| Objective: To develop sensitive and specific LC-MS/MS methods for determination of nicotinic acid (NA), nicotinuric acid (NUA) and nicotin- amide (NAM) in human plasma and to study the clinical pharmacokinetics of nicotinic acid sustain release capsules.Method: To simultaneous determine nicotinic acid, nicotinuric acid and nicotinamide by a liquid chromatographic?tandem mass spectrometric method. NA, NUA, NAM and the internal standard, paracetamol, were isolated from 100μL plasma by protein precipitation with methanol, and then chromatographed on a Venusil ASB C18 column (150 mm×4.6 i.d., 5μm), using methanol?water?acetic acid?ammonia solution (30: 70: 0.02: 0.002, v/v/v/v) as the mobile phase. The detection was performed on a tandem mass spectrometer equipped with an atmospheric pressure chemical ionization source. Detection was performed by atmospheric pressure chemical ionization (APCI) in multiple reaction monitoring (MRM) mode using the transitions m/z 124→m/z 80 for NA, m/z 181→m/z 135 for NUA, m/z 123→m/z (78 + 80) for NAM and m/z 152→m/z 110 for paracetamol (internal standard).Result: Linear calibration curves of NA, NUA and NAM were obtained in the concentration ranges of 2.00?1000, 2.00?1000, and 15.0?1000 ng/mL, respectively. This method was successfully applied for the pharmacokinetic study of nicotinic acid sustained release capsules. Thirty volunteers received after a single oral dose of 500, 750, 1000 mg nicotinic acid. Maximal nicotinic acid plasma level was observed after (2.75±0.589) h, (2.65±1.16) h, (3.95±1.74) h, respectively; Cmax was (767±879)μg·L-1, (609±642)μg·L-1, (297±377)μg·L-1, respectively; T1/2 was (6.07±2.35) h, (8.43±4.40) h, (13.0±10.9) h, respectively; AUC(0-24 was (1677±1223)μg·h·L-1, (1195±572)μg·h·L-1, (628±358)μg·h·L-1, respectively; AUC0-∞ was (1751±1195)μg·h·L-1, (1301±572)μg·h·L-1, (796±352)μg·h·L-1. Maximal nicotinuric acid plasma level was observed after (2.70±0.675) h, (2.70±0.715) h, (3.10±0.966) h, respectively; Cmax was (1694±1201)μg·L-1, (1011±436)μg·L-1, (577±302)μg·L-1, respectively; T1/2 was (2.87±2.03) h, (2.87±1.29) h, (2.74±1.90) h, respectively; AUC(0-24 was (5722±4538)μg·h·L-1, (2743±1201)μg·h·L-1, (1403±655)μg·h·L-1, respectively; AUC0-∞ was (5748±4520)μg·h·L-1, (2754±1208)μg·h·L-1, (1413±661)μg·h·L-1. Maximal nicotinamide plasma level was observed after (4.65±0.709) h, (5.10±1.87) h, (5.70±2.08) h, respectively; Cmax was (513±225)μg·L-1, (302±98.0)μg·L-1, (223±58.8)μg·L-1, respectively; T1/2 was (6.69±4.26) h, (16.3±14.8) h, (8.05±5.52) h, respectively; AUC(0-24 was (4121±1621)μg·h·L-1, (2674±1133)μg·h·L-1, (1618±665)μg·h·L-1, respectively; AUC0-∞ was (4727±1631)μg·h·L-1, (4230±2251)μg·h·L-1, (1961±985)μg·h·L-1 respectively.Ten volunteers received after multiple oral dose of 1000 mg nicotinic acid. Maximal nicotinic acid plasma level was observed after (2.75±0.635) h, Cmax was (1901±1133)μg·L-1, T1/2 was (10.5±8.26) h, AUC(0-24 was (3470±1977)μg·h·L-1, AUC0-∞ was (3589±1958)μg·h·L-1, AUCss was (3329±1974)μg·h·L-1; Maximal nicotinruic acid plasma level was observed after (2.77±1.11) h, Cmax was (2052±929)μg·L-1, Tmax was (3.25±0.890) h, AUC(0-24 was (7205±4348)μg·h·L-1, AUC0-∞ was (7217±4353)μg·h·L-1, AUCss was (7131±4312)μg·h·L-1; Maximal nicotinamide plasma level was observed after (12.4±8.11) h, Cmax was (558±264)μg·L-1, Tmax was (4.85±1.55) h, AUC(0-24 was (6312±2884)μg·h·L-1, AUC0-∞ was (8772±3795)μg·h·L-1, AUCss was (4111±1963)μg·h·L-1.Conclusion: A sensitive, rapid and convenient LC?MS/MS method was developed and validated for determination of NA, NUA and NAM in human plasma. The method was proved suitable for the pharmacokinetic study of nicotinic acid sustained release capsules. |
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