| 1. Development of dipyridamole compound sustained - release tablets analysis methodA method has been developed for determination of dipyridamole and aspirin. An RP-HPLC method has been carried out on a Diamonsil C18 column with UV detection at 275 nm. The mobile phase was methanol-0.05 mol·L-1 potassium dihydrogen phosphate buffer (52: 48) which a flow rate of 1.0 mL·min-1. The content of Aspirin and Dipyridamole was calculated by internal standardization method. There was a good linear relationship for Aspirin within the range of 6～16μg'mL(-1) ( r=0.9999 ). The average recovery of low, middle and high content was (101.4±1.1)%, (97.1±1.3)% and (94.2±1.5)% (n=3), respectively. There was a good linear relationship for Dipyridamole within the range of 20～120μg'mL-1 ( r=0.9998 ). The average recovery of low, middle and high content was (98.6±2.3)%, (99.0±1.6)% and (101.4±2.3)% (n=3), respectively. The method is simple, specific and not interfered by excipients. A new method for limit of free salicylic acid has been developed. The content of free salicylic acid was less than 1.5 % of aspirin content.2. The pharmacokinetics of dipyridamole and aspirin in miceA HPLC-UV method has been established for determination of dipyridamole and salicylic acid concentration in whole blood and tissues of mice. A Diamonsil C18 (200×4.6 ram, 5μm) column with a mobile phase composed of methanol-0.05 mol·L-1 potassium dihydrogen phosphate buffer (52: 48) was used in separation. The detection wavelength was 237nm and the flow rate was 0.9mL'min-1. The biological samples were analysed after sedimentate albumen, and the concentration of dipyridamole and salicylic acid were calculated by calibration curve accompanied. There were good linear relationships for dipyridamole and salicylic acid in whole blood within the range of 0.1～20.0μg'mL-1. The intra-day and inter-day precision of QC samples were less than 15%, respectively. The recovery of extraction RSD was less than 10%, respectively. There were good linear relationships for dipyridamole and salicylic acid in liver within the range of 1.0～200.0μg'g-1. The intra-day and inter-day precision of QC samples were less than 15%, respectively. The recovery of extraction RSD was less than 10%, respectively. After a i. g. administration of dipyridamole and aspirin to mice in low, middle and high doses respectively, dipyridamole had a maximal whole blood concentration between 0.25～1h, and had a linear corelation between Cmax, AUC0-t and dose(P＜0.1). The ratio of Cmax and dose had insignificant difference after variance analysis(P＞0.05). The ratio of AUC0-t and dose had insignificant difference after variance analysis(P＞0.05). Salicylic acid had a maximal whole blood concentration between 0.25～1h, and had a linear corelation between Cmax, AUC0-t and dose( P＜0.05). The ratio of Cmax and dose had insignificant difference after variance analysis(P＞0.05). The ratio of AUC0-t and dose had insignificant difference after variance analysis(P＞0.05).Dipyridamole distributed in tissues rapidly after absorbed into blood. The maximal concentration in every tissue achieved at stomach, spleen, liver, small intestine, lung, kidney and heart in turn, which were linearity with dose except spleen and heart. The T1/2 in tissues were not longer than that in blood, which showed that Dipyridamole was not accumulated in tissues. The ratio of AUC0-t in tissues and AUC0-t in plasma indicated that distribution in stomach was the widest and in brain least, Dipyridamole was uneasy to pass the blood-brain barrier.Salicylic acid distributed in tissues rapidly after absorbed into blood. The maximal concentration in every tissue achieved at small intestine, stomach, kidney, liver, spleen, lung, brain and heart in turn, which were linearity with dose except brain and small intestine. The T1/2 in tissues were longer than that in blood. The ratio of AUC0-t in tissues and AUC0-t in plasma indicated that distribution in stomach was the widest. Salicylic acid was easy to pass the blood-brain barrier.3. The pharmacokinetics and bioequivalence of dipyridamole compound sustainedrelease tablets in humanHPLC-UV methods have been established for determination of dipyridamole and salicylic acid concentration in human plasma. There was good linear relationships for dipyridamole in plasma within the range of 0.01-4.0μg'mL-1. There was good linear relationships for salicylic acid in plasma within the range of 0.01～2.0μg'mL-1. The intra-day and inter-day precision of dipyridamole and salicylic acid QC samples were less than 15%, respectively. The recovery of extraction were all more than 60%. The recovery of extraction RSD was less than 10%, respectively.A single oral dose and multiple oral doses of 200mg dipyridamole and 25mg aspirin test or reference preparations were given to 18 healthy volunteers in a randomized cross-over design. Main pharmacokinetic parameters were as following. After a single dose of test and reference preparation, dipyridamole: Tmax were (3.89±0.47), (1.69±0.42) h; Cmax were (1.27±0.33), (2.1z±0.75)μg-mL-1; t1/2 were (8.40±1.92), (4.784±1.13) h; AUC0-t were (7.89±2.70), (8.36±3.41)μg·h·mL-1; AUC0-∞ were (8.994±3.12), (8.564±3.50)μag·h·mL-1, respectively; salicylic acid: Tmax were (2.11±0.53), (4.78±0.81) h; Cmax were (0.97±0.47), (0.95±0.48)μg-mL-1; t1/2were (4.224±0.68), (5.464±1.09) h; AUC0-twere (4.064±1.65), (3.98±1.73)μg·h·mL-1; AUC0-∞ were (4.13±1.65), (4.15±1.79)μg·h·mL-1, respectively. After multiple doses, dipyridamole- Tmax were (3.94±0.80), (1.90±0.58) h; Cssmax were (1.23±0.38), (1.31±0.32)μg·mL-1; AUCss were (7.48±2.72), (7.73±2.62)μg·h·mL-1, respectively. After a single dose, relative bioavailability of dipyridamole and salicylic acid were (97.2±16.7)% and (103.1±9.8)%, respecrively; after multiple doses, relative bioavailability of dipyridamole was (96.7±13.4)%. Test and reference formulations are bioequivalent.Key words: dipyridamole compound sustained - release tablets; aspirin; dipyridamole; salicylic acid; pharmacokinetics... |
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