Tribulus terrestris and Sport Performance: A Quantitative and Qualitative Evaluation of Its Advertisement and Availability via Online Shopping in Six Different Countries.

Dietary supplements are commonly used among athletes, and the Internet may be an easy source of these products. Tribulus terrestris is an herbal supplement with multiple properties. Of interest to athletes are reports that its consumption can lead to muscle mass gain and a faster recovery process. The objective of this cross-sectional study was to determine the availability of Tribulus terrestris via the Internet in six countries (Canada, Puerto Rico, Russia, Spain, Ukraine, and the United States of America) via a specifically designed computer program. The characteristics of the websites selling this substance, the country from which it can be purchased, the route of administration, and recommendations for its use were analyzed. The results of the study show that this supplement is marketed mainly in Russia, Ukraine, and Spain on many websites that are mostly dedicated to sports products. Just over half of the webpages (59.14%) identified only distribute this supplement within the same country. The main claims for its consumption refer to sports performance benefits, but there are also claims that it may improve male hormone levels and sexual function. Athletes should be encouraged to seek professional advice prior to ingesting this supplement to ensure that it is suitable for their specific training and sports objectives.

Online information and availability of three doping substances (anabolic agents) in sports: role of pharmacies.

Background: The Internet has become an important source for easy access to doping substances, where people and athletes may acquire, outside pharmacies and without a (medical) prescription. These online websites do not always offer quality-assured products, and are outside the regular distribution channels of medicines. The aim of this study was to estimate the availability and accessible information on the Internet about the sale of three doping substances (oxandrolone, DHEA, androstenedione). Methods: Cross-sectional exploratory study, being an observation at a point in time of the online availability of these three doping substances (WADA S1 category: anabolic agents), purchased from Spain, Puerto Rico, Canada, United States, Ukraine and Russia. The characteristics of the websites, the countries the webs sold to, the pharmaceutical forms offered and the recommendations for its use were analyzed by using a computer tool designed ad hoc. Results: There were significant differences between countries in the number of webpages that sold the products (Chi-square test, p < 0.05). Oxandrolone was available for purchase mainly when buying from Spain (27.12%) and Ukraine (26.58%), in websites dedicated to sports (77.26%). For DHEA, most of the pages offered it if the search was done from Canada (23.34%) and Russia (21.44%). Products containing androstenedione or DHEA are claimed to enhance sports performance or for sports use without providing details. Compared to the total number of websites checked, the proportion of pharmacies offering these products was low, ranging from 4.86% for DHEA to 15.79% for androstenedione. Conclusion: The three substances selected are easily available without control through the Internet. Only a small number of websites offering them were online pharmacies, and requested a prescription. Most of the doping substances are purchased from the country where they are requested. Product information described benefits for sports performance, but did not do the same with their side effects. It would be advisable for these products to be sold through pharmacies, to guarantee their quality and provide evidence-based information on their safe use, benefits and risks, and only with a prescription. Athletes should be encouraged to consult health professionals about those supplements suitable for their type of training and sports objectives.

Pharmacokinetics of menbutone after intravenous and intramuscular administration to sheep.

Menbutone is a drug currently approved in several European Union (EU) countries to treat digestive disorders in different animal species. The objective of this study was to establish the pharmacokinetic parameters resulting from intravenous (IV) and intramuscular (IM) administration of this drug in sheep. Menbutone was administered to 12 animals at the dose of 10 mg/kg for both IV and IM routes. Plasma samples were collected up to 24 h (15 points, IV route; 14 points, IM route). Concentrations were determined using high-performance liquid chromatography with photodiode-array (PDA) detection, following a method validated according to the EMEA/CHMP/EWP/192217/2009 guideline. Pharmacokinetic data were analyzed by non-compartmental methods. After IV administration, a total clearance (Cl) of 63.6 ± 13.6 mL/h/kg, a volume of distribution at steady-state (Vss) of 259.6 ± 52.7 mL/kg, and an elimination half-life (t½λ) of 6.08 ± 2.48 h were calculated. After IM administration, menbutone peak plasma concentration (Cmax) was 18.8 ± 1.9 µg/mL, the time to reach Cmax (tmax) 3.75 ± 0.45 h, the mean absorption time (MAT) 3.31 ± 1.36 h, and the fraction of dose absorbed (F) 103.1 ± 23.0 %. The results obtained indicate that menbutone absorption after IM administration is quick and complete.

Herbs as an Active Ingredient in Sport: Availability and Information on the Internet.

The use of supplements containing herbal active ingredients in sport has increased in recent years. Their consumption is explained by the benefits they may provide and because their natural origin do not involve health complications, from the point of view of the consumers. The aim of this study is to analyze the availability of four supplements (caffeine, turmeric, ginseng, cannabidiol) on the internet and understand the nature of these websites. A descriptive, observational, and cross-sectional study design was used. A detailed search was carried out with specifically developed software. The searches and data evaluation took 10 days. The websites consulted correspond to those that sell supplements, or some sport websites in the case of the Spanish ones, whereas those in English belong to pharmacies, parapharmacies, or herbalists. It is concluded that the websites do not provide adequate information to ensure proper consumption and lack advice on the choices of supplements and their administration guidelines.

Improvement of Albendazole Bioavailability with Menbutone Administration in Sheep.

The pharmacokinetic interaction between a benzimidazole (albendazole, ABZ) and a choleretic drug (menbutone, MEN) was evaluated in sheep. The plasma disposition of albendazole sulfoxide (ABZSO, active metabolite) and albendazole sulfone (ABZSO2, inactive metabolite) was investigated following an oral administration of albendazole (ABZ) (5 mg/kg) alone or with menbutone (MEN) (intramuscular, 10 mg/kg). Blood samples were collected over 3 days post-treatment, and drug plasma concentrations were measured by high performance liquid chromatography (HPLC). ABZSO was measured from 0.5 to 48 h, and ABZSO2 from 2 to 60 h. No parent drug was detected at any sampling time. Mean maximum plasma concentration (Cmax) and the area under the plasma concentration-time curve (AUC) were 12.8% and 21.5% higher for ABZSO when ABZ and MEN were administered together, which indicates a significant increase in the amount absorbed. The rate of absorption was not modified, with similar values for the time to reach Cmax (tmax) (11.5 h with ABZ + MEN and 10.7 h with ABZ treatment), although no significant differences were observed for these latter pharmacokinetic parameters. Regarding ABZSO2, Cmax, AUC and tmax values were similar after both treatments (ABZ or ABZ + MEN). The results obtained indicate that co-administration of ABZ and MEN may be an interesting and practical option to increase the efficacy of this anthelmintic.

Use of medicinal plants by veterinary practitioners in Spain: A cross-sectional survey.

Medicinal plants have been used in veterinary medicine since ancient times, and they are gaining importance in Eastern Europe. The aim of this study was to conduct a survey on the use of medicinal plants in Spain. A cross-sectional study with an online questionnaire was carried out among Spanish small animal veterinarians, to evaluate the use patterns of medicinal plants and attitudes of professionals toward it. 313 veterinarians took part in the study. Most of them were female (80.2%) and age ranged 35-49 (49.5%). 80.3% of respondents use phytotherapy. Musculoskeletal and gastrointestinal disorders were those most frequently treated, with cannabis, aloe and thyme the most often medicinal plants used. The most common pattern of user was women working in clinics.

Distribution of Flumequine in Intestinal Contents and Colon Tissue in Pigs after Its Therapeutic Use in the Drinking Water.

Flumequine concentrations in plasma, colon tissue and intestinal contents were evaluated in 12 healthy pigs after oral administration (12 mg/kg every 24 h for 5 consecutive days in drinking water). Plasma, colon tissue and intestinal content samples were collected from animals sacrificed on days 3, 6 and 7. Concentrations were measured by high performance liquid chromatography after having validated the method, following the European Medicines Agency (EMA) requirements. The drug was not detected in any plasma sample. In colon tissue, concentrations were higher on day 3 (0.230 ± 0.033 µg/g, descending colon; 0.156 ± 0.093 µg/g, ascending colon) than on day 6 (0.187 ± 0.123 µg/g, descending colon; 0.107 ± 0.007 µg/g, ascending colon). Concentrations were considerably higher in intestinal contents, again on day 3 (1.349 ± 1.401 µg/g, descending colon; 0.591 ± 0.209 µg/g, ascending colon) than on days 6 (0.979 ± 0.346 µg/g, descending colon; 0.595 ± 0.075 µg/g, ascending colon) and 7 (0.247 ± 0.172 µg/g, descending colon; 0.172 ± 0.086 µg/g, ascending colon). Measured concentrations were lower than those effective against the most common intestinal pathogenic microorganisms in swine and, more specifically, Brachyspira hyodysenteriae.

Availability of Antibiotics for Veterinary Use on the Internet: A Cross-Sectional Study.

The misuse or overuse of antibiotics can favor the emergence of antimicrobial resistance, with a direct impact on human and animal health as well as on ecosystems. In this work, we have analyzed the web pages in which antibiotics for veterinary use can be purchased online. By using a specifically developed software, we carried out a detailed search to know if each individual antibiotic and the families included in the OIE list of antimicrobial agents of veterinary importance (in English and in Spanish) were sold, reviewing the offers according to the administration route and the species for which the antibiotics were intended. The greatest offer of antibiotics was for those compounds considered critically important by OIE. In the search in English, penicillins were available on 55.8% of the sites, tetracyclines on 55.0%, and fluoroquinolones on 52.7%. In Spanish, the families with the greatest presence were fluoroquinolones (67.9% of the sites), tetracyclines (67.9% of the sites), and penicillins (65.4% of the sites). Regarding individual antibiotics, the most offered in both searches were amoxicillin (49.6% of the sites in English and 57.7% in Spanish) and doxycycline (46.5% of the sites in English and 53.8% in Spanish). Most offers were for oral and parenteral administration and intended for cats and dogs and for bovines.

The Online Sale of Antibiotics for Veterinary Use.

Antibiotics are essential medicines against infectious diseases in both humans and animals. An inappropriate use of antibiotics can impair animal health and enhance the risk of bacterial resistance, as well as its transfer from animals to humans. The objective of this study was to assess the possibility of purchasing antibiotics for veterinary use on the internet, to evaluate if a prescription is required, and to determine the availability of drugs classified as the highest priority critically important antimicrobials (HP-CIA). The Google and Bing search engines and both simple and complex search strings in Spanish and in English were used. The simple search string was "buy veterinary antibiotics". Complex searches used wildcards and specific syntax. The searches carried out in Spanish revealed that 50% of websites operated in South America, and 65% of websites did not require a valid prescription. Fluoroquinolones were offered in 84% of these websites (45% without prescription), macrolides were offered in 63% of these websites (43% without prescription), and 3rd- and 4th-generation cephalosporins in 54% of these websites (38% without prescription). For the searches in English, 57% of these websites operated in the United States of America (USA), and 55% of them did not require a prescription. Fluoroquinolones were offered in 79% of these websites (49% without prescription), macrolides were offered in 72% of these websites (45% without prescription), and 3rd- and 4th-generation cephalosporins were offered in 49% of these websites (27% without prescription). Therefore, it is easy to illegally access antibiotics via the internet.

Assessment of the Antioxidant/Hypolipidemic Relationship of Sideritis hyssopifolia in an Experimental Animal Model.

Many publications have described the potential cardioprotective action of different medicinal plants, relating this effect with blood lipid levels. However, these publications do not justify the right amount of plant administered, which can vary greatly. Sideritis hyssopifolia is a little woody plant endemic to western and southwestern Europe. We have quantified its antioxidant activity, which can be used as an indicator of its cardioprotective action. This study evaluates the antioxidant capacity of Sideritis hyssopifolia to design a feed whose hypolipidemic effects are proven in cholesterol-fed New Zealand rabbits. Antioxidant action was assessed in infusions, which were prepared with 1 or 3 g of plant in 200 mL of water by using an ABTS assay and expressed as Ascorbic acid Equivalent Antioxidant Capacity (AEAC). Aqueous infusions with infusion times of 10 min and prepared with 3 g plant exhibited the strongest antioxidant activity. Sideritis hyssopifolia showed an intermediate antioxidant capacity for the concentrations and times of the infusion tested. According to our results, we suggest incorporating 2.36 g of S. hyssopifolia every 150 g of rabbit feeding stuff (15.73 g/kg). This chow decreased cholesterol, HDL-cholesterol, LDL-cholesterol, and triglycerides levels in cholesterol-fed rabbits, as well as the atherogenic index. This reduction was similar to that obtained with simvastatin.

Hypoglycemic and hypolipidemic potential of a high fiber diet in healthy versus diabetic rabbits.

The aim of this study was to investigate potential hypoglycaemic and hypolipidemic effects of Plantago ovata husk included in the diet, in healthy and diabetic rabbits. We also examined the effects of this fiber in other biochemical parameters. Two groups of 18 rabbits were used. The first group was fed with standard chow and the second with chow supplemented with Plantago ovata husk (3.5 mg/kg/day). On day 14 diabetes mellitus was induced by the intravenous administration of alloxan (80 mg/kg). After an oral glucose load (3 g), glucose, insulin, and other biochemical parameters were determined on day 14 (healthy rabbits) and on day 28 (diabetic rabbits). In healthy rabbits, fiber did not modify glucose or insulin levels but decreased significantly total cholesterol, LDL-cholesterol, atherogenic index, and glycosylated hemoglobin. In diabetic rabbits, fiber was more beneficial in mild diabetics than in severe diabetics with significant decreases in glucose levels and increases in insulin concentrations. In these animals fiber caused an important reduction in cholesterol, indicating a beneficial effect of Plantago ovata husk in diabetic rabbits. Although further studies in patients are necessary, we think that Plantago ovata husk offers interesting perspectives to be administered to patients with diabetes mellitus.

Effects of slowed gastrointestinal motility on levodopa pharmacokinetics.

Autonomic disorders are often seen in Parkinson's disease, with disturbances of the gastrointestinal tract occurring most frequently. These disorders, mainly a delay in gastric emptying and slowed gastrointestinal motility, can modify the pharmacokinetics and effectiveness of drugs used to treat Parkinson's disease and administered orally. In this study, we evaluated in a rabbit model the pharmacokinetics of levodopa (administered with carbidopa) in the context of gastrointestinal motility slowed by the administration of an anticholinergic drug. Levodopa+carbidopa (20:5mg/kg) and the anticholinergic biperiden (100 microg/kg) were orally administered to rabbits over one of two time periods (7 or 14 days) to verify the stabilization of levodopa concentrations. The values of the area under the curve (AUC) and C(max) were higher on the final day of treatment with an increase in AUC of 25% on day 7 and 33.4% on day 14; for C(max), the increase was 15% on day 7 and 12.8% on day 14. The values of AUC and C(max) were lower than those obtained when levodopa was administered to rabbits with normal gastrointestinal motility. The values obtained for C(min) (baseline sample obtained before administration) also increased with treatment duration (24% and 47.4% on days 7 and 14, respectively). These values were higher than those obtained in the absence of anticholinergic administration. We conclude that, under our experimental conditions of slowed gastrointestinal motility, levodopa absorption diminishes, and final concentrations and C(min) are higher than under conditions of normal motility.

Effects of Plantago ovata husk on levodopa (with Carbidopa) bioavailability in rabbits with autonomic gastrointestinal disorders.

Gastrointestinal dysfunction is common in Parkinson's disease. Fiber therapy could be used to reduce the symptoms of gastrointestinal motility disorders. In a previous study, we showed that slowed gastrointestinal motility modified levodopa pharmacokinetics: area under the plasma concentration-time curve (AUC) and maximum plasma concentration (C(max)) decreased and the elimination was delayed. In this study, we evaluated whether or not the hydrosoluble fiber Plantago ovata husk is useful in improving levodopa pharmacokinetics in rabbits with autonomic gastrointestinal disorders induced by the administration of the anticholinergic biperiden. Levodopa + carbidopa (20:5 mg/kg), biperiden (100 microg/kg), and P. ovata husk (at two different doses: 100 and 400 mg/kg) were administered orally to rabbits for two periods of time (7 or 14 days). In all groups of animals, the AUC values were approximately 50% higher on the final day of treatment than on day 1. C(max) was also higher, with the greater increase at the 400 mg/kg dose of fiber, which resulted in a boost of approximately 35%. On day 1 of treatment and with both doses of fiber, AUC values were very similar to those obtained in previous work in rabbits with normal gastrointestinal motility, but the C(max) was lower. However, after 7 or 14 days, the AUC values were higher, but C(max) remained lower. The greatest differences were observed in plasma concentration before drug administration (C(min)), for which the highest increase was obtained with the dose of 400 mg/kg fiber on day 14 of treatment (349.8%). P. ovata husk could be beneficial in patients with Parkinson's disease because it regulates stool transit in the intestine and because it improves levodopa pharmacokinetics when gastrointestinal peristalsis is slowed. These changes could lead to a possible delay in the onset of dyskinesias and to changes in prognosis.

Pharmacokinetics of doxycycline in sheep after intravenous and oral administration.

The pharmacokinetics of doxycycline were investigated in sheep after oral (PO) and intravenous (IV) administration. The IV data were best described using a 2- (n = 5) or 3- (n = 6) compartmental open model. Mean pharmacokinetic parameters obtained using a 2-compartmental model included a volume of distribution at steady-state (V(ss)) of 1.759+/-0.3149L/kg, a total clearance (Cl) of 3.045+/-0.5264mL/kg/min and an elimination half-life (t(1/2beta)) of 7.027+/-1.128h. Comparative values obtained from the 3-compartmental mean values were: V(ss) of 1.801+/-0.3429L/kg, a Cl of 2.634+/-0.6376mL/kg/min and a t(1/2beta) of 12.11+/-2.060h. Mean residence time (MRT(0-infinity)) was 11.18+/-3.152h. After PO administration, the data were best described by a 2-compartment open model. The pharmacokinetic parameter mean values were: maximum plasma concentration (C(max)), 2.130+/-0.950microg/mL; time to reach C(max) (t(max)), 3.595+/-3.348h, and absorption half-life (t(1)/(2k)(01)), 36.28+/-14.57h. Non-compartmental parameter values were: C(max), 2.182+/-0.9117microg/mL; t(max), 3.432+/-3.307h; F, 35.77+/-10.20%, and mean absorption time (MAT(0-infinity)), 25.55+/-15.27h. These results suggest that PO administration of doxycycline could be useful as an antimicrobial drug in sheep.

The hydrosoluble fiber Plantago ovata husk improves levodopa (with carbidopa) bioavailability after repeated administration.

The influence of treatment duration (7 or 14 days) with Plantago ovata husk/levodopa/carbidopa in the bioavailability and other pharmacokinetic parameters of levodopa were evaluated in rabbits. Fiber was administered at two different doses, 100 and 400 mg/kg, and the dosage of levodopa/carbidopa was 20:5 mg/kg. These doses were administered once a day. When 100 mg/kg of fiber was administered, the mean AUC value obtained for levodopa increased 20.2% from day 1 to day 7, and 27.2% from day 1 to day 14; C(max) was 8.6% higher on day 7 and 11.7% higher on day 14. When administering 400 mg/kg of fiber, the increase in AUC values was 17.6% on day 7 and 24.9% on day 14, and that of C(max) 11.1% on day 7 and 11.3% on day 14. The concentration determined immediately before drug administration (C(min)) increased progressively with the duration of treatment, and the highest increase (53.2%) was observed on day 14 with 100 mg/kg of fiber. There was also a delay in levodopa elimination (higher MRT and lower Cl) in a fiber-dose dependent manner. In summary, we found that there was an improvement in the extent of levodopa absorbed with higher final concentrations and that levodopa elimination was slower with the administration of P. ovata husk.

Bioavailability of a commercial formulation of ivermectin after subcutaneous administration to sheep.

OBJECTIVE: To evaluate bioavailability and other pharmacokinetic variables of a commercial formulation of ivermectin after IV administration to sheep. ANIMALS: 6 healthy adult sheep. PROCEDURES: A single dose of a commercial formulation of ivermectin (200 microg/kg) was administered IV to each sheep. After a washout period of 3 weeks, each sheep was administered ivermectin by SC injection. Plasma samples were obtained for up to 36 and up to 42 days after IV and SC administration, respectively. Ivermectin concentrations were quantified by use of high-performance liquid chromatography with fluorescence detection. RESULTS: Results obtained indicated that after IV administration, ivermectin is cleared slowly from plasma, tends to distribute and accumulate in the peripheral compartment, and is slowly eliminated from the body. After SC administration, noncompartmental analysis revealed that bioavailability of ivermectin is nearly complete (98.20%), has a slow mean absorption time of 0.96 days, and reaches a maximum plasma concentration of 19.55 ng/mL at 3.13 days. CONCLUSIONS AND CLINICAL RELEVANCE: The commercial formulation of ivermectin used in this study can be administered SC to sheep on the basis of a nearly complete bioavailability. In addition, the maximum plasma concentration and interval from SC injection until maximum plasma concentration is obtained are higher than those reported by other authors who used other routes of administration.

Pharmacokinetics of a novel formulation of ivermectin after administration to goats.

OBJECTIVE: To evaluate the pharmacokinetics of a novel commercial formulation of ivermectin after administration to goats. ANIMALS: 6 healthy adult goats. PROCEDURE: Ivermectin (200 microg/kg) was initially administered IV to each goat, and plasma samples were obtained for 36 days. After a washout period of 3 weeks, each goat received a novel commercial formulation of ivermectin (200 microg/kg) by SC injection. Plasma samples were then obtained for 42 days. Drug concentrations were quantified by use of high-performance liquid chromatography with fluorescence detection. RESULTS: Pharmacokinetics of ivermectin after IV administration were best described by a 2-compartment open model; values for main compartmental variables included volume of distribution at a steady state (9.94 L/kg), clearance (1.54 L/kg/d), and area under the plasma concentration-time curve (AUC; 143 [ng x d]/mL). Values for the noncompartmental variables included mean residence time (7.37 days), AUC (153 [ng x d]/mL), and clearance (1.43 L/kg/d). After SC administration, noncompartmental pharmacokinetic analysis was conducted. Values of the variables calculated by use of this method included maximum plasma concentration (Cmax; 21.8 ng/mL), time to reach Cmax (3 days), and bioavailability (F; 91.8%). CONCLUSIONS AND CLINICAL RELEVANCE: The commercial formulation used in this study is a good option to consider when administering ivermectin to goats because of the high absorption, which is characterized by high values of F. In addition, the values of Cmax and time to reach Cmax are higher than those reported by other investigators who used other routes of administration.

Hydrosoluble fiber (Plantago ovata husk) and levodopa I: experimental study of the pharmacokinetic interaction.

Fiber therapy could be used in patients with Parkinson disease to reduce the symptoms of gastrointestinal disorders; however, it could interact with levodopa reducing its effectiveness. In this experimental study we have investigated whether the presence of Plantago ovata husk (water-soluble fiber) modifies in rabbits the bioavailability and other pharmacokinetic parameters of levodopa (20 mg/kg) when administered by the oral route at the same time. We have also studied whether pharmacokinetic modifications are fiber-dose dependent (100 and 400 mg/kg). The extent of levodopa absorbed when administering 100 mg/kg of fiber (AUC=43.4 mug min ml(-1)) is approximately the same as when levodopa is administered alone (AUC=47.1 microg min ml(-1)); however, Cmax is lower (1.04 versus 1.43 microg ml(-1)). Results obtained indicate that fiber at the higher dose increases the extent of levodopa absorbed (AUC=62.2 microg min ml(-1)), being the value of Cmax similar (1.46 microg ml(-1)). The value of tmax increases from 10 min when levodopa is administered alone to 20 min when the animals receive fiber. On the other hand, since certain time on, levodopa concentrations are always higher in the groups that receive fiber: 60 min with 100 mg/kg fiber and 20 min with 400 mg/kg fiber. Fiber also increases the mean residence time (MRT). P. ovata husk administration with levodopa could be beneficial, not only in patients with constipation, due to: lower adverse reactions (lower values of Cmax) and longer and more stable effects (higher final concentrations and more time in the body).

Hydrosoluble fiber (Plantago ovata husk) and levodopa II: experimental study of the pharmacokinetic interaction in the presence of carbidopa.

Levodopa combined with carbidopa constitutes one of the most frequent medication in the treatment of Parkinson's disease. Plantago ovata husk (water-soluble fiber) improves levodopa absorption conditions, but when this drug is administered with carbidopa, fiber could reduce its effectiveness. The purpose of this study is to investigate whether the presence of P. ovata husk modifies in rabbits the bioavailability and other pharmacokinetic parameters of levodopa (20 mg/kg) when administered by the oral route with carbidopa (5 mg/kg). We have also studied whether pharmacokinetic modifications are fiber-dose dependent (100 and 400 mg/kg). When levodopa and carbidopa were administered with 100 mg/kg P. ovata husk, the value of AUC for levodopa diminishes 29.7% (sign, n=6, P<0.05) and Cmax 28.1% (sign, n=6, P<0.05) in relation to the values obtained when these drugs were administered without fiber. If the dose of fiber was 400 mg/kg, the decrease was smaller: 20.4% for AUC (no significant difference) and 24.6% for Cmax (sign, n=6, P<0.05), that may indicate an inhibitory action of AADC by the fiber or any of its partial hydrolysis products. On the other hand, since certain time on, levodopa concentrations are always higher in the groups that receive fiber: 210 min with 100 mg/kg and 150 min with 400 mg/kg. The administration of P. ovata husk with levodopa/carbidopa to patients with Parkinson disease could be beneficial and in particular in those patients who also suffer constipation due to an improvement of levodopa kinetic profile with higher final concentrations, a longer plasma half-life and lower Cmax.

Effect of glucomannan and the dosage form on ethinylestradiol oral absorption in rabbits.

To the beneficial properties of dietary fiber in human health, several disadvantages can be added as the possible modification of the bioavailability of other drugs when administered by the oral route. In this study, the influence of glucomannan in the oral bioavailability of ethinyl estradiol (EE), when administered to female rabbits in two different dosage forms (enteric capsules and dispersed in water), was established. To carry out the study, three groups of six animals each were used. All animals received 1 mg kg(-1) oral EE, and rabbits in groups 2 and 3 received 1.5 g glucomannan dispersed in water or in enteric capsules, respectively, immediately before EE. When comparing the results obtained after the administration of EE/glucomannan dispersed in water with those obtained after the administration of this estrogen without fiber, we can see that Cmax is 1.4 times lower, AUC 1.9 times lower and that tmax is identical (10 min). However, after the administration of fiber in enteric capsules, AUC and Cmax are higher (4.1 and 7.8 times, respectively) than when the estrogen was administered alone, and also, there is a delay in tmax (20 min). After the administration of glucomannan in the enteric capsule, the fiber forms, as in the stomach, a highly viscous solution in the gut that would limit EE access to the mucosal surface delaying its absorption. However, this effect could be compensated by a reduction of EE metabolism in the intestinal wall, leading to a higher absorption of the estrogen.