib - can cause hypothyroidism, requiring increased levothyroxine dose)

• Antacids (aluminum, magnesium, calcium - reduced oral absorption, but not relevant for IV)
• Iron supplements (reduced oral absorption, not relevant for IV)
• Calcium supplements (reduced oral absorption, not relevant for IV)
• Bile acid sequestrants (e.g., Cholestyramine, Colestipol - reduced oral absorption, not relevant for IV)
• Proton pump inhibitors (e.g., Omeprazole - reduced oral absorption, not relevant for IV)
• Sucralfate (reduced oral absorption, not relevant for IV)
• Estrogens (increased TBG, may require increased levothyroxine dose)
• Androgens (decreased TBG, may require decreased levothyroxine dose)
• Glucocorticoids (can inhibit TSH secretion and T4 to T3 conversion)
• Phenytoin, Carbamazepine, Rifampin (enzyme inducers, increase levothyroxine metabolism, may require increased dose)
• Beta-blockers (can reduce T4 to T3 conversion)
• SSRIs (can affect thyroid function tests, usually no dose adjustment needed)

• Dietary fiber (reduced oral absorption, not relevant for IV)
• Soy products (reduced oral absorption, not relevant for IV)

• Fatigue
• Weight changes (gain or loss)
• Cold intolerance
• Constipation
• Dry skin
• Hair loss
• Bradycardia
• Depression
• Muscle aches
• Memory impairment
• Nervousness
• Irritability
• Heat intolerance
• Diarrhea
• Tremor
• Palpitations
• Tachycardia
• Weight loss
• Insomnia

Levothyroxine is essential for maintaining euthyroidism during pregnancy. Hypothyroidism during pregnancy can lead to adverse maternal and fetal outcomes. Dose requirements often increase during pregnancy (by 25-50% or more) due to increased TBG and fetal thyroid hormone demands. Monitor TSH every 4-6 weeks and adjust dose to maintain TSH in the trimester-specific target range.

Levothyroxine is considered compatible with breastfeeding. Only small amounts are excreted into breast milk, which are not sufficient to cause adverse effects in the infant or affect infant thyroid function.

Dosing is weight-based and adjusted based on TSH and Free T4 levels. Close monitoring is crucial for normal growth and neurocognitive development. IV formulation is typically reserved for severe cases like myxedema coma or when oral administration is not possible.

Lower starting doses are often recommended due to increased sensitivity to thyroid hormones and a higher prevalence of underlying cardiovascular disease. Monitor for cardiac symptoms (e.g., angina, arrhythmias) and adjust dose cautiously. TSH target range may be slightly higher for very elderly patients.

• Levothyroxine injection is primarily used for myxedema coma or when oral administration is contraindicated or not feasible (e.g., severe malabsorption, NPO status).
• In myxedema coma, IV hydrocortisone should be administered prior to or concurrently with levothyroxine to prevent adrenal crisis, as myxedema coma can be associated with adrenal insufficiency.
• The IV dose is typically 50% of the patient's usual oral dose due to 100% bioavailability compared to variable oral absorption.
• Administer IV levothyroxine slowly, usually over 1-3 minutes.
• Monitor patients closely for signs of cardiac decompensation, especially in those with pre-existing cardiovascular disease, as rapid thyroid hormone replacement can precipitate arrhythmias or angina.
• Transition to oral therapy as soon as clinically appropriate.

• Liothyronine (T3) injection (e.g., Cytomel Injection) - used in some cases of myxedema coma, often in combination with levothyroxine due to its faster onset of action.
• Desiccated thyroid extract (oral only) - contains both T4 and T3, derived from animal thyroid glands.

If your symptoms or health problems persist or worsen, it is essential to contact your doctor promptly. To ensure safe use, never share your medication with others, and do not take medication prescribed for someone else. Store all medications in a secure location, out of reach of children and pets, to prevent accidental ingestion. Dispose of unused or expired medications properly. Unless instructed to do so by a healthcare professional, do not flush medications down the toilet or drain. If you are unsure about the correct disposal method, consult your pharmacist, who can also inform you about potential drug take-back programs in your area. Some medications may come with an additional patient information leaflet, which your pharmacist can provide. If you have any questions or concerns about your medication, discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately contact your local poison control center or seek emergency medical attention. Be prepared to provide information about the medication taken, the quantity, and the time of ingestion.