What is the role of alkylating agents in the treatment of frequently relapsing nephrotic syndrome (FRNS)?

Updated: Mar 04, 2020
  • Author: Jerome C Lane, MD; Chief Editor: Craig B Langman, MD  more...
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Cyclophosphamide (CYP) is the predominant alkylating agent used in the treatment of FRNS and SDNS. CYP offers the benefit of possible sustained remission after a defined course of treatment, although with the possible risk of infertility and other adverse effects.

In a Cochrane meta-analysis, CYP was found to have significantly reduced the risk of relapse at 6-12 months and 12-24 months compared with steroid treatment alone. [69]

CYP (2 mg/kg daily) is given orally for 8-12 weeks. An early study found that a 12-week course was more effective than an 8-week course in producing sustained remission of nephrotic syndrome. [70] However, a subsequent randomized trial did not reach the same conclusion, [71]  and a Cochrane report found no benefit to extending the duration of CYP treatment beyond 8 weeks. Intravenous CYP, given monthly for 6 months, was as effective at 1 year as oral CYP in the Cochrane report. [72]

A meta-analysis reported remission rates following treatment with CYP to be 72% after 2 years and 36% after 5 years for patients with FRNS, and 40% and 24%, respectively, for those with SDNS. [73]

Patients treated with CYP must have weekly complete blood cell counts to monitor for leukopenia. Patients must also maintain adequate hydration and take CYP in the morning (not at bedtime) to limit the risk of hemorrhagic cystitis. Families must be counseled to report gross hematuria, fever, or severe illness.

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