Absolute bioavailability of moxonidine

In a randomized 2-way cross-over study with eighteen healthy male volunteers, two moxonidine preparations (tablets, treatment A vs. intravenous solution, treatment B) were tested to investigate absolute bioavailability and pharmacokinetics of moxonidine. The preparations were administered as single doses of 0.2 mg; prior to and up to 24 h after administration blood samples were collected and the plasma moxonidine concentrations determined. Urine samples were collected prior to and at scheduled intervals up to 24 h after administration for the determination of unchanged moxonidine. Moxonidine plasma and urine concentrations were determined by a validated gas chromatographic/mass spectrometric method with negative ion chemical ionization. The mean areas under the plasma concentration/time curves were calculated as [mean +/- standard deviation] 3438 +/- 962 pg.h/ml (AUC(0----Tlast)) and 3674 +/- 1009 pg.h/ml (AUC(0----infinity)) for treatment A; 3855 +/- 1157 pg.h/ml (AUC(0----Tlast)) and 4198 +/- 1205 pg.h/ml (AUC(0----infinity)) for treatment B. Mean peak plasma concentrations of 1495 +/- 646 pg/ml were attained at 0.56 +/- 0.28 h after oral treatment, mean peak plasma concentrations after intravenous treatment reached 3965 +/- 1342 pg/ml at 0.17 +/- 0.01 h (= coinciding with end of infusion). The mean terminal half-lives of moxonidine were derived as 1.98 h after administration of the tablet and as 2.18 h after infusion. The amounts of moxonidine excreted in urine during the 24 h following administration (Ae(24h)) in absolute figures and as percentage of the dose administered were 102 +/- 26 micrograms or 51 +/- 13% for the tablet and 122 +/- 33 micrograms or 61 +/- 16% for the infusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pharmacokinetics of dihydroartemisinin in Artekin tablets for single and repeated dosing in Chinese healthy volunteers

Aim. To study the pharmacokinetics of dihydroartemisinin (DHA) in Artekin (compound dihydroartemisinin) tablets in Chinese healthy volunteers. Methods. Eighteen healthy volunteers (9 males, 9 females) received Artekin tablets for oral administration. The plasma samples of DHA were analysed by liquid-liquid extraction and determined by HPLC/ESI/MS. Results. The plasma DHA concentration-time curves of single dose and repeated doses of DHA were fitted to a two-compartment open model. The mean pharmacokinetic parameters of DHA in a single dose were: t(1/2(beta))=1.245 +/- 0.495 h, C(max)=243.6 +/- 56.15 microg/l, AUC(0 --> infinity)=450 +/- 69 h x microg/l, V(d)=5.75 +/- 2.2 l/kg and Cl=3.245 +/- 0.38 l/h/kg, while in repeated doses they were: t(1/2(beta))=1.085 +/- 0.298 h, AUC(0 --> infinity)=444.35 +/- 80.43 h x ng/ml, V(d)=4.62 +/- 1.128 ml/kg, Cl=3.0125 +/- 0.875 ml/h/kg, respectively. Conclusion. The study showed that DHA in Artekin was rapidly absorbed, distributed and eliminated in the healthy subjects. The pharmacokinetic properties of DHA in Artekin were not affected by gender in a single dose. While in repeated doses accumulation of DHA did not appear after repeated doses.     

Pharmacokinetics of dihydroergocristine and its major metabolite 8'-hydroxy-dihydroergocristine in human plasma

Dihydroergocristine (DHEC) is a semi-synthetic drug mainly used for age-related cognitive impairment. In this study, its major metabolite 8'-hydroxy-dihydroergocristine (8'-OH-DHEC) was produced in incubates of a bovine liver preparation using dihydroergocristine mesylate (DHECM) as substrate. Purification was achieved by flash silica gel column and reverse phase liquid chromatographies, and identification was based on accurate molecular mass measurements, mass fragmentation spectra and NMR ((1)H/(13)C) chemical shifts. By using the substance produced in vitro, a fast, sensitive, specific and robust LC/MS/MS method for the simultaneous determination of DHEC and its major metabolite in human plasma was developed and validated. Bromocriptine was used as internal standard and limits of quantification for DHEC and 8'-OH-DHEC were 10 pg/ml and 20 pg/ml, respectively. Pharmacokinetic parameters were investigated on 12 male healthy volunteers to whom a single dose of 18 mg DHECM was administered in tablets (Iskevert). The peak of DHEC was 0.28 +/- 0.22 microg/l, the t(max) 0.46 +/- 0.26 h, the AUC(last) 0.39 +/- 0.41 microg/l.h and the terminal elimination half-life 3.50 +/- 2.27 h. The peak of 8'-OH-DHEC was 5.63 +/- 3.34 microg/l, the t(max) 1.04 +/- 0.66 h, the AUC(last) 13.36 +/- 5.82 microg/l.h and the terminal elimination half-life 3.90 +/- 1.07 h. Dosing of 18 mg DHECM was well tolerated, causing no adverse events.     

Pharmacokinetic and bioequivalence study of meloxicam tablets in healthy male subjects

Meloxicam (CAS 71125-38-7), a non-steroidal anti-inflammatory drug (NSAID), is used for the treatment of osteoarthritis and rheumatic arthritis. In the present study, two different oral meloxicam formulations (Melcam 15 mg tablets as test preparation and tablets of a reference preparation) were investigated in 24 healthy male subjects in order to prove bioequivalence between both preparations. A single 15 mg oral dose was administered according to an open, randomised, two-period cross-over design in the fasted state. Blood samples for the determination of meloxicam plasma concentrations were collected at pre-defined time points up to 96 h following drug administration. A wash-out period of 7-8 days separated both treatment periods. Meloxicam plasma concentrations were determined by means of a validated HPLC method with UV-detection. Maximum plasma concentrations (C(max)) of 1,146.9 ng/ml (test) and 1,064.8 ng/ml (reference) were achieved. Areas under the plasma concentration-time curve (AUC(0-infinity) of 34,499.0 ng x h/ml (test) and 33,784.3 ng x h/ml (reference) were determined. The results showed nearly identical rate and extent of drug absorption. Also further pharmacokinetic parameters were well comparable. Thus, t(max) showed values of 5.00 h for both test and reference. The plasma elimination half-life (t1/2) was 18.29 h (test) und 18.94 h (reference). Both primary target parameters C(max). and AUC(0-infinity, were tested parametrically by analysis of variance (ANOVA) and the 90% confidence intervals were between 99.46%-105.24% (AUC0-infinity)) and 103.37%-112.46% (C(max)). Bioequivalence between test and reference preparation was demonstrated since for both parameters AUC and C(max) the 90% confidence intervals of the T/R ratios of logarithmically transformed data were in the generally accepted range of 80%-125%.     

Comparative pharmacokinetics of two tablet formulations of amoxicillin: bioequivalence assessment

The aim of the present study was to compare the bioavailability of amoxicillin (CAS 26787-78-0) from two different amoxicillin tablets (Demoksil 1 g tablet as test preparation and 1 g tablet of the originator product as reference preparation). The study was conducted according to an open-label, randomised two-period cross-over design with a wash-out phase of 4-7 days. Blood samples for pharmacokinetic profiling were taken up to 10 h post-dose, and amoxicillin plasma concentrations were determined with a validated LC-MS/ MS method. Maximum plasma concentrations (C(max)) of 13,296.4 ng/ml (test) and 12,797.7 ng/ml (reference) were achieved. Areas under the plasma concentration-time curve (AUC(0-infinity)) of 39,556.7 ng x h/ml (test) and 38,599.1 ng x h/ml (reference) were calculated. The median t(max) was 1.62 h (test) and 1.54 h (reference). Plasma elimination half-lives (t(1/2)) of 1.64 h (test) and 1.65 h (reference) were determined. Both primary target parameters, AUC(0-infinity) and C(max) were tested parametrically by analysis of variance (ANOVA) and the 90% confidence intervals were between 96.76%-108.46% (AUC(0-infinity)) and 97.80%-111.98% (C(max)). Bioequivalence between test and reference preparation was demonstrated since for both parameters, AUC and C(max) the 90% confidence intervals of the T/R-ratios of logarithmically transformed data were in the generally accepted range of 80%-125%.     

A simple high-performance liquid chromatographic method for the determination of acyclovir in human plasma and application to a pharmacokinetic study

A rapid, simple and sensitive reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the measurement of acyclovir (CAS 59277-89-3) concentrations in human plasma and its use in bioavailability studies is evaluated. The method was linear in the concentration range of 0.05-4.0 microg/ml. The lower limit of quantification (LLOQ) was 0.05 microg/ml in 0.5 ml plasma sample. The intra- and inter-day relative standard deviations across three validation runs over the entire concentration range were less than 8.2%. This method was successfully applied for the evaluation of pharmacokinetic profiles of acyclovir capsule in 19 healthy volunteers. The main pharmacokinetic parameters obtained were: AUC(o-t) 6.50 +/- 1.47 and 7.13 +/- 1.44 microg x h/ml, AUC(0-infinity) 6.77 +/- 1.48 and 7.41 +/- 1.49 microg x h/ml, C(max) 2.27 +/- 0.57 and 2.27 +/- 0.62 microg/ml, t(1/2) 2.96 +/- 0.41 and 2.88 +/- 0.33 h, t(max) 0.8 +/- 0.3 and 1.0 +/- 0.5 h for test and reference formulations, respectively. No statistical differences were observed for C(max) and the area under the plasma concentration--time curve for acyclovir. 90% confidence limits calculated for C(max) and AUC from zero to infinity (AUC(0-infinity)) of acyclovir were included in the bioequivalence range (0.8-1.25 for AUC).     

法莫替丁咀嚼片的人体生物等效性研究

目的 :比较法莫替丁咀嚼片、普通片的人体生物等效性。方法 :20名健康志愿受试者随机、交叉、单剂量口服法莫替丁咀嚼片和普通片 ,用高效液相色谱法测定血药浓度 ,以3p97计算机软件计算两种制剂的药动学参数并比较生物等效性。结果 :口服咀嚼片和普通片后 ,两者的体内药 -时曲线符合二室模型 ,Cmax 分别为 (156 30±105 63)、 (156 83±99 62)ng/ml ,Tmax 分别为(2 28±0 66)、(2 28±0 77)h ,AUC(0～24 ) 分别为 (857 55±517 39)、(912 94±638 17) (ng·h)/ml,咀嚼片的相对生物利用度为(93 93±14 49) %。结论 :经方差分析和单、双侧t检验 ,表明法莫替丁咀嚼片与普通片具有生物等效性     

Pharmacokinetics and comparative bioavailability of two terbinafine hydrochloride formulations after single-dose administration in Chinese healthy subjects

The bioavailability of a new terbinafine (CAS 91161-71-6) preparation was compared with a commercially available original preparation (reference) of the drug in 19 Chinese healthy male volunteers. The study was performed in an open, randomized, single blind two-sequence, two-period crossover design. Under fasting conditions, each subject received a single oral dose of 250 mg terbinafine as a test or reference formulation with a 7-day washout period between the two preparations. The plasma concentrations of terbinafine were analyzed by a sensitive liquid chromatography-ultraviolet spectrometry method. The pharmacokinetic parameters included AUC(0-t) AUC(0-infinity), C(max), t1/2, and T(max). The values of AUC(0-t) demonstrated nearly identical bioavailability of terbinafine from the examined formulations. The AUC(0.48) of terbinafine was 5982.85 +/- 2449.17 and 6761.63 +/- 3140.33 ng x h/ml for the test and reference formulation, respectively. The maximum plasma concentration (C(max)) of terbinafine was 1656.25 +/- 623.18 ng/ml for the test and 1552.07 +/- 660.35 ng/ml for the reference product, respectively. No statistical differences were observed for C(max) and the area under the plasma concentration time curve for terbinafine. The 90% confidence limits calculated for C(max) and AUC from zero to infinity (AUC(0-infinity)) of terbinafine were within the bioequivalence range (80%-125% for AUC). This study shows that the test formulation is bioequivalent to the reference formulation of terbinafine.     

复方愈麻美芬缓释片在Beagle犬体内的药物动力学研究

目的对Beagle犬服用复方愈麻美芬缓释片和国外对照缓释片的药动学特性和生物利用度进行比较。方法HPLC法测定 6只Beagle犬服药后的血药浓度 ,计算出有关药物动力学参数 ,经统计学分析并将两者的计算参数进行比较。结果 6只Beagle犬服用复方愈麻美芬缓释片的血药浓度与服用国外对照缓释片基本一致。复方愈麻美芬缓释片中愈创木芬甘油醚的tpeak 为(3 0 0 0± 0 14 4 )h ,ρmax为 (13 79± 0 5 70 )mg·L-1,t1/ 2 为 (2 35 3± 0 2 5 5 )h ,AUC为 (139 1±9 0 83)mg·L-1·h ;氧去甲右美沙芬的tpeak为 (4 4 2 9± 0 0 88)h ,ρmax为 (0 30 1± 0 0 4 0 )mg·L-1,t1/ 2 为 (6 4 4 5± 0 5 5 1)h ,AUC为 (4 35 4± 0 4 79)mg·L-1·h ;盐酸伪麻黄碱的tpeak为 (2 6 10±0 14 6 )h ,ρmax 为 (1 174± 0 2 0 6 )mg·L-1,t1/ 2 为 (2 84 4± 0 82 5 )h ,AUC为 (8 2 6 6±2 0 30 )mg·L-1·h。与国外对照缓释片相比 ,复方愈麻美芬缓释片的生物利用度为 :愈创木芬甘油醚为 119 8% ;氧去甲右美沙芬为 10 2 4 % ;盐酸伪麻黄碱为 115 6 % ;两制剂tmax、ρmax和AUC间无显著的统计学差异。结论经双单侧t检验分析 ,服用复方愈麻美芬缓释片后其生物利用度与服用国外对照缓释片等效     

Average bioequivalence of generic clarithromycin tablets in healthy Thai male volunteers

The objective of this study was to assess bioequivalence of 500-mg clarithromycin tablets in 24 healthy volunteers. In a randomized, single dose, fasting state, two-period, crossover study design with a 1-week washout period, each subject received a 500-mg clarithromycin tablet. Plasma samples were collected over a 24-h period after administration and were analyzed by using a validated method using high performance liquid chromatography (HPLC) with electrochemical detection. The time to reach the maximal concentration (t(max),h), the peak concentration (C(max),ng/ml) and the area under the curve (AUC(0- infinity),ng h/ml) of the Reference and Test formulations were 2.1+/-0.7 vs 2.1+/-0.7, 2474+/-702 vs 2559+/-744 and 15803+/-6120 vs 17683+/-6650, respectively. Relative bioavailability was 1.12. The 90% confidence interval (90% CI) of C(max) and AUC(0- infinity) were 95.6-110.8% and 3.5-122.0%, respectively. Bioequivalence between the test and reference preparation can be concluded.     

Cisapride-cimetidine interaction: enhanced cisapride bioavailability and accelerated cimetidine absorption

The pharmacokinetic interaction between the gastrointestinal motility-stimulating substance cisapride and the H2-antagonist cimetidine was examined in 8 healthy volunteers (25 +/- 2 years of age). Steady-state kinetics of both substances were investigated after separate 1-week treatments of oral cisapride, 10 mg t.i.d., cimetidine, 400 mg t.i.d., and the two drugs combined. Cimetidine increased the cisapride peak plasma concentration from 58 +/- 25 ng/ml to 84 +/- 19 ng/ml (p = 0.01) and AUC0-24 from 509 +/- 289 ng/ml.h to 738 +/- 148 ng/ml.h (p = 0.02). Cisapride shortened the time to the peak concentration of cimetidine from 1.3 +/- 0.6 h to 0.6 +/- 0.2 h (p = 0.005) and reduced the cimetidine AUC0-24 from 11.0 +/- 2.3 micrograms/ml.h to 9.0 +/- 2.0 micrograms/ml.h (p = 0.05). It is concluded that cimetidine inhibits cisapride metabolism, whereas cisapride enhances the gastrointestinal absorption of cimetidine.     

Possibility of a patch system as a new oral delivery system

A new oral patch system has been designed to increase the residence time of model drugs within the gastrointestinal tract. The system consisted of three layers (1) water-insoluble backing layer (2) drug-carrying adhesive layer composed of a model drug, fluorescein (FL) or fluorescein isothiocyanate-dextran (FD), and gel-forming polymer and (3) pH-sensitive enteric polymer. These three layers system was prepared as 3.0 mm diameter patches. As references, tablet containing FL or FD was prepared. In vitro dissolution studies showed that the mean dissolution time (MDT) of model drugs from patch preparation was 0.739+/-0.021 h for FL and 0.407+/-0.021 h for FD, which were longer than from tablet, 0.327+/-0.008 h for FL and 0.270+/-0.019 h for FD. The two test preparations were orally administered to beagle dogs in a crossover manner at a FL dose of 30 mg/dog and the measured plasma FL concentrations were used for pharmacokinetic analysis. With FL patch preparation, area under the plasma drug concentration vs. time curve (AUC) was 2.12+/-0.24 microgh/ml and mean residence time (MRT) was 4.60+/-0.18 h, which were greater than those of tablet, AUC was 1.52+/-0.16 microgh/ml and MRT was 3.18+/-0.09 h, respectively. Oral patch preparation also increased both AUC and MRT of FD, a model macromolecular drug, which was formulated into both patches and tablets and administered to dogs (30 mg/dog). The AUC and MRT of FD from the patch preparation were 1.11+/-0.13 microgh/ml and 5.58+/-0.55 h and from tablets were 0.53+/-0.08 microg h/ml and 4.09+/-0.29 h, respectively. These results suggest that oral patch preparation has as a potential a new oral delivery system to obtain a long residence time of drug in the gastrointestinal tract.     

对孟鲁司特钠分散片的人体生物等效性研究

目的：比较国产孟鲁司特钠分散片（受试制剂）与进口孟鲁司特钠片（参比制剂）的人体生物利用度。方法：20名健康受试者进行随机交叉试验,分别先后单次口服10mg两种孟鲁司特钠制剂,采用LC-MS法测定血浆中孟鲁司特浓度。结果：受试制剂和参比制剂的主要药动学参数分别为：t1/2（4.6±0.5）和（4.6±0.5）h,tmax（3.8±1.1）和（3.9±1.0）h,cmax（408.6±79.1）和（498.7±114.2）ng/ml,AUC0～24（3541±643.7）和（3143±436.8）ng.h.ml-1,AUC0～∞（3655±660.7）和（3260±450.4）ng.h.ml-1,结果表明主要药动学参数无显著性差异,受试制剂的相对生物利用度为（90.6±16.1）%。结论：国产孟鲁司特钠分散片与进口孟鲁司特钠片在健康人体内生物等效。     

2种西洛他唑制剂人体药动学比较研究

目的:比较2种西洛他唑制剂在正常人体内药动学情况。方法:22名健康志愿受试者单剂量随机交叉口服西洛他唑胶囊或片剂100mg,采用高效液相色谱法测定血药浓度,3p97程序计算药动学参数与相对生物利用度。结果:胶囊和片剂在体内药-时曲线均符合二室模型,tmax分别为(3·10±1·09)h、(3·43±1·25)h,Cmax分别为(0·77±0·27)、(0·82±0·42)μg/ml,AUC0~t分别为(9·94±2·66)、(10·62±3·21)(μg·h)/ml。经配对t检验,2种制剂药动学参数无显著性差异(P>0·05),胶囊的相对生物利用度为(95·43±15·47)%。结论:2种制剂具有生物等效性。     

Effect of Tamarindus indica. L on the bioavailability of ibuprofen in healthy human volunteers.

The influence of Tamarindus indica L fruit extract incorporated in a traditional meal on the bioavailability of Ibuprofen tablets 400 mg dose when given concurrently was studied in 6 healthy human volunteers. There was a statistically significant increase in the plasma levels of Ibuprofen and its metabolites hydroxy-ibuprofen and carboxy-ibuprofen respectively, when the meal containing Tamarindus indica fruit extract was administered with the ibuprofen tablets than when taken under fasting state or with the meal without the fruit extract. The C(max), AUC(0-6 hr) and Ka for ibuprofen increased from 38 +/- 0.70 microg/ml to 42 +/- 0.98 microg/ml (p > 0.05); and 28.03 +/- 2.40 microg/ml x hr to 56.51 +/- 0.16 microg/ml x hr (p < 0.05) and 1.048 +/- 0.02hr(-1) to 2.781 +/- 0.11 hr(-1) (p < 0.05) respectively. There was no change in the t(max) (120.00 +/- 0.43m) but there was a decrease in the k(el) from 0.63 +/- 0.20 hr(-1) to 0.46 +/- 0.11 hr(-1) (p<0.05). Similarly the C(max), AUC(0-6 h) and Ka for hydroxy-ibuprofen rose from 43 +/- 0.76 microg/ml to 45 +/- 0.16 microg/ml (p < 0.05); 39.04 +/- 2.30 microg/ml x hr to 59.49 +/- 2.39 microg/ml.hr in (p < 0.05) and 1.498 +/- 0.79hr(-1) to 3.442 +/- 0.23 hr(-1) (p < 0.05) respectively; while the C(max), AUC(0-6 h) and Ka for carboxy-ibuprofen rose from 48 +/- 0.7 microg/ml to 51 +/- 0.16 microg/ml (p < 0.05); 41.972 +/- 0.68 microg/ml x hr to 63.948 +/- 0.12 microg/ml x hr (p < 0.05) and 1.649 +/- 0.08 hr(-1) to 4.187 +/- 0.42 hr(-1) (p < 0.05) respectively. The study has indicated that Tamarindus indica L. fruit extract significantly increased the bioavailability of Ibuprofen.     

Pharmacokinetics and metabolism of diltiazem in rats: comparing single vs repeated subcutaneous injections in vivo

The objective of the study was to determine the effect of repeated administration on the pharmacokinetics and metabolism of diltiazem (DTZ) using an in vivo rat model. Male SD rats (n = 6-10 per group) weighing 350-450 g were used. Each rat received either a single 20 mg/kg dose of DTZ by subcutaneous (s.c.) injection or 5 mg/kg s.c. twice daily for five doses. Plasma concentrations of DTZ and its major metabolites were determined by HPLC for up to 8 h. Compared with the single dose, repeated administration resulted in higher dose normalized plasma concentrations of DTZ (AUC 26.4+/-14.2 vs 13.9+/-11.5 microg-h/ml), longer apparent half-life (t(1/2) = 12.5+/-14.6 vs 3.7+/-1.4 h) and lower systemic clearance (CL = 1.1+/-1.0 vs 2.9+/-2.7 l/h/kg). Higher dose normalized plasma concentrations, longer t(max), but shorter apparent t(1/2) of the major metabolites were observed following the repeated administration. The results also suggest that possible binding of DTZ may occur at the site of injection when administered subcutaneously in the higher dose.     

Bioequivalence of two oral formulations of nizatidine capsules in healthy male volunteers

PURPOSE: The purpose of this randomized, crossover study was to compare the bioavailability of a generic and an innovator formulation of nizatidine 300 mg capsules under fasting conditions. METHODS: Twenty blood samples per period were collected from 20 healthy, Arab male volunteers over 16 h, plasma nizatidine concentrations were determined by HPLC assay, and pharmacokinetic parameters were determined by the non-compartmental method. RESULTS: Mean+/-SD C(max), T(max), AUC(0-->t), AUC(0-->infinity), and t1/2 were 2.96+/-0.54 and 3.28+/-0.68 microg/ml, 1.31+/-0.70 and 0.93+/-0.38 h, 9.04+/-1.66 and 9.03+/-1.94 microg x h/ml, 9.17+/-1.64 and 9.12+/-1.94 microg x h/ml, and 1.64+/-0.21 and 1.58+/-0.22 h for the generic and innovator formulation, respectively. The parametric 90% confidence intervals on the mean of the difference between log-transformed values were 98.06% to 103.21%, 98.74% to 103.71%, and 83.37% to 101.34%, for AUC(0-->t), AUC(0-->infinity), and C(max), respectively. CONCLUSION: The results indicate that these two formulations are equivalent in the rate and extent of absorption.     

In vivo evaluation of guargum-based colon-targeted oral drug delivery systems of celecoxib in human volunteers.

The present study involved the in vivo evaluation of orally administered guar gum-based colon-targeted tablet formulations of celecoxib (colon-targeted tablet-20 or colon-targeted tablet-30) as compared with an immediate release capsule in 15 human volunteers. Blood samples were obtained at different time intervals and the plasma concentration of celecoxib was estimated by reversed phase HPLC. The immediate release capsules of celecoxib might have disintegrated very fast in GI tract and absorbed quickly from stomach and small intestine thereby producing peak plasma concentration (Cmax of 478 +/- 57 ng/ml) within 3.8 +/- 0.1 h (Tmax). Though celecoxib could be seen in plasma after oral administration of colon-targeted tablet-20 or colon-targeted tablet-30 between 1 and 2 h, low levels of drug were observed upto 8 h resulting in peak concentration (Cmax) of 78 +/- 6 ng/ml or 88 +/- 15 ng/ml at 10.5 +/- 1.9 h or 13.5 +/- 1.4 h (Tmax) respectively, whereas the immediate release capsules produced peak plasma concentration (Cmax) of 478 +/- 57 ng/ml at 3.8 +/- 0.1 h (Tmax). Colon-targeted tablets showed decreased AUC(0-infinity), Cmax and absorption rate constant, prolonged absorption time (ta), and increased t1/2 in comparison with the immediate release capsules. The results of the study indicated that the guar gum-based colon-targeted tablets of celecoxib did not release the drug significantly in stomach and small intestine, but delivered to the colon resulting in a slow absorption of the drug and making it available for local action in the colon.     

Banana juice reduces bioavailability of levodopa preparation

This study aimed to examine the effects of banana juice on levodopa bioavailability in rats. When a levodopa preparation (EC-Doparl tablets) was orally administered with banana juice made by mixing with a fresh banana and water, there were significant decreases in C(max) (17.4+/-2.5 vs. 8.6+/-3.1 microg/ml; alpha=0.05) and AUC (1882.8+/-49.2 vs. 933.5+/-286.6 microg.min/ml; alpha=0.05) for levodopa. On the other hand, administration of the levodopa preparation with a commercial beverage containing 10% banana juice resulted in no significant change in C(max) or AUC. These results indicate that concomitant intake of levodopa preparations with banana juice, but not with a commercial banana beverage, may cause a drug-food interaction reducing levodopa bioavailability, and we should pay attention to such interactions during levodopa therapy for patients with Parkinson's disease.     

Relative bioavailability of three cefixime formulations

Three galenic formulations of cefixime (tablet, syrup and dry suspension) containing 200 mg each were compared with respect to their relative bioavailability in twelve healthy volunteers. All three formulations showed reliable absorption. Mean peak plasma concentrations were reached after 3.3-3.5 h, mean terminal half lives were 2.9-3.1 h. 18-24% of the dose administered were recovered unchanged in the urine. Best bioavailability was obtained with the dry suspension (AUC0-infinity = 25.8 +/- 7.0 micrograms/ml h; Cmax = 3.4 +/- 0.9 microgram/ml), followed by the tablet (AUC0-infinity = 20.9 +/- 8.1 micrograms/ml h; Cmax = 3.0 +/- 1.0 micrograms/ml) and the syrup which is based on triglycerides (AUC0-infinity = 17.8 +/- 5.9 micrograms/ml h; Cmax = 2.4 +/- 0.7 micrograms/ml). The statistical analysis resulted in bioinequivalence between dry suspension and syrup. It is concluded that best bioavailability of cefixime after oral administration is guaranteed when taken in an "aqueous medium" either as dry suspension or as tablet with "plenty of liquid".