Eribulin Zentiva

What Is Eribulin Zentiva and What Is It Used For?

Eribulin Zentiva is a chemotherapy medicine containing eribulin mesylate, used to treat locally advanced or metastatic breast cancer and unresectable liposarcoma. It belongs to the halichondrin class of antineoplastic agents and works by disrupting the formation of microtubules that cancer cells need to divide.

Eribulin mesylate is a structurally simplified synthetic analogue of halichondrin B, a naturally occurring substance first isolated from the marine sponge Halichondria okadai found in Japanese coastal waters. The compound was developed through a remarkable feat of synthetic chemistry, as the natural source could not provide sufficient quantities for clinical use. Eribulin represents one of the most complex molecules ever synthesized for pharmaceutical purposes.

Eribulin Zentiva is approved by the European Medicines Agency (EMA) for two distinct clinical indications. The first is locally advanced or metastatic breast cancer in adult patients who have progressed after at least one prior chemotherapy regimen for advanced disease. Previous therapy should have included an anthracycline (such as doxorubicin or epirubicin) and a taxane (such as paclitaxel or docetaxel), either in the adjuvant or metastatic setting, unless the patient was not suitable for these treatments. This makes eribulin a valuable option for patients who have limited remaining treatment choices.

The second approved indication is for the treatment of adult patients with unresectable liposarcoma who have received prior anthracycline-containing therapy for advanced or metastatic disease. Liposarcoma is a rare type of soft tissue sarcoma that develops from fat cells, and treatment options for advanced cases remain limited. Eribulin was the first drug to demonstrate an overall survival benefit specifically in the liposarcoma subtype within a randomized controlled trial (Study 309/EORTC 62043).

The mechanism of action of eribulin is unique among tubulin-targeting agents. While taxanes (such as paclitaxel and docetaxel) stabilize microtubules and prevent their breakdown, and vinca alkaloids (such as vinorelbine) inhibit microtubule polymerization at the vinca domain, eribulin specifically inhibits the growth phase of microtubule dynamics without significantly affecting the shortening phase. It binds to a distinct site on the plus ends of microtubules, sequestering tubulin into non-productive aggregates. This leads to G2/M cell cycle arrest, disruption of mitotic spindles, and ultimately apoptotic cell death after prolonged mitotic blockade.

What Should You Know Before Taking Eribulin Zentiva?

Before starting Eribulin Zentiva, your oncologist will assess your blood counts, liver and kidney function, heart rhythm (ECG), and overall fitness. Women of childbearing potential must use effective contraception. Eribulin is contraindicated in pregnancy, during breastfeeding, and in patients with severe hepatic impairment.

Contraindications

Eribulin Zentiva must not be used in the following situations:

• Hypersensitivity to eribulin mesylate or to any of the excipients listed in the formulation
• Breastfeeding – it is not known whether eribulin is excreted in human milk, but due to its mechanism of action, breastfeeding must be discontinued during treatment
• Severe neutropenia (absolute neutrophil count < 0.5 x 10⁹/L) lasting more than 7 days at any point during treatment

Warnings and Precautions

Several important warnings and precautions apply to the use of Eribulin Zentiva. Your healthcare team will carefully monitor you throughout treatment to manage these risks effectively.

Myelosuppression: Eribulin frequently causes suppression of bone marrow function, most commonly manifesting as neutropenia (low white blood cell count). This is the most clinically significant adverse effect and can lead to serious infections. Complete blood counts must be performed before each dose, and treatment should not be administered if the absolute neutrophil count (ANC) is below 1.0 x 10⁹/L or platelet count is below 75 x 10⁹/L. Febrile neutropenia (fever with low white blood cell count) has been reported in approximately 5% of patients and requires immediate medical attention with broad-spectrum antibiotics.

Peripheral neuropathy: Eribulin can cause peripheral neuropathy, manifesting as numbness, tingling, burning sensations, or pain in the hands and feet. Patients who already have peripheral neuropathy from prior chemotherapy (especially taxanes or platinum compounds) may be at greater risk. If Grade 3 or 4 peripheral neuropathy develops, treatment should be delayed until improvement to Grade 2 or lower, with a dose reduction considered upon resumption.

QT prolongation: Eribulin has been associated with QT interval prolongation on electrocardiogram (ECG). Caution is advised in patients with congestive heart failure, bradyarrhythmias, concurrent use of QT-prolonging drugs, or electrolyte abnormalities (particularly hypokalemia or hypomagnesemia). ECG monitoring should be considered in patients at risk.

Hepatic impairment: Patients with moderate or severe hepatic impairment (Child-Pugh B or C) may have increased exposure to eribulin and require dose reduction. Liver function tests should be monitored throughout treatment. Patients with severe hepatic impairment should use a reduced dose of 0.97 mg/m², while those with moderate impairment should receive 1.11 mg/m².

Pregnancy and Breastfeeding

Eribulin Zentiva is expected to cause fetal harm based on its mechanism of action and findings from animal studies. It is contraindicated during pregnancy, and women of childbearing potential must be advised to avoid becoming pregnant while receiving eribulin.

Contraception: Women of childbearing potential must use highly effective contraception during treatment and for at least 3 months after the last dose of eribulin. Male patients with female partners of childbearing potential should also use effective contraception during treatment and for 3 months after the final dose, as eribulin may impair male fertility.

Breastfeeding: It is not known whether eribulin or its metabolites are excreted in human breast milk. Due to the potential for serious adverse reactions in nursing infants, breastfeeding must be discontinued during treatment with eribulin and should not be resumed for at least 2 weeks after the final dose.

Fertility: Based on animal studies, eribulin may impair fertility in both males and females. Male patients should consider sperm banking before starting treatment. Female patients should discuss fertility preservation options with their oncologist before commencing therapy.

How Does Eribulin Zentiva Interact with Other Drugs?

Eribulin has a relatively limited drug interaction profile compared to many other chemotherapy agents, as it is not significantly metabolized by cytochrome P450 enzymes. However, caution is needed with QT-prolonging drugs, anticoagulants, and certain CYP3A4 inhibitors. Always inform your oncologist about all medications you are taking.

The pharmacokinetics of eribulin suggest that it undergoes minimal hepatic metabolism. It is primarily eliminated unchanged via biliary excretion, with the cytochrome P450 enzyme system playing a negligible role in its clearance. This means that drug interactions mediated through CYP enzymes are generally not clinically significant. Nevertheless, several important interactions should be considered.

Major Interactions

The most clinically significant interactions with eribulin relate to its potential for QT interval prolongation and its immunosuppressive effects. Concurrent use of other QT-prolonging medications can increase the risk of potentially life-threatening cardiac arrhythmias, including torsades de pointes. Patients receiving eribulin alongside any QT-prolonging medication should have regular ECG monitoring and electrolyte assessments.

Live vaccines must be avoided during eribulin treatment and for a period after completing therapy. The immunosuppressive effects of eribulin can lead to inadequate immune responses to vaccination and, more dangerously, the risk of disseminated infection from live vaccine organisms. Inactivated vaccines may be administered but may have reduced effectiveness.

Minor Interactions

In vitro studies have shown that eribulin is a weak inhibitor of CYP3A4, but clinical pharmacokinetic studies have not demonstrated significant interactions with substrates of major CYP enzymes. The drug is not a significant inducer of CYP enzymes. Transport-mediated interactions via P-glycoprotein are theoretically possible but have not been shown to be clinically significant at therapeutic concentrations.

What Is the Correct Dosage of Eribulin Zentiva?

The recommended dose of Eribulin Zentiva is 1.23 mg/m² administered intravenously over 2 to 5 minutes on Days 1 and 8 of a 21-day cycle. Dose reductions are required for hepatic impairment and for patients experiencing specific toxicities. Treatment continues until disease progression or unacceptable toxicity.

Eribulin Zentiva is available as a 0.44 mg/ml solution for injection. The dose is calculated based on body surface area (BSA), which takes into account the patient's height and weight. The medication is prepared and administered by trained healthcare professionals in a hospital or specialized oncology infusion center. The solution may be administered undiluted or diluted in up to 100 ml of 0.9% sodium chloride solution.

Adults

The standard recommended dose for adults is 1.23 mg/m² administered intravenously over 2 to 5 minutes on Days 1 and 8 of each 21-day treatment cycle. It is important to note that the EMA-approved dose of eribulin mesylate (1.23 mg/m²) is expressed differently than the FDA-approved dose (1.4 mg/m²), which refers to the eribulin free base equivalent. Both represent the same actual amount of drug administered.

Prior to each dose, complete blood counts must be evaluated. Treatment should be delayed if Day 1 ANC is less than 1.5 x 10⁹/L or platelet count is less than 75 x 10⁹/L, or if Day 8 ANC is less than 1.0 x 10⁹/L or platelet count is less than 75 x 10⁹/L. If toxicities do not resolve to acceptable levels within a maximum delay of one week, the Day 8 dose should be omitted.

Children

The safety and efficacy of Eribulin Zentiva have not been established in children and adolescents below 18 years of age. There are no relevant data from clinical trials in the pediatric population, and eribulin is not recommended for use in patients under 18 years of age.

Elderly

No specific dose adjustment is required for elderly patients solely based on age. However, elderly patients may be more susceptible to certain adverse effects such as neutropenia, fatigue, and peripheral neuropathy. Individual assessment of organ function, comorbidities, and overall performance status should guide dosing decisions. In clinical trials, patients aged 65 years and older had a higher incidence of Grade 3-4 neutropenia, fatigue, and asthenia compared to younger patients.

Dose Reductions for Toxicity

Dose reductions may be required based on the severity of adverse reactions experienced during treatment. The recommended dose reduction levels are:

• First dose reduction: 0.97 mg/m² (from the standard 1.23 mg/m²)
• Second dose reduction: 0.62 mg/m²
• Discontinuation: If further dose reduction below 0.62 mg/m² is needed, eribulin should be discontinued

Missed Dose

Eribulin Zentiva is administered by healthcare professionals in a clinical setting, so missed doses are managed by the treating oncology team. If a scheduled Day 8 dose is missed due to toxicity, the dose is omitted and the next cycle begins on Day 22 (or later if recovery has not occurred). The Day 8 dose should not be given later than Day 8 within a cycle. If a dose is missed due to logistical reasons, the treating physician will determine the appropriate timing for the next administration.

Overdose

There is no specific antidote for eribulin overdose. In the event of an accidental overdose, the patient should be closely monitored and supportive care should be provided. Anticipated symptoms of overdose include severe neutropenia, severe peripheral neuropathy, and other known adverse effects in an amplified form. Granulocyte colony-stimulating factor (G-CSF) support may be considered for severe neutropenia. Due to the intravenous route of administration, overdose is unlikely in clinical practice but could theoretically occur through preparation or administration errors.

What Are the Side Effects of Eribulin Zentiva?

The most common side effects of Eribulin Zentiva include neutropenia, fatigue, nausea, alopecia (hair loss), constipation, peripheral neuropathy, and decreased appetite. Neutropenia is the most clinically significant adverse reaction and requires regular blood count monitoring. Most side effects are manageable with appropriate supportive care.

Like all chemotherapy medicines, Eribulin Zentiva can cause side effects, although not everyone experiences them. The safety profile of eribulin has been well characterized across multiple phase II and phase III clinical trials, including the pivotal EMBRACE study (Study 305) in metastatic breast cancer and Study 309 in liposarcoma. Understanding the frequency and nature of these side effects helps patients and healthcare providers prepare for and manage them effectively.

Side effects are classified by frequency according to standard medical convention. The following grid presents the most commonly reported adverse reactions organized by their frequency of occurrence.

It is essential to report any side effects you experience to your oncology team promptly. Many side effects can be effectively managed with supportive care measures, including anti-emetic medications for nausea, growth factors (G-CSF) for neutropenia, and dose modifications if needed. Some adverse effects, particularly peripheral neuropathy, may persist after treatment is discontinued and require long-term monitoring and management.

How Should You Store Eribulin Zentiva?

Eribulin Zentiva is stored and handled by hospital pharmacies. Unopened vials should be stored at room temperature (below 25°C) in the original carton to protect from light. Once drawn into a syringe, the solution should be used within 4 hours at room temperature or 24 hours when refrigerated.

As Eribulin Zentiva is an intravenous chemotherapy medication, it is stored and prepared exclusively in hospital pharmacy or oncology unit settings by trained pharmaceutical personnel. Patients do not need to store this medication at home. However, understanding the storage requirements helps ensure the quality and safety of the administered product.

Unopened vials of Eribulin Zentiva should be stored below 25°C. The vials do not need to be refrigerated but should be kept in the original outer carton to protect from light. The solution is a clear, colorless aqueous solution; vials should be visually inspected before use and discarded if discoloration or particulate matter is observed.

Once the required dose has been drawn from the vial into a syringe, the solution should be used within 4 hours if stored at room temperature (15-25°C), or within 24 hours if stored in a refrigerator (2-8°C). If diluted in 100 ml of 0.9% sodium chloride, the infusion solution should be used immediately or within 24 hours if refrigerated. Any unused portion remaining in the vial after a single dose extraction should be discarded in accordance with local requirements for the handling and disposal of cytotoxic drugs.

Eribulin Zentiva should be kept out of the sight and reach of children. Do not use this medicine after the expiry date which is stated on the carton and vial label after "EXP." The expiry date refers to the last day of that month.

What Does Eribulin Zentiva Contain?

Each ml of Eribulin Zentiva solution contains 0.44 mg of eribulin mesylate (equivalent to 0.38 mg of eribulin as free base). The other ingredients are ethanol, hydrochloric acid (for pH adjustment), sodium hydroxide (for pH adjustment), and water for injections.

The active substance in Eribulin Zentiva is eribulin mesylate. Each 2 ml vial contains 0.88 mg of eribulin mesylate, providing a concentration of 0.44 mg/ml. When expressed as the free base equivalent (as used in some prescribing information, particularly in the United States), each vial contains 0.76 mg of eribulin (0.38 mg/ml). This difference in expression is purely a matter of convention and does not reflect any difference in the actual amount of drug administered.

The excipients (inactive ingredients) in the formulation serve important roles in ensuring the stability, solubility, and appropriate pH of the solution:

• Ethanol (anhydrous): Acts as a co-solvent to maintain eribulin mesylate in solution
• Hydrochloric acid (dilute): Used to adjust the pH of the solution to the optimal range
• Sodium hydroxide: Used in combination with hydrochloric acid for pH adjustment
• Water for injections: The primary vehicle for the injectable solution

Eribulin Zentiva does not contain preservatives and is intended for single use only. The solution appears as a clear, colorless liquid. Each carton typically contains one vial of 2 ml solution. The product is a biosimilar or generic version of eribulin marketed by Zentiva, containing the same active substance, in the same strength and pharmaceutical form, as the originator product.

Frequently Asked Questions About Eribulin Zentiva