During high-dose methotrexate therapy the aim is to clear the drug efficiently while protecting normal cells, using leucovorin rescue and supportive measures like IV hydration to reduce toxicity. A medication that can dramatically raise methotrexate toxicity is trimethoprim-sulfamethoxazole, known as Bactrim. It can interfere with how methotrexate is cleared by the kidneys and add to folate pathway disruption, increasing the risk of serious side effects such as bone marrow suppression, mucositis, and nephrotoxicity. Because of this, Bactrim should be stopped during high-dose methotrexate treatment. The other options fit into the supportive management rather than raising toxicity. Granisetron is an antiemetic used to prevent chemotherapy-induced nausea and does not impair methotrexate clearance. Leucovorin is given after high-dose methotrexate to rescue normal cells from toxicity and should not be discontinued. IV hydration supports kidney clearance of methotrexate and should be continued to prevent drug precipitation in the kidneys.

Leukemia in children most often presents with signs of bone marrow failure and infiltration, so symptoms like bone pain from marrow expansion, pallor from anemia, and bleeding or easy bruising from low platelets are common initial clues. Jaundice, however, points to liver involvement or hemolysis, which is not a typical presenting feature of childhood leukemia. While jaundice can occur if the liver is affected or if there are other concurrent issues, it is not the usual first sign the disease presents with.

Nephrotoxicity from cisplatin is the main late effect you need to watch for. Cisplatin damages the cells of the renal tubules and glomeruli, which can reduce kidney filtration and disrupt electrolyte balance. Because of this, monitoring should focus on kidney function and electrolytes: baseline and periodic serum creatinine and BUN, estimated GFR, urine output, and electrolytes such as magnesium and potassium. Maintaining good hydration around treatment and adjusting the dose if kidney function declines are key protective steps; in some regimens a nephroprotective strategy may be used. Other potential toxicities you might hear about with different drugs (like cerebellar dysfunction, pulmonary fibrosis, or Cardiomyopathy) are not the primary late effects of cisplatin, though they can occur with other chemotherapies.

Vesicant extravasation management centers on rapidly limiting tissue exposure to the drug and starting the appropriate antidote as soon as possible. The immediate step is to stop the infusion right away. If possible, leave the cannula in place and attempt to aspirate any residual vesicant from the tissue through the cannula; this helps reduce further spread. Do not push more fluid through the cannula to flush the drug, as that can drive it deeper into tissue. After aspiration, remove the cannula when no additional drug can be retrieved or per local protocol. Apply the antidote specified for the drug involved (drug-specific antidotes may include dexrazoxane for anthracyclines, hyaluronidase for certain agents), and provide local care accordingly. Elevate the limb and use the appropriate temperature therapy (cold or warm compress) as directed by the agent’s guidelines, since different vesicants respond to different treatments. Continuous monitoring for evolving pain, swelling, or necrosis is essential, with escalation of care as needed.