Tirosint 25mcg 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 hormones
Pregnancy Category
Category A
FDA Approved
Aug 2000
DEA Schedule
Not Controlled
Overview
What is this medicine?
Tirosint is a medicine that replaces a hormone normally made by your thyroid gland. This hormone is essential for your body's energy and metabolism. It's used to treat an underactive thyroid (hypothyroidism) or to suppress thyroid-stimulating hormone (TSH) in certain thyroid conditions. It helps your body function properly.
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
If you miss a dose, take it 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
If you miss a dose, take it 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, typically 30-60 minutes before breakfast, with a full glass of water.
- Avoid taking with other medications, especially antacids, iron, or calcium supplements, for at least 4 hours.
- Maintain a consistent schedule for taking the medication each day.
- 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.
- Regular blood tests (TSH) are crucial to ensure the correct dose.
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 orally once daily for primary hypothyroidism. Tirosint 25mcg is a specific strength, often used for initial titration or maintenance in sensitive patients.
Dose Range:
25 - 300 mg
Condition-Specific Dosing:
primaryHypothyroidism:
Initial: 1.6 mcg/kg/day. Adjust by 12.5-25 mcg increments every 4-6 weeks based on TSH.
subclinicalHypothyroidism:
Initial: 12.5-25 mcg/day. Adjust based on TSH.
cardiacDisease:
Initial: 12.5-25 mcg/day. Adjust slowly.
elderly:
Initial: 12.5-25 mcg/day. Adjust slowly.
TSHSuppression:
Higher doses may be required, titrated to target TSH.
Pediatric Dosing
Neonatal:
Initial: 10-15 mcg/kg/day. Adjust based on TSH and T4.
Infant:
Initial: 6-8 mcg/kg/day (3-6 months); 5-6 mcg/kg/day (6-12 months). Adjust based on TSH and T4.
Child:
Initial: 4-5 mcg/kg/day (1-5 years); 3-4 mcg/kg/day (6-12 years). Adjust based on TSH and T4.
Adolescent:
Initial: 2-3 mcg/kg/day (12-17 years). Adjust based on TSH and T4.
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment needed.
Moderate:
No specific adjustment needed.
Severe:
No specific adjustment needed.
Dialysis:
No specific adjustment needed. Levothyroxine is highly protein-bound and not significantly removed by dialysis.
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 naturally occurring thyroid hormone, L-thyroxine. It is converted to its active metabolite, L-triiodothyronine (T3), in peripheral tissues. T3 and T4 bind to thyroid hormone receptors in the cell nucleus, regulating gene expression and controlling numerous metabolic processes, including protein, fat, and carbohydrate metabolism, and influencing growth and development.
Pharmacokinetics
Absorption:
Bioavailability:
48-80% (variable, affected by food and other drugs)
Tmax:
2-4 hours
FoodEffect:
Decreased absorption when taken with food, certain medications (e.g., calcium, iron, antacids, proton pump inhibitors), or certain foods (e.g., soy, dietary fiber). 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 (T4 crosses BBB, but T3 is more active in CNS)
Elimination:
HalfLife:
6-7 days (euthyroid); 9-10 days (hypothyroid); 3-4 days (hyperthyroid)
Clearance:
Not available (highly variable)
ExcretionRoute:
Primarily renal (conjugated metabolites), some fecal (unabsorbed drug and biliary excretion)
Unchanged:
<1% (renal)
Pharmacodynamics
OnsetOfAction:
Gradual, typically 3-5 days for initial effects, full therapeutic effect may take 4-6 weeks.
PeakEffect:
4-6 weeks (when steady-state TSH levels are achieved)
DurationOfAction:
Long (due to long half-life)
Safety & Warnings
BLACK BOX WARNING
Thyroid hormones, including Tirosint, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss. In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction. Larger doses may produce serious or even life-threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects.
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 change
Diarrhea, stomach cramps, or vomiting
Mood changes, such as irritability, nervousness, excitability, or anxiety
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. 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, 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.
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 change
Diarrhea, stomach cramps, or vomiting
Mood changes, such as irritability, nervousness, excitability, or anxiety
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. 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, 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.
Seek Immediate Medical Attention If You Experience:
- Symptoms of too much thyroid hormone (hyperthyroidism): rapid heart rate, palpitations, chest pain, nervousness, tremor, insomnia, excessive sweating, heat intolerance, unexplained weight loss, diarrhea.
- Symptoms of too little thyroid hormone (hypothyroidism, if dose is too low): persistent fatigue, weight gain, cold intolerance, constipation, dry skin, hair loss, 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 dosage 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 dosage 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.
If you have diabetes (high blood sugar), consult your doctor, as this medication may affect your blood sugar control. Your doctor may need to adjust your diabetes medications. Monitor your blood sugar levels as directed by your doctor and undergo regular blood tests as advised.
When taking biotin or products containing biotin, discontinue use 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 becoming pregnant or fathering a child. If you plan to conceive, consult your doctor before starting treatment.
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, plan to become pregnant, or are breastfeeding, inform your doctor to discuss the potential benefits and risks to you and your baby.
Pediatric Patients
When administering this medication to a child, monitor their weight and consult your doctor if it changes, 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.
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.
If you have diabetes (high blood sugar), consult your doctor, as this medication may affect your blood sugar control. Your doctor may need to adjust your diabetes medications. Monitor your blood sugar levels as directed by your doctor and undergo regular blood tests as advised.
When taking biotin or products containing biotin, discontinue use 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 becoming pregnant or fathering a child. If you plan to conceive, consult your doctor before starting treatment.
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, plan to become pregnant, or are breastfeeding, inform your doctor to discuss the potential benefits and risks to you and your baby.
Pediatric Patients
When administering this medication to a child, monitor their weight and consult your doctor if it changes, 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.
Overdose Information
Overdose Symptoms:
- Palpitations
- Tachycardia
- Arrhythmias
- Chest pain
- Tremor
- Nervousness
- Insomnia
- Diaphoresis
- Heat intolerance
- Weight loss
- Diarrhea
- Vomiting
- Fever
- Seizures (rare)
- Coma (rare)
What to Do:
Call 1-800-222-1222 (Poison Control). Seek immediate medical attention. Management is supportive and symptomatic, including beta-blockers for cardiac effects, and measures to reduce absorption if recent ingestion.
Drug Interactions
Major Interactions
- Amiodarone (can cause hypo- or hyperthyroidism)
- Oral anticoagulants (e.g., warfarin - increased anticoagulant effect)
- Sympathomimetics (e.g., pseudoephedrine - increased cardiac effects)
- Tyrosine kinase inhibitors (e.g., imatinib, sunitinib - may increase levothyroxine requirements)
- Orlistat (decreased levothyroxine absorption)
Moderate Interactions
- Antacids (aluminum, magnesium, calcium - decreased absorption, separate by 4 hours)
- Iron supplements (decreased absorption, separate by 4 hours)
- Calcium supplements (decreased absorption, separate by 4 hours)
- Bile acid sequestrants (e.g., cholestyramine, colestipol - decreased absorption, separate by 4-5 hours)
- Sucralfate (decreased absorption, separate by 4 hours)
- Proton pump inhibitors (e.g., omeprazole - decreased absorption, may require dose increase)
- H2 blockers (e.g., cimetidine - decreased absorption)
- Soy products (decreased absorption, may require dose increase)
- Dietary fiber (decreased absorption)
- Estrogens (increased TBG, may increase levothyroxine requirements)
- Androgens (decreased TBG, may decrease levothyroxine requirements)
- Carbamazepine, Phenytoin, Rifampin (increased metabolism, may increase levothyroxine requirements)
- Beta-blockers (may decrease T4 to T3 conversion)
- Corticosteroids (may decrease T4 to T3 conversion)
- Digoxin (decreased digoxin levels, monitor)
- Insulin/Oral Hypoglycemics (increased requirements, monitor glucose)
Minor Interactions
- Certain foods (e.g., grapefruit juice - minor effect on absorption)
Monitoring
Baseline Monitoring
TSH (Thyroid-Stimulating Hormone)
Rationale: To confirm diagnosis of hypothyroidism and establish baseline.
Timing: Prior to initiation of therapy.
Free T4 (Free Thyroxine)
Rationale: To assess baseline thyroid hormone levels.
Timing: Prior to initiation of therapy.
Cardiac status (ECG, history of CAD)
Rationale: To assess for underlying cardiac disease, as thyroid hormone replacement can exacerbate cardiac conditions.
Timing: Prior to initiation, especially in elderly or those with cardiac risk factors.
Routine Monitoring
TSH
Frequency: Every 4-6 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 TSH suppression)
Action Threshold: Adjust dose if TSH is outside target range.
Free T4
Frequency: May be checked with TSH, especially if TSH is suppressed or in central hypothyroidism.
Target: 0.8-1.8 ng/dL (or laboratory specific range)
Action Threshold: Adjust dose if T4 is outside target range or symptoms persist despite normal TSH.
Clinical symptoms (e.g., fatigue, weight, cold intolerance, mood)
Frequency: At every visit.
Target: Resolution of hypothyroid symptoms.
Action Threshold: Consider dose adjustment or further investigation if symptoms persist.
Symptom Monitoring
- Fatigue
- Weight changes (gain or loss)
- Cold intolerance
- Constipation
- Dry skin
- Hair loss
- Bradycardia
- Depression
- Memory impairment
- Muscle aches
- Hoarseness
- Menstrual irregularities
- Nervousness
- Palpitations
- Tremor
- Heat intolerance
- Diarrhea
- Insomnia
- Chest pain
Special Patient Groups
Pregnancy
Levothyroxine is essential for normal fetal development and is considered Category A. Hypothyroidism during pregnancy can lead to adverse maternal and fetal outcomes. Dose requirements often increase during pregnancy.
Trimester-Specific Risks:
First Trimester:
Untreated maternal hypothyroidism in the first trimester is associated with increased risk of miscarriage, preterm birth, and impaired neurocognitive development in the offspring.
Second Trimester:
Continued need for adequate thyroid hormone for fetal brain development.
Third Trimester:
Dose requirements may continue to increase as pregnancy progresses.
Lactation
Levothyroxine is compatible with breastfeeding. Minimal amounts are excreted into breast milk, and it is not expected to cause adverse effects in breastfed infants.
Infant Risk:
L1 (Safest) - No known risk to the infant.
Pediatric Use
Dosing is weight-based and higher per kg than in adults, especially in neonates and infants, due to rapid growth and development. Regular monitoring of TSH and T4 is crucial to ensure proper neurocognitive development. Tirosint capsules may be opened and mixed with water or breast milk for administration to infants and children.
Geriatric Use
Lower initial doses and slower titration are recommended due to increased sensitivity to thyroid hormones and a higher prevalence of underlying cardiac disease. Close monitoring for cardiac symptoms is important.
Clinical Information
Clinical Pearls
- Tirosint is a liquid-filled capsule formulation of levothyroxine, which may offer more consistent absorption compared to tablet formulations, especially in patients with gastrointestinal absorption issues or those taking multiple interacting medications.
- Always take levothyroxine on an empty stomach, 30-60 minutes before food or other medications, to optimize absorption.
- Consistency is key: take at the same time each day.
- Patients should be advised against switching between different levothyroxine products (brands or generic) without consulting their physician, as bioavailability differences can lead to changes in TSH levels.
- The 25mcg strength is often used for fine-tuning doses or for initial titration in sensitive patients (e.g., elderly, cardiac patients).
- Symptoms of over- or under-dosing can mimic other conditions; always correlate with TSH and Free T4 levels.
Alternative Therapies
- Liothyronine (T3, Cytomel): Used in specific cases, often in combination with levothyroxine, but not as monotherapy for routine hypothyroidism.
- Desiccated Thyroid Extract (Armour Thyroid, NP Thyroid): Natural thyroid hormone derived from porcine thyroid glands, containing both T4 and T3. Dosing can be less precise due to variable hormone content.
- Levothyroxine tablets (e.g., Synthroid, Levoxyl, Unithroid, generic levothyroxine sodium tablets)
Cost & Coverage
Average Cost:
Varies widely by pharmacy and insurance plan, typically $20-$100+ per 30 capsules
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (generic), Tier 2 or 3 (brand)
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication, including the amount taken and the time it happened, to ensure you receive the best possible care.