HPLC/MS研究国产盐酸班布特罗片及其代谢物特布他林人体生物等效性

目的研究国产班布特罗片剂和进口片剂进行人体生物等效性研究。方法20名健康受试者随机交叉给药,用液相色谱/质谱联用测定血浆中班布特罗其代谢物特布他林的浓度。结果经数据处理,单次口服国产和进口班布特罗片剂后班布特罗的药代动力学参数:AUC_0-t分别为(52±21)μg·h·L^-1和(51±20)μg·h·L^-1,T_max分别为(2.9±0.9)h和(2.6±0.7)h,C_max分别为(6.0±2.6)μg·L^-1和(6.2±2.9)μg·L^-1。特布他林:AUC_0-t分别为(191±30)μg·h·L^-1和(197±37)μg·h·L^-1,T_max分别为(4.2±1.0)h和(4.2±1.0)h,C_max分别为(10±5)μg·L^-1和(10±4)μg·L^-1。国产班布特罗片剂单次给药后的相对生物利用度为102%±8%(班布特罗),100%±12%(特布他林)。结论经统计学证明两制剂有生物等效性。     

伏立康唑胶囊人体药动学及相对生物利用度研究

目的 研究健康受试者口服伏立康唑胶囊的药动学和相对生物利用度。方法 20名健康受试者随机服用伏立康唑受试胶囊剂和参比片剂各100 mg,用HPLC-MS/MS测定血浆中伏立康唑的浓度。结果 主要药动学参数,伏立康唑受试制剂与参比制剂的T_max分别为(0.75±0.15)和(0.84±0.25)h,C_max分别为(605.4±136.6)和(595.2±134.7)ng·mL^-1;t_1/2分别为(4.91±1.44)和(5.06±2.06)h,AUC_0-15分别为(1737.6±325.1)和(1750.6±352.8)ng·h·mL^-1。受试制剂与参比制剂的AUC_0-15和C_max经双单侧t检验,T_max经非参数检验,差异均无统计学意义。结论 统计学结果表明,2种制剂生物等效。     

家犬单剂量和多剂量口服阿昔莫司缓释制剂的药代动力学和生物等效性研究

目的研究阿昔莫司缓释片在家犬体内单剂量和多剂量的药代动力学和生物等效性。方法测定6只家犬单剂量和多剂量口服缓释片和普通胶囊后的血药浓度。结果阿昔莫司的药-时曲线符合非隔室模型。单剂量给药后，缓释片和普通胶囊的AUC分别为(158±30)和(147±37) μg·h·mL^-1；T_max分别为(4.3±0.8)和(2.6±1.3) h；C_max分别为(29±6)和(42±10) μg·mL^-1；T_1/2分别为(2.3±0.7)和(1.60±0.10) h；MRT分别为(6.0±0.8)和(3.9±0.7) h；F_r为(108±16)%。多剂量给药后，缓释片和普通胶囊的AUC分别为(209±23)和(195±26) μg·h·mL^-1；T_max分别为(6.3±0.8)和(3.4±1.5) h；C_max分别为(27±4)和(36±5) μg·mL^-1；Cmin分别为(2.2±1.0)和(0.20±0.20) μg·mL^-1；C_av分别为(8.7±1.0)和(8.1±1.1) μg·mL^-1；FI分别为(293±73)%和(448±91)%；F_r为(114±19)%。结论单剂量实验的双单侧检验结果表明：缓释片和普通胶囊生物等效；缓释片具有良好的缓释效果。多剂量实验结果表明：缓释片和普通胶囊生物等效；缓释片的波动系数优于普通胶囊。     

高效毛细管电泳法研究盐酸班布特罗国产胶囊与进口片剂的人体生物等效性高效毛细管电泳法研究盐酸班布特罗国产胶囊与进口片剂的人体生物等效性

目的研究国产盐酸班布特罗胶囊和进口片剂的人体生物等效性。方法采用高效毛细管电泳法测定血浆中班布特罗及其代谢物特布他林的浓度。结果单次口服国产班布特罗胶囊和进口班布特罗片剂后班布特罗的药代动力学参数:AUC0-t分别为(71±18)和(72±13) μg·h·L^-1,实测C_max分别为(8.1±1.8)和(9.2±2.3) μg·L^-1,实测t_max分别为(3.6±1.3)和(3.7±1.0) h。特布他林药代动力学参数:AUC0-t分别为(129±33)和(130±34) μg·h·L^-1,实测C_max分别为(7.8±2.3)和(8.5±2.9) μg·L^-1,实测t_max分别为(5.4±0.8)和(5.6±1.1) h,国产班布特罗胶囊单次给药后的相对生物利用度为(100±16)%(班布特罗),(101±13)%(特布他林)。结论经统计学证明两制剂具有生物等效性。     

乳酸左氧氟沙星分散片健康人体生物等效性研究

目的对乳酸左氧氟沙星分散片和左氧氟沙星片进行生物利用度比较,判定两种制剂是否为等效制剂。方法20名男性健康受试者随机交叉给药,分别口服单剂量乳酸左氧氟沙星分散片(试验制剂)及乳酸左氧氟沙星片(参比制剂)200mg,采用HPLC法测定血药浓度,计算两者的药动学参数及相对生物利用度,并求证两种制剂的生物等效性。结果口服200mg试验制剂或参比制剂的主要药动学参数t_1/2β分别为(5.68±1.79)和(5.38±1.52)h;t_max分别为(0.84±0.79)和(0.95±0.47)h;c_max分别为(2.27±0.47)和(2.26±0.58)μg·mL^-1;AUC_0～t分别为(14.90±2.14)和(15.62±2.49)μg·mL^-1.h;AUC_0～∞分别为(15.17±2.34)和(15.87±2.67)μg·mL^-1.h。试验制剂对于参比制剂的平均相对生物利用度F值:AUC_0～t为(97.23±17.71)%,AUC_0～∞为(97.43±17.76)%。两种制剂的AUC_0～t,AUC_0～∞及c_max经对数转换后双单侧t检验,结果接受两种制剂生物等效的假设。C_max的90%置信区间结果为88.1%～117.3%,AUC_0～t为89.2%～102.5%,AUC_0～∞为89.3%～102.9%,t_max经秩和检验无显著性差异。整个试验期间,受试者均未发生药物不良反应。结论按照生物等效性判定标准,可判定两种制剂生物等效。     

两种国产格列齐特片人体生物利用度的研究

目的 比较两种格列齐特片的生物等效性。方法 用HPLC法测定血浆中格列齐特浓度,研究8名受试者口服两种国产片剂的药动学和生物利用度,并用方差分析和双单侧检验及90%可信限考察生物等效性。结果 8名受试者口服单剂量格列齐特片的药动学参数,试验品的t_max3.38±0.52h,C_max19.91±3.61μg·ml^-1,t_1/26.52±2.40h,AUC 278.86±94.74μg·h·ml^-1;对照品的t_max3.38±0.52h,C_max17.59±3.13μg·ml^-1,t_1/27.77±3.34h,AUC 300.94±87.49μg·h·ml^-1,相对生物利用度为92.46±10.47%。结论 两种片剂经统计分析,C_max的90%可信区间在79.1～99.6%,AUC的可信区间在105.8%～107.4%,这两种片剂完全生物等效。     

LC-MS/MS法测定人血浆中辛伐他汀的浓度及相对生物利用度

目的 建立人体血浆中辛伐他汀的LC-MS/MS测定方法,研究辛伐他汀片在男性健康志愿者体内的药代动力学行为,评价其生物利用度和生物等效性。方法 20名健康成年男性志愿者采用随机分组自身交叉对照试验设计,单剂量口服辛伐他汀片40 mg后,用LC-MS/MS联用法测定血浆中药物浓度。结果 试验制剂和参比制剂的主要药代动力学参数:t_max分别为(1.8±1.3)h和(2.10±1.00)h;c_max分别为(7.12±1.61)μg·L^-1和(7.38±1.54)μg·L^-1;AUC_(0-24)分别为(30.50±11.25)μg·L^-1·h^-1和(30.17±10.21)μg·L^-1·h^-1;t_1/2分别为(3.90±0.78)h和(3.76±0.85)h。以AUC_(0-24)计算的试验制剂的相对生物利用度为101.2%±7.8%。结论 建立的分析方法准确灵敏,测得的数据可靠,统计学分析表明两种制剂生物等效。     

他克莫司缓释胶囊在Beagle犬体内的药动学与生物等效性研究

目的 研究他克莫司片在beagle犬体内的药动学和生物等效性。方法 采用随机自身交叉对照实验,将6例beagle犬按照先参比制剂后受试制剂、先受试制剂后参比制剂2种给药序列进行随机分配,每组3例,每个周期单次口服3 mg参比制剂或受试制剂,用LC-MS/MS测定样品浓度,再采用WinNonlin 6.3版软件计算药动学参数,比较受试制剂和参比制剂的生物等效性。结果 受试制剂和参比制剂他克莫司药动学参数T_max分别为(1.08±0.41)h和(0.83±0.13)h,C_max分别为(11.63±1.35)ng·mL^-1和(14.83±4.70)ng·mL^-1,AUC_0-48分别为(62.93±32.06)h·ng·mL^-1和(62.89±28.14)h·ng·mL^-1,半衰期t_1/2分别为(10.90±4.26)h和(10.99±3.12)h。Beagle犬口服受试制剂后T_max,t_1/2在受试制剂和参比制剂间无明显差异;峰浓度C_max约为参比制剂给药后的85.34%,90%置信区间为87.21%~102.16%;相对生物利用度(AUC_last,受试/AUC_last,参比)为99.42%,90%置信区间为85.53%~115.56%,表明受试制剂和参比制剂较接近。结论 他克莫司缓释胶囊受试制剂和参比制剂具有生物等效性。     

氟康唑片在健康人体的药物动力学和生物等效性研究

摘 要 目的:研究氟康唑片在健康人体的药物动力学并评价其生物等效性。方法: 采用双周期自身随机交叉试验设计。20名健康男性志愿者分别单剂量口服受试制剂和参比制剂200 mg,以非那西丁为内标,采用HPLC法测定血药浓度。用DAS软件计算药动学参数和进行统计分析。结果:单次口服受试制剂和参比制剂200 mg后的主要药动学参数：t_max（1.08±0.44）和（1.35±0.76）h,C_max（5.40±0.60）和（5.37±0.72）μg·ml^-1,t_1/2(29.1±3.4)和（29.0±3.5）h,AUC_（0-t）（191.3±13.8）和(190.4±15.7) μg·h·ml^-1,AUC_(0-∞)(204.0±17.5) 和（202. 4±18.1）μg·h·ml^-1,MRT（34.7±1.7）和（34.0±1.9）h,以AUC_（0-t）计算,受试制剂的相对生物利用度为100.9%±6.8%。结论:两种氟康唑片剂具有生物等效性。     

硫酸沙丁胺醇渗透泵控释片的人体药代动力学与生物利用度

目的:研究自制硫酸沙丁胺醇渗透泵控释片与进口控释片的人体药代动力学与生物利用度。方法:利用高效液相色谱荧光检测法,采用交叉实验设计对本品和进口硫酸沙丁胺醇控释片进行人体生物利用度对照研究。结果:硫酸沙丁胺醇控释片与进口硫酸沙丁胺醇控释片的血药浓度曲线下面积AUC 分别为(63.67 ±10.37)ng·h·mL^-1和(60.21 ±11.95) ng·h·mL^-1,最大血药浓度C_max 分别为(8.60 ±1.93) ng·mL^-1 和(8.20 ±1.40)ng·mL^-1,达峰时间T_max 分别为(6.3 ±1.0) h 和(6.8 ±1.3) h,多剂量给药达稳态时血药浓度波动系数FD 分别为1.09 ±0.23 和1.14±0.25。结论:经方差分析和双单侧检验,两种制剂生物等效。     

罗红霉素片剂生物利用度的比较研究

为比较不同剂型罗红霉素的生物利用度,用微生物管碟检定法(藤黄微球菌CMCC(B)28001)测定了10名男性健康受试者口服罗红霉素分散片(制剂A)和罗红霉素片(制剂B)后不同时间血浆中活性药物的浓度,绘制了血药浓度—时间曲线。结果表明,受试者交叉口服含罗红霉素150mg的制剂A和制剂B后,血浆T_max分别为1.7±0.9和3.7±1.6h,C_max分别为4.97±1.17和2.04±1.26μg·ml^-1,AUC_0→∞分别为62.2±11.9和35.0±16.9μg·h·ml^-1。以制剂A为参比,制剂B中罗红霉素的相对生物利用度仅为59.8%±32.6%,两种制剂的药物吸收程度有显著差异(P<0.01)。初步分析提示,罗红霉素在胃中的迅速溶出是保证其片剂生物利用度的关键之一。     

Relative bioavailability of a commercial trifluoperazine tablet formulation using a radioimmunoassay technique

The relative bioavailability of a new conventional tablet formulation (5 mg) of trifluoperazine dihydrochloride was studied in 24 healthy volunteers. Using a sensitive radioimmunoassay technique, plasma trifluoperazine concentrations were measured up until 24 h following ingestion of single 5-mg doses of trifluoperazine. The mean +/- SD for the peak concentration (Cmax), time to Cmax, area under the curve from 0 to 24 h (AUC240), and terminal elimination half-life following the administration of the test formulation were 2.15 +/- 1.07 ng/mL, 4.10 +/- 1.38 h, 21.04 +/- 11.92 ng X h/mL, and 9.5 +/- 7 h, respectively. Following the ingestion of the original trifluoperazine tablet formulation (5 mg) these same parameters were estimated to be 1.92 +/- 0.88 ng/mL, 4.02 +/- 1.10 h, 18.03 +/- 10.11 ng X h/mL, and 9.3 +/- 7 h, respectively. Large intersubject variations in Cmax and AUC240 were observed. The relative bioavailability of the test formulation was calculated to be 106.5 +/- 25.5%.     

利用生物粘附技术提高萘哌地尔的生物利用度

目的为提高萘哌地尔生物利用度,制备生物粘附性萘哌地尔胶囊。方法制备萘哌地尔胶囊、生物粘附胶囊I和II;比较两种生物粘附性胶囊与大鼠离体胃肠组织的粘附力;用自身对照方式单剂量分别给予家犬3种胶囊200mg,比较3种胶囊在家犬体内的药物动力学与生物利用度。结果与普通胶囊相比,生物粘附性萘哌地尔胶囊I和II在家犬体内的血药峰浓度(C_max)下降,达峰时间(T_max)延迟,药时曲线下面积(AUC_0→∞)明显增加,两者为生物不等效制剂,与普通胶囊相比,萘哌地尔粘附胶囊I与II的生物利用度分别为150%±14%和154%±23%,两种生物粘附胶囊的药动学参数间无明显差异。结论利用生物粘附技术能明显提高萘哌地尔的生物利用度。     

Single dose absorption profiles and bioavailability of two different salbutamol tablets

In a single dose cross-over experiment in twelve healthy adults a comparison of the absorption profiles and the relative bioavailability was made between a new salbutamol containing tablet (preparation A = Salbutax) and a commercially available and accepted formulation as reference (preparation B), both containing 4 mg salbutamol. Salbutamol plasma concentrations were measured frequently during a period of 16 h post dosing. Maximum salbutamol plasma concentrations after intake of product A and product B on an empty stomach were reached after 2.3 +/- 0.9 (= mean +/- S.D.) and 2.4 +/- 1.1 h, respectively, and accounted for 14.3 +/- 2.5 and 12.8 +/- 2.6 micrograms X l-1, respectively. The differences were not found to be significant (p greater than 0.05). The areas under the plasma concentration-time curves (AUC0----16), as obtained after administration of tablet A and tablet B, accounted for 73.5 +/- 14.0 and 65.0 +/- 11.8 micrograms X l-1 X h, respectively, the difference being marginally significant (p = 0.05). This results in a relative bioavailability of 114.3 +/- 15.7% for the product A 4-mg tablets. It is concluded that both products can be considered as having comparable bioavailability.     

2种司帕沙星胶囊人体生物利用度与生物等效性研究

目的:比较2种司帕沙星胶囊的人体药动学参数、生物利用度,评价二者的生物等效性。方法:22名男性健康志愿者随机交叉单剂量口服200mg受试制剂或参比制剂后,应用高效液相色谱法测定血浆中司帕沙星浓度,并利用3p97程序计算药动学参数及评价二者生物等效性。结果:受试制剂与参比制剂体内药-时曲线符合二室模型,Cm ax分别为(0.85±0.23)、(0.90±0.27)μg.mL-1,tm ax分别为(5.59±2.28)、(4.95±1.17)h,AUC0~120分别为(27.92±6.09)、(29.65±8.49)μg.h.mL-1,AUC0~∞分别为(29.95±6.51)、(31.74±9.38)μg.h.mL-1。受试制剂相对生物利用度为(97.47±18.32)%。结论:受试制剂与参比制剂具有生物等效性。     

Pharmacokinetics of methylphenidate after oral administration of two modified-release formulations in healthy adults

OBJECTIVE: To compare the rate and extent of absorption of DL-threo-methylphenidate (MPH) from two modified-release MPH formulations at their respective recommended starting doses in healthy adult volunteers. DESIGN: Open-label, randomised, crossover, bioavailability study. PARTICIPANTS: Twenty healthy adult male and female volunteers. METHODS: Subjects received single doses of two modified-release formulations of MPH, a 20mg capsule (Ritalin) LA) and an 18 mg tablet (Concerta). A total of 19 plasma samples was collected over 24 hours, and MPH plasma concentrations were determined by liquid chromatography-mass spectrometry (LC-MS/MS). These values were used to calculate standard noncompartmental pharmacokinetic parameters describing the rate (peak concentration and time to peak concentration) and extent (area under the concentration-time curve, AUC) of absorption of the two formulations. The relative bioavailability of the two drugs was assessed using a 90% confidence interval, based on the lower and upper endpoints of the confidence interval for the ratios of the geometric means (log transformed) being within the 0.80-1.25 equivalence criterion. RESULTS: Nineteen subjects, ten male and nine female, aged 21-34 years completed both treatment phases of the study. The Ritalin LA formulation displayed a distinctly biphasic pharmacokinetic profile, with mean initial peak plasma concentration of 7 microg/L at an average of 2.1 hours after administration and a second peak of 9.3 microg/L occurring at 5.6 hours. In contrast, the profile of the Concerta formulation rapidly reached an initial plateau concentration of 3.4 microg/L at 3.3 hours after administration and a second mean plateau concentration of 5.9 microg/L approximately 6 hours after administration. Substantially more MPH was absorbed from Ritalin LA than from Concert over the first 4 hours; the respective AUC(4) values were 18.5 and 9.3 microg x h/L (p < 0.001). The overall extent of absorption of MPH was similar between the two formulations. Oral clearance was identical between the two dosage forms. CONCLUSIONS: The Ritalin LA formulation exhibited more rapid initial absorption and reached significantly higher peak plasma concentrations compared with the Concerta formulation, although the oral bioavailability of MPH was similar between the two formulations. The Ritalin LA capsule demonstrated a distinctly bimodal plasma concentration-time profile. MPH plasma concentrations resulting from Concerta reached a peak at 6 hours. These results indicate that the recommended starting dose of the Ritalin LA 20 mg capsule formulation provides more rapid absorption and higher peak plasma concentrations than the recommended 18 mg starting dose of the Concerta formulation.     

Influence of food on the bioavailability of theophylline from a sustained-released theophylline preparation.

In a single-dose cross-over study with 12 healthy male volunteers the relative bioavailability of theophylline (CAS 58-55-9) in a dosage of 700 mg (sustained-release preparation) under fasting- and non-fasting conditions was investigated. The areas under the plasma concentration-time curves AUC amounted to 184.2 +/- 42.7 micrograms.h/ml (fasting) and 157.9 +/- 32.9 micrograms.h/ml (non-fasting, p = 0.031). The bioavailability was reduced by approx. 15% by concomitant food intake. The 95% confidence intervals for AUC and Cmax were 76-99% and 78-105%, respectively, and therefore narrowly outside the usual 80-120% limits. There were no therapeutically relevant changes with regard to the parameters Cmax, tmax and MRT. The MRT values of 13.4 and 13.9 h respectively showed furthermore that theophylline represents a twice-daily formulation. No "dose-dumping effect" was observed.     

Relative bioavailability of a new oral form of cyclosporin A in patients with rheumatoid arthritis.

The relative bioavailability of cyclosporin A (CsA) from a new microemulsion oral formulation (NEO) and the currently used soft gelatine capsule (SGC) was determined at steady state in 12 patients with rheumatoid arthritis. The AUC(0,12 h) values of cyclosporin A were significantly greater after NEO than SGC (2873 +/- 848 ng ml-1 h (mean +/- s.d.) vs 2355 +/- 1128 ng ml-1 h; P = 0.02, 95% CI (confidence interval of the difference: 81 to 955 ng ml-1 h). Cmax values were significantly higher after NEO than after SGC (811 +/- 244 ng ml-1 vs 495 +/- 291 ng ml-1, P < 0.0001, 95% CI of the difference: 209 to 422 ng ml-1).     

Lack of bioequivalence between different formulations of isosorbide dinitrate and hydralazine and the fixed-dose combination of isosorbide dinitrate/hydralazine: the V-HeFT paradox

OBJECTIVE: To investigate whether the apparent discrepancy between the efficacy of the combination of isosorbide dinitrate (ISDN) and hydralazine demonstrated in the first V-HeFT trial (V-HeFT I) and that in V-HeFT II could be explained by pharmacokinetic differences in the study drug formulations, and to compare the pharmacokinetic profile of the fixed-dose combination of ISDN/hydralazine (FDC ISDN/HYD; BiDil) formulation used in A-HeFT with that of the V-HeFT study drug formulations. STUDY PARTICIPANTS AND METHODS: A bioequivalence study was performed (n = 18-19 per group) comparing the ISDN and hydralazine formulations used in V-HeFT I, V-HeFT II and A-HeFT in healthy volunteer men and women aged 18-40 years. In phase A of the study, subjects received a reference solution of hydralazine hydrochloride/ISDN (37.5mg/10mg) orally. Slow acetylators were identified and randomised into three groups in phase B to receive a single oral dose of identical amounts of hydralazine hydrochloride/ISDN (37.5mg/10mg) from either (i) a hydralazine capsule plus an ISDN tablet (the V-HeFT I formulation); (ii) a hydralazine tablet plus an ISDN tablet (the V-HeFT II formulation); or (iii) FDC ISDN/HYD (the A-HeFT formulation). Blood/plasma concentrations of hydralazine and ISDN were determined from the blood samples taken between 0 and 36 hours. RESULTS: In phase B, the maximum observed concentrations (C(max)) were 65.9 +/- 53.9, 28.2 +/- 15.8 and 51.5 +/- 54.3 ng/mL of unchanged hydralazine, and 23.1 +/- 12.3, 21.7 +/- 13.4 and 26.7 +/- 18.7 ng/mL of ISDN for the V-HeFT I, V-HeFT II and A-HeFT formulations, respectively. The area under the blood/plasma concentration-time curve (AUC) values were 32.6 +/- 13.4, 23.3 +/- 15.1 and 32.6 +/- 18.5 ng x h/mL of hydralazine, and 24.4 +/- 9.0, 24.8 +/- 8.0 and 23.5 +/- 6.3 ng x h/mL of ISDN for the V-HeFT I, V-HeFT II and A-HeFT formulations, respectively. For comparison of bioequivalence, the C(max) and AUC were normalised to 65kg bodyweight, and point estimates and 90% confidence intervals of the C(max) ratios, AUC ratios and ratios of the AUC in phase B normalised for clearance by the AUC in phase A (AUCR) were calculated. The three formulations were not bioequivalent based on the C(max) and AUC comparisons. CONCLUSIONS: The blood concentrations of hydralazine obtained with the tablet formulation tested in V-HeFT II were markedly lower than those obtained with the capsule formulation tested in V-HeFT I or the FDC ISDN/HYD single tablet used in A-HeFT. The apparently modest effect on survival observed in V-HeFT II could be explained in part by the poor hydralazine bioavailability of the tablet preparation used in this trial. ISDN exposures were similar in the two trials. The ISDN-hydralazine formulation used in V-HeFT II was not bioequivalent to the formulation used in V-HeFT I or to the FDC ISDN/HYD that had demonstrated a significant survival benefit in A-HeFT.     

Pharmacokinetics and bioequivalence study of clindamycin hydrochloride formulations after single-dose administration in healthy Chinese male volunteers

The aim of the present study was to compare the bioavailability of clindamycin (CAS 18323-44-9) from three clindamycin hydrochloride (CAS 21 462-39-5) capsules (clindamycin 75 mg capsule as test 1 preparation, 150 mg capsule as test 2 preparation and a commercially available original 150 mg capsule of the drug as reference preparation) in 24 Chinese healthy male volunteers, aged between 22 and 28. The study was conducted according to a randomized, double-blind, 3-period, 3-treatment, 3-sequence, single-dose, crossover design with a wash-out phase of 7 days. Blood samples for pharmacokinetic profiling were taken up to 14 h post-dose, and clindamycin plasma concentrations were determined with a validated liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method. Maximum plasma concentrations (C(max)) of 3.06 +/- 1.10 microg/mL (test 1), 3.10 +/- 1.59 microg/mL (test 2) and 3.06 +/- 1.15 microg/mL (reference) were achieved. Areas under the plasma concentration-time curve (AUC(0-infinity)) of 10.73 +/- 4.29 microg x h/mL (test 1), 10.54 +/- 4.10 microg x h/ mL (test 2) and 11.29 +/- 4.98 microg x h/mL (reference), AUC(0-t) of 10.32 +/- 4.09 microg x h/ mL, 10.26 +/- 3.96 microg x h/mL, 10.94 +/- 4.86 g x h/mL were calculated. The median T(max) was 0.80 +/- 0.52 h, 0.77 +/- 0.37 h, 1.01 +/- 0.6 h for test 1, test 2 and reference formulation, respectively. Plasma elimination half-lives (t1/2) of 2.72 +/- 0.58 h (test 1), 2.39 +/- 0.37 h (test 2) and 2.63 +/- 0.66 h (reference) were determined. Both primary target parameters, AUC(0-infinity) and AUC(0-t) were tested parametrically by analysis of variance (ANOVA) and relative bioavailabilities were 98.0 +/- 16.2% (test 1) and 97.2 +/- 20.3% (test 2) for AUC(0-infinity), 97.5 +/- 16.3% (test 1) and 97.8 +/- 20.2% (test 2) for AUC(0-t). Bioequivalence between test and reference preparation was demonstrated for both parameters, AUC(0-infinity) and AUC(0-t). The 90% confidence intervals of the T/R-ratios of logarithmically transformed data were in the generally accepted range of 80%-125%. That means that the two test formulations are bioequivalent to the reference formulation for clindamycin.