Influence of fatty acid patterns on the intestinal absorption pathway of quercetin in thoracic lymph duct-cannulated rats

Since it is known that dietary fats improve the bioavailability of the flavonol quercetin, we purposed to investigate whether this effect is due to increased lymphatic transport of quercetin. In rats with implanted catheters in the thoracic lymph duct, we administered quercetin into the duodenum with TAG emulsions containing either long-chain fatty acids (LCT) or medium-chain fatty acids (MCT). Controls received quercetin together with a glucose solution. LCT administration increased the lymphatic output of quercetin (19·1 (sem1·2) nmol/8 h) as well as the lymph-independent bioavailability of the flavonol, determined as area under the plasma concentration curve (1091 (sem142) μm× min). Compared with glucose administration, MCT neither increased the lymphatic output (12·3 (sem1·5) nmol/8 h) nor the bioavailability of quercetin (772 (sem99) μm× min) significantly (glucose group: 9·8 (sem1·5) nmol/8 h and 513 (sem55) μm× min, respectively). Because LCT are released within chylomicrons into the intestinal lymph while MCT are mainly released into the portal blood, we conclude from the present results that dietary fats that are mainly composed of LCT improve quercetin bioavailability by increasing its transport via the lymph, thereby circumventing hepatic first-pass metabolism of the flavonol. In addition, LCT could enhance quercetin absorption by improving its solubility in the intestinal tract.

A Novel Domperidone Hydrogel: Preparation, Characterization, Pharmacokinetic, and Pharmacodynamic Properties

The purpose of the present study was to prepare a novel domperidone hydrogel. The domperidone dispersion was prepared by the solvent evaporation method. The characteristics of domperidone dispersion were measured by dynamic light scattering (DLS), scanning electronic microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffractometry, and solubility test, respectively. Domperidone hydrogel was prepared by directly incorporating the domperidone dispersion in Carbopol hydrogel to increase its mucoadhesive properties to gastrointestinal tract (GIT). The in vivo pharmacokinetic and pharmacodynamic studies were investigated to evaluate the relative oral bioavailability and the propulsion efficacy of domperidone hydrogel as compared with market domperidone tablet (Motilium tablet). The particle size of domperidone dispersion in distilled water was 454.0 nm. The results of DSC and X-ray indicated that domperidone in dispersion was in amorphous state. The solubility of domperidone in the dispersion in distilled water, pH of 1, 5, and 7 buffer solution was 45.7-, 63.9-, 13.1-, and 3.7-fold higher than that of raw domperidone, respectively. The area under the plasma concentration curve (AUC0–24) in domperidone hydrogel was 2.2-fold higher than that of tablet. The prolonged propulsion efficacy in the domperidone hydrogel group compared to that in tablet group was observed in the pharmacodynamic test.

Folate absorption from folate-fortified and processed foods using a human ileostomy model

Data on folate absorption from food from validated human studies using physiological folate doses are still needed to estimate dietary requirements and to formulate recommendations. The aim of the present work was to study the effects from fortified and processed foods on folate absorption in ileostomy volunteers (n 9) using the area under the plasma concentration curve (AUC) and kinetic modelling. Using a standardized single-dose protocol, dairy products fortified with a candidate fortificant (6S)-5-methyltetrahydrofolate ((6S)-5-CH3-H4folate), folic acid-fortified bread and a dessert crème containing natural yeast folate polyglutamates were compared with folate supplements. Absorbed folate was estimated by AUC and a kinetic model, and non-absorbed folate by ileostomal folate excretion. Median apparent absorption from test foods ranged from 55 to 86%. Added folate-binding proteins (FBP) significantly reduced folate absorption from dairy products, as in the absence of FBP, AUC–dose-corrected ratios were increased and ileal folate excretion decreased. After in vivo gastrointestinal passage of dairy products containing FBP, up to 43% of the ingested FBP was found in ileostomal effluent. Folate absorption was similar for (6S)-5-CH3-H4folate fortificant from fermented milk and for folic acid from fortified bread. Folic acid, ingested as food fortificant in bread, was significantly less absorbed compared with an isolated supplement. We conclude that all tested foods were suitable matrices for folate fortification. However, dairy products, fortified with the new candidate fortificant (6S)-5-CH3-H4folate, are suitable if no active FBP is present.

Bioavailability of Praziquantel Increases with Concomitant Administration of Food

ABSTRACT In the present study we found that after a single oral dose of 1,800 mg of praziquantel, following a high-lipid diet and a high-carbohydrate diet, the maximum levels in plasma increased 243 and 515% and the area under the plasma concentration curve from 0 to 8 h increased 180 and 271%, respectively.

Intestinal absorption of undegraded proteins in men: presence of bromelain in plasma after oral intake

The human adult intestinal epithelium has traditionally been described as nonpermeable to proteins. However, indirect evidence suggests that reduced absorption of undegraded proteins might take place under physiological conditions. Using bromelain (an enzyme obtained from pineapple stems) as a model protein, we studied the extent of this mucosal permeation in 19 healthy men. The protein was detected in plasma by immunoassay and by its proteolytic activity after oral administration. The estimated plasma half-life was 6–9 h. After oral multidosing (3 g/day), plasma concentration reached as much as 5,000 pg/ml by 48 h. From the plasma concentration curve, it could be estimated that an average of 10.8 micrograms of bromelain was present in plasma in the 3- to 51-h period. The presence of undegraded bromelain in plasma was shown unequivocally by immunoprecipitation of plasma samples with antibromelain antibodies, followed by gel electrophoresis and immunodetection. Moreover, the enzyme retained its biological activity, at least in part. Circulating bromelain was found associated with alpha 2-macroglobulin and alpha 1-antichymotrypain. The results of this work confirm the existence of a small but significant intestinal transport of undegraded proteins in healthy men.

Kinetics of plasma homocysteine in healthy subjects after peroral homocysteine loading

The kinetics of plasma homocysteine were determined in 13 healthy subjects after peroral administration and in one person after intravenous injection. Various forms of homocysteine completely dissolved in an aqueous solution were rapidly absorbed after peroral administration, and the bioavailability was estimated to be 0.53. The volume of distribution was 0.66 L/kg. The area under the plasma concentration curve (AUC0-48 h) was proportional to the administered dose (33.5-134 mumol/kg body wt), and showed small interindividual variations. Plasma homocysteine showed first-order elimination kinetics for at least 6 h. The half-life (t1/2) was 223 +/- 45 min, and there was a significant correlation between t1/2 values determined on two different occasions in the same individual. The transient hyperhomocysteinemia was associated with an increase in plasma methionine, which probably reflects intracellular remethylation of homocysteine. Less than 2% of the administered homocysteine dose was recovered in the urine. These findings may form the basis for future studies on the regulation of plasma homocysteine in health and disease, and should motivate the evaluation of a homocysteine loading test as a diagnostic tool.

Phase I/II trial of granisetron: a novel 5-hydroxytryptamine antagonist for the prevention of chemotherapy-induced nausea and vomiting.

A new class of antiemetic agents, the 5-hydroxytryptamine (5-HT3) antagonists, have been shown to possess potent antiemetic properties in the ferret model. We conducted a phase I/II trial of the 5-HT3 antagonist BRL43694 (granisetron) in 24 chemotherapy-naïve patients who were receiving any combination of doxorubicin and/or cisplatin. The first 12 patients received 40 micrograms/kg and the second 12 received 80 micrograms/kg of granisetron intravenously before beginning chemotherapy. Nausea was assessed by a patient-completed visual analogue scale and episodes of retching recorded by the patient and an independent observer. Fifty-two percent of the 22 evaluable patients had no retching or vomiting and 32% had no nausea during the first 24 hours after chemotherapy. Pharmacokinetic measurements were performed. The disposition of granisetron was best described using a two-compartment model. The area under the plasma concentration curve (AUC) was 277 +/- 226 ng.h/mL and 359 +/- 282 ng.h/mL at 40 and 80 micrograms/kg, respectively. The total body clearance was 0.319 +/- 0.315 L/kg/hr and 0.483 +/- 0.504 L/kg/hr at the 40 and 80 micrograms/kg doses. Wide interpatient variation in model independent parameters was observed. There was no suggestion of dose-dependent efficacy at the two dose levels studied. We conclude that granisetron shows promise as a well-tolerated and effective antiemetic. Randomized trials comparing this drug with standard regimens are currently underway.

The Constant Blood Withdrawal Method for the Area under the Plasma Concentration Curve

The area under the plasma concentration curve (AUC) was measured after an intragastric administration of either plain or buffered acetylsalicylic acid, using either an intermittent sampling, or the recently introduced constant blood withdrawal method. Six dogs were used in each study. The AUC by the constant withdrawal method was significantly higher than the AUC by the intermittent sampling method. There was no significant difference between the AUC of the plain and buffered acetylsalicylic acid. The higher AUC by the constant withdrawal method was attributed to the inclusion of the initial plasma levels, which is an inherent advantage of the constant blood withdrawal method.