Leuject (Cladribine)

Cladribine is used in conditions where selective depletion of lymphocytes provides therapeutic benefit, primarily within immune‑mediated and hematologic disease categories, and has been approved for specific indications by regulatory agencies.

• Multiple sclerosis: reduces disease activity and slows progression by depleting pathogenic lymphocytes.
• Hairy cell leukemia: induces remission by targeting malignant B‑cells through inhibition of DNA synthesis.

• Cladribine is a purine nucleoside analog that enters cells via nucleoside transporters and is phosphorylated intracellularly to its active triphosphate form. The active metabolite incorporates into DNA, causing strand breaks and inhibiting DNA synthesis and repair. This leads to selective apoptosis of proliferating lymphocytes, particularly B‑ and T‑cells, thereby reducing the immune cell population responsible for disease activity. The resulting lymphocyte depletion contributes to clinical remission in the targeted diseases.

Cladribine may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Injection site pain: mild to moderate discomfort at the injection site.
• Flu‑like symptoms: fever, chills, and muscle aches.
• Nausea: transient gastrointestinal upset.
• Fatigue: generalized tiredness.
• Lymphopenia: reduced lymphocyte counts, often mild.
• Headache: occasional mild headache.

Serious or Rare Side Effects

• Severe infections: opportunistic infections due to immunosuppression.
• Profound lymphopenia: marked decrease in lymphocytes requiring monitoring.
• Secondary malignancies: rare development of new cancers.
• Autoimmune hepatitis: liver inflammation of autoimmune origin.
• Severe skin reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis.

When using Cladribine, several precautions should be observed to ensure patient safety and product integrity.

• Monitor blood counts: perform regular complete blood count assessments.
• Screen for infections: evaluate for active or latent infections before initiation.
• Avoid live vaccines: do not administer live attenuated vaccines during treatment.
• Assess organ function: check hepatic and renal function prior to therapy.
• Contraindicated in severe immunodeficiency: patients with profound immune compromise should not receive.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Cladribine can interact with other medicines, and awareness of these interactions helps to minimize risks.

Major Interactions (Avoid)

• Concurrent myelosuppressive chemotherapy: may cause excessive bone‑marrow suppression.
• Live vaccines: increase risk of vaccine‑derived infection.
• Strong immunosuppressants (e.g., azathioprine): amplify immunosuppression.

Moderate Interactions (Monitor Closely)

• Non‑live vaccines: reduced efficacy, monitor immune response.
• Antiviral agents (e.g., acyclovir): may require dose adjustment.
• Anticoagulants: monitor coagulation parameters as infection risk may alter metabolism.