How can the trimethoprim in the Aspen Co-Trimoxazole 40 mg/200 mg per 5 ml Paediatric Suspension product affect creatinine measurements using the alkaline picrate reaction?

Trimethoprim in the Aspen Co-Trimoxazole 40 mg/200 mg per 5 ml Paediatric Suspension product may cause approximately 10% overestimation of serum/plasma creatinine using the alkaline picrate reaction, while functional inhibition of renal tubular creatinine secretion may cause a spurious fall in estimated creatinine clearance.