lc-ms method for studying the pharmacokinetics and bioequivalence of clonidine hydrochloride in healthy male volunteers

background: a simple and sensitive high performance liquid chromatography-electrospray ionization mass spectrometry method has been evaluated for the assignment of clonidine hydrochloride in human plasma. methods: the mobile phase composed of acetonitrile-water 60:40 (v/v) and 0.2% formic acid 20 µl of sample was chromatographically analyzed using a repacked zorbax-xdb-ods c18 column (2.1 mmx30 mm, 3.5 μ). detection of analytes was achieved by tandem mass spectrometry with electrospray ionization (esi) interface in positive ion mode operated under the multiple-reaction monitoring mode (m/z 230.0 →213). sample pretreatment consisted of a one-step protein precipitation (ppt) with methanol and perchloric acid (hclo4) of 0.10 ml plasma. results: standard curve was linear (r=0.998) over the concentration range of 0.01-10.0 ng/ml and showed suitable accuracy and precision. the limit of quantification (loq) was 0.01 ng/ml. the mean (sd) cmax, tmax, auc0–t and auc0–∞ values after administration of the test and reference formulations, respectively, were in this manner: 6.16 (0.32) versus 6.21 (0.07) ng/ml, 30.12 (0.86) versus 30.13 (0.73) hr, 290.37 (1.13) versus 293.39 (1.22) ng/ml/hr, and 350.17 (1.98) versus 352.96 (1.67) ng/ml/hr. the mean (sd) t1/2 was 120.12 (1.90) hr for the test formulation and 120.96 (1.54) hr for the reference formulation. no statistical differences were showed for cmax and the area under the plasma concentration-time curve for test and reference tablets. conclusion: the method is rapid, simple, very steady and precise for the separation, assignment, pharmacokinetic and bioavailability evaluation of clonidine in healthy iranian adult male volunteers.