Tirosint 150mcg Capsules
WARNING: Do not use this drug for weight loss. Severe and sometimes deadly side effects may happen with this drug if it is taken in large doses or with other drugs for weight loss. If you have questions, talk with the doctor. @ COMMON USES: It is used to add thyroid hormone to the body.It is used to manage thyroid cancer.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Thyroid hormone replacement
Pharmacologic Class
Thyroid hormone
Pregnancy Category
Category A
FDA Approved
Aug 2004
DEA Schedule
Not Controlled
Overview
What is this medicine?
Tirosint is a medicine that replaces a hormone your body normally makes, called thyroid hormone. It's used when your thyroid gland isn't making enough of this hormone, a condition called hypothyroidism. Taking this medicine helps your body function properly, improving symptoms like tiredness, weight gain, and feeling cold.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely.
Take your medication on an empty stomach, at least 30 to 60 minutes before breakfast.
Swallow the capsule whole - do not chew, break, or crush it.
Avoid taking iron products, antacids containing aluminum or magnesium, or calcium carbonate within 4 hours before or 4 hours after taking your medication.
If you take other medications, they may need to be taken at a different time than your current medication. Consult with your doctor or pharmacist to determine the best schedule.
Certain foods, such as soybean flour (found in infant formula), may interact with your medication. Discuss this with your doctor.
If you regularly consume grapefruit juice or eat grapefruit, inform your doctor.
Important Notes
There are different brands and forms of this medication. Do not switch between them without consulting your doctor.
Continue taking your medication as directed by your doctor or healthcare provider, even if you feel well.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, away from the bathroom.
Protect your medication from heat and light.
Do not remove your medication from the blister pack until you are ready to take it. Take the medication immediately after opening the blister pack, and do not store the removed medication for future use.
What to Do If You Miss a Dose
Take a missed dose as soon as you remember.
If it is close to the time for your next dose, skip the missed dose and resume your regular schedule.
Do not take two doses at the same time or take extra doses.
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely.
Take your medication on an empty stomach, at least 30 to 60 minutes before breakfast.
Swallow the capsule whole - do not chew, break, or crush it.
Avoid taking iron products, antacids containing aluminum or magnesium, or calcium carbonate within 4 hours before or 4 hours after taking your medication.
If you take other medications, they may need to be taken at a different time than your current medication. Consult with your doctor or pharmacist to determine the best schedule.
Certain foods, such as soybean flour (found in infant formula), may interact with your medication. Discuss this with your doctor.
If you regularly consume grapefruit juice or eat grapefruit, inform your doctor.
Important Notes
There are different brands and forms of this medication. Do not switch between them without consulting your doctor.
Continue taking your medication as directed by your doctor or healthcare provider, even if you feel well.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, away from the bathroom.
Protect your medication from heat and light.
Do not remove your medication from the blister pack until you are ready to take it. Take the medication immediately after opening the blister pack, and do not store the removed medication for future use.
What to Do If You Miss a Dose
Take a missed dose as soon as you remember.
If it is close to the time for your next dose, skip the missed dose and resume your regular schedule.
Do not take two doses at the same time or take extra doses.
Lifestyle & Tips
- Take on an empty stomach, preferably 30-60 minutes before breakfast, with a full glass of water.
- Take at the same time each day for consistent absorption.
- Do not take with other medications, vitamins, or supplements (especially calcium, iron, antacids) within 4 hours of taking Tirosint, as they can interfere with absorption.
- Avoid grapefruit juice as it may affect absorption.
- Inform your doctor about all other medications, supplements, and herbal products you are taking.
- Do not stop taking this medication without consulting your doctor, even if you feel better.
Available Forms & Alternatives
Available Strengths:
- Tirosint 13mcg Capsules
- Tirosint 25mcg Capsules
- Tirosint 50mcg Capsules
- Tirosint 75mcg Capsules
- Tirosint 88mcg Capsules
- Tirosint 150mcg Capsules
- Tirosint 137mcg Capsules
- Tirosint 100mcg Capsules
- Tirosint 112mcg Capsules
- Tirosint 125mcg Capsules
- Tirosint 175mcg Capsules
- Tirosint 200mcg Capsules
- Tirosint-Sol 100mcg/ml Oral Sol
- Tirosint-Sol 137mcg/ml Oral Sol
- Tirosint-Sol 150mcg/ml Oral Sol
- Tirosint-Sol 175mcg/ml Oral Sol
- Tirosint-Sol 88mcg/ml Oral Sol
- Tirosint-Sol 200mcg/ml Oral Sol
- Tirosint-Sol 13mcg/ml Oral Sol
- Tirosint-Sol 25mcg/ml Oral Sol
- Tirosint-Sol 50mcg/ml Oral Sol
- Tirosint-Sol 112mcg/ml Oral Sol
- Tirosint-Sol 75mcg/ml Oral Sol
- Tirosint-Sol 125mcg/ml Oral Sol
- Tirosint-Sol 37.5mcg/ml Oral Sol
- Tirosint-Sol 44mcg/ml Oral Sol
- Tirosint-Sol 62.5mcg/ml Oral Sol
- Tirosint 37.5mcg Capsules
- Tirosint 44mcg Capsules
- Tirosint 62.5mcg Capsules
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
Initial dose typically 1.6 mcg/kg/day for primary hypothyroidism, adjusted based on TSH levels. Tirosint 150mcg is a specific strength used for maintenance.
Dose Range:
25 - 300 mg
Condition-Specific Dosing:
hypothyroidism_initial:
1.6 mcg/kg/day (average 100-125 mcg/day)
hypothyroidism_elderly_cardiac:
Initial 12.5-25 mcg/day, titrate slowly
thyroid_cancer_suppression:
Higher doses to suppress TSH to target levels (e.g., <0.1 mIU/L)
Pediatric Dosing
Neonatal:
10-15 mcg/kg/day (0-3 months)
Infant:
6-8 mcg/kg/day (3-6 months); 5-6 mcg/kg/day (6-12 months)
Child:
4-5 mcg/kg/day (1-5 years); 3-4 mcg/kg/day (6-12 years)
Adolescent:
2-3 mcg/kg/day (12-17 years, during growth spurt); 1.6 mcg/kg/day (after growth spurt)
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment needed
Moderate:
No specific adjustment needed
Severe:
No specific adjustment needed
Dialysis:
No specific adjustment needed; monitor TSH and clinical response
Hepatic Impairment:
Mild:
No specific adjustment needed
Moderate:
No specific adjustment needed
Severe:
No specific adjustment needed
Pharmacology
Mechanism of Action
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.
Pharmacokinetics
Absorption:
Bioavailability:
48-79% (highly variable, affected by food and other medications)
Tmax:
2-4 hours
FoodEffect:
Significantly decreased absorption when taken with food; should be taken on an empty stomach, 30-60 minutes before breakfast.
Distribution:
Vd:
10-13 L
ProteinBinding:
>99% (primarily to thyroxine-binding globulin (TBG), transthyretin, and albumin)
CnssPenetration:
Limited
Elimination:
HalfLife:
6-7 days (euthyroid); 9-10 days (hypothyroid); 3-4 days (hyperthyroid)
Clearance:
Not available
ExcretionRoute:
Renal (approximately 80% of metabolites), fecal (approximately 20% of metabolites)
Unchanged:
<1% (renal)
Pharmacodynamics
OnsetOfAction:
Gradual, over several days to weeks
PeakEffect:
3-6 weeks (for full therapeutic effect and TSH stabilization)
DurationOfAction:
Long (due to long half-life)
Safety & Warnings
Side Effects
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, or anxious
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 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)
Other side effects not listed here
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.
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, or anxious
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 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)
Other side effects not listed here
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.
Seek Immediate Medical Attention If You Experience:
- Symptoms of too much thyroid hormone (hyperthyroidism): rapid heart rate, palpitations, chest pain, excessive sweating, heat intolerance, nervousness, tremors, insomnia, diarrhea, significant weight loss.
- Symptoms of too little thyroid hormone (hypothyroidism) if dose is too low or missed: persistent fatigue, weight gain, constipation, dry skin, hair loss, feeling cold, depression.
Before Using This Medicine
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:
+ An overactive thyroid gland
+ A weak adrenal gland
+ Difficulty swallowing
This list is not exhaustive, and it is crucial to discuss all your health problems with your doctor.
Additionally, provide your doctor and pharmacist with a comprehensive list of all the medications you are taking, including:
Prescription medications
Over-the-counter (OTC) medications
Natural products
* Vitamins
It is vital to verify that it is safe to take this medication with all your other medications and health conditions. Never start, stop, or change the dose of any medication without first consulting 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:
+ An overactive thyroid gland
+ A weak adrenal gland
+ Difficulty swallowing
This list is not exhaustive, and it is crucial to discuss all your health problems with your doctor.
Additionally, provide your doctor and pharmacist with a comprehensive list of all the medications you are taking, including:
Prescription medications
Over-the-counter (OTC) medications
Natural products
* Vitamins
It is vital to verify that it is safe to take this medication with all your other medications and health conditions. Never start, stop, or change the dose of any medication without first consulting your doctor.
Precautions & Cautions
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 allow your supply of this medication to run out. You may not experience the full effects of this medication for several weeks.
Special Considerations
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 individual risk factors with your doctor. Additionally, this medication may affect fertility, making it more difficult to become pregnant or father a child. If you plan to conceive, consult with your doctor before starting treatment.
If you are 65 years 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 potential benefits and risks to you and your baby.
Pediatric Patients
If you are giving this medication to a child and their weight changes, consult with your doctor, as the dosage may need to be adjusted. Never give your child more of this medication than prescribed, as this may increase the risk of severe side effects. In some cases, this medication may affect growth in children and teens, so regular growth checks may be necessary. Consult with your doctor to monitor your child's growth and development.
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 allow your supply of this medication to run out. You may not experience the full effects of this medication for several weeks.
Special Considerations
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 individual risk factors with your doctor. Additionally, this medication may affect fertility, making it more difficult to become pregnant or father a child. If you plan to conceive, consult with your doctor before starting treatment.
If you are 65 years 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 potential benefits and risks to you and your baby.
Pediatric Patients
If you are giving this medication to a child and their weight changes, consult with your doctor, as the dosage may need to be adjusted. Never give your child more of this medication than prescribed, as this may increase the risk of severe side effects. In some cases, this medication may affect growth in children and teens, so regular growth checks may be necessary. Consult with your doctor to monitor your child's growth and development.
Overdose Information
Overdose Symptoms:
- Palpitations
- Tachycardia
- Arrhythmias
- Chest pain
- Tremor
- Nervousness
- Insomnia
- Diaphoresis
- Heat intolerance
- Weight loss
- Diarrhea
- Vomiting
- Fever
- Seizures (rare)
- Heart failure (rare)
What to Do:
Seek immediate medical attention or call a poison control center. Management is supportive and symptomatic, often involving beta-blockers for cardiovascular effects. Call 1-800-222-1222.
Drug Interactions
Major Interactions
- Amiodarone (alters thyroid hormone metabolism)
- Oral anticoagulants (e.g., Warfarin - may increase anticoagulant effect)
- Antidiabetic agents (may increase insulin/oral hypoglycemic requirements)
- Ion exchange resins (e.g., Cholestyramine, Colestipol - reduce absorption of levothyroxine)
- Sucralfate (reduces absorption of levothyroxine)
- Proton pump inhibitors (e.g., Omeprazole - may reduce absorption of levothyroxine)
- H2 receptor blockers (e.g., Ranitidine - may reduce absorption of levothyroxine)
- Calcium carbonate (reduces absorption of levothyroxine)
- Iron supplements (reduces absorption of levothyroxine)
- Soy products (may reduce absorption of levothyroxine)
- Orlistat (may reduce absorption of levothyroxine)
Moderate Interactions
- Estrogens (e.g., oral contraceptives, hormone replacement therapy - increase TBG, increasing levothyroxine requirement)
- Androgens (decrease TBG, decreasing levothyroxine requirement)
- Glucocorticoids (may decrease TBG)
- Beta-blockers (may decrease conversion of T4 to T3)
- Tricyclic antidepressants (may increase sensitivity to catecholamines)
- Digoxin (may decrease digoxin levels)
- Phenytoin, Carbamazepine, Rifampin (increase levothyroxine metabolism)
- Sertraline (may increase levothyroxine requirement)
Monitoring
Baseline Monitoring
Thyroid Stimulating Hormone (TSH)
Rationale: To confirm diagnosis of hypothyroidism and establish baseline.
Timing: Prior to initiation of therapy
Free Thyroxine (FT4)
Rationale: To assess baseline thyroid hormone levels.
Timing: Prior to initiation of therapy
Clinical symptoms of hypothyroidism
Rationale: To establish baseline symptom severity.
Timing: Prior to initiation of therapy
Routine Monitoring
Thyroid Stimulating Hormone (TSH)
Frequency: Every 4-8 weeks after initiation or dose change, then every 6-12 months once stable
Target: 0.4-4.0 mIU/L (for primary hypothyroidism, individualized for other conditions)
Action Threshold: TSH outside target range; adjust dose
Free Thyroxine (FT4)
Frequency: May be monitored if TSH is suppressed or in central hypothyroidism, or if TSH/clinical correlation is poor
Target: 0.8-1.8 ng/dL (or laboratory reference range)
Action Threshold: FT4 outside target range; adjust dose
Clinical symptoms of hypo/hyperthyroidism
Frequency: At every visit
Target: Resolution of hypothyroid symptoms without development of hyperthyroid symptoms
Action Threshold: Persistent hypothyroid symptoms or new hyperthyroid symptoms; evaluate TSH/FT4 and adjust dose
Symptom Monitoring
- Fatigue
- Weight gain
- Constipation
- Cold intolerance
- Dry skin
- Hair loss
- Bradycardia (hypothyroid)
- Nervousness
- Irritability
- Weight loss
- Heat intolerance
- Palpitations
- Tremor
- Diarrhea
- Tachycardia (hyperthyroid)
Special Patient Groups
Pregnancy
Levothyroxine is safe and essential during pregnancy. Thyroid hormone requirements often increase during pregnancy (by 25-50% or more) due to increased TBG and fetal needs. Close monitoring of TSH is crucial.
Trimester-Specific Risks:
First Trimester:
Untreated maternal hypothyroidism in the first trimester is associated with adverse fetal neurodevelopmental outcomes and increased risk of miscarriage.
Second Trimester:
Continued need for increased dose; essential for fetal brain development.
Third Trimester:
Continued need for increased dose; essential for fetal brain development.
Lactation
Levothyroxine is compatible with breastfeeding. Only small amounts are excreted into breast milk, and it is not expected to cause adverse effects in breastfed infants.
Infant Risk:
L1 (Safest)
Pediatric Use
Essential for normal growth and development. Dosing is weight-based and higher per kg than in adults, especially in infants. Regular monitoring of TSH and FT4 is critical to ensure proper neurocognitive development and growth. Treatment is lifelong.
Geriatric Use
Lower starting doses (e.g., 12.5-25 mcg/day) are recommended, especially in patients with underlying cardiovascular disease, due to increased sensitivity to thyroid hormones and potential for cardiac adverse effects. Dose titration should be slower and more cautious. Monitor for cardiac symptoms.
Clinical Information
Clinical Pearls
- Tirosint capsules contain levothyroxine in a liquid gel formulation, which may be beneficial for patients with absorption issues or sensitivities to excipients found in tablet formulations.
- Consistency is key: take the medication at the same time every day, on an empty stomach, and separate from other medications and supplements.
- TSH is the primary monitoring parameter for primary hypothyroidism. It takes 4-8 weeks for TSH levels to stabilize after a dose change.
- Patients should be educated on symptoms of both hypo- and hyperthyroidism to report any changes to their healthcare provider.
- Lifelong therapy is typically required for primary hypothyroidism.
- Do not switch between different brands or formulations of levothyroxine without consulting a healthcare provider, as bioavailability can vary, requiring TSH re-monitoring.
Alternative Therapies
- Liothyronine (T3, Cytomel)
- Liotrix (T4/T3 combination, Thyrolar)
- Desiccated Thyroid Extract (Armour Thyroid, Nature-Throid)
Cost & Coverage
Average Cost:
Varies widely by strength and pharmacy (e.g., $30-$100+) per 30 capsules
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (generic levothyroxine is often Tier 1, brand Tirosint may be Tier 2 or 3)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure safe use, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet; consult your pharmacist for more information. If you have any questions or concerns about this medication, discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. Be prepared to provide details about the overdose, including the medication taken, the amount, and the time it occurred.