Sildenafil is a selective inhibitor of cGMP-specific type 5 phosphodiesterase used for the treatment of pulmonary arterial hypertension (PAH) in the adults. In pediatrics, PAH treatment options include the off-label use of sildenafil. Sildenafil is metabolized in the liver by cytocrome P450 into its active metabolite, N-desmethyl sildenafil. The determination of plasma levels of sildenafil and N-desmethyl sildenafil could be useful for therapy optimization and pharmacokinetic studies. We have developed and validated a method for the quantification of sildenafil and its metabolite in plasma of children by rapid extraction, using high-performance liquid chromatography with ultraviolet detection. The calibration range was fitted at least square model (r2 ≥ 0.999), with an accuracy and an intra- and inter-day relative standard deviation <15% for both analytes. The mean recovery was 102.5% for sildenafil and 101.8% for N-desmethyl sildenafil. This simple method could be successfully used in children with PAH under treatment with sildenafil.
Keywords: HPLC; N-desmethyl sildenafil; PAH; sildenafil; stability.
Copyright © 2016 John Wiley & Sons, Ltd.