A simple, reproducible and efficient dual separation mode high performance
liquid chromatographic (HPLC) method was developed for simultaneous
determination of antihypertensive drug combinations including;
hydrochlorothiazide (HCTZ), valsartan (VAL), amiloride (AML) and captopril
(CAP). The newly developed PlatinumTM column, which provides a dual-mode
separation with its polar and non-polar sites, was used for rapid separation of
these co-administered drugs. Good resolution was obtained when PlatinumTM
column was used compared with C18 column. Additionally, simple
isocraticmodewith mobile phase containing methanol and 0.02 mole L-1 phosphate
buffer adjusted to pH 3.0 (45:55, v/v) was used for separation. The flow rate was
0.5mLmin-1 and effluent was monitored at 270 nm. All the investigated drugs
were completely separated within less than 6 min. The linearity range obtained
for the developed HPLC method was 0.5–100 μgmL-1 with detection limits of
0.13–1.2 μgmL-1 for all the studied drugs. The method was validated in
accordance with the requirements of ICH guidelines and shown to be suitable for
-2-
intended applications. The method was successfully used for determination of the
studied drugs in pure form and pharmaceutical dosage forms without prior need
for separation. The method is valuable for quality control laboratories for
simultaneous determination of these co-administered antihypertensive drugs in
binary, ternary and quaternary mixtures.