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  1. Allopurinol and its metabolite alloxanthine (oxypurinol) both are active and both are competitive inhibitors of xanthine oxidase.
  2. Allopurinol does not inhibit the metabolism of 6-Thioguanine but it does inhibit the metablism of 6-Mercaptopurine, Azathioprine and Theophylline since the metablism of the latter three depends upon the enzyme xanthine oxidase.
  3. Allopurinol is indicated in the following category of chronic gout patients, over producers of uric acid, under excretors of uric acid, those with tophi and/or renal urate stones.
  4. Tophi are a symptom of gout. Tophus (plural: tophi) happens when crystals of the compound known as sodium urate monohydrate or uric acid builds up around the joints. Tophi often look like swollen, bulbous growths on the joints just under the skin.
  5. Allopurinol has a therapeutic effect in radiotherapy induced hyperuricaemia, hydrochlorothiazide induced hyperuricaemia and Kala-azar but no therapeutic effect in acute gouty arthritis.
  6. Visceral leishmaniasis (VL) also known as kala azar is the most severe form of leishmaniasis. 
  7. Kala-azar is a chronic and potentially fatal parasitic disease of the viscera (the internal organs, particularly the liver, spleen, bone marrow and lymph nodes) due to infection by the parasite called Leishmania donovani.
  8. Toxoids are toxins whose pathogenic potential is negated while they still retains their immunogenic potential which makes them capable of to be used as vaccines.
  9. Endotoxins are found in the cell wall of Gram-negative bacteria and exotoxins are molecules that some bacteria make internally and secrete to the outside. Endotoxins and exotoxins are released when a bacterium lyses.
  10. Endotoxin is extremely heat-stable and thus autoclaving and boiling will not destroy all the endotoxin present. However, exotoxins are heat-labile and are autoclavable.