Cyclodextrin Micellar LC for Direct Selective Analysis of Combined Dosage Drugs in Urine.

Two cyclodextrin micellar liquid chromatographic methods were developed and applied to the simultaneous determination of bisoprolol/hydrochlorothiazide and atenolol/chlorthalidone combinations in urine matrices without sample pretreatment. These combined β-blockers and diuretics chemotherapies are commonly used in the treatment of hypertension and cardiovascular diseases. Hybrid isocratic mobile phases containing hydroxypropyl-β-cyclodextrin, sodium dodecyl sulfate, phosphate buffer and methanol on a Luna C18 column with 0.5 mL min(-1) flow rate and 25.0°C column temperature were used. The methods were sensitive enough for the determination of analytes at the therapeutic urine levels with limits of detections down to 1.0 µg mL(-1); relative standard deviations and recoveries were ranged between 1.5-4.4% and 98.00-109.52%, respectively. Urinary excretion studies showed that the detection of drugs is possible up to 24 h after their ingestion. The selective proposed separations with less consumption of organic solvents over the hitherto ones could be attributed to the four point competitive interactions among analysts, pseudostationary phases and a real stationary phase.