Simultaneous determination of dantrolene with ibuprofen and diclofenac in plasma by HPLC-DAD : application to comparative pharmacokinetic study

Muscle relaxants and pain killers with their different types are widely used as combination approach for treatment of pain associated with several muscle spasm conditions. A sensitive and simple HPLC-UV detection method was developed in this work for simultaneous assay of Dantrolene (DNT) and co-administrated: Ibuprofen (IBU) and Diclofenac (DIC). After simple protein precipitation, separation was achieved using C₁₈ column (150 × 4.6 mm) with a mobile phase of acidified water with orthophosphoric acid (pH = 3.5) and acetonitrile using gradient elution with a flow rate of 1 mL/min. The DAD was adjusted at 380, 219, 280 and 240 nm to measure DNT, IBU, DIC, and dexamethasone (internal standard), respectively. Linearity was demonstrated over the range from 0.1 to 3 μg/mL, 1 to 40 μg/mL, and 0.1 to 2 μg/mL for DNT, IBU, and DIC, respectively. The validated method was applied successfully to compare the effect of co-administration of IBU or DIC on the pharmacokinetic profile of DNT.