A 70-kg client with symptomatic acquired methemoglobinemia after dapsone exposure has an authorized methylene blue dose of 1 mg/kg IV. The vial contains 5 mg/mL. Complete the calculation.
Drop-down Cloze
Choose your responses, then check the answer.
Explanation
The dose is 70 mg and the volume is 14 mL. Before administration, the nurse must confirm G6PD and serotonergic-medication risks and patent IV access.
Quick answer Prepare 70 mg, or 14 mL, after the safety screen.
Why this is correct One milligram per kilogram for 70 kg equals 70 mg. At 5 mg/mL, 70 mg divided by 5 mg/mL equals 14 mL. Methylene blue can cause hemolysis in G6PD deficiency and serious serotonin toxicity with serotonergic drugs and opioids.
Easy analogy or mental picture Calculate the antidote, then check the two locked doors: G6PD and serotonergic exposure.
Memory hook 1 mg/kg; divide milligrams by 5 mg/mL.
NCLEX decision rule Calculation accuracy does not replace contraindication and interaction screening.
Why the other choices are wrong Pulse oximetry alone can be misleading in methemoglobinemia, and an empiric repeat dose should not be given without reassessment.
References
1DailyMed: Dapsone GelMethemoglobinemia warning and cyanosis recognition
2DailyMed: Methylene Blue Injection1 mg/kg dose, 5 mg/mL concentration, G6PD and serotonergic safety warnings