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PubMedDate not supplied

[Evaluation of the biological availability of 2 carbamazepine preparations].

The biological availability was determined of two carbamazepine preparations: Amizepin POLFA and Tegretol GEIGY in tablets. The study was carried out in 10 patients giving them the drug in doses of 400 mg by the crossover method at an interval of 3 weeks. The statistical analysis of the mean maximal values, mean times of reaching of maximal concentrations, and mean areas under the curve of serum carbamazepine concentration changes for both forms of the drug showed a comparable biological availability of Amizepin and Tegretol. The relative degree of bioavailability of Amizepin amounted to 98% of that of Tegretol. The values of pharmacokinetic parameters of both drugs were compared. The value of distribution volume was greater in the case of Tegretol, and the difference was statistically significant. No significant differences were found between the remaining calculated parameters.

Adult↗
PubMed1994

Aluminum inhibition of hexokinase activity in vitro: a study in biological availability.

We have used the HK/G6PDH coupled enzyme assay to determine the biological availability of aluminum in mixed-ligand media of biological interest. The biological availability of aluminum was measured as the inhibition of the activity rate of the assay and was shown to be dependent upon the equilibration state of the aluminum stock solutions (prior to their addition to the assay) and the comparative reaction kinetics of competitive aluminum equilibria in the assays. Aluminum was found to inhibit the assay, however, the inhibition by aluminum was abolished when silicic acid was present in both the aluminum stock solution and the assay medium. The assay is proposed as a model system for investigating the biological availability of aluminum in heterogenous media of biochemical significance.

Aluminum↗
PubMed1998

Relative biologic availability and pharmacokinetics of albuterol preparations in healthy Chinese.

The authors' goal was to study the biologic availability and pharmacokinetics of two different formulations of controlled-release (CR) tablets of albuterol. A two-way, cross-over biologic availability study was performed with 20 healthy male volunteers to evaluate the relative biologic availability of two CR tablets of albuterol versus two different formulations of immediate-release (IR) albuterol tablets. Albuterol concentrations in plasma were measured using an HPLC procedure. Each patient subject received a 4.8-mg CR tablet every 12 hours for 6 days and a 4.8-mg IR tablet every 8 hours for 6 days. Tests of single doses and steady state were assayed for CR and IR albuterol tablets. The mean Cmax and tmax for two CR tablets given after a single dose were 7.3+/-1.5, 7.9+/-1.4 microg x L(-1) and 4.6+/-0.8, 4.8+/-0.5 hours, respectively. The Cmax and tmax for two IR tablets given after a single dose were 12.5-/+1.3, 15.3 +/-2.3 microg x L(-1) and 1.3+/-0.4, 1.6+/-0.4 hours, respectively. The relative biologic availability of two CR albuterol tablets were 106.0+/-6.2% and 109.8+/-9.0%, respectively. Administration of CR albuterol twice a day provides an alternative to administration of IR albuterol three or four times a day.

Adult↗
PubMed1994

Application of NONMEM method for evaluation of relative biological availability of ofloxacin.

The nonlinear mixed effect model (NONMEM) method for analysis of population pharmacokinetics, was applied to evaluate the relative biological availability of 2 ofloxacin (Ofl) products. The data of randomized crossover study of 2 kinds of Ofl tablets in 12 healthy volunteers were analyzed by NONMEM, as well as standard approach. The relative biological availability evaluated by NONMEM (F = 97.3 +/- 5.0%) was close to that by standard approach (F = 98.2 +/- 3.6%). NONMEM was also valid in accurately evaluating the relative biological availability using sparse clinical data (F = 91.7 +/- 8.0%) which could not be analyzed by standard approach. Thus, the usefulness and advantages of NONMEM were ascertained for the evaluation of biological availability using observational or experimental data.

Adult↗
PubMed1983

Biological availability of selenodicysteine in chicks.

The biological availability of selenium (Se) in selenodicysteine (SDC) for chicks was evaluated using plasma glutathione peroxidase (SeGSHpx) activity and tissue Se levels as criteria. In each of two trials day-old Single Comb White Leghorn chicks were fed a basal diet low in Se but supplemented with vitamin E during Days 1 to 14. On Day 15 three replicate groups of eight chicks were assigned to each dietary treatment. Dietary treatments consisted of feeding the basal diet alone or supplemented with approximately 50, 100, or 150 ppb Se as either sodium selenite or SDC from Days 15 to 27. Pooled samples of blood, liver, and breast muscle were obtained from four chicks per replicate group on Day 27. Activity of SeGSHpx and the concentration of Se in plasma, whole blood, muscle, and liver were highly correlated (P less than .0001) with supplemental dietary Se. In Trial 1 no differences were observed between the slopes for each compound upon determining linear regression equations for SeGSHpx, plasma Se, whole blood Se, muscle Se, or liver Se versus supplemental dietary Se. In Trial 2 there were no differences between the slopes for each compound in equations for SeGSHpx, plasma Se, or whole blood Se versus supplemental dietary Se. The ratio of slopes (SDC/sodium selenite) was .82 for both muscle Se and liver Se versus dietary Se. Thus, data indicate that Se in SDC is highly available for chicks.

Animals↗
PubMed1979

[Biological availability of digoxin and beta-acetyldigoxin after single-dose administration (author's transl)].

The biological availability of digoxin tablets (Lanicor) and beta-acetyldigoxin tablets (Novodigal) was tested after single-dose administration. Plasma levels over 48 hours, the area under the blood-level curves and the cumulative urinary excretion over seven days served as a measure of biological availability. The area under the blood-level curve after 1.0 mg digoxin by mouth was 40.7 +/- 1.7 ng . ml-1 . h and after 1.0 mg beta-acetyldigoxin by mouth 39.1 +/- 1.4 ng . ml-1 h, compared with 56.1 +/- 1.4 after 1.0 mg digoxin intravenously. Seven days later 0.67 +/- 0.12 mg digoxin of the orally administered digoxin, 0.68 +/- 0.12 mg digoxin of the orally administered beta-acetyldigoxin and 0.81 +/- 0.08 mg of the intravenously administered digoxin were excreted in the urine. There was no significant difference in the biological availability of the two drugs (P greater than 0.05).

Acetyldigoxins↗
PubMed1978

Biological availability to the rat of intrinsic and extrinsic iron with soybean protein isolates.

Evaluations were conducted to assess the biological availability of iron in three food grade isolated soybean proteins and to evanuate the influence of these proteins on iron added to the diet from a source of known high biological availability. Ferrous sulfate was used as the standard iron source in all experiments. The biological availability was measured by a 14-day hemoglobin repletion after a 4 week depletion period using multiple dose response and comparing the test samples and standard iron source by the slope ratio assay procedure. The relative iron bioavailability for three isolated soybean proteins was A = 60%; B = 64% and C = 59% with a mean value of 61%. Autoclaving isolated soybean protein B at 108.4 degrees improved iron bioavailability over the unheated samples while isolated soybean protein A was unaffected by this treatment. Iron added to the diets containing isolated soybean protein had bioavailabilities similar to that of iron present in the soybean which supports the common dietary iron pool hypothesis. The high iron content (0.18 mg/g protein) coupled with the bioavailability data make the isolated soybean proteins a good dietary iron source.

Animals↗
PubMed1995

Relative biological availability of manganese from manganese proteinate, manganese sulfate, and manganese monoxide in broilers reared at elevated temperatures.

The relative biological availabilities of Mn from Mn proteinate, MnSO4, and MnO were compared under two different environmental conditions. Commercial broilers were reared in brooder batteries between Days 1 and 21 and fed diets containing 0, 1,000, 2,000, or 3,000 mg supplemental Mn/kg diet. On Day 22, birds were transferred to individual cages in two environmental chambers maintaining the same dietary Mn sources and supplemental levels. The temperature in one chamber cycled between 18 and 23.9 C (thermoneutral, TN), and in the other chamber cycled between 23.9 and 35 C (heat distress, HD). Birds in the HD environment were exposed to 8 h of 23.9 C, 4 h of 23.9 to 35 C, 4 h of 35 C, and 8 h of 35 to 23.9 C. Tibia Mn increased linearly (P < .05) with level of supplementation when measured on Days 22 and 47. Based on ratios of slopes from multiple linear regression analysis of bone Mn on Mn intake from various sources, the biological availabilities of Mn proteinate and MnO relative to MnSO4 (100%) were 120 and 91%, respectively, in 21-d-old chicks. In 49-d-old birds, corresponding relative biological availabilities of Mn from proteinate and oxide were 125 and 83%, respectively, in birds reared under TN, and 145 and 82%, respectively, for HD birds.

Animals↗
PubMed1986

An in vitro method for estimating biologically available vitamin B6 in processed foods.

1. An in vitro method which used enzymic digestion of the food matrix to release biologically available vitamin B6 is described. 2. Vitamin B6-fortified liquid model foods were thermally processed. After these foods had been freeze-dried, one part was subjected to enzymic hydrolysis at pH 2.0 with pepsin (EC 3.4.23.1) followed by a hydrolysis at pH 8.0 with pancreatin. The vitamins that were found in the supernatant fraction, after an acidified methanol treatment of the hydrolysate, were estimated by high-performance liquid chromatography (HPLC). The other part was given to rats who were kept on a vitamin B6-depleted diet. 3. The biologically available vitamin B6 content of the processed model foods, as determined by rat bioassay, showed good correlation with the vitamin B6 determined by HPLC. 4. It has proved possible to use this in vitro, two-stage enzymic digestion system followed by HPLC determination to determine biologically available vitamin B6 in vitamin B6-fortified processed model foods.

Animals↗
PubMed1984

Biopharmaceutical investigations of rectal suppositories. Part 1: Pharmaceutical and biological availability of theophylline.

The influence of suppository base and some tensides on the release and resorption of theophylline from model rectal suppositories was investigated in a preliminary way. It was established that the original Bulgarian suppository base Novosup ensures higher pharmaceutical and biological availability of theophylline in comparison with other investigated lipophilic bases. The preliminary inclusion of Tween 80 in Witepsol H 15 increased the pharmaceutical and biological availability of the drug. A linear relationship between the pharmaceutical and biological availability was observed after administration of model suppositories in rabbits.

Animals↗
PubMed1998

Distinct classes of chaperoned IL-6 in human blood: differential immunological and biological availability.

Transport of IL-6 in blood is fundamental to the biology of this cytokine. In the present study, IL-6 transport, immunological reactivity, and biological availability were investigated in blood from melanoma patients subjected to different active specific immunization regimens (an anti-idiotypic mAb immunization protocol (mAb-keyhole limpet hemocyanin (KLH)-Calmette-Guerin bacillus (BCG), an autologous anti-cancer vaccine protocol (AAAP), or both). Sera were subjected to Sephadex G-200 gel filtration chromatography, and the structure and biological activity of IL-6 complexes in the eluate fractions were probed using five IL-6 ELISAs and two bioassays. Sera from patients administered mAb-KLH+BCG followed by AAAP contained three distinct classes of IL-6 eluting at 30, 200, and 450 kDa, each with its characteristic ELISA reactivity and bioactivity: the 30- and 450-kDa complexes were bioactive in the B9 and Hep3B assays, but the 200-kDa complex was not. The 30- and 450-kDa IL-6 complexes were preferentially reactive in the 7IL6/5IL6 ELISA, the 200-kDa IL-6 complexes were preferentially reactive in the 4IL6/5IL6 ELISA, while the three commercial ELISAs (R&D, Endogen, and Genzyme) detected essentially only the 30-kDa IL-6. In contrast, 1) sera from AAAP patients contained biologically active 30- and 450-kDa IL-6 complexes, while 2) sera from mAb-KLH+BCG patients contained 200-kDa IL-6 complexes inactive in ex vivo bioassays. Both the 450- and 200-kDa complexes included soluble IL-6R, with the 200-kDa complexes additionally containing ligand-occupied anti-IL-6 and anti-soluble IL-6R IgG. The data indicate the existence of specific mechanisms that regulate the transport and function of IL-6 in vivo.

Antibodies, Neoplasm↗
PubMed1975

[Biological availability of diagoxin in patients with or without gastric resection (Billroth II) (author's transl)].

Biological availability of digoxin tablets was measured during maintenance therapy in ten hospitalized patients who had had a Billroth II gastric resection at least two years previously. Twelve patients on digoxin maintenance for heart failure but without gastro-intestinal disease served as controls. The mean value of daily digoxin urinary excretion over ten days in the resection group was 38.09 +/- 0.70% of the administered dose. The serum-digitalis level 12 and 24 hours after the last dose of glycoside (0.5 mg) was 1.30 +/- 0.04 ng/ml and did not significantly differ from that of the control group, nor did digoxin elimination in urine and the digoxin/creatinin excretion ratio. It is concluded that two-third gastric resection with exclusion of antigrade duodenal passage does not influence biological availability of digoxin given in tablets.

Adult↗