6-TG-40mg Tab

Side Effects of 6-TG-40mg Tab

Myelosuppression especially leukopenia, thrombocytopenia, anaemia; hyperuricaemia; nausea; vomiting; diarrhoea; anorexia and stomatitis; rash; dermatitis; jaundice; increased risk of infections. Potentially Fatal: Hepatotoxicity, life-threatening infections due to myelosupression.

Drug Interactions

Increased risk of heptotoxicity, portal hypertension and oesophageal varices during long-term continuous therapy with busulfan. Increased haematological toxicity with aminosalicylate derivatives (e.g. olsalazine, mesalazine or sulfasalazine), which may inhibit the thiopurine methyltransferase enzyme. May decrease phenytoin or carbamazepine levels.

Contraindications

Pregnancy, lactation, prior resistance to drug. Immunisation with live vaccines.

Mechanism of Action

Tioguanine, an antineoplastic that acts as an antimetabolite, has actions similar to those of mercaptopurine. It is an analogue of the natural purine, guanine and is rapidly converted to ribonucleotides which are then incorporated into the DNA and RNA after repeated dosing. The cytotoxic effects arises from the substitution of the ribonucleotides into DNA.Tioguanine has some immunosuppressive activity and there is complete cross-resistance between tioguanine and mercaptopurine. Absorption: Incomplete and variable absorption from GI tract. Average bioavailbility: 30%. Distribution: Does not cross the blood-brain barrier significantly; crosses the placenta. Metabolism: Rapidly and extensively metabolised in liver and other tissues. Inactivated mainly by methylation to aminomethylthiopurine; some are deaminated to thioxanthine which may be further oxidised by xanthine oxidase to thiouric acid. Inactivation is independent of xanthine oxidase and is unaffected by enzyme inhibition. Excretion: Excreted in urine mainly as metabolites and unchanged drug (negligible).

Special Precautions

Renal or hepatic impairment. Inherited deficiency of thiopurine methyltransferase. Resistance to tioguanine therapy in Lesch-Nyhan syndrome. Monitor haemoglobin concentration, haematocrit, total WBC count, differential count and platelet count at least once a wk or more frequently during therapy. Discontinue treatment temporarily at first signs of unusually large decrease in leukocytes, platelets or haemoglobin. Resume therapy if leukocyte or platelet count increases or stays at an acceptable level for 2-3 days. Withhold therapy if there is worsening of LFT, jaundice, hepatomegaly, anorexia with tenderness in the right hypochondrium, or if there is evidence of toxic hepatitis, biliary stasis or severe bone marrow depression. Not recommended for maintenance therapy or long-term continuous treatments due to hepatotoxicity.

How to Use

Take orally with food and water, as directed by your physician.

How to Store

Keep in a cool, dry place away from sunlight and moisture.

Safety Concerns

• Alcohol: Avoid during treatment.
• Breastfeeding: Not recommended.
• Pregnancy: Contraindicated.
• Liver/Kidney: Use with caution.

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