Comparative bioavailability of josamycin,a macrolide antibiotic,from a tablet and solution and the influence of dissolution on in vivo release

The bioavailability of josamycin from a tablet formulation (2 × Josacine® 500 mg tablets) was investigated and compared with the bioavailability of a solution (containing 1 g drug and buffered at pH 4.0) following administration to six healthy human volunteers. Bioavailability profiles for the solution indicated that the drug was inherently rapidly absorbed with a mean C_max of 1.64±0.67 mg L⁻¹ attained at a mean t_max of 0.39±0.08 h. The AUC_0–last was 1.510±0.687 mg h L⁻¹. Bioavailability was significantly lower from the tablets than from the solution. Highly variable serum concentration–time profiles were obtained from the tablets and C_max values ranged from 0.05 to 0.71 mg L⁻¹ with a t_max range of 0.33–2.0 h. AUC_0–last values ranged from 0.03 to 0.95 mg h L⁻¹. Dissolution of josamycin from the tablets was generally unaffected at low pH (pH 1.2–5.0), but, rather, limited predominantly by tablet disintegration. However, dissolution was increasingly limited as the pH increased from 5.0 to 9.0. Besides poor disintegration, the particularly low intrinsic dissolution rate and solubility of josamycin at these pH values is likely to further reduce the dissolution rate. Comparison of the solution and tablet serum concentration–time profiles suggests that the absorption of josamycin from the tablets was dissolution rate limited. This is supported by the in vitro dissolution–pH topogram, which suggests that dissolution will be particularly rate limiting if dissolution of whole or parts of tablets occurs in gastro-intestinal fluid above pH 5.0. © 1998 John Wiley & Sons, Ltd.     

盐酸普萘洛尔缓释片与常释片的生物利用度比较研究

目的：通过双交叉试验证明盐酸普萘洛尔缓释片有缓释作用。方法：用HPLC方法,测定血清中普萘洛尔浓度,进行盐酸普萘洛尔缓释片与常释片的生物利用度比较及峰谷浓度波动研究。结果：12位健康男性受试者一次交叉口服缓释片和常释片(均为40 mg)后的C_max分别为62.4±23.3和95.9±12.6 ng.mL^-1,AUC分别为360.2±80.6和383.5±74.2 ng.h.mL^-1,缓释片相对于常释片的相对生物利用度为95%;12位受试者连续服缓释片和常释片后平均稳态浓度分别为42.2±12.2和32.7±7.1 ng.mL^-1,波动度(DF)分别为0.90±0.35和2.09±0.34。结论：两种制剂具生物等效性,且缓释片比常释片有峰谷浓度差异小、血药浓度波动幅度小的特点。     

尼莫地平口腔崩解片的药动学及相对生物利用度研究

目的研究尼莫地平口腔崩解片在人体内的药动学,比较其与市售尼莫地平片人体内药物动力学及相对生物利用度。方法将6名健康志愿者随机分成两组,交叉单剂量口服尼莫地平口腔崩解片A和市售片B各60 mg,采用HPLC法测定血浆中尼莫地平的浓度。结果口服尼莫地平口腔崩解片A和市售片B后,主要药代动力学参数分别为Cmax(256.23±54.64)g/ml、(102.415±36.96)g/ml;Tmax分别为(0.7049±0.035)h、(1.3317±0.123)h;T1/2分别为(0.2734±0.031)h、(1.1958±0.141)h;AUC0-t分别为(622.77±98.03)g/(ml.h)、(354.63±96.24)g/(ml.h)。尼莫地平口腔崩解片A相对于市售片B的人体生物利用度为177.27%。结论自制尼莫地平口崩片速释效果明显,并能提高生物利用度。     

THE EFFECT OF FOOD ON THE BIOAVAILABILITY OF IBUPROFEN AND FLURBIPROFEN FROM SUSTAINED RELEASE FORMULATIONS

The effect of food on the plasma concentration–time profile of sustained release dosage forms of ibuprofen and flurbiprofen has been investigated in healthy Asian Indian volunteers, in two separate studies. In study 1, 20 volunteers were administered a single 200 mg multiple-unit sustained release capsule of flurbiprofen (Froben SR^™), after an overnight fast or a heavy vegetarian breakfast. Food produced a statistically significant increase in the mean (±SE) maximal plasma concentration (C_max ) and area under the plasma concentration–time curve (AUC_0–48 . C_max (±SE) increased from 9·88± 0·48 mg L⁻¹ (fasting) to 11·36±0·88 mg L⁻¹ (postprandial) and AUC_0–48 (±SE) increased from 120·78±9·64 mg h L⁻¹ (fasting) to 149·73±12·24 mg h L⁻¹ (postprandial). The mean (±SE) time to peak (t_max ) was also significantly delayed from 3·85±0·27 h to 8·70±0·89 h. In study 2, 18 volunteers were administered a single 800 mg erodible sustained release matrix tablet of ibuprofen (Brufen Retard^™), after an overnight fast or along with a heavy vegetarian breakfast. The formulation exhibited multiple peaks (n≥2) on the plasma concentration–time curve. Although food did not affect the bioavailability of this formulation, there was a statistically significant increase in the mean (±SE) concentration of the first peak (C_peak1 ) from 14·21±1·38 mg L⁻¹ (fasting) to 20·14±1·38 mg L⁻¹ (with food). The time at which C_peak1 was reached was not influenced by the intake of food. Results indicate that while qualitative changes in the plasma concentration versus time curves are primarily influenced by the nature of the formulation and the type of meal, bioavailability is influenced by the absorption characteristics of the drug as well. Thus, despite a significant increase in peak plasma concentrations of both drugs with a meal, the bioavailability of flurbiprofen alone was enhanced.     

Lack of bioequivalence of a generic mefloquine tablet with the standard product

Objective: To assess the bioequivalence between a generic tablet of mefloquine (Mephaquin^®?= M1) with the reference tablet (Lariam^®?=?M2) in healthy volunteers. Methods: This open label, randomized two-way cross-over study was performed in a single centre. Following an overnight fast, eighteen healthy volunteers received a single oral dose of 750?mg mefloquine either in the form of three M1 lactabs or three M2 tablets. Serial blood samples were collected up to 8 weeks after drug administration. Plasma samples were analysed for mefloquine and its carboxylic acid metabolite using liquid chromatography and subsequent tandem mass spectrometry (LC-MS/MS). The pharmacokinetic parameters of mefloquine and its metabolite were estimated by non-compartmental methods. Results: The pharmacokinetics of mefloquine after administration of M1 and M2 tablets were significantly different as reflected by the respective mean values of maximum plasma concentration (C_max 656 vs 1018?ng?·?ml^?1), time to reach maximum concentration (t_max 46 vs 13?h) and area under the plasma concentration-time curve (AUC_0→∞ 338 vs 432?μg?·?h?·?ml^?1). No significant differences existed between the elimination half-lives of the two formulations (394 vs 396?h). The relative bioavailability (M1 vs M2) was 0.78 and ranged from 0.38 to 1.37. Bioequivalence could not be demonstrated for log-transformed data of AUC_0→∞ or AUC_0→last within a predefined range of 80–125% and for C_max within a range of 70–143%. Conclusions: The observed differences in C_max, t_max and AUC are consistent with a slower rate and lower extent of mefloquine absorption after administration of M1. Statistical evaluation of these kinetic data showed that the M1 tablet is not bioequivalent to the M2 tablet. Clinical consequences of this finding cannot be excluded.     

Disposition and bioavailability of the β1-adrenoceptor antagonist talinolol in man

In an open randomized crossover study, the pharmacokinetics and bioavailability of the selective β₁-adrenoceptor antagonist talinolol (Cordanum®—Arzneimittelwerk Dresden GmbH, Germany) were investigated in twelve healthy volunteers (five female, seven male; three poor and nine extensive metabolizers of the debrisoquine hydroxylation phenotype) after intravenous infusion (30 mg) and oral administration (50 mg), respectively. Concentrations of talinolol and its metabolites were measured in serum and urine by HPLC or GC-MS. At the end of infusion a peak serum concentration (C_max) of 631 ± 95 ng mL^?1 (mean ± SD) was observed. The area under the serum concentration-time curve from zero to infinity (AUC_0-∞) was 1433 ± 153 ng h mL^?1. The following parameters were estimated: terminal elimination half life (t_1/2), 10.6 ± 3.3 h; mean residence time, 11.6 ± 3.1 h; volume of distribution, 3.3 ± 0.5 L kg^?1; and total body clearance, 4.9 ± 0.6 mL min^?1 kg^?1. Within 36 h 52.8 ± 10.6% of the administered dose was recovered as unchanged talinolol and 0.33 ± 0.18% as hydroxylated talinolol metabolites in urine. After oral administration a C_max of 168 ± 67 ng mL^?1 was reached after 3.2 ± 0.8h. The AUC_0-∞ was 1321 ± 382 ng h mL^?1. The t_1/2 was 11.9 ± 2.4 h. 28.1 ± 6.8% of the dose or 55.0 ± 11.0% of the bioavailable talinolol was eliminated as unchanged talinolol and 0.26 ± 0.17% of the dose as hydroxylated metabolites by kidney. The absolute bioavailability of talinolol was 55 ± 15% (95% confidence interval, 36–69%). Talinolol does not undergo a relevant first-pass metabolism, and its reduced bioavailability results from incomplete absorption. Talinolol disposition is not found to be altered in poor metabolizers of debrisoquine type.     

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。     

酮洛芬缓释片与常释片在健康受试者的药代动力学及生物利用度

目的:酮洛芬缓释片与常释片单次给药的生物利用度和多次给药的峰谷浓度波动大小。方法:采用以萘普生(naproxen)为内标的HPLC测定方法,测定健康男性受试者按交叉试验单剂量和多剂量服用酮洛芬缓释片和常释片后的血中酮洛芬浓度。结果:单剂量服用酮洛芬缓释片和常释片后,常释片的Cmax显著高于缓释片(P<0.01),缓释片给药后的Tmax延迟,t_1/2ke显著延长,相对生物利用度为97.13%。缓释片在稳态时的C_min为0.401μg·mL^-1,而常释片为0.190μg·mL^-1(P<0.01)。在稳态时缓释片的峰谷浓度波动度(DF)、峰谷比(PTR)都显著小于常释片,说明缓释片的峰谷浓度波动程度优于常释片。结论:经统计学检验表明这两种制剂具有生物等效性,该缓释片具有峰谷浓度差异小,波动幅度小的特点,显示出缓释特征。     

Disposition and clinical pharmacokinetics of theophylline after administration of a new sustained release tablet

Summary The systemic disposition of theophylline after taking a new, sustained release tablet (Theolair Retard^® 250 mg, Theolair S. R.^®, Riker Laboratories) has been studied in 8 hospitalized patients. Absolute bioavailability was determined from the ratios of the areas under the serum concentration-time curves after intake of the tablet and after intravenous infusion of aminophylline in the same patient. The absolute bioavailability of Theolair Retard^® 250 mg was 110.9±20.8% (mean ± SD). Maximal serum concentrations were reached after 7.3±3.5 h, the large intersubject variation being due to differences in gastric emptying time. The tablets appear to release theophylline slowly in acid conditions, but more rapidly in an alkaline medium. Invasion was found to be either monophasic with a rate constant of about 0.8 h^–1 (intestine), or biphasic with rate constants of 0.2 h^–1 (stomach) and 0.8 h^–1 (intestine). The peak levels accounted for 7.9±2.2 mg · 1^–1. The profiles of the serum concentration-time curves were such that the concentrations remained above 80% of c^max for 6.5±3.3 h. The relevant pharmacokinetic parameters (half-life of elimination, total body clearance and volume of distribution) were determined and were used to calculate the individual dosage regimens required to obtain therapeutic serum concentrations. The optimal dosing interval to obtain an average steady state serum concentration of 12.5 mg · l^–1 was 9.8±3.1 h.     

Bioavailability of methotrexate tablets

The bioavailability of methotrexate 10 mg tablets has been determined to be 62±16%. After administration of a dose of 30 mg/m² a maximum plasma concentration of ca. 20. 10^?7 mole/l was found after ca. 1.7 h. The methotrexate plasma half-life was 2.4 h. It was concluded that the 10 mg tablet formulation at the dosage investigated is a suitable clinical methotrexate preparation.     

Absorption kinetics of oral and rectal flecainide in healthy subjects

Summary The absorption kinetics of different pharmaceutical formulations of orally and rectally administered flecainide have been assessed in a cross-over study in 7 healthy volunteers. The subjects received single doses of flecainide after a washout period of at least one week. A tablet, an oral solution, a rectal solution and a 10 min i.v. infusion during 10 min each containing 100 mg flecainide were administered to the subjects in a randomized order.The mean absolute bioavailability was 98%, 78% and 81% for the rectal and oral solutions and the tablet. The lag time after administration of the oral solution was 0.33 h and it was 0.86 h after the tablet and 0.18 h after the rectal solution. The mean time to the peak serum concentration (t_max) after the rectal solution (0.67 h) was shorter than after either the tablet (4 h) or oral solution (1 h). The maximum serum concentration (C_max) was 0.29 mg · 1^–1 after the rectal solution, 0.14 mg · 1^–1 after the tablet and 0.17 mg · 1^–1 after the oral solution. All the volunteers showed significantly higher serum flecainide concentrations during the first 20 min of the absorption phase after rectal administration of 100 mg flecainide as a solution compared to its oral administration.In conclusion: based on the absolute bioavailability, C_max, t_max, and lag times, rectal administration of flecainide solution gave a better absorption profile than after oral tablet or solution.     

硫酸沙丁胺醇微球缓释片的制备及初步药动学研究

目的 探讨硫酸沙丁胺醇微球缓释片的制备方法,并对微球缓释片在家犬体内的药动学进行初步研究。方法 运用喷雾干燥法制备硫酸沙丁胺醇缓释微球,直接压片得到硫酸沙丁胺醇微球缓释片。对微球缓释片和市售普通片进行家犬体内单剂量给药实验,建立了血药浓度测定的高效液相色谱法。结果 普通片和微球缓释片的药动学参数Cmax分别为（155.1±3.4）和（126.7±1.9）ng·mL^-1;Tmax分别为（1.5±0.6）和（4.1±0.8）h;t1/2分别为（4.12±0.93）和（5.73±0.64）h,相对生物利用度为109.7%。结论 硫酸沙丁胺醇微球缓释片具有缓释效果。     

Bioequivalence study of two enalapril maleate tablet formulations in healthy male volunteers Pharmacokinetic versus pharmacodynamic approach

Objective: Two different conventional release enalapril maleate tablet formulations were evaluated for their relative bioavailability (Eupressin tablets 10 mg, Biosintética as the test formulation vs Renitec tablets 10 mg Merck Sharp & Dhome, as the reference formulation). A single 20 mg oral dose of each preparation was administered to 18 healthy male adult volunteers and their bioequivalence was assessed by comparing the serum enalaprilat and total enalapril (enalaprilat plus enalapril maleate) concentration-time curves. Angiotensin converting enzyme (ACE) activity was also quantified in each serum sample. Results: The pharmacokinetic parameters obtained for each formulation were the area under the time-concentration curve from 0 to 24 h (AUC_[0–24]), maximum concentration C_max and the time at which it occurred (t_max). When serum enalaprilat concentration-time curves were employed to assess bioequivalence, the formulations were bioequivalent in the extent but not in the rate of absorption. However, no difference in either the extent or the rate of absorption were observed when serum total enalapril vs time curves were analysed. ACE activity-time curves were similar for both formulations and showed that ACE was 90% inhibited 3–5 h after enalapril administration, and till approximately 50% after 24 h. At that time, circulating enalaprilat and total enalapril levels were less than the tenth of C_max. Conclusion: The results show that complete bioequivalence of the two formulations can be concluded from serum total enalapril concentration data, and that serum ACE activity is not a suitable pharmacodynamic variable for assessing bioequivalence. Received: 29 May 1995/Accepted in revised form: 30 October 1995     

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。     

Absorption of effervescent paracetamol tablets relative to ordinary paracetamol tablets in healthy volunteers

Objectives: The aim of this study was to compare the rate of absorption between ordinary paracetamol tablets and effervescent paracetamol tablets. Methods: Twenty healthy volunteers participated in an open randomised crossover study and were given a 1000-mg dose of either ordinary paracetamol tablets (2 × 500 mg Panodil tablets, SmithKline Beecham) or effervescent paracetamol tablets (2 × 500 mg Pinex Brusetablett, Alpharma AS) with a 3-week washout period in between. Blood samples were collected for 3 h. Maximum serum concentration (C_max) and the time to maximum serum concentration (t_max) were recorded and the area under the concentration versus time curve (AUC) was calculated. Results: The mean t_max was significantly shorter when paracetamol effervescent tablets were taken (27 min) rather than ordinary paracetamol tablets (45 min) (P=0.004). There was no significant difference between the mean C_max of 143 μmol/l with effervescent tablets and that of 131 μmol/l with ordinary tablets. The mean AUC_0–3 h was significantly higher with paracetamol effervescent tablets (223.8 μmol · h · l⁻¹) than with ordinary tablets (198.2 μmol · h · l⁻¹; P=0.003). After 15 min, 17 (85%) subjects in the effervescent group had a serum concentration of 70 μmol/l (lower therapeutic serum concentration) or higher relative to only 2 (10%) subjects in the ordinary tablet group (P=0.001). Conclusion: Paracetamol effervescent tablets are absorbed significantly faster than ordinary paracetamol. Thus, effervescent tablets might offer significantly faster pain relief when paracetamol is used. Received: 4 October 1999 ;/ Accepted in revised form: 15 February 2000     

Bioequivalence study of nabumetone tablets in man

A nabumetone tablet in development (Nabuton^R) was tested for its bioequivalence to the reference tablet (Uniton^R). Seventeen healthy Korean male subjects participated in this study. Each subject received a 1-g dose of nabumetone (2 tablets each) in an unbalanced, randomized, two-way crossover investigation. Serum concentrations of 6-methoxy-2-naphthylacetic acid (6-MNA), a major metabolite of nabumetone, were measured over 120 hr interval by a high-performance liquid chromatography. The maximum serum concentration (C_max) and time to reach the maximum concentration (T_max) were read directly, but area under the serum concentration time curve from time 0 to 120 hr (AUC) and mean residence time (MRT) of 6-MNA were calculated from the serum 6-MNA concentration-time curves. The serum curves showed multiple peaks of 6-MNA in most subjects, and the C_max and T_max were read from the highest serum peaks. Calculated bioavailability parameters for test and reference tablets were 1498.6∶1377.9 μg·hr/ml for AUC; 25.2∶23.1 μg/ml for C_max; 11.8∶16.4 hr for T_max and 42.6∶43.8 hr for MRT, respectively. The pairedt-test revealed no significant differences in all the parameters between the two tablets. Analysis of variance (ANOVA) revealed no significant differences between groups and formulations in all the parameters (C_max, T_max, AUC and MRT) indicating the crossover design of the experiment was properly performed. But significant differences (p<0.05) between subject/groups and periods were found for all the parameters indicating substantial intersubject and interperiodic variations for these parameters.     

Pharmacokinetics and haemodynamic effects of ISDN following different dosage forms and routes of administration

The pharmacokinetics and haemodynamic effects of isosorbide dinitrate (ISDN) have been investigated following administration of single doses as a sublingual (SL) spray (2.5 mg), sublingual tablet (5 mg) and peroral tablet (10 mg) in a randomised, placebo-controlled double-blind cross-over trial in 16 healthy volunteers.After the sublingual spray C_max was higher (39.0 ng·ml^-1) and t_max was shorter (3.9 min) than after the sublingual (22.8 ng·ml^-1 and 13.8 min) and peroral (16.9 ng·ml^-1 and 25.6 min) tablets. The AUC of ISDN did not differ following any of the three formulations (1031; 879; 997 ng·ml^-1·min, for the spray, SL tablet and PO-tablet, respectively). Mononitrate metabolites of ISDN (IS-2-MN and IS-5-MN) and total nitrates in plasma increased in proportion to the administered dose. This indicates that the fraction of the dose absorbed was the same for all the formulations but that the extent of first-pass metabolism increased in the order sublingual spray < sublingual tablet < peroral tablet. Thus, compared to the spray, the relative bioavailability of ISDN was 48% and 28% from the sublingual and peroral tablets, respectively.The haemodynamic effects were quantified using the a/b ratio of the finger pulse wave and the systolic blood pressure and heart rate under orthostatic conditions. For the a/b ratio of the finger pulse, the maximal effect was higher (e_max=130%) and the time to e_max (t_emax) shorter (16.6 min) after the spray than the sublingual tablet (84.4% and 25.5 min) or peroral tablet (90.2 and 31.3 min). The onset of effect was within 3, 5 and 7.5 min after the spray, sublingual and peroral tablets, respectively. A larger change in the orthostatically-induced decrease in systolic blood pressure and increase in heart rate was obtained following peroral than sublingual administration despite the similar plasma concentrations of ISDN. This probably reflects the larger amount of pharmacodynamically active mononitrate metabolites formed after oral dosing. The integrated effect following administration of 2.5 mg ISDN as spray was similar to that of a sublingual tablet of 5 mg.     

Repeated dose pharmacokinetics of pancopride in human volunteers

The aim of this study was to assess the pharmacokinetic profile of pancopride after repeated oral dose administration of 20 mg pancopride in tablet form once a day for 5 d in 12 healthy male volunteers. Plasma levels were measured by HPLC using a solid phase extraction method and automated injection. The minimum quantification limit of pancopride in plasma was 2 ng mL^?1. The maximum plasma concentration (mean ± SD) after the first dose was 92.5 ± 41.5 ng mL^?1 and t_max was 1.7 ± 0.9 h. The elimination half-life (t_1/2) was 14.3 ± 6.9 h. The area under the concentration-time curve from zero to infinity (AUC) was 997 ± 396 ng h mL^?1. The maximum plasma concentration (mean ± SD) at steady state (day 5) was 101.8 ± 36.9 ng mL^?1 and t_max was 2.2 ± 1.2 h. The elimination half-life (t_1/2) was 16.3 ± 2.7 h and the minimum plasma concentration (C) was 16.6 ± 6.9 ng mL^?1. The area under the concentration-time curve during the dosing interval (AUC) was 995 ± 389 ng h mL^?1. The average plasma concentration at steady state (C) was 43.3 ± 16.1 ng mL^?1 and the experimental accumulation ratio (R_AUC) was 1.34 ± 0.19, whereas the mean theoretical value (R) was 1.40 ± 0.29. The results obtained showed a good correlation between the experimental plasma levels and the expected values calculated using a repeated dose two-compartment model assessed by means of the Akaike value. It is concluded that the pharmacokinetics of pancopride are not modified after repeated dose administration. The safety parameters showed no clinically relevant alterations.     

Mucoadhesive bilayer buccal tablet of carvedilol-loaded chitosan microspheres: in vitro,pharmacokinetic and pharmacodynamic investigations

A multiple-unit system comprising mucoadhesive bilayer buccal tablets of carvedilol-loaded chitosan microspheres (CMs) was developed to improve bioavailability and therapeutic efficacy of carvedilol. Drug-loaded CMs were prepared by spray drying, evaluated for powder and particle characteristics, and optimized batch of CMs was compressed into bilayer buccal tablets using Carbopol. Tablets were evaluated for physicochemical parameters, in vitro drug release, in vivo pharmacokinetic and pharmacodynamic studies. Optimized formulation, CMT1 (CMT, chitosan microsphere tablet) showed maximum mucoadhesive force (50?±?1.84?dyne/cm²), exhibited 73.08?±?3.05% drug release and demonstrated zero-order kinetics with non-Fickian release mechanism. Pharmacokinetic studies in rabbits showed significantly higher C_max (71.26?±?6.45?ng/mL), AUC_0–10 (AUC, area under the curve 390.75?±?5.23?ng/mL/h) and AUC_0–∞ (664.72?ng/mL/h) than carvedilol oral tablet. Pharmacodynamic studies confirmed reduction in mean arterial pressure, heart rate, body weight and triglyceride on administration of bilayer buccal tablet compared to oral carvedilol tablet. Multiple-unit system exhibited enhanced bioavailability and sustained release of carvedilol, indicating its improved therapeutic potential for the treatment of hypertension.     

Pharmacokinetics and dose-dependency of LB30870 in rats, dogs, and monkeys

This study was to examine the pharmacokinetics of LB30870, a thrombin inhibitor, after IV and oral administration to rats, dogs, and monkeys. In rats and dogs, LB30870 showed linear pharmacokinetics after IV and oral administration. The oral bioavailability (BA) in rats was about 30 % with high inter-subject variability in the time to reach peak plasma concentration (T_max). Oral absorption of a solution and prototype tablet formulations of LB30870 were tested in dogs. T_max was 30 min and the BA values were 40.8–43.1 % with solution formulation. BA values after oral administration of the two tablet formulations at the dose of 100 mg/dog were 27.0 and 30.8 %. T_max were 60 min in the tablet formulation, indicating that the disintegration and dissolution of tablets caused delay in T_max compared to solution formulation. After IV administration of LB30870 to monkeys, the plasma concentrations decreased bi-exponentially and BA was 15.0 % after oral (20 mg/kg) dosing. In summary, linear pharmacokinetics of LB30870 were observed in both rats and dogs. The differences in BA among species could be due to difference in absorbed fraction and/or the first pass extraction (pre-systemic elimination) of LB30870.