Development and validation of an HPLC method involving solid-phase extraction for the analysis of hydrophobic drugs in the presence of polyamidoamine (PAMAM) dendrimers

Two rapid and accurate isocratic high performance liquid chromatographic (HPLC) methods of analysis for nifedipine and furosemide in the presence of poly-amidoamine (PAMAM) dendrimers is described. Solid-phase extraction (SPE) using C-18 extraction cartridges and methanol as the eluent, was used to extract the drugs from the dendrimer and dendrimer plasma solutions. For both drugs, chromatographic separation was performed with a 5 mu m, 250 x 4 mm, octadecyl silane (C18) column. In the first method, nifedipine was analyzed using methanol:water (2:1 v/v) as the mobile phase with a flow rate of 0.7 mL/min. The injection volume was 20 mu L with detection at 254 mn and a retention time of I I minutes. In the second method, furosemide was analyzed using water: acetonitrile: acetic acid (60:40:1 v/v) as the mobile phase with a flow rate of 1.0 mL/min, injection volume of 20 mu L, and detection at 272 urn. The retention time for furosemide was 8.5 minutes.