Pharmacokinetics and relative bioavailability of carboxyamido-triazole with respect to food and time of administration: use of a single model for simultaneous determination of changing parameters.

Carboxyamido-triazole (CAI) is an anti-invasive, antimetastatic, antiangiogenic agent in clinical development for cancer treatment. It has been postulated that food might enhance the oral absorption of micronized CAI based on an apparent discrepancy in steady state maximum concentrations when taken without regard to meals vs. fasting. The purpose of this study was to determine if a standardized meal affects the absorption and pharmacokinetics of this agent. Twelve patients with refractory cancers and good end organ function were randomized to receive two doses of CAI (250 mg/m2) with and without a standardized high fat meal. One cohort of 6 patients received these doses at 9 AM, and the remaining 6 patients received CAI at 9 PM. Blood was obtained prior to each dose, and serially thereafter. A series of pharmacokinetic (PK) models were fit to the concentration-time data. PK parameters were ultimately calculated using a model which allows simultaneous estimation of parameters from both test doses using nonlinear least squares analysis with ADAPT II. This model estimates independent absorption rate constants and relative fraction absorbed for each condition. AUC0-t was determined using the trapezoidal method, extrapolated to infinity, and used to calculate the relative bioavailability. No significant differences in PK parameters were noted between the morning and evening cohorts. However, the relative bioavailability, as measured by AUC0-infinity, of CAI was significantly increased when administered with a high fat meal compared to fasting (138.9 vs. 52.2 micrograms * hr/ml; p = 0.0005). The magnitude of the increase in relative bioavailability of CAI taken with food could have profound implications for patients who may inadvertently take this medication shortly after eating.     

口服甲苯咪唑微丸的药物动力学及生物利用度

目的：比较５ 只家兔单剂量口服甲苯咪唑微丸及片剂后的药动学与生物利用度。方法：采用ＲＰＨＰＬＣ 法测定血药浓度,３Ｐ８７ 程序计算药动学参数。结果：微丸的Ｃｍａｘ、Ｔ１／２ 、ＡＵＣ分别为６４３．４９ ｎｇ·ｍｌ－ １ 、１ ．０５ ｈ、８ １７０ ．９４ ｈ·ｎｇ·ｍｌ－１ 。结论：微丸与片剂的ＡＵＣ有统计学显著性差异（ Ｐ＜０ ．０５）,相对生物利用度为５２８ ．６０ ％ 。     

The relative bioavailability of metoprolol following oral and rectal administration to volunteers and patients

The pharmacokinetics, efficacy and safety of metoprolol tartrate 25 mg fatty suppositories were studied in 5 healthy volunteers and in 8 patients suffering from instable angina pectoris. Metoprolol 25 mg capsules were used as a control oral dosage form. Metoprolol showed a considerable rectal bioavailability (AUC, C max) and was absorbed quickly from the rectum (T max). In both groups rectal bioavailability was comparable. However, oral bioavailability was much lower in the volunteer group than in the patient group. Furthermore, ratios of metoprolol/aOHmetoprolol concentrations in plasma and urine gave an indication for a partial avoidance of the first pass effect after rectal administration. Further research is necessary to define an exact rectal dosage of metoprolol. In all patients, a substantial drop in heart rate, systolic and diastolic blood pressure was seen after administration of the first suppository. Metoprolol suppositories appear to be an effective, safe and suitable alternative for patients who are in need for beta blocking medication and who are unable to take oral medication for a certain amount of time.     

A new topical formulation enhances relative diclofenac bioavailability in healthy male subjects

AIMS

To evaluate the relative plasma and tissue availability of diclofenac after repeated topical administration of a novel diclofenac acid-based delivery system under development (DCF100C).

METHODS

This was a single-centre, open-label, three-period, crossover clinical trial of five discrete diclofenac formulations. Test preparations comprised two concentrations (1.0% and 2.5%) of DCF100C, with and without menthol and eucalyptus oil (total daily doses of 5 mg and 12.5 mg). Voltaren® Emulgel® gel (1.0%) was the commercially available comparator (total daily dose of 40 mg). Topical application was performed onto the thigh of 20 male healthy subjects for 3 days. Applying a Youden square design, each drug was evaluated in 12 subjects, with each subject receiving three test preparations. Blood sampling and in vivo microdialysis in subcutaneous adipose and skeletal muscle tissues were performed for 10 h after additional final doses on the morning of day 4.

RESULTS

All four DCF100C formulations demonstrated a three- to fivefold, dose-dependent increase in systemic diclofenac availability compared with Voltaren® Emulgel® and were approximately 30–40 times more effective at facilitating diclofenac penetration through the skin, taking different dose levels into account. Tissue concentrations were low and highly variable. The 2.5% DCF100C formulation without sensory excipients reached the highest tissue concentrations. AUC(0,10 h) was 2.71 times greater than for Voltaren® Emulgel® (90% CI 99.27, 737.46%). Mild erythema at the application site was the most frequent adverse event associated with DCF100C. There were no local symptoms after treatment with the reference formulation.

CONCLUSION

DCF100C formulations were safe and facilitated greater diclofenac penetration through the skin compared with the commercial comparator. DCF100C represents a promising alternative to oral and topical diclofenac treatments that warrants further development.     

The effect of food and bile acid administration on the relative bioavailability of cyclosporin.

1. The relative bioavailability of cyclosporin was studied in 11 healthy volunteers after single oral capsule doses of cyclosporin on three separate occasions; fasting, with breakfast and with breakfast together with bile acid tablets (400 mg of cholic acid and 100 mg of dehydrocholic acid). 2. There was a significant increase in the area under the blood concentration vs time curve (AUC) of cyclosporin when the drug was taken together with breakfast and bile acid tablets (9078 ng ml-1 h) as compared with breakfast alone (7453 ng ml-1 h, P less than 0.05) or fasting conditions (7283 ng ml-1 h, P less than 0.01). 3. A blood drug concentration vs time curve displaying two peaks was present in 9/11 subjects when cyclosporin was taken with breakfast or with breakfast and bile acid tablets, but only one peak was present when cyclosporin was taken during fasting, suggesting an enterohepatic circulation of cyclosporin or a second absorption phase after the meal. 4. In a separate study, 12 h trough blood cyclosporin concentrations were measured before and after 1 week of bile acid treatment in 19 clinically stable, out-patient transplant recipients who were treated with oral cyclosporin solution (mean dose 2.0 mg kg-1 twice daily). The administration of cyclosporin was not standardized with regard to food intake. There was no significant difference in the blood concentrations of cyclosporin before and after bile acid treatment (114 +/- 38 ng ml-1 vs 121 +/- 38 ng ml-1).(ABSTRACT TRUNCATED AT 250 WORDS)     

Pharmacokinetics and relative bioavailability of heptabarbital and heptabarbital sodium after oral administration to man

Summary A method has been developed for the quantitative determination of heptabarbital [5-(1-cyclohepten-1-yl)-5-ethylbarbituric acid] in human plasma after administration of single therapeutic doses of the drug. It involves a single extraction step followed by gas chromatography with alkali flame ionization detection, and the results were linear in the concentration range 0.125 – 5.0 µg/ml plasma. The pharmacokinetics and relative bioavailability of heptabarbital and heptabarbital sodium were studied in a crossover design in 7 healthy volunteers after oral administration of 20 tablets containing 200 mg heptabarbital and hard gelatine capsules containing an equivalent amount of its sodium salt. Heptabarbital concentrations in plasma were determined at regular intervals. The absorption of heptabarbital from the tablets was quite slow and peak level times varied from 1.5 to 4 h. The sodium salt was absorbed more rapidly and peak concentrations occurred between 1/3 and 2 h. In all cases the elimination of heptabarbital could be described by a single first-order process with an average half-life of 7.6 h (range 6.1 – 11.2 h). The half-life of the drug in each individual was about the same in the two trials. The relative bioavailability in each volunteer was estimated by comparing the areas under the plasma concentration curves. The sodium salt had an average bioavailability of 83% relative to the free acid. In some volunteers urinary excretion of unchanged heptabarbital was measured; cumulative excretion amounted to 0.16 – 0.30% of the administered dose. Four volunteers received one tablet each night for eight or ten days, but no accumulation was found. In three volunteers the half-life of the drug prior to and after these experiments did not change, whereas in the other volunteer the half-life decreased from 7.1 to 4.6 h. The possibility of enzyme induction should be considered when heptabarbital is taken regularly. It was concluded that heptabarbital was a suitable drug for the treatment of insomnia, since its half-life was rather short. Heptabarbital sodium may be used for induction of sleep, whereas Medomin^® tablets, i.e. heptabarbital free acid, may be prescribed when the maintenance of sleep is the primary reason for treatment with a hypnotic drug.     

Pharmacokinetics and bioavailability of diclofenac in the rat.

Diclofenac sodium is a widely used drug with interesting absorption and disposition features when administered to laboratory animals. The present study was undertaken to assess the pharmacokinetics of the drug after iv and gastrointestinal dosing to rats. Renal excretion of unchanged drug was negligible, but biliary excretion of the drug (unchanged and conjugated) was detected in bile duct-cannulated rats; it accounted for 27.2 and 31.2% of the total dose following iv and intraduodenal administration, respectively. Most of the drug excreted in the bile was conjugated diclofenac; unchanged drug accounted for only 4.7 and 5.4% of total diclofenac excreted in the bile after iv and intraduodenal dosing, respectively. In normal animals, intestinal absorption of the drug excreted in the bile resulted in higher drug concentrations in plasma than those obtained in bile duct-cannulated rats, but only after 60 min of dosing. When administered directly into the duodenum, diclofenac absorption was extremely fast and the maximum plasma diclofenac concentration was reached within 2 min. After oral dosing, an early peak was also observed, but it was lower than that obtained after intraduodenal dosing: 71% diclofenac bioavailability was found in bile duct-cannulated rats intraduodenally dosed, whereas in normal animals dosed by mouth a bioavailability of 79% was obtained. In normal animals intraduodenally dosed, an apparent bioavailability of 106% was observed. All of these features, particularly the influence of enterohepatic circulation on drug bioavailability, are discussed.     

Comparative bioavailability of diclofenac hydroxyethylpyrrolidine vs diclofenac sodium in man

Summary A pharmacokinetic study in man has been made of a new dosage form of diclofenac hydroxyethylpyrrolidine (DIEP); soluble salt packed in sachets was compared with diclofenac sodium as enteric coated tablets.Oral DIEP 2×50 mg showed a significant difference in absorption kinetics (ka, lag time and t_max) as compared to oral diclofenac sodium 2×50 mg. A relevant plasma concentration of diclofenac was detected just 15 min after DIEP, while diclofenac sodium produced a measurable plasma concentration only 0.5–1 h after the treatment. C_max and t_1/2 after DIEP and diclofenac sodium were comparable. Comparison of the two AUC values showed that DIEP was bioequivalent to diclofenac sodium (Q=100%).     

替米沙坦片人体相对生物利用度研究

目的:比较国产与进口替米沙坦片药动学及人体生物等效性.方法:20例健康男性志愿者随机交叉口服替米沙坦片受试制剂或参比制剂80mg,采用HPLC-荧光检测法测定血浆中替米沙坦浓度,经3P97软件统计,进行相对生物利用度与生物等效性分析.结果:受试者口服替米沙坦受试制剂和参比制剂后,血浆中替米沙坦T max ,C max ,AUC 0～t ,AUC 0～∞和t 1/2 分别为(0.91±0.19)和(0.86±0.21)h;(672.7±275.1)和(710.2±312.9)μg·L -1 ;(4221.4±2909.0)和(4430.2±3487.9)μg·h·L -1;(4568.1±3032.5)和(4742.6±3657.3)μg·h·L -1 ;(30.7±7.0)和(28.0±5.9)h.以AUC 0～t 计算,替米沙坦片相对生物利用度平均为(98.1±12.1)%.结论:经方差分析和双单侧t检验,两种制剂具有生物等效性.     

The relative bioavailability of co-trimoxazole suspensions

The relative bioavailability of a co-trimoxazole suspension manufactured by VEB Berlin-Chemie (B); Belocid-Suspension was compared with a widespread used suspension (V) in healthy male students (22-29 ys. aged). A single oral dose of 160 mg trimethoprim (TPM) and 800 mg sulphamethoxazole (SMZ) produced similar blood levels with either preparation. The TMP peak levels were 1.44 +/- 0.18 (B) and 1.40 +/- 0.26 mg/l (V), respectively after 1.5 and 1.0 h on an average. The AUC amounted to 18.94 +/- 2.25 (B) and 17.19 +/- 3.62 mg . h/l (V), respectively. About one half (52.5%) of the given TMP dose was excreted unchanged by kidney within 48 h after administration of the respective suspension. The SMZ peak levels run to 37.2 +/- 10.3 (B) and 38.6 +/- 5.4 mg/l (V) after 3.6 +/- 3.5 and 1.3 +/- 0.8 h. The AUC were identical: 682.3 +/- 126.2 (B) vs. 686.9 +/- 165.8 mg . h/l (V). After both preparations 67% of the given SMZ dose could be detected in urine within 48 h. In two out of the eight volunteers the absorption of B was delayed, but it passed off to the same extent. In all other cases absorption of the suspension was accelerated in comparison with tablet administration studies reported. Peak blood levels of TMP and SMZ after ingestion of the suspensions reach the lower range of values resulting from tablet intake. Both suspensions are regarded interchangeable with respect to bioavailability, which is also comparable to co-trimoxazole tablets.     

Pharmacokinetics and relative bioavailability of cyclobarbital calcium in man after oral administration

Summary The pharmacokinetics and relative bioavailability of cyclobarbital calcium have been studied after oral administration of Phanodorm, of tablets according to the Formularium Nederlandse Apothekers (1968; FNA), and an aqueous solution. Six healthy volunteers participated in the investigation on three occasions and each received the three preparations. The dose administered was 300 mg cyclobarbital calcium. Plasma concentrations of cyclobarbital were determined at regular intervals. Absorption from the three preparations was rapid and was faster from the solution. Peak concentrations were usually attained within 1 h. The elimination of cyclobarbital could be described by a single first-order process with an average half-life of 11.6 h (range 8 – 17 h). There was little intra-subject variation of the half-life. Relative bioavailability for each volunteer was estimated by comparing the areas under the plasma concentration curves. The FNA-tablets and Phanodorm exhibited similar bioavailability, whereas the average bioavailability of the solution was 78% of that of FNA-tablets; the reason for this unexpected finding is unknown. It was concluded that cyclobarbital cannot be regarded as a uniformly suitable drug for the treatment of insomnia. The long half-life that was apparent in some of the volunteers (15 – 17 h) creates a substantial risk of residual effects on the following morning. In principle, however, the calcium salt of cyclobarbital may be used for induction of sleep, because of its rapid absorption.     

The relative bioavailability and pharmacokinetics of carbamazepine

Differences in the bioavailability after administration of two pure carbamazepine samples that were different in particle sizes have been found. Carbamazepine was given to each of 3 healthy male volunteers in a single oral dose of 400 mg in gelatin capsules. The other carbamazepine sample was administered after a three-week time interval. Plasma was collected during the following 96 hr. Quantitative determination of carbamazepine was performed by gas liquid chromatography. By comparing the areas under the various curves for each volunteer, the relative bioavailability of one of the carbamazepines in relation to the other one was found of approximately 70%. There were no differences in the half-life time.     

Relative bioavailability of diclofenac after a single administration of a new multiple-unit formulation of enteric-coated pellets

The relative bioavailability of diclofenac (CAS 15307-86-5) was investigated after a single administration of a multiple-unit formulation containing 75 mg diclofenac sodium in enteric-coated pellets (A) in comparison to an enteric-coated tablet with 50 mg diclofenac sodium (B), a capsule containing 140 mg diclofenac resinate (C) and a dispersible tablet containing 46.5 mg diclofenac acid (D). The study was carried out in a four-way crossover design in 16 healthy male volunteers. Serum concentrations of diclofenac were determined with a validated and specific HPLC-method. After dose normalisation, a mean relative bioavailability of 99% (B), 142% (C) and 116% (D) was determined for the pellet formulation. According to the corresponding 90%-confidence interval, bioequivalence for the extent of bioavailability of the test formulation can be concluded compared to the enteric-coated tablet. In comparison to the formulations C and D, the test formulation showed an increased extent of bioavailability. Further differences in pharmacokinetics were observed for the rate-dependent parameters. For the test formulation, the highest mean maximum serum concentration (1595 ng/ml) was measured with a corresponding tmax of 0.8 h. For the reference formulations, mean peak serum concentrations of 1285 ng/ml after 2.0 h (B), 370 ng/ml after 1.8 h (C) and 735 ng/ml after 1.9 h (D) were observed. Despite the enteric-coating of the pellets, a short lagtime of 0.4 h was determined for the test formulation. For the other rapid-release formulation (D), the lagtime was of a similar magnitude (0.3 h), while drug release and absorption from the enteric-coated tablet and the diclofenac resinate capsule were delayed (1.8 and 0.7 h, respectively). Due to the rapid and high bioavailability of diclofenac, the multiple-unit formulation fulfills the prerequisites for the oral treatment of acute painful conditions when prompt analgesic and anti-inflammatory efficacy is desired.     

Pharmacokinetics and relative bioavailability of levomepromazine after repeated administration of tablets and syrup

Summary Plasma levels of levomepromazine and its sulphoxide were measured in 8 psychiatric patients after repeated doses of levomepromazine tablets or syrup. The rate and extent of absorption of the drug were similar for the two dosage forms, although the extent of presystemic metabolism appeared to be slightly greater after administration of syrup than of tablets. The biological half-life of levomepromazine ranged from 16.5h to 77.8h, and a 13-fold variation was seen in the ratio of the total clearance to the absorbed fraction of the dose (Cl/F_po). It is postulated that individual variation in the dose required for therapy was due in part to individual variation in the pharmacokinetics of the drug.     

The bioavailability of cefpodoxime proxetil tablets relative to an oral solution

The bioavailability of cefpodoxime proxetil tablets relative to an oral solution of cefpodoxime proxetil in a sucrose/alcohol/citric acid vehicle was studied in 11 healthy volunteers in a randomized, crossover study. Fasted subjects took one cefpodoxime proxetil 100 mg tablet or 50 mL of a 2 mg mL^?1 cefpodoxime proxetil oral solution on two separate occasions. In a third study period, all subjects took a 100 mg dose of the oral solution with a high-fat meal to investigate the effect of food on cefpodoxime proxetil absorption from the oral solution. Serial blood samples were obtained over a 24h period, and urine was collected for 48h after dosing. Cefpodoxime concentrations in plasma and in urine were determined using HPLC methods. The bioavailability of cefpodoxime proxetil tablets relative to the oral solution was 82%, as determined from AUC ratios. There was no difference in the rate of cefpodoxime absorption between dosage forms. Food had no effect on the extent of drug absorption from the oral solution but did result in delayed absorption. These results suggest that complete dissolution of cefpodoxime proxetil is critical for optimal bioavailability.     

The relative bioavailability of paracetamol following administration of solid and liquid oral preparations and rectal dosage forms

Determination of the Relative Bioavailability of Paracetamol Following Administration of Solid and Liquid Oral Preparations and Rectal Dosage Forms. The relative bioavailability of paracetamol from two solid and two liquid oral preparations and two rectal dosage forms, each containing 500 mg of the active ingredient, was investigated in 12 healthy male individuals. The plasma concentration-time curves of paracetamol following administration of the oral formulations were very similar; consequently there were only minor differences of the AUC0-12h (21.4, 21.9; 23.0, 22.8 micrograms.h/ml), cmax (8.8, 9.1; 10.0, 10.7 micrograms/ml), tmax (35, 25; 20, 19 min), and the terminal plasma elimination half-life t1/2 beta (2.95, 2.85; 2.86, 2.99 h) for the solid and the liquid test and reference preparations, respectively. The suppositories (test and reference formulation) differed from the oral dosage forms, but were comparable to each other with respect to AUC0-12h (18.2, 18.8 micrograms.h/ml), cmax (3.3, 3.5 micrograms/ml), tmax (1.6, 2.45 h), and t1/2 beta (3.55, 3.54 h). In all test preparations the 95% confidence limits for AUC0-12h completely were enclosed in the range of 80-120% relative bioavailability (independently of whether parametric or non-parametric statistical methods were applied); the limits for the oral formulations were quite narrow, thus indicating a highly consistent release of the active compound from the tablets as well as from the liquid dosage form. A comparison of the mean values of cmax by analysis of variance at the 80% probability level did not reveal any significant differences between the test and the corresponding reference formulations; based on non-parametric statistical methods, the 95% confidence limits for cmax were enclosed in the range of 70-130%.(ABSTRACT TRUNCATED AT 250 WORDS)     

别嘌醇片的人体相对生物利用度

目的评价两种别嘌醇片剂的生物利用度。方法20名健康志愿者,进行随机2周期交叉实验,采用HPLC-UV法测定人血浆中别嘌醇的浓度并计算药动学参数及生物利用度。结果受试剂与参比剂的药?时曲线下面积(AUC0-8)为(5·34±0·74)和(5·64±0·87)μg·h-1·ml-1,峰浓度(Cmax)分别为(2·03±0·42)和(1·99±0·39)μg/ml。达峰时间(Tmax)分别为(1·36±0·58)和(1·64±0·67)h。别嘌醇受试剂的相对生物利用度(F)为(97·9±16·9)%。InAUC0-t、InCmax经方差分析后无显著性差异(P>0·05);AUC0-t、Cmax经双单侧t检验有显著性差异(P<0·05),Tmax经非参数法检验无显著性差异(P>0·05)。结论两制剂具有生物等效性。     

国产罗红霉素胶囊剂的药代动力学及相对生物利用度测定

目的研究健康志愿者单剂口服罗红霉素胶囊剂后药代动力学及其与进口品种比较的相对生物利用度.方法10例受试者分别交叉空腹口服单剂国产罗红霉素胶囊剂和进口罗红霉素片剂各300mg,留取72h内血、尿标本,以微生物琼脂弥散法测定其血、尿药物浓度,以3P87程序计算药代动力学参数.结果受试者口服国产罗红霉素胶囊剂后体内过程符合血管外二室模型,其血药峰浓度(Cmax)为(10.26±2.75)mg·L     

Pharmacokinetics and bioavailability of diclofenac in the rat

Diclofenac sodium is a widely used drug with interesting absorption and disposition features when administered to laboratory animals. The present study was undertaken to assess the pharmacokinetics of the drug after iv and gastrointestinal dosing to rats. Renal excretion of unchanged drug was negligible, but biliary excretion of the drug (unchanged and conjugated) was detected in bile duct-cannulated rats; it accounted for 27.2 and 31.2% of the total dose following iv and intraduodenal administration, respectively. Most of the drug excreted in the bile was conjugated diclofenac; unchanged drug accounted for only 4.7 and 5.4% of total diclofenac excreted in the bile after iv and intraduodenal dosing, respectively. In normal animals, intestinal absorption of the drug excreted in the bile resulted in higher drug concentrations in plasma than those obtained in bile duct-cannulated rats, but only after 60 min of dosing. When administered directly into the duodenum, diclofenac absorption was extremely fast and the maximum plasma diclofenac concentration was reached within 2 min. After oral dosing, an early peak was also observed, but it was lower than that obtained after intraduodenal dosing: 71% diclofenac hioavailability was found in bile duct-cannulated rats intraduodenally dosed, whereas in normal animals dosed by mouth a bioavailability of 79% was obtained. In normal animals intraduodenally dosed, an apparent bioavailability of 106% was observed. All of these features, particularly the influence of enterohepatic circulation on drug bioavailability, are discussed.The present work is part of a research project developed with a grant for the Plan Nacional de I + D (FAR 90-0092) of the Ministry of Industry and Energy of Spain.     

盐酸育亨宾胶囊的人体相对生物利用度

目的:比较两种盐酸育亨宾(Yoh)制剂的人体相对生物利用度.方法:采用HPLC测定人血清Yoh浓度.10名健康志愿者po5.4mgYoh,采用自身交叉对照试验,以片剂为对照药(A药)对胶囊(B药),进行人体相对生物利用度比较.结果:B药的相对生物利用度为(95.60土5.84)%.A,B两制剂的Ka分别为(4.27土3.39)和(3.02士1.23)h~-1,吸收迟滞时间(t_0)分别为(0.35士0.24)和(0.33士0.20)h,达峰时间(t_p)分别为(0.94士0.38)和(1.03士0.29)h,峰浓度(c_max)分别为(56.78士27.90)和(51.84士28.46)μg/L,消除半衰期(T_(1/2ke))分别为(1.14±0.50)和(1.04±0.50)h,药-时曲线下面积(AUC)分别为(143.74±114.99)和(135.53±105. 00)(μg·h/L),t检验,两种剂型各参数均无显著性差异(P>0.05).结论:A、B两制剂生物等效.