The therapeutic application of Лорета (Letrozole) is commonly used for managing conditions driven by estrogen-sensitive cellular activity, providing supportive benefits across key therapeutic domains. The medication is used for managing hormone receptor-positive breast cancer and, in specific clinical settings, anovulatory infertility. This medication is primarily used across conditions marked by systemic hormonal imbalances.

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Quick Fact: Relief for Hormonal Imbalance This medication is primarily used across conditions marked by systemic hormonal imbalances, supporting patients during episodes of heightened discomfort related to these conditions.

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Endocrine Therapy for Hormone Receptor-Positive Cancer

This domain addresses the use of the medicine across all stages of hormone receptor-positive breast cancer. It may assist with managing the proliferation of cancer cells and may help reduce the risk of cancer recurrence following surgery or other primary treatments. This is commonly used to help with long-term management of the disease status.

Functional Restoration in Anovulatory Infertility

This domain covers the application of the medicine in reproductive endocrinology, specifically managing anovulatory infertility, which often presents in conditions such as Polycystic Ovary Syndrome (PCOS). This medicine may assist in inducing ovulation in women who experience difficulty conceiving due to hormonal imbalances, and may contribute to supporting the process of conception.

Regulatory References

1. NIH DailyMed Prescribing Information

The eligibility profile for Лорета (Letrozole) is determined by strict regulatory criteria focused on hormonal status, age, and specific health conditions. The medicine is primarily established for use in postmenopausal adult women.

Eligibility Status	Patient Population	Classification
Allowed	Postmenopausal women (Adults)	Established Use
Contraindicated	Premenopausal women	Absolute Prohibition
Contraindicated	Pregnant or Breastfeeding women	Absolute Prohibition
Contraindicated	Known hypersensitivity to Letrozole or excipients	Absolute Prohibition

Age-Related and Organ Function Restrictions

The medicine is not recommended for the pediatric population, including children and adolescents, because its safety and effectiveness have not been formally established in patients under 18 years of age. For geriatric patients, standard adult dosing applies.

Use requires special caution or is not recommended for patients with severe hepatic impairment (Child-Pugh Class C), as systemic exposure to the medicine is approximately doubled in this population, warranting close supervision. Caution is also advised for patients with a history of osteoporosis or those at risk of high cholesterol, where regulatory bodies recommend monitoring of bone mineral density or serum cholesterol.

Interactions with other medicines and products

Interaction scope	Official Regulatory Information
Interacting categories	Estrogen-containing therapies, other anti-oestrogens, potent CYP3A4 inhibitors/inducers, and medicines primarily eliminated by CYP2C19 with a narrow therapeutic index.
Specific interactions	Co-administration with Tamoxifen and Estrogen-containing products is formally documented to be avoided due to the risk of pharmacodynamic antagonism.
Mechanistic basis	The official basis of interactions includes pharmacodynamic antagonism with hormonal agents, and pharmacokinetic modulation via the cytochrome P450 system. Letrozole is a substrate of CYP3A4 and CYP2A6, and an in vitro inhibitor of CYP2A6 and CYP2C19.
Exposure effects	Tamoxifen co-administration is linked to a clinically significant reduction of Letrozole plasma concentrations by an average of 38%. Potent CYP3A4 inducers, such as the herbal product St. John's Wort, may reduce Letrozole systemic exposure.
Population notes	In patients with Severe Hepatic Impairment (Child-Pugh C), systemic exposure (AUC) to Letrozole is approximately doubled compared to healthy subjects due to reduced clearance.

Interaction Classifications (High-Level)

The regulatory interaction profile for Letrozole is structured around avoiding contraindicated combinations and managing pharmacokinetic modulation. The label specifically confirms that administration is not affected by food, meaning no timing separation is required for meals. Additionally, co-administration studies with Warfarin and Cimetidine have shown no clinically significant effects on pharmacokinetics. This entire structure is derived directly from EMA and FDA regulatory documents.

The action of Лорета is determined by its selective mechanism of enzyme inhibition, resulting in a marked and sustained reduction in active estrogen levels throughout the body.

Aromatase Enzyme Inhibition: The Molecular Target

The primary biological action involves selective and reversible competitive inhibition of the aromatase enzyme (CYP19A1). By binding to the enzyme's active site, the drug prevents it from performing its catalytic function—the conversion of androgens into estrogens—thereby initiating the drug's core mechanistic cascade.

Halting the Estrogen Biosynthesis Cascade

This targeted enzyme blockade halts the final step in the Estrogen Biosynthesis Pathway, particularly in peripheral tissues. The resulting lack of active estrogen production leads to the drug's key physiological consequence: creating a state of systemic hormonal deprivation. This condition removes the hormonal signaling required for estrogen-dependent cellular activity, which underlies the drug's physiological consequences.

Mechanistic Selectivity and Functional Constraint

The mechanism is selective to the aromatase enzyme, maintaining minimal interaction with other steroidogenic enzyme systems. The significant systemic effect is functionally constrained by the body's overall endocrine status, achieving its greatest functional capacity when peripheral aromatization is the dominant source of circulating estrogen.

Official Administration Protocol

Лорета (Letrozole) is administered as a film-coated tablet exclusively by the oral route. The standard usage protocol is characterized by a fixed, non-titrated dose of 2.5 mg taken once daily. This specific 2.5 mg regimen serves as the usual starting and maintenance dose for its approved therapeutic applications. The tablets must be swallowed whole and may be taken without regard to meals, which allows for flexibility in the daily schedule.

Duration and Special Dosing Rules

The duration of use is defined by the clinical setting. For adjuvant therapy, the standard use pattern involves administration for a period of up to five years. Conversely, in the context of advanced or metastatic disease, administration is generally continued until tumor progression is evident.

Specific procedural adjustments are specified for certain patient populations. Older adults do not require any dose modification. For patients with severe hepatic impairment (Child-Pugh C), the dose frequency is reduced to 2.5 mg administered every other day. No dose adjustment is specified for patients with renal impairment where creatinine clearance is greater than or equal to 10 mL/min. If a dose is missed, the standard procedure is to skip the missed dose entirely if the time for the next scheduled dose is imminent, ensuring that doses are not doubled. This fixed-dose, once-daily pattern defines a consistent hormonal exposure protocol for the entire course of therapy.

Research Evidence / Overview of Studies for Лорета (Letrozole)

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Evidence Base for Endocrine Therapy in Breast Cancer

The research base studying this medicine in hormone receptor-positive breast cancer consists primarily of large, international, randomized controlled trials (RCTs). These studies compare the medicine to an inactive substance (placebo) or to another hormone treatment, Tamoxifen. The trials included monitoring outcomes related to disease status over the long term.

Studies on Initial and Extended Adjuvant Use

Research has examined the use of the medicine following initial treatment, known as adjuvant therapy. Studies monitored how long patients remained free of cancer recurrence (Disease-Free Survival, or DFS). Some trials reported measurements of Disease-Free Survival in the context of comparison with another hormone treatment, Tamoxifen.

Studies also explored the effect of taking the medicine for an additional period after a patient had completed five years of initial hormone therapy (extended adjuvant use). Findings describe patterns observed in these studies where the extended use was compared to placebo in assessing disease status.

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Evidence Base for Functional Restoration in Infertility

The research base where this medicine was studied for anovulatory infertility, especially in women with Polycystic Ovary Syndrome (PCOS), is composed of randomized controlled trials and systematic reviews. The trials primarily compared the medicine to Clomiphene Citrate.

• What was studied: Researchers monitored key reproductive outcomes, including measurements of Live Birth Rate, Ovulation Rate, and Clinical Pregnancy Rate over defined time intervals. The research generally focused on reproductive-age women with anovulatory infertility.
• What was reported: Large studies reported that, in women with PCOS, measurements of cumulative Live Birth Rate were recorded in the context of comparison with the comparator drug. Research also described patterns where the rate of multiple gestations (such as twins or triplets) was observed and compared with the comparator.
• What remains uncertain: Follow-up durations for tracking the long-term developmental outcomes of children conceived after this treatment are still emerging, and certainty remains low in this specific area.

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Long-Term Follow-up and Durability of Study Endpoints

Long-term follow-up of the initial breast cancer trials contributes to understanding the reported findings over time. Researchers continue to monitor the participants from these trials to assess long-term overall survival. Studies describe patterns in survival measurements over the extended follow-up period in certain groups, which were monitored alongside accounting for patient crossover. However, definitive, consistent differences in Overall Survival measurements across all patient groups and follow-up periods are not yet fully established.

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Known Gaps and Unanswered Questions in the Research

• Optimal Duration of Extended Therapy: Comparative evidence is lacking between all possible durations for extended adjuvant treatment (e.g., whether five years is sufficient or if a longer period is warranted).
• Specific Populations: Data for anovulation where conditions other than PCOS were the focus remain limited.
• Predictive Markers: Studies are still exploring factors that may be related to changes observed during the study period.

Common questions about Лорета (FAQ)

Q: Are the long-term effects of using Лорета known?

Studies and official information indicate that long-term use of the medicine is associated with a greater risk of decreased bone mineral density (osteoporosis) and subsequent bone fracture. The official safety profile also documents serious adverse events related to the cardiovascular system, such as ischemic cardiac and thromboembolic events.

Q: What specific foods or supplements should be avoided while taking this medicine?

Regulatory documents advise caution or avoidance of grapefruit and grapefruit juice, as these may interfere with the metabolism of the medicine. Strong herbal supplements, such as St. John's Wort, may also reduce the amount of the drug in the body and should be used with caution. Official product information notes the importance of consulting a healthcare professional before combining the medicine with any supplement.

Q: What makes Лорета different from other medicines used for the same purpose?

This medicine is classified as a non-steroidal aromatase inhibitor. Its primary mechanism is described as selectively blocking the aromatase enzyme, which is responsible for creating estrogen in the body. This action results in a significant and sustained reduction in estrogen levels, which is the basis for its therapeutic use.

Q: Does taking Лорета affect a person's quality of sleep?

According to the official product information, difficulty falling asleep or staying asleep, known as insomnia, is listed as a possible side effect. Other central nervous system effects, such as drowsiness or fatigue, are also documented as reported effects.

Q: Does the official research summarize how effective Лорета was in clinical studies?

Yes, official regulatory research outlines key findings from clinical trials. For example, studies in breast cancer monitored measurements like Disease-Free Survival, and research for anovulatory infertility monitored measurements of Live Birth Rate in the context of comparisons with other treatments.

Q: Does Лорета contain any known allergens or inactive ingredients that might cause a reaction?

The tablets contain the inactive ingredient lactose monohydrate, along with other excipients. The official eligibility profile strictly states that the medicine is contraindicated (should not be used) in patients who have a known hypersensitivity or severe allergic reaction to the active substance (Letrozole) or any of the inactive ingredients.

Q: Are there warnings about driving or operating heavy machinery while taking Лорета?

Official warnings state that the medicine may cause adverse effects like fatigue, dizziness, or drowsiness. Because of these potential effects, caution is advised regarding driving or operating heavy machinery until a person understands how the medicine affects them.

Q: Are there specific medical tests required before a person can start taking Лорета?

For females who still have the potential to become pregnant, the official guidance states that a pregnancy test is required prior to starting treatment. This is to confirm non-pregnancy before beginning therapy.

Q: What are the official warning signs listed for a serious adverse effect of Лорета?

Official patient information lists warning signs for serious events that should prompt immediate medical attention. These include symptoms such as sudden chest pain, difficulty breathing, a sudden severe headache, or pain and warmth in the lower leg.

Q: How is the mechanism of action of Лорета officially described in simple terms?

The mechanism is simply described as the medicine selectively blocking a protein (an enzyme) called aromatase. By interfering with the enzyme's function, the medicine inhibits the final step of estrogen production, which reduces the overall amount of estrogen in the body.

Q: How long does it typically take for a person to notice the effects of Лорета?

Pharmacokinetic studies indicate that the medicine acts quickly at a hormonal level, achieving a significant reduction in estrogen levels within 72 hours of the first dose. The time a person takes to notice a therapeutic benefit may vary and can be longer than the initial hormonal effect.

Q: Does the official product information mention an interaction between Лорета and alcohol?

While a formal pharmacokinetic drug interaction is not typically listed, regulatory sources note that alcohol may worsen certain side effects of this medicine, such as hot flashes, dizziness, and fatigue.

Q: Is there a generic alternative or bioequivalent medicine for Лорета?

Yes, regulatory databases, such as the FDA Orange Book, confirm that lower-cost generic versions of the active ingredient, Letrozole, are widely available. These generic products are approved as bioequivalent alternatives to the original brand name medicine.

Q: Does the effect of Лорета build up in the body over time?

Yes, pharmacokinetic data indicates that the active substance accumulates in the body during the initial weeks of therapy. It generally reaches a stable level in the bloodstream after approximately two to six weeks of continuous daily dosing.

Q: Is the drug Лорета known by any other name internationally?

Yes, the single active ingredient is known globally as Letrozole. The original brand name product for this medicine is known as Femara® in many international regulatory markets.

Q: Are there specific warnings about stopping the use of Лорета suddenly?

Official patient warnings advise that a person should not stop taking the medicine abruptly. The official guidance emphasizes that the decision to stop treatment, and the duration of therapy, must be medically supervised.

Q: How long is the medicine expected to remain in the system after the last dose is taken?

Regulatory documents indicate that the medicine has an elimination half-life of approximately two days. This means it can take about 10 days to 2 weeks for the drug to be almost completely eliminated from the body after the final dose is taken.

Q: Is Лорета known to cause weight gain or weight loss?

Yes, official adverse reaction data reports that changes in weight were a common side effect observed in clinical trials. Both weight gain and weight loss are documented as common side effects in the regulatory data.

Q: Can over-the-counter pain relievers be taken safely with Лорета?

While the official interaction tables do not list every single over-the-counter (OTC) pain reliever, regulatory documents recommend seeking guidance from a healthcare professional. This is advised before taking any OTC medication, including pain relievers, to review potential unlisted interactions or additional side effect risks.

Q: Does the time of day a person takes Лорета matter for its effectiveness?

Official dosing guidelines state that the medicine should be taken once daily at approximately the same time each day. This consistent timing helps to maintain stable and continuous levels of the drug in the bloodstream.

Q: Is Лорета classified as a controlled substance?

No, regulatory authorities in major markets, such as the U.S. and Canada, do not classify this medicine as a controlled substance. It is designated only as a prescription drug.

Q: Is the medicine affected by interaction with grapefruit or grapefruit juice?

Yes, some regulatory consumer information advises caution or avoidance of grapefruit and grapefruit juice. This is because they may interfere with the way the body processes the medicine, which could potentially affect the drug's intended action.

Q: What is described in the official documents as the recommended course of action for a suspected overdose of Лорета?

Official patient information directs that if a suspected overdose occurs, immediate action is required. The recommended course of action is to contact a poison control center or seek emergency medical treatment right away.

How to Store and Dispose of Лорета?

The storage and disposal requirements for Лорета (Letrozole) are defined by official regulatory labeling to ensure product quality and safety.

Storage Requirement	Condition
Temperature	Store at Controlled Room Temperature, between 20°C and 25°C.
Handling	Protect from moisture; do not allow the tablets to freeze.
Packaging	Keep the medicine in its original blister and carton until the expiration date.
Child Safety	Must be stored securely and kept out of the sight and reach of children.

Unused or expired tablets should not be discarded in household trash or wastewater. Disposal must follow officially documented procedures, such as returning the medicine to a pharmacist or using a drug take-back program, to properly manage pharmaceutical waste and protect the environment.