Levothyroxine 100mcg/5ml Inj, 5ml

Levothyroxine (T4) is a synthetic form of the naturally occurring thyroid hormone, thyroxine. It is converted to its active metabolite, liothyronine (T3), in peripheral tissues. T3 and T4 act on specific 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.

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 medical attention immediately:

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 irritability, nervousness, excitability, anxiety, or other emotional changes
Shakiness
Trouble sleeping
Sensitivity to heat
Excessive sweating
Fever
Muscle cramps
Muscle weakness
Flushing
Bone pain
Changes in menstrual periods
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 may not experience any side effects or may only have mild ones. If you are bothered by any of the following side effects or if they 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 a comprehensive list of all possible side effects. If you have questions or concerns about side effects, contact 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 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 developing weak bones (osteoporosis), particularly after menopause. Discuss your risk factors with your doctor, who can help determine if you are at higher risk.

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

If you are pregnant, plan to become pregnant, or are breastfeeding, inform your doctor to discuss the benefits and risks of this medication to you and your baby.

Pediatric Patients

When giving this medication to a child, monitor their weight changes and consult your doctor, as the dosage may need to be adjusted. Never exceed the recommended dose, as this may 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 consult your doctor to determine the best course of action.

• Amiodarone (can cause hypo- or hyperthyroidism, alters T4 to T3 conversion)
• Warfarin (enhances anticoagulant effect)
• Antidiabetic agents (may increase insulin/oral hypoglycemic requirements)
• Sympathomimetics (increased risk of cardiac effects)

• Iron supplements (oral) (decreased levothyroxine absorption if co-administered orally, not relevant for IV)
• Calcium supplements (oral) (decreased levothyroxine absorption if co-administered orally, not relevant for IV)
• Proton pump inhibitors (oral) (decreased levothyroxine absorption if co-administered orally, not relevant for IV)
• Sucralfate (oral) (decreased levothyroxine absorption if co-administered orally, not relevant for IV)
• Cholestyramine/Colestipol (oral) (decreased levothyroxine absorption if co-administered orally, not relevant for IV)
• Estrogens (increase TBG, potentially increasing levothyroxine requirements)
• Androgens (decrease TBG, potentially decreasing levothyroxine requirements)
• Beta-blockers (may decrease T4 to T3 conversion)
• Corticosteroids (may decrease T4 to T3 conversion)
• Phenytoin, Carbamazepine, Rifampin (increase levothyroxine metabolism, potentially increasing requirements)

• Dietary fiber (oral) (decreased levothyroxine absorption if co-administered orally, not relevant for IV)

• Symptoms of hypothyroidism (e.g., fatigue, weight gain, constipation, cold intolerance, dry skin, hair loss, depression, bradycardia)
• Symptoms of hyperthyroidism (e.g., palpitations, tachycardia, nervousness, tremor, weight loss, heat intolerance, diarrhea, insomnia, chest pain)

Levothyroxine is essential for normal fetal development and is considered safe and necessary during pregnancy. Hypothyroidism during pregnancy can lead to adverse maternal and fetal outcomes. Levothyroxine requirements often increase during pregnancy.

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

Dosing is weight-based and crucial for normal growth and development. Untreated congenital hypothyroidism can lead to irreversible intellectual disability and growth retardation. Close monitoring of TSH and Free T4 is essential. IV formulation is used when oral is not feasible or in severe cases like myxedema coma.

Lower starting doses are often recommended due to increased sensitivity to thyroid hormones and a higher prevalence of underlying cardiovascular disease. Close monitoring for cardiac side effects is important. Dose adjustments should be gradual.

• When converting from oral to IV levothyroxine, the IV dose is typically 50% of the patient's daily oral dose due to 100% bioavailability of the IV form compared to variable oral absorption.
• For myxedema coma, a large IV loading dose is often given to rapidly replete thyroid hormone stores, followed by daily maintenance doses.
• Administer IV levothyroxine slowly, typically over 1-3 minutes. Ensure compatibility if co-administering with other IV fluids or medications.
• Patients with adrenal insufficiency must be treated with corticosteroids prior to or concurrently with levothyroxine to prevent adrenal crisis.
• Monitor patients closely for signs of hyperthyroidism, especially those with underlying cardiovascular disease, as rapid thyroid hormone replacement can precipitate angina, arrhythmias, or myocardial infarction.

• Liothyronine (T3) injection (e.g., Triostat) - used in specific situations, sometimes in combination with levothyroxine for myxedema coma.
• Desiccated thyroid extract (oral) - contains both T4 and T3, but not available in injectable form.

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 otherwise, avoid flushing medications down the toilet or pouring them down the drain. If you are unsure about the proper disposal method, consult your pharmacist for guidance. Many communities offer drug take-back programs, which your pharmacist can help you locate. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist. 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 amount, and the time it was taken to ensure timely and effective treatment.