Idelara

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Medically reviewed

Marina Burgos

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Idelara

Property Description
Active ingredient Letrozole (INN)
Form Film-coated tablet
Pharmacological class Nonsteroidal Aromatase Inhibitor
General Purpose Estrogen level reduction in hormonal therapy
Origin Synthetic, Third-Generation Compound

What Type of Medicine is Idelara (Letrozole)?

Idelara is a pharmaceutical product whose single active ingredient is Letrozole, classifying it as a synthetic antineoplastic agent used for hormonal therapy. Letrozole is also globally recognized under its original trade name, Femara, and is widely available in generic form.

Letrozole is formally categorized as a selective, nonsteroidal aromatase inhibitor, placing it within the potent third-generation class of antiestrogen drugs. The medication is presented as an oral, film-coated tablet intended for systemic administration. This classification confirms it acts on the body’s hormonal system, a defining characteristic that distinguishes it from traditional cytotoxic agents. Letrozole functions as a highly selective inhibitor. The World Health Organization (WHO) classifies the substance Letrozole under the Anatomical Therapeutic Chemical (ATC) code L02BG04, designating it within the group of Aromatase inhibitors.

How Does Idelara Work and What is Its General Purpose?

Idelara's primary function is to achieve profound estrogen reduction by selectively targeting a key enzyme in the body.

The drug works by inhibiting the aromatase enzyme, which is responsible for the final step of converting other hormones (androgens) into estrogen in peripheral tissues, a process that accounts for the majority of estrogen production in postmenopausal women. By competitively and reversibly blocking this enzyme, Letrozole significantly lowers the systemic concentration of circulating estrogen. This action fulfills the drug's general purpose: to create a state of severe estrogen deprivation, which is a therapeutic strategy used in clinical settings to manage hormone-dependent cellular growth.

What side effects are possible with Idelara?

Possible side effects and safety information

The safety profile for Idelara is established through regulatory documents, with adverse effects classified by frequency and body system. These effects are primarily related to the lowering of systemic estrogen levels.


Adverse Reaction Scope

The most frequently reported adverse reactions are classified as Very Common (affecting at least 1 in 10 patients) and include hot flashes, arthralgia (joint pain), hypercholesterolemia, fatigue, and increased sweating. Common side effects (affecting 1 to 10 in 100 patients) include headache, dizziness, nausea, constipation, diarrhea, bone pain, and peripheral edema (swelling of extremities).

Serious adverse reactions officially documented in labeling include an increased risk of osteoporosis and bone fractures, which are specifically noted risks with long-term use. Other serious events include thromboembolic events (such as pulmonary embolism or arterial thrombosis), ischemic cardiac events (like angina or myocardial infarction), and rare cases of hepatitis or severe skin reactions.


Safety Constraints and Considerations

The regulatory labeling includes specific safety limitations. Idelara is contraindicated in women who are premenopausal and during pregnancy or lactation. Use requires caution and close supervision in patients with severe hepatic impairment (Child-Pugh C), as systemic exposure to the drug may be approximately doubled in this population. The official safety documents advise monitoring of both bone mineral density and serum cholesterol levels due to the documented adverse effects on bone health and metabolism. Caution is also advised when driving or operating machinery, as fatigue, dizziness, and somnolence have been reported.

Overdose and Emergency Response

Overdose and When to Seek Help

The official regulatory profile for Idelara (Letrozole) overdose is based on limited human data reported in clinical experience. In known cases, single ingested doses up to 62.5 mg (equivalent to 25 tablets) resulted in no serious adverse reactions being documented by the regulator.

Despite the absence of specific severe outcomes in these limited reports, any accidental over-ingestion mandates that an individual tell a doctor at once or contact the nearest hospital casualty department immediately, as required by official regulatory statements. The prompt seeking of medical attention is necessary to ensure appropriate professional management.

Overdose Management and Monitoring

Management Aspect Official Regulatory Statement
Documented Presentations No serious adverse reactions reported in known high-dose cases.
Treatment Limitation No firm recommendations for specific treatment can be made due to limited data.
Supportive Measures General supportive care is appropriate, and frequent monitoring of vital signs is required.
Procedural Action Emesis could be induced if the patient is alert, as described in official labeling.

Connection to the Overall Overdose Profile

Regulatory documents define the overdose profile primarily through the necessity of supportive intervention and the explicit constraint of limited data. The documentation confirms that while high single doses have been reported without serious outcomes, the required emergency action remains consistent: immediate contact with emergency services to initiate appropriate supportive care and monitoring of physiological status.

Therapeutic Uses of Idelara

What Idelara Treats: Main Uses and Benefits

Idelara, a medication focused on systemic imbalance, is commonly used to help manage hormone receptor-positive breast cancer in postmenopausal women. This anti-cancer therapy is applied across conditions presenting with systemic or localized discomfort driven by malignant cell growth.

The medication is applied to address disease stability in several contexts: supportive therapy to manage recurrence risk (adjuvant or extended adjuvant), as a first-line approach for advanced or metastatic disease, and in the pre-surgical (neoadjuvant) setting to assist in reducing tumor size.

“The core purpose of this treatment is to help maintain stability by managing the underlying hormone-driven growth.”


Recurrence Prevention in Early-Stage Disease

Idelara is commonly used as a long-term, supportive therapy for postmenopausal women who have successfully completed initial treatment for hormone-receptor-positive breast cancer. The main benefit is supporting the reduction of cancer recurrence risk, which contributes to improved day-to-day comfort during symptomatic periods.

Controlling Advanced or Metastatic Cancer

The medication is applied as a primary hormonal treatment for postmenopausal patients diagnosed with advanced, locally spread, or metastatic breast cancer. In this context, the therapeutic goal is to stabilize the disease by curbing uncontrolled cellular proliferation. This clinical use may assist with managing the disease progression, which generally supports sustained stability and patient comfort.


Quick Fact: Relief for Hormone-Driven Proliferation Idelara is considered relevant in conditions where symptoms are linked to organ-specific functional stress caused by hormone-sensitive malignant cell growth, supporting patients during difficult episodes by easing distress.

Eligibility and Restrictions for Use

Eligibility Map: Who can and cannot use Idelara — Official Regulatory Information


Eligibility scope

Populations for whom use is allowed (as stated in label):

  • Women with a clearly established postmenopausal endocrine status.
  • Adults with no required dose adjustment for elderly/geriatric patients.

Populations for whom use is not recommended (if applicable):

  • Children and adolescents (under 18 years); safety and efficacy have not been established.
  • Patients with rare hereditary problems of galactose intolerance or similar metabolic disorders (due to lactose excipients).

Populations for whom use is contraindicated:

  • Women with a premenopausal endocrine status.
  • Women who are pregnant or breast-feeding/lactating.
  • Patients with a known hypersensitivity to letrozole or any other component.

Age-related eligibility rules:

  • Pediatric Population: Use is not recommended.
  • Older Adults: No dose adjustment is required.

Condition-specific eligibility rules:

  • Severe Hepatic Impairment (Child-Pugh C): Conditional use; a dose reduction is required, and the patient must be under close supervision.
  • Severe Renal Impairment (CrCl < 10 mL/min): Conditional use; insufficient data are available, and the potential risk/benefit must be carefully considered.

Pregnancy and lactation eligibility status (if explicitly documented):

  • Contraindicated in both pregnancy and lactation.

Eligibility-related restrictions:

  • Females of reproductive potential must use effective non-hormonal contraception during treatment and for a period afterward.
  • Patients with history of osteoporosis/fractures should have their Bone Mineral Density (BMD) formally assessed and monitored.

Eligibility classifications (high-level)

Eligibility severity classification (as defined in official documents): Contraindicated, Not Recommended, Conditional Use.

Regulatory basis (EMA / FDA / etc.): Prescribing Information / Summary of Product Characteristics.

Eligibility-context constraints (as defined in official documents): Endocrine Status, Organ Function, Age, Hypersensitivity.


Resulting eligibility structure

Official eligibility statements:

  • Use is strictly limited to women of confirmed postmenopausal endocrine status.
  • The medicine is formally contraindicated in all premenopausal women, pregnant women, and breastfeeding women.
  • Use in the pediatric population (children and adolescents) is officially not recommended because safety and efficacy have not been established.

Connection to the overall eligibility profile (2–4 sentences): Official regulatory documents establish a strict eligibility profile for this medicine based primarily on endocrine status, making use contraindicated in women who are not postmenopausal. Eligibility is further defined by organ function constraints, mandating conditional use or specific dosage alteration for patients with severe hepatic impairment. The profile also includes absolute age-related exclusions, formally classifying the drug's use as not established or not recommended in the pediatric population.

What should I know about interactions with other medicines?

Idelara Interactions with other medicines and products

The official regulatory profile for Idelara primarily identifies interactions that affect its plasma exposure and intended hormonal effect. This information is classified based on the level of restriction required, as documented in government labeling.

Interaction Type Interacting Agents / Condition Regulatory Statement
Contraindicated Combination Oestrogens (and oestrogen-containing therapies), Anti-oestrogens (e.g., Tamoxifen) Co-administration must be avoided; results in pharmacodynamic antagonism and substantially decreases Idelara plasma concentration.
Metabolic Caution Medicinal products primarily cleared by CYP2C19 (e.g., specific narrow therapeutic index drugs) Caution is indicated due to Idelara's documented in vitro inhibitory effect on the CYP2C19 enzyme. Idelara is also metabolized by CYP2A6 and CYP3A4.
Food & Alcohol Food May be taken with or without food; documented as having no clinically significant effect on plasma concentrations.
Population-Specific Risk Severe Hepatic Impairment (Child-Pugh C) Systemic exposure and half-life are approximately doubled in this population, requiring close professional supervision.

This regulatory framework establishes clear constraints regarding hormonal co-administration and notes potential pharmacokinetic interference. The profile also addresses the impact of food and outlines specific considerations for patients with impaired liver function, strictly adhering to constraints documented in official labeling.

Mechanism of Action

Specific Aromatase Enzyme Inhibition

Idelara's entire function hinges on its action as a highly selective, competitive inhibitor of the Aromatase Enzyme (CYP19A1). The drug binds reversibly to the enzyme's active site, competitively blocking its ability to catalyze the final step of estrogen biosynthesis in the body. This interaction characterizes the drug's action as molecular interference, which prevents hormone production at the enzymatic source.


Systemic Estrogen Synthesis Shutdown

The molecular block initiates a cascade focused on peripheral estrogen production, primarily occurring in adipose tissue, muscle, and liver, which constitute the predominant non-ovarian sources of the hormone. By arresting this pathway, the mechanism creates a state of profound and sustained systemic estrogen deprivation; this resulting state functionally modulates estrogen-dependent biological processes.


Mechanistic Constraints of the Endocrine Axis

The mechanism is constrained by its interaction with the Hypothalamic-Pituitary-Gonadal (HPG) axis in individuals with active ovarian function. The systemic drop in estrogen triggers the HPG axis to increase gonadotropin release, which stimulates the ovaries to produce more hormones, leading to a functional counteraction of the peripheral inhibition. This dynamic is a physiological constraint of the aromatase inhibition mechanism.

Dosage and Administration Information

How to Use Idelara

Idelara (Letrozole) is administered through the oral route as a 2.5 mg film-coated tablet. The medication is generally taken once daily, and it can be consumed without regard to meals, meaning it may be taken with or without food. The tablet must be swallowed whole with water and should not be crushed or chewed.

The duration of use is defined by the specific therapeutic context. For adjuvant and extended adjuvant supportive use, the treatment is typically continued for a median of five years or until tumor recurrence is documented, whichever comes first. Conversely, for the management of advanced or metastatic disease, the administration of Idelara is sustained until the point of documented disease progression. For use in the neoadjuvant setting, the course generally lasts for a shorter, defined period of four to eight months.

Population-Specific Dosing and Procedures

The standard 2.5 mg once-daily dose is maintained for most adult patients. No dosage adjustment is required for older adults or for patients presenting with mild to moderate hepatic impairment, or for those with renal impairment (creatinine clearance ge 10 mL/min).

A specific dose modification is required for patients with severe hepatic impairment (Child-Pugh C), where the dose is reduced to 2.5 mg every other day. In the event of a missed dose, if the time until the next scheduled dose is less than 2-3 hours, the missed dose is skipped entirely; otherwise, it is taken as soon as remembered. It is explicitly stated that a double dose should not be taken to compensate for a missed one.

Recent Clinical Evidence

Research Evidence: Overview of Studies for Idelara (Letrozole)

Idelara was evaluated in large, multi-center randomized controlled trials (RCTs) to explore its evaluation in postmenopausal women with hormone receptor-positive breast cancer. These studies monitored the drug's use across different phases of the condition.


1. Research for Initial Supportive Therapy in Early-Stage Disease

In the context of supportive therapy following surgery, research has explored the use of Idelara for up to five years. Researchers primarily examined Disease-Free Survival (DFS), which is an endpoint used by researchers to measure the time until a recurrence event or the development of cancer in the opposite breast. Major studies compared Idelara to another hormonal therapy, tamoxifen. Studies reported that the time until a recurrence event was measured in the group studied with Idelara. Research monitored the incidence of a recurrence at a distant site and reported observations of this outcome in the Idelara study group.

What remains less clear is a definitive, isolated measure of Overall Survival (OS). In some pivotal trials, patient crossover complicated the final analysis of whether the research indicates a long-term difference in overall survival when compared to the original treatment assignment.


2. Evidence for Extended Supportive Therapy

Studies have monitored the effects of extending hormonal therapy for an additional five years in postmenopausal women who had already completed five years of prior therapy. These trials explored long-term symptom patterns related to recurrence. Studies tracked the measurement of Disease-Free Survival over the duration of the study period and reported patterns observed in the group receiving Idelara. Research also explored the incidence of cancer developing in the opposite breast and reported observations related to this outcome in the extended treatment group.


3. Studies in Advanced or Metastatic Disease

Research has also examined Idelara as a first-line treatment for postmenopausal women with locally advanced or metastatic hormone receptor-positive breast cancer. The core outcomes studied included Progression-Free Survival (PFS), which is the length of time the condition does not get worse, and the Objective Response Rate (ORR), which is a measurement of tumor size reduction. Initial studies reported observations of the median time until disease progression in the group studied with Idelara. More recent studies have explored Idelara in combination with other targeted therapies.


4. What Remains Unclear and Evidence Gaps

A key limitation across several major supportive trials is the impact of patient crossover on the final overall survival measurements. Data for pre-menopausal women, older adults with significant comorbidities, or other special populations remain insufficient or were not the primary focus of the pivotal trials.

Key Studies & References

  1. Letrozole for 5 years after tamoxifen for early breast cancer: long-term outcomes of the BIG 1-98 randomized trial

Frequently Asked Questions (FAQ)

Common questions about Idelara (FAQ)

Q: How is Idelara different from other treatments for [Condition X]?

A: Official documents describe Idelara as a nonsteroidal aromatase inhibitor, which is a drug class that functions by reducing estrogen production throughout the body. This mechanism is a strategy that differs from other hormonal therapies, such as selective estrogen receptor modulators. Research has compared its profile to other hormonal therapies, noting differences in side effect patterns and outcomes in specific studies.

Q: Do I need to avoid any specific foods while taking Idelara?

A: Regulatory materials state that the medicine can be taken with or without food and do not list any specific foods that are formally contraindicated (must be avoided). Official guidance related to the documented risk of increased serum cholesterol levels often includes general health suggestions regarding saturated fats.

Q: How long does it usually take before a person notices the effects of Idelara?

A: Pharmacokinetic studies, which track how the body handles the drug, indicate that the medicine achieves maximal systemic estrogen reduction within 2 to 4 days of starting treatment. The drug concentration in the body reaches a therapeutic balance, known as steady-state, after approximately 60 days of daily use.

Q: Is Idelara meant to cure the condition or just manage the symptoms?

A: Research evidence indicates that the medicine is used as a supportive or management therapy. Regulatory studies evaluate the drug using endpoints like Disease-Free Survival (DFS) and Progression-Free Survival (PFS), which are measurements of time until a recurrence or progression event, rather than a definitive cure.

Q: Does taking Idelara affect blood pressure?

A: According to official product information, raised blood pressure (hypertension) is documented as an uncommon adverse reaction observed in patients using the drug.

Q: Why is it important to tell my doctor about all the supplements I take when starting Idelara?

A: The medicine is known to interact with certain liver enzymes, primarily an enzyme called CYP2C19. The disclosure of all products helps a healthcare professional consider the potential for documented drug interactions.

Q: How long does Idelara stay in my system after I stop taking it?

A: Based on official pharmacokinetic data, the medicine has a terminal plasma half-life of approximately 2 to 5 days. The drug is typically cleared from the system approximately 20 days after the last dose.

Q: Can I use alcohol while I am taking Idelara?

A: Regulatory-based patient information sources state that there is no evidence indicating that drinking alcohol causes a direct drug interaction or affects the safety or usefulness of the drug. It is important to note that limiting alcohol is sometimes suggested in patient literature as a non-drug method to manage certain side effects, like hot flashes.

Q: Can Idelara affect my sleep patterns?

A: Official documents state that insomnia (difficulty falling or staying asleep) is documented as a common adverse reaction associated with the use of the medicine.

Q: What if I experience a rare or serious side effect mentioned in the official papers?

A: For any rare or serious symptoms documented in official papers (such as signs of a heart attack, stroke, or severe skin reactions), official guidance states that patients should seek immediate medical attention. For side effects that are persistent or bothersome, the advice is to consult with a healthcare professional.

Q: Does Idelara interact with caffeine?

A: Caffeine is not listed as a formal drug-drug interaction in regulatory documents. However, patient advice often suggests limiting the intake of caffeine (along with alcohol and spicy food) to help manage certain documented side effects, such as hot flashes and night sweats.

Q: What happens if I take too much Idelara by mistake?

A: If an overdosage is known or suspected, official patient information states that a doctor or the nearest poison control center should be contacted immediately for professional medical advice. Medical treatment may be necessary.

Q: What is the likelihood of experiencing a certain common side effect of Idelara?

A: Official documents classify side effects into categories based on their frequency. Very Common side effects affect more than 1 in 10 patients (or >10%), and Common side effects affect 1 to 10 in 100 patients (or 1% to 10%).

Q: Is Idelara a new kind of treatment, or has it been around for a while?

A: The medicine's active ingredient, Letrozole, first received U.S. FDA approval in 1997. It is classified as a third-generation compound in its class, having first received approval in 1997.

Q: Is it true that Idelara can cause changes in appetite?

A: Changes in appetite are documented as adverse reactions. This can include both an increase in appetite and a loss of appetite, based on data collected from clinical trials.

Q: What happens if I forget to take Idelara one day?

A: If a dose is missed, official instructions advise to take it as soon as remembered, unless it is close to the next scheduled dose (e.g., within 2-3 hours), in which case the missed dose should be skipped. The inhibitory effect on the enzyme is sustained due to the drug’s long half-life.

Q: Is Idelara safe to use for a long time?

A: Official labeling defines that the treatment is used for specific long-term durations in certain therapeutic contexts, such as up to five years for supportive therapy. The official documents note a specific, dose-related risk of osteoporosis and bone fractures associated with extended use, which requires monitoring of bone health.

Q: Are there any long-term effects of using Idelara?

A: The known long-term risks documented in regulatory labeling primarily include an increased risk of osteoporosis and related bone fractures due to the drug's effect on estrogen levels. Official guidance advises the monitoring of bone mineral density and cholesterol levels during long-term use.

Q: Is Idelara approved for use in children?

A: Official documents state that the medicine is not approved for use in children and adolescents (under 18 years of age). This is because its safety and effectiveness have not been established in this particular population.

Q: Does Idelara cause weight gain or weight loss?

A: According to official documentation, both weight gain and weight loss are documented as adverse reactions. Weight gain is listed as a common reaction, while weight loss is documented as a less common reaction.

Q: Are there different strengths of Idelara tablets?

A: For its approved oncology indications, the medicine is available as a 2.5 mg film-coated tablet. Other strengths are not specified for these therapeutic uses in official prescribing information.

Q: What should I do if a side effect of Idelara is making me feel uncomfortable?

A: For side effects that are persistent, bothersome, or making a patient feel uncomfortable, the official advice is to consult with a healthcare professional or doctor.

Q: Is Idelara a habit-forming medicine?

A: The medicine is not classified as a controlled substance by regulatory agencies, and official documents do not list dependence or habit formation as an adverse reaction or risk.

Q: What official documents describe how to stop taking Idelara?

A: Regulatory documents define the expected duration of use for different therapeutic contexts (e.g., typically five years for supportive therapy). The determination of when and how to stop treatment is made by a healthcare professional based on the individual's clinical status.

Q: Why do some people say Idelara did not work for them?

A: Research evidence indicates that some patients may experience disease progression or recurrence despite treatment. This is consistent with the general understanding that the medicine may not provide the desired outcome for all patients in clinical practice.

Q: Is Idelara safe for people with a history of depression?

A: Official documents confirm that Depression is documented as an uncommon adverse reaction associated with the use of this medicine.

How should Idelara be stored and disposed of?

How to Store and Dispose of Idelara (Letrozole)

Idelara tablets must be stored according to regulatory requirements to ensure product integrity.

Storage Parameter Requirement
Temperature Store at controlled room temperature (20 C to 25 C / 68 F to 77 F).
Environment Keep the medicine in a closed container away from heat, moisture, and direct light.
Prohibitions The product must not be frozen and should avoid temperatures outside the acceptable range (15 C to 30 C).
Child Safety The medication must be kept out of the reach of children.
Disposal Do not keep outdated or unused medicine. Consult a healthcare professional or follow local community regulations for the proper disposal of the unused product.

These conditions maintain the drug's labeled stability until its expiration date.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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