Background: Pediatric patients with steroid-resistant nephrotic syndrome (SRNS) and focal
segmental glomerulosclerosis (FSGS) may relapse and current second line agents include
mycophenolate mofetil. However, there is no current information about the use of the
sodium salt of mycophenolic acid (SMPA) in this population.
Objectives: We conducted a prospective study on the efficacy and pharmacokinetics of
SMPA in children with FSGS.
Patients and Methods: Patients without NPHS2 pathogenic variants received SMPA at
dosages between 460 to 720 mg/m2/d for 12 months after previous treatments failure.
Clinical and biochemical assessments were performed. Blood samples were obtained after
the first dose and at steady state (3 months after the onset of treatment) and total and free
mycophenolic acid (MPA) was quantitated using HPLC-UV.
Results: Two patients showed partial remission after the 12-month period of SMPA
treatment with a notable decrease in proteinuria and an increase in serum albumin levels.
Maximum MPA concentrations after the first dose and at steady state were 11.6 µg/mL
and 10.5 µg/mL, respectively, without drug accumulation. Maximum MPA free levels
after the first dose and at steady state were 192.9 and 120.6 ng/mL, respectively. MPA
levels became undetectable after 4 hours of the administration in all cases.
Conclusions: SMPA is a promising agent for pediatric patients with SRNS and FSGS but
SMPA schedule of treatment should be revised with shorter intervals of administration
and higher doses than those used in the present study in order to attain higher systemic
exposures and accumulation of the immunosuppressant drug. Further efficacy and
pharmacokinetic studies should be performed to confirm these findings.