Kladribine

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Kladribine

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Method of action: Antitumour

Treatment option: Leukemia

Medically reviewed

Laura Arias

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 Kladribine

Property Description
Active ingredient Cladribine (2-Chlorodeoxyadenosine)
Form Tablets (Oral) and Solution for Injection (Intravenous)
Pharmacological class Antimetabolite, Purine Nucleoside Analog, Immunosuppressant
General purpose Selective reduction and modulation of immune cells
Origin Synthetic compound

Defining Kladribine: A Purine Analog Antimetabolite

Kladribine is a synthetic medicine whose active ingredient is Cladribine, chemically known as 2-Chlorodeoxyadenosine (2-CdA). It is primarily classified as an antimetabolite and an immunosuppressant. This classification reflects its fundamental nature as a drug designed to mimic a natural chemical in the body, specifically a purine nucleoside analog.

This design allows it to interfere with the metabolic processes of certain hyperactive cells, which is the foundation for its therapeutic application in conditions linked to an overactive immune response. Cladribine is a single active pharmaceutical ingredient, making it a single product entity. This nucleoside analog is designed to prevent cell proliferation.


Unique Forms and the Goal of Immune Reconstitution

Kladribine is uniquely available in two distinct preparations: as tablets for oral administration and as a solution for injection for intravenous use. The high-level purpose of this synthetic cytotoxic compound is to achieve controlled, selective lymphocyte depletion to dampen the body's inflammatory immune activity.

The active compound, Cladribine, provides flexibility in treatment, being available in forms for both non-institutional and institutional use. By selectively targeting and reducing the population of certain immune cells, particularly lymphocytes, the drug aims to stop or significantly modify the inflammatory processes driven by the immune system, providing a form of immune modulation. The mechanism involves long-lasting reductions in certain white blood cells. This indicates the medicine works by reducing specific cells that cause inflammation.


Kladribine's Core Mechanism in Simple Terms

Kladribine works by utilizing selective cytotoxicity against immune cells, which triggers a process called apoptosis, or programmed cell death. This mechanism is utilized to target specific immune cell lines. This interference leads to the eventual removal of the overactive immune cells. The result is a profound, but temporary, reduction in the number of certain lymphocytes, which is how the drug achieves its intended effect of immune modulation.

Regulatory References

  1. EMA Summary

What side effects are possible with Kladribine?

Possible side effects and safety information

Kladribine's official safety profile is strongly defined by its function as an immunosuppressant and antimetabolite, with adverse reactions documented according to frequency and body system involvement in regulatory sources.


Adverse Reaction Classifications

Classification Representative Side Effect System-Organ Class
Very Common (ge 1/10) Lymphopenia, Infections, Headache Blood and Lymphatic System, Infections
Common (ge 1/100 to <1/10) Herpes Zoster, Neutropenia, Rash Infections, Blood and Lymphatic System, Skin
Uncommon (ge 1/1,000 to <1/100) Liver Injury Hepatobiliary Disorders

Documented Serious Adverse Reactions

The regulatory label identifies several serious safety concerns. Malignancy is a documented risk, and its increase may persist for years following treatment completion. Serious Infections, including fatal cases of Tuberculosis and Hepatitis B, have been reported and necessitate pre-treatment screening for active and latent infections. The risk of Teratogenicity is also explicitly noted, leading to strict contraindications in pregnancy.

Population-Specific Safety Notes

The medicine is strictly contraindicated in patients with: moderate or severe renal impairment, active malignancy, HIV infection, and women who are pregnant or breastfeeding. Due to the teratogenicity risk, effective contraception is required for six months after the last dose in both male and female patients. Safety and efficacy are not established for the pediatric population.

Exposure-Related Safety Patterns

Lymphopenia is dose-dependent and typically transient, with regulatory documents emphasizing that counts must recover before the subsequent annual treatment course. The overall safety structure emphasizes the critical need for continuous blood count monitoring before and throughout the duration of the regulated treatment period.

Overdose and Emergency Response

The official regulatory documents state that experience with overdose of oral Kladribine is limited. The principal documented manifestation associated with an overdose situation is lymphopenia, which is defined by authorities as a dose-dependent physiological effect on the blood cells.

Overdose Management and Required Actions

Aspect Regulatory Statement
Manifestation Lymphopenia is the documented dose-dependent clinical outcome.
Specific Treatment There is no known specific antidote to an overdose.
Required Action Patients must contact their regional poison control centre for management of a suspected overdose.
Monitoring Particularly close monitoring of hematological parameters is required.

Treatment following a suspected overdose consists of initiating appropriate supportive measures and placing the patient under careful observation. Regulatory documentation notes that due to the extensive intracellular and tissue distribution of the medicine, procedural interventions like hemodialysis are unlikely to eliminate the drug to a significant extent. The official overdose profile is therefore defined by the known hematological manifestation, the lack of a specific reversal agent, and a reliance on supportive care, mandatory close monitoring of blood parameters, and immediate consultation with a poison control centre for management guidance.

Therapeutic Uses of Kladribine

What Kladribine Treats: Main Uses and Benefits

Kladribine is commonly used across conditions presenting with acute episodes, relevant in conditions characterized by periods of heightened symptoms. It is primarily applied in addressing relapsing forms of multiple sclerosis (MS) in adults, and is relevant for forms such as relapsing-remitting disease and active secondary progressive disease. This focus on relapsing forms is relevant for managing symptoms that become more disruptive during flare-ups.

The application of Kladribine is relevant for easing symptoms that interfere with daily comfort. It helps address symptom clusters that may become intense or disruptive, supporting patients during episodes of heightened discomfort.

The medicine is applied in clinical settings that involve acute or unstable symptom patterns to help ease the overall symptom burden. One core patient-oriented support is that it supports the patient during difficult episodes by easing distress and may assist with maintaining functional stability.

“It is commonly used when short-term symptomatic assistance is needed and supports general well-being during symptomatic phases.”

Note on Secondary Indications: Kladribine (in a different formulation) is also commonly used to help with managing certain conditions presenting with systemic or localized discomfort.

Quick Fact: Relevant for Symptoms that Interfere with Daily Functioning

Regulatory References

  1. European Medicines Agency Mavenclad Overview

Eligibility and Restrictions for Use

Who Can and Cannot Use Kladribine? (Official Regulatory Information)

Kladribine is officially approved for use in adults with relapsing forms of multiple sclerosis (MS). Eligibility is strictly defined by regulatory authorities and includes several absolute contraindications, primarily due to the drug’s immunosuppressive profile.


Official Contraindications

Kladribine must not be used in the following populations, as stated in prescribing information:

  • Patients with a current malignancy (active cancer).
  • Patients with active chronic infections (e.g., HIV, active hepatitis, or tuberculosis).
  • Patients currently receiving immunosuppressive or myelosuppressive therapy.
  • Patients with moderate or severe renal impairment (creatinine clearance less than 60 mL/min).
  • Pregnant women and women who are breastfeeding on or shortly after a treatment day.

Population Restrictions and Limitations

Use in children below the age of 18 years is not recommended as safety and efficacy have not been established. Caution is recommended when treating older adults. Additionally, both female and male patients of reproductive potential are required to use effective contraception during treatment and for a minimum of six months after the final dose. Treatment initiation is also contingent on a normal lymphocyte count.

What should I know about interactions with other medicines?

Interactions with other medicines and products

The official regulatory profile for Kladribine outlines interaction constraints based on both pharmacodynamic and pharmacokinetic mechanisms.

Pharmacodynamic and Contraindicated Combinations

The highest restriction applies to Live or Attenuated Live Vaccines, which are formally contraindicated during treatment and until lymphocyte counts have recovered to a defined threshold. Co-administration is not recommended with other Immunosuppressive or Myelosuppressive agents due to the potential for additive hematological effects. This regulatory caution also extends to Antiviral and Antiretroviral drugs.

Pharmacokinetic and Timing Constraints

Pharmacokinetic interactions involve specific drug transport proteins. Concomitant use with inhibitors of BCRP (Breast Cancer Resistance Protein) or ENT/CNT (Equilibrative/Concentrative Nucleoside Transporters) should be avoided due to the potential for altered Kladribine bioavailability.

Administration rules must also be followed. Other Oral Medicines require a minimum 3-hour separation from Kladribine tablets to prevent altered absorption. While taking Kladribine with food reduces the maximum concentration (C max), the overall exposure (AUC) remains unchanged. Finally, patients needing a blood transfusion must receive irradiated cellular blood components to prevent transfusion-associated complications.

Mechanism of Action

The action of Kladribine is centered on achieving selective, long-lasting modulation of the adaptive immune system by targeting the genetic processes of immune cells. The mechanism proceeds through distinct phases, from enzyme-dependent activation to profound cellular elimination.

Activation by Selectively Vulnerable Lymphocyte Enzymes

The drug is a prodrug that achieves its unique selectivity through a targeted metabolic process. It is phosphorylated and activated by the enzyme deoxycytidine kinase (dCK), which is highly prevalent in lymphocytes (B and T cells). This enzyme profile allows the toxic active metabolite, Cd-ATP, to accumulate to damaging levels almost exclusively within the targeted immune cells, serving as the essential first step in the mechanism.


Dual Interference with Genetic Material and Synthesis

Once concentrated inside the lymphocyte, the active metabolite engages in a dual cytotoxic mechanism. It acts as an antimetabolite, incorporating into the cell's DNA to cause immediate strand breaks, while simultaneously acting as an inhibitor of Ribonucleotide reductase (RNR), crippling the cell's ability to synthesize new DNA precursors for repair. This overwhelming, irreparable damage triggers the intrinsic apoptotic pathway (programmed cell death) in the targeted lymphocytes.


Significant and Durable Immune Cell Depletion

The resulting widespread, controlled destruction and clearance of the B and T lymphocyte population leads to a significant and long-lasting reduction in their circulating counts (lymphopenia). This reduction in cellularity is the core physiological effect of the drug, which serves as the mechanism for long-lasting systemic immune modulation.

Dosage and Administration Information

Kladribine is used according to two distinct administration protocols based on its formulation: oral tablets (10 mg strength) for one indication, and solution for intravenous infusion (1 mg/mL strength) for another. The oral regimen is characterized by a cumulative dose and an intermittent dosing schedule.


Official Oral Administration (Tablets)

Property Official Instruction
Route of Administration Oral
Dosing Schedule Cumulative dose of 3.5 mg/kg body weight administered over two years, divided into two treatment courses.
Treatment Course Timing Each course consists of two treatment cycles (e.g., in Month 1 and Month 2), separated by 23 to 27 days. The second course is administered at least 43 weeks after the first.
Daily Dose/Preparation Administered as 1 or 2 tablets once daily for 4 or 5 consecutive days, depending on weight. Tablets must be swallowed whole with water and can be taken with or without food.
Drug Separation Administration must be separated from any other oral drug by at least 3 hours during the 4- to 5-day cycle.
Missed Dose Rule If one dose is missed, it must be taken on the following day, and the cycle is extended by one day. If two consecutive doses are missed, the cycle is extended by two days.

Population-Specific Use

No dose adjustment is required for patients with mild hepatic impairment. Use is not recommended in patients with moderate or severe renal impairment, defined as creatinine clearance less than 60 mL/min. Safety and efficacy have not been established for use in patients under 18 years of age.

These instructions define a specific use protocol with fixed dose limits and long drug-free periods, supporting a standardized administration pattern.

Recent Clinical Evidence

Kladribine: Recent Clinical Evidence

Clinical research on kladribine has focused on its use in the investigation of certain chronic conditions, primarily through trials examining its long-term effects on disease activity and progression. The evidence is derived mostly from randomized, double-blind, placebo-controlled trials, which are considered the standard for evaluating drug response.

Summary of Clinical Trials

Studies have focused on whether the drug may be associated with changes in measures of disease relapse and disability progression over two to four years. Trials have also examined potential associations with changes in the quality of life for individuals.

  • Target Population: Initial studies included adults with specific disease characteristics, and later-stage trials expanded the inclusion criteria to assess a wider patient population.
  • Study Design: The majority of pivotal investigations were randomized, double-blind, placebo-controlled trials.
  • Primary Outcomes: The primary endpoints for most studies centered on validated clinical scales and objective markers related to disease activity.

Efficacy and Comparative Assessment

Studies have examined the investigation of core disease symptoms. Research has investigated the tolerability and observed response when kladribine is used in combination with other existing standards of care for complex presentations.

  • Evidence Status: The current body of evidence is primarily derived from Phase 3 clinical trials which provided data on the primary endpoints. Ongoing post-market surveillance and extended-duration studies are continuing to collect data regarding tolerability over extended periods.

Mechanisms and Special Populations

Preclinical studies have explored the drug's observed interactions with certain biological pathways. Pharmacokinetic studies have described how the drug is absorbed, distributed, metabolized, and excreted in the human body. Tolerability studies have included participants with pre-existing mild renal or hepatic impairment to collect data regarding the drug's disposition and tolerability in these populations. Subgroup analyses have also been conducted to determine whether different patient characteristics were associated with varied response.

Frequently Asked Questions (FAQ)

Common questions about Kladribine (FAQ)

Q: Does Kladribine treatment need to be done in a hospital?

The required setting depends on the formulation. Official documents state that the oral tablet formulation is typically taken by mouth outside of a hospital. However, the injection formulation is administered by intravenous infusion, which is usually done in a clinical or institutional setting.

Q: How long do the effects of Kladribine typically last after a full course of treatment?

Official information indicates that Kladribine is administered as two separate treatment courses over two years. Following the completion of the second course, no further treatment is required in Years 3 and 4. This dosing protocol reflects the regulatory assessment of the medicine’s expected activity over a four-year period.

Q: Is it true that Kladribine might increase the risk of certain infections?

Yes, official regulatory documents indicate that treatment is associated with an increased risk of serious infections, including reports of life-threatening and fatal cases. The risk is associated with the medicine's designed action on the immune system.

Q: What does the research say about Kladribine for people over 65?

Official prescribing information indicates that safety and efficacy have not been established for patients over 65 years of age. Due to limited data in this group, caution is recommended in the treatment of older adults.

Q: What are the requirements for monitoring blood tests during Kladribine use?

Official product information describes that a complete blood count (CBC), including a differential of white blood cells and specific lymphocyte counts, is required to be monitored before starting treatment, during treatment cycles, and periodically afterward.

Q: Can Kladribine be used by people who have a history of tuberculosis?

Pre-treatment screening for tuberculosis is a required step described in regulatory documents. While active tuberculosis is a contraindication, latent (inactive) infection is required to be fully resolved or controlled before treatment is initiated.

Q: Do patients need to take other medicines alongside Kladribine?

Official information states that patients who experience very low white blood cell counts, specifically lymphocyte counts below a certain threshold (less than 200 cells/mu L), may need to take anti-herpes prophylaxis medicine to prevent viral reactivation.

Q: Why does Kladribine sometimes require specific patient screening tests?

Screening tests are conducted to identify conditions that are absolute contraindications or high-risk factors for serious complications, as described in regulatory warnings. These tests check for conditions like HIV, tuberculosis, or hepatitis B/C, and determine if female patients are pregnant.

Q: Is there official information about using Kladribine in combination with other immunomodulators?

Regulatory documents advise that co-administration is not recommended with other agents that suppress the immune system (immunosuppressive) or affect blood cell counts (myelosuppressive). This caution is related to the potential for an additive effect on reducing blood cell counts.

Q: Can Kladribine affect mood or cause emotional changes?

Official regulatory reports have documented depression as a serious side effect. Central nervous system effects are reported in association with the medicine.

Q: How is Kladribine documented to interact with common pain medications like ibuprofen?

The official administration instructions describe that Kladribine should be separated from any other oral medicine, which includes common pain relievers, by at least 3 hours during the active dosing cycles. This is done to help prevent altered absorption of Kladribine.

Q: Are there long-term health effects associated with Kladribine use?

Yes, regulatory labels identify an increased risk of malignancy (cancer) as a serious safety concern. This risk may persist for years following the completion of treatment, and regulatory guidance includes the recommendation to follow standard cancer screening guidelines.

Q: Is Kladribine known to cause hair loss?

Hair loss, medically known as alopecia, is listed in official regulatory documents as an uncommon side effect, meaning it is reported in less than 1/100 patients.

Q: Does Kladribine cause fatigue or tiredness?

Fatigue or tiredness is not listed in the most frequent side effect categories. However, it is reported in regulatory literature in association with certain serious adverse reactions, such as the development of anemia or liver injury.

Q: Are headaches a common side effect of Kladribine?

Yes, headache is listed in the official safety profile as a very common adverse reaction, as it is listed in the 'very common' category (reported in ge 1/10 patients).

Q: Do official sources describe any specific dietary changes needed while on Kladribine?

No specific dietary changes are described as mandatory in the official prescribing information. The tablets may be taken with or without food.

Q: Is Kladribine approved in many countries around the world?

Yes, official manufacturer releases and regulatory summaries confirm that the medicine has regulatory approval in a wide range of global jurisdictions, including the US, European Union, Canada, and Australia.

Q: What are the known potential risks described in clinical studies for Kladribine?

The major risks detailed in clinical and regulatory documents include severe lymphopenia (low white blood cell counts), serious infections, an increased risk of malignancy (cancer), and the potential for fetal harm (teratogenicity) if taken during pregnancy.

Q: Can Kladribine affect my ability to get pregnant?

Due to the serious risk of fetal harm (teratogenicity), regulatory documents describe that both male and female patients of reproductive potential must use effective contraception for a minimum of six months after the last dose.

Q: Are there any specific vaccines to avoid while receiving Kladribine?

Yes, live or attenuated live vaccines are explicitly contraindicated (must not be given) during treatment and until your lymphocyte counts have recovered to a safe level, as confirmed by regulatory guidance.

Q: Can Kladribine be taken if I am currently taking over-the-counter pain relievers?

The official administration instructions describe that Kladribine should be separated from any other oral medicine, which includes over-the-counter pain relievers, by at least 3 hours during the active dosing cycles. This is done to help prevent altered absorption of Kladribine.

Q: Does Kladribine interact with common vitamins or supplements?

Similar to other oral medicines, official regulatory instructions recommend separating the administration of Kladribine tablets from any oral vitamins or supplements by at least 3 hours. This separation helps prevent any interference with Kladribine's absorption.

Q: Is Kladribine safe to use during pregnancy according to official sources?

No, regulatory sources state it is strictly contraindicated (must not be used) in women who are pregnant. This is due to the potential for the drug to cause teratogenicity, meaning harm to the developing fetus.

Q: Does Kladribine affect the liver?

Yes, liver injury is listed in the regulatory safety profile as a documented adverse reaction. Liver function tests are required before starting treatment to monitor for this potential effect.

Q: Is Kladribine a first-line treatment option in official guidelines?

Official indications often state that the drug is used for patients who have had an inadequate response to, or are unable to tolerate, an alternate drug indicated for the condition. This means its use may follow other treatment approaches, depending on specific clinical guidelines.

Q: Why do official documents mention Kladribine and certain skin cancers?

Official regulatory labels include an increased risk of malignancy (cancer) as a serious safety concern. The guidance recommends that patients are continuously monitored for this risk according to standard cancer screening guidelines.

Q: How is the patient monitored after completing the full course of Kladribine?

After completing the two-year course, patients must continue to be monitored for long-term risks, specifically for the development of malignancy (cancer) and signs of infection, as advised by official regulatory documents.

Q: Are there any known drug interactions with birth control pills and Kladribine?

Official regulatory instructions describe that women using systemically acting hormonal contraceptives (like birth control pills) must use a barrier method of contraception during treatment and for at least 4 weeks after the last dose in each treatment year.

Q: Is Kladribine treatment only started after other treatments have failed?

Official indications often specify that the drug is for patients who have had an inadequate response to, or are unable to tolerate, an alternate drug indicated for the condition. This means its use may follow other treatment approaches.

How should Kladribine be stored and disposed of?

Official Kladribine Storage and Disposal Requirements

Storage and handling requirements for Kladribine are strictly defined by regulatory documents based on the product form. Both forms must be kept out of the sight and reach of children.


Feature Kladribine Tablets (Oral) Kladribine Injection (IV)
Required Temperature Controlled Room Temperature (20 C to 25 C) Refrigerate (2 C to 8 C), Do Not Freeze
Protection Store in the original package to protect from moisture Store in original vial
Stability/Handling Must be swallowed immediately upon removal from blister. Limit direct skin contact. Vials are single use only. Diluted solution has an 8-hour maximum refrigerated stability limit.

Both the tablets and the injection are classified as cytotoxic drugs and require special handling procedures. Any unused or expired product, including waste materials, must be handled and disposed of in accordance with local requirements for antineoplastic medicinal products.

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

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