Levothyroxine 200mcg Inj, 1 Vial

Levothyroxine (T4) is a synthetic form of the natural thyroid hormone, thyroxine. It is converted to its active metabolite, liothyronine (T3), in peripheral tissues. T3 then binds to thyroid hormone receptors in the cell nucleus, regulating gene expression and controlling numerous metabolic processes, including protein, carbohydrate, and lipid metabolism, and influencing growth and development.

Urgent Side Effects: Seek Medical Help Right Away

While rare, some people may experience severe and potentially life-threatening side effects when 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. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or do not go away, contact your doctor:

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

Reporting Side Effects

This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, consult 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 the symptoms that occurred.
Certain health conditions, including:
+ An overactive thyroid gland
+ A weak adrenal gland

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
Any natural products or vitamins you are using
* Your health problems, both past and present

Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to confirm it is safe to do so. This will help prevent potential interactions and ensure the safe use of this medication.

Important Information for All Patients Taking This Medication

It is crucial that you inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. To ensure uninterrupted treatment, do not allow your supply of this medication to run out. You may not experience the full effects of this medication for several weeks.

If you have diabetes (high blood sugar), consult with your doctor, as this medication may affect your 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.

If you are taking biotin or a product containing biotin, stop taking it 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 developing weak bones (osteoporosis), particularly after menopause. Discuss your risk factors with your doctor, who can help determine if you are at higher risk or answer any questions you may have.

This medication may also affect fertility, potentially making it difficult to become pregnant or father a child. If you plan to conceive, consult with your doctor before starting this medication.

Special Considerations

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

If you are pregnant, planning to become pregnant, or breastfeeding, inform your doctor, who will discuss the benefits and risks of this medication for both you and your baby.

Pediatric Patients

If your child is taking this medication and experiences any changes in weight, consult with your doctor, as the dosage 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)
• Antacids (aluminum, magnesium, calcium) - for oral form, but relevant if patient transitions to oral
• Iron supplements - for oral form, but relevant if patient transitions to oral
• Sucralfate - for oral form, but relevant if patient transitions to oral
• Bile acid sequestrants (cholestyramine, colestipol) - for oral form, but relevant if patient transitions to oral
• Proton pump inhibitors (e.g., omeprazole) - for oral form, may reduce absorption
• Certain anticonvulsants (e.g., carbamazepine, phenytoin, phenobarbital) - may increase levothyroxine metabolism
• Rifampin - may increase levothyroxine metabolism
• Sertraline - may increase levothyroxine requirements
• Tyrosine kinase inhibitors (e.g., imatinib, sunitinib) - may increase levothyroxine requirements

• Oral anticoagulants (e.g., warfarin) - levothyroxine may enhance anticoagulant effect, requiring dose reduction of anticoagulant
• Beta-blockers (e.g., propranolol) - may reduce conversion of T4 to T3
• Tricyclic antidepressants (e.g., amitriptyline) - increased risk of cardiac arrhythmias and CNS excitation
• Insulin and oral hypoglycemics - levothyroxine may increase blood glucose, requiring adjustment of antidiabetic agents
• Digitalis glycosides (e.g., digoxin) - levothyroxine may decrease digoxin levels or effect
• Estrogens (oral) - may increase TBG, increasing levothyroxine requirements
• Androgens - may decrease TBG, decreasing levothyroxine requirements

• Dietary fiber - for oral form, may reduce absorption
• Soy products - for oral form, may reduce absorption

• Fatigue
• Weight gain or loss
• Cold or heat intolerance
• Constipation or diarrhea
• Dry skin
• Hair loss
• Muscle aches or weakness
• Depression or anxiety
• Memory problems
• Bradycardia or tachycardia
• Palpitations
• Tremors
• Nervousness
• Insomnia

Levothyroxine is considered safe and essential during pregnancy. Thyroid hormone requirements often increase during pregnancy, necessitating dose adjustments.

Levothyroxine is compatible with breastfeeding. Only small amounts are excreted into breast milk, which are not considered harmful to the infant.

Dosing is highly individualized based on age, weight, and severity of hypothyroidism. Close monitoring of TSH and Free T4 is essential. IV formulation is generally reserved for severe cases (e.g., myxedema coma) or when oral administration is not possible. Over-treatment can lead to craniosynostosis in infants and accelerated bone maturation in children.

Lower initial doses are generally recommended due to increased sensitivity to thyroid hormones and higher prevalence of underlying cardiovascular disease. Dose titration should be gradual and cautious, with close monitoring for cardiac side effects.

• IV levothyroxine is primarily used for myxedema coma or when oral administration is not feasible (e.g., NPO status, severe malabsorption).
• For myxedema coma, a large loading dose is typically given, followed by daily maintenance doses. Consider lower loading doses in patients with known cardiac disease.
• Always rule out or treat adrenal insufficiency with glucocorticoids before or concurrently with levothyroxine in patients with suspected myxedema coma to prevent adrenal crisis.
• The IV dose is typically 50% of the patient's usual oral dose when converting from oral to IV due to 100% bioavailability of the IV form.
• Monitor cardiac status closely, especially during the initial phase of treatment for myxedema coma, due to the risk of arrhythmias and myocardial ischemia.
• Thyroid function tests (TSH, Free T4) should be monitored regularly to guide dose adjustments, though TSH response may be delayed due to the long half-life.

• Liothyronine (T3) injection (for rapid onset in severe cases, often used in combination with levothyroxine for myxedema coma)
• Desiccated thyroid extract (contains T4 and T3, not available in injectable form)

If your symptoms or health problems do not improve or worsen over time, it is essential to contact your doctor for further guidance. To ensure safe use, never share your medication with others, and do not take medication prescribed to 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 otherwise, 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 medical attention. Be prepared to provide information about the medication taken, the amount, and the time of the incident.