Lanvis (Tioguanine)

Lanvis (tioguanine) is used in hematologic malignancies and inflammatory bowel disease, acting on rapidly proliferating cells.

• Acute lymphoblastic leukemia: helps achieve remission by inhibiting leukemic cell proliferation and inducing apoptosis of abnormal lymphoblasts.
• Chronic myeloid leukemia: contributes to disease control through cytotoxic effects on malignant myeloid cells and may be used in combination with other targeted therapies.
• Inflammatory bowel disease: reduces intestinal inflammation by suppressing immune cell activity, aiding in maintenance of remission for ulcerative colitis and Crohn’s disease.

• Tioguanine is metabolized intracellularly to thioguanine nucleotides, which are incorporated into DNA and RNA in place of guanine bases. This incorporation disrupts purine synthesis, leading to faulty nucleic acid function, inhibition of cell division, and induction of apoptosis in rapidly dividing lymphoid and myeloid cells, providing both antineoplastic and immunosuppressive effects. The active metabolites also inhibit enzymes involved in de novo purine synthesis, further enhancing cytotoxicity.

Tioguanine may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Vomiting: occasional episodes, often transient.
• Diarrhea: loose stools that may affect hydration.
• Myelosuppression: reduced blood cell counts, leading to anemia or neutropenia.
• Elevated liver enzymes: mild transaminase increase.
• Mouth ulcers: painful lesions in oral mucosa.

Serious or Rare Side Effects

• Severe bone marrow failure: pancytopenia requiring medical intervention.
• Hepatotoxicity: significant liver injury or cholestasis.
• Infections: opportunistic infections due to immunosuppression.
• Secondary malignancies: rare development of other cancers.
• Hypersensitivity reactions: rash, fever, or anaphylaxis.
• Pancreatitis: inflammation of the pancreas, potentially severe.

When prescribing tioguanine, clinicians should observe several precautionary measures to minimize risk.

• Baseline blood counts: obtain complete blood count before initiation and monitor regularly.
• Liver function: assess hepatic enzymes and adjust dose if impairment is present.
• Renal function: evaluate kidney function, especially in patients with reduced clearance.
• Infection risk: monitor for signs of infection and advise patients to report fevers promptly.
• Pregnancy and lactation: avoid use unless benefits outweigh risks; discuss with obstetric specialist.
• Store at ambient temperature: keep tablets in original container, protect from moisture and light.

Tioguanine interacts with several medicines that can alter its efficacy or safety.

Major Interactions (Avoid)

• Allopurinol: increases tioguanine toxicity; concurrent use is contraindicated.
• Azathioprine: additive myelosuppression; avoid combined therapy.
• Methotrexate: heightened bone marrow suppression when used together.

Moderate Interactions (Monitor Closely)

• Warfarin: tioguanine may enhance anticoagulant effect; monitor INR.
• NSAIDs: may increase risk of gastrointestinal toxicity.
• Antiviral agents (e.g., ribavirin): potential for increased hematologic toxicity.