This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nephrotic and Nephritic syndrome, Subject name: Medicine
A 7-year-old child has steroid dependent Nephrotic syndrome. His weight is 30 kg and height is106 cm. He is having truncal obesity with sub-capsular bilateral cataracts.Which is the best drug for this patient? 
Select and explain. 
A. Mycophenolate, B. Levamisole, C. Cyclophosphamide, D. Azathioprine
C: Cyclophosphamide
Answer: C: Cyclophosphamide 
Explanation: Steroid-dependent patients, frequent relapses, and steroid-resistant patients may be candidates for alternative agents, paicularly if the child suffers severe coicosteroid toxicity (cushingoid appearance, hypeension, cataracts, and/or growth failure). Cyclophosphamide prolongs the duration of remission and reduces the number of relapses in children with frequently relapsing and steroid-dependent nephrotic syndrome. The potential side effects of the drug (neutropenia, disseminated varicella, hemorrhagic cystitis, alopecia, sterility, increased risk of future malignancy) should be carefully reviewed with the family before initiating treatment. The dose of cyclophosphamide is 2-3 mg/kg/24 hr given as a single oral dose, for a total duration of 8-12 wk. Alternate-day prednisone therapy is often continued during the course of cyclophosphamide administration. During cyclophosphamide therapy, the white blood cell count must be monitored weekly and the drug should be withheld if the count falls below 5,000/mm3