Bioavailability Of Single Dose Research Articles

Effect of Lactobacillus sporogenes on oral isoflavones bioavailability: single dose pharmacokinetic study in menopausal women

To verify the single dose bioavailability of two oral formulations of soy isoflavones, with and without lactobacilli, in menopausal women in antibiotic therapy. Twelve menopause women (mean age 54.3 years, BMI 25.0 kg/m2) participated in a controlled cross-over study. Reference and test treatments were: R = tablets containing soy isoflavones 60 mg (genistin 30 mg + daidzin 30 mg) + calcium and vitamin D3; E = R + 500 million vital spores of Lactobacillus sporogenes (E is Estromineral, a food supplement containing soy isoflavones 60 mg, calcium 141 mg and vitamin D3 5 microg). The design included 2 periods of 5 days of amoxicillin + clavulanate treatment with a 2-week wash-out. After each period alternatively a single dose of each formulation was given in randomised sequence. Genistein and daidzein were determined in plasma by HPLC, sampled 10 times within 24 h after dosing. Genistein pharmacokinetics parameters were higher after E than after R administration: peak plasma concentration (Cmax) +24.3%, area under the concentration curve (AUC0-24) +24.4% and mean residence time +11.0%. Daidzein Cmax and AUC showed a larger variability on R, evidenced by higher scatter from the mean on the formulation without lactobacilli. A trend is shown for a greater absorption of genistein from a formulation containing lactobacilli.

Superior calcium bioavailability of effervescent potassium calcium citrate over tablet formulation of calcium citrate after Roux-en-Y gastric bypass

BackgroundCalcium supplementation is commonly recommended for patients after Roux-en-Y gastric bypass to avert bone loss. To test the hypothesis that effervescent (liquid) potassium-calcium-citrate (PCC) might be more bioavailable than a tablet formulation of calcium citrate (Citracal Petite), the present study compared a single dose response of the 2 compounds. The present study was conducted at the University of Texas Southwestern Medical School at Dallas. MethodsA total of 15 patients who had undergone Roux-en-Y gastric bypass were included in a 2-phase, crossover, randomized study comparing the single-dose bioavailability of PCC versus Citracal Petite. After following a restricted diet for 1 week, the participants ingested either a single dose of 400 mg elemental calcium as PCC or Citracal Petite. Sequential serum and urine samples were collected for a 6-hour period after the dose and analyzed for calcium, parathyroid hormone, and acid-base parameters. ResultsCompared with citracal petite, PCC significantly increased the serum calcium concentrations at 2, 3, and 4 hours after the oral load. The peak to baseline variation and increment in serum calcium (area under the curve) were significantly greater after PCC (P = .015 and P = .002, respectively). Concurrently, the baseline to nadir variation and decrement in serum parathyroid hormone (area over the curve) were significantly greater after PCC (P = .004 and P = .005, respectively). Moreover, compared with Citracal Petite, PCC caused a significantly greater increment in urinary citrate (P < .0001) and potassium (P = .0004) and a significantly lower increase in urinary ammonium (P = .045). ConclusionIn patients who have undergone Roux-en-Y gastric bypass, PCC was superior to Citracal Petite in conferring bioavailable calcium and suppressing parathyroid hormone secretion. PCC also provided an alkali load.

Bioavailability of Phytochemical Constituents From a Novel Soy Fortified Lycopene Rich Tomato Juice Developed for Targeted Cancer Prevention Trials

Studies suggest that tomato and soy foods may contribute to a lower risk of certain cancers. We developed a novel soy germ tomato juice to be used in controlled cancer prevention trials. This study describes an initial test of compliance, phytochemical bioavailability, and effects on biomarkers of blood lipids. Healthy men and women (n = 18) consumed a soy germ-fortified juice daily (300 mL supplying 66 mg isoflavones and 22 mg lycopene) for 8 wk. A single-dose bioavailability study was completed on day 1 and isoflavones in plasma and urine, and lycopene in the plasma, were measured. All subjects completed the trial, with 97.7% ± 3.5% (mean ± SD) of the scheduled juice consumed. No adverse effects were documented. The postprandial study indicated that 3.1% ± 2.3% of lycopene was absorbed and that 49.3% ± 12.1% isoflavones ingested were recovered in 24-h urines. Lycopene plasma concentration changed from 0.60 ± 0.22 to 1.24 ± 0.30 μmol/L during 8 wk of consumption. Juice consumption significantly improved resistance of LDL+VLDL-C to Cu2+-mediated oxidation (P = 0.039), HDL-C (47.3 ± 15.8 to 51.7 ± 14.8 mg/dL, P < 0.001), and the ratio of total-C/HDL-C (4.25 ± 1.59 to 3.63 ± 1.16, P < 0.001) at 8 wk. A well-characterized soy-fortified tomato juice can be produced in large scale for multiinstitutional long-term cancer prevention trials and showed excellent compliance with no toxicity, while demonstrating absorption of biologically active phytochemicals.

Pharmacokinetics of Solithromycin (CEM-101) after Single or Multiple Oral Doses and Effects of Food on Single-Dose Bioavailability in Healthy Adult Subjects

The pharmacokinetics of orally administered solithromycin (CEM-101), a novel fluoroketolide, were evaluated in healthy subjects in three phase 1 studies. In two randomized, double-blinded, placebo-controlled studies, escalating single oral doses of solithromycin (50 to 1,600 mg) or seven oral daily doses (200 to 600 mg) of solithromycin were administered. A third study evaluated the effects of food on the bioavailability of single oral doses (400 mg) of solithromycin. Following single doses, the median time to peak concentration (Tmax) ranged from 1.5 h to 6 h. The mean maximum measured plasma concentration (Cmax) ranged from 0.0223 μg/ml to 19.647 μg/ml, and the area under the concentration-versus-time curve from time zero to time t (AUC0-t) ranged from 0.0402 μg·h/ml to 28.599 μg·h/ml. There was no effect of high-fat food on the oral bioavailability of solithromycin. In the multiple-dose study, after 7 days, the mean maximum measured plasma solithromycin concentration at steady-state (Cmax,ss) ranged from 0.248 to 1.50 μg/ml, and the area under the concentration-versus-time curve over the final dosing interval (AUCτ) ranged from 2.310 to 18.41 μg·h/ml. These values indicate a greater than proportional increase in exposure at 200 and 400 mg but a proportional exposure at 600 mg. Median Tmax values remained constant between day 1 and day 7. Moderate accumulation ratios of solithromycin were observed after 7 days of dosing. All dose regimens of solithromycin were well tolerated, and no discontinuations due to an adverse event occurred. The human pharmacokinetic profile and tolerability of solithromycin, combined with its in vitro potency and efficacy in animal models against a broad spectrum of pathogens, support further development of solithromycin.

Food effects on the pharmacokinetics of morphine sulfate and naltrexone hydrochloride extended release capsules

Morphine sulfate and naltrexone hydrochloride extended release capsules, indicated for chronic moderate-to-severe pain, contain extended-release morphine pellets with a sequestered naltrexone core. If pellets are tampered by crushing, naltrexone is released to reduce morphine-induced effects that appeal to opioid abusers. The primary objective of this study was to assess single-dose relative bioavailability of morphine when morphine sulfate and naltrexone hydrochloride extended release capsules were taken under fed and fasting conditions and when pellets were sprinkled on apple sauce. This was a single-center, randomized, open-label study in 36 healthy adult volunteers. Subjects took a 100-mg morphine sulfate and naltrexone hydrochloride extended release capsule intact with 240 mL water, under fed and fasted conditions, and when the capsule was opened and pellets were sprinkled over apple sauce and consumed without chewing; each treatment was separated by a 14-day washout. Plasma samples were collected just before dosing through 72 hours postdose for pharmacokinetic analyses of morphine, and through 168 hours postdose for naltrexone and its major metabolite 6-β-naltrexol. Morphine bioavailability was similar for all treatments. There was a lack of sprinkle effect (sprinkle vs. whole, fasted); 90% confidence intervals (CIs) of ratios of log-transformed least squares means for area under the plasma concentration-time curve (AUC) and peak plasma concentration (C(max)) fell within 80%-125% boundaries. For the food effect, 90% CIs were within the boundaries for AUC, but C(max) was reduced and time to C(max) was delayed by 2.5 hours under fed conditions. Naltrexone remained sequestered under all treatment conditions with only trace systemic exposure. Results indicated that morphine sulfate and naltrexone hydrochloride extended release capsules can be administered without regard to meals, and contents can be sprinkled over apple sauce and consumed without chewing by patients with difficulty swallowing.

A comparative bioavailability study of two formulations of itraconazole 100 mg capsule in healthy human Indian subjects under fasting conditions

The objective of the study was to evaluate the effect of time of administration of food post-dosing on the oral bioavailability of two formulations of itraconazole 100 mg capsule in 24 healthy adult Indian subjects under fasting conditions. Three different paradigms for time of administrations of food post-dose were selected: 4 h, 5 h, and 6 h. A randomized two-treatment, four-period, three-sequence, single dose bioavailability study was conducted. After dosing, serial blood samples were collected for up to 72 h. Plasma samples were analyzed for Itraconazole (ITZ) and its metabolite Hydroxy Itraconazole (OH-ITZ) by a sensitive and validated simultaneous liquid-chromatographic and mass-spectrometric (LC-MS/MS) method. A comparison of effect of post-dose fasting up to 4 h, 5 h, and 6 h on pharmacokinetic parameters of the two formulations was done, and it was found that pharmacokinetic parameters (Cmax, AUC0–t, AUC0–∞, Tmax) were consistent for both formulations in all the paradigms tested. This result sugg...

A Comparison of the pharmacokinetics of the anticancer MET inhibitor foretinib free base tablet formulation to bisphosphate salt capsule formulation in patients with solid tumors

This phase I, open-label, randomized, 2-part crossover study assessed the safety, pharmacokinetics and relative bioavailability of single doses of the anticancer MET inhibitor foretinib (formerly known as GSK1363089, EXEL-2880 and XL-880) free base tablet formulation compared to a bisphosphate salt capsule formulation (Part 1), and assessed the safety, efficacy, and pharmacokinetics of the bisphosphate salt capsule administered 3 times a week in cancer patients (Part 2). In Part 1, patients were randomized in a crossover manner to receive a single oral dose of foretinib formulated as a bisphosphate salt capsule (240 mg; 183 mg free base equivalent) followed one week later by a single dose of a free base tablet (180 mg), or vice versa where the treatment sequence was reversed. In Part 2, patients self-administered oral doses of bisphosphate salt capsules (200 mg) 3 times a week until disease progression. Twelve patients with solid tumors were enrolled and completed Part 1, and 10 patients continued into Part 2. Most AEs were mild or moderate in severity. The most common drug-related AEs were fatigue, diarrhea, and nausea. The least-squares (LS) mean total area under the curve was 3144 and 3514 ng*h/mL for the free base tablet and bisphosphate salt capsule, respectively, with a ratio of 0.89 (90% confidence interval, CI: 0.69, 1.16). The LS mean maximal concentration (Cmax) was 81.6 and 98.5 ng/mL for the free base and bisphosphate salt, respectively, with a ratio of 0.83 (90% confidence interval, CI: 0.67, 1.02). The time to reach Cmax was ∼4 h for both formulations. The pharmacokinetics of foretinib were not clinically different between the 2 formulations. Of the 10 patients assessed for efficacy, 3 patients achieved stable disease. Foretinib was well tolerated as single doses of both the free base and bisphosphate salt formulations. The pharmacokinetics and relative bioavailability of the 2 formulations were not clinically different. The bisphosphate salt formulation was well tolerated on a 3-times a week dosing schedule, and reached steady-state plasma concentration after 2 weeks.

Plasma folate concentrations after a single dose ingestion of whole and skimmed folic acid fortified milks in healthy subjects

Since mandatory folic acid fortification of grains and cereals was introduced in order to prevent neural tube defects, the number of products that are being fortified with folic acid is growing, especially milk and dairy products. However, the effectiveness of this action remains controversial. To investigate the efficiency of skimmed milk as a vehicle for folic acid fortification by the determination of the acute absorption from low-fat fortified milk compared to fortified and unfortified whole milk in healthy subjects. A single-dose bioavailability study was performed using three commercially available milks (whole and skimmed milk fortified with folic acid and unfortified whole milk). Healthy volunteers (3 women, 2 men) were administered a single dose of 430ml of each milk, at 1-week intervals between test days. Plasma total folate concentrations, at baseline and hourly from 1.5 up to 6.5h after ingestion, were measured. Plasma folate concentration was significantly increased, when compared to baseline values, 1.5h after ingestion of skimmed fortified milk, and 2.5h after whole fortified milk, and remained significantly higher than baseline values for up to 6.5h after both treatments. The highest plasma folate concentration (20.9±3.1nmol/l) was obtained 6.5h postprandial in response to skimmed fortified milk. The acute absorption of folic acid, calculated on the basis of area under the plasma folate concentration curve, was significantly higher from skimmed fortified milk compared to fortified and unfortified whole milk. The absorption of folic acid from fortified skimmed milk is faster than the absorption of folic acid from fortified whole milk, and it renders significantly higher plasma folate concentration when compared to whole milk. These findings indicate that skimmed milk could be considered an efficient food matrix for folic acid fortification.

Oral ileocolonic drug delivery by the colopulse-system: A bioavailability study in healthy volunteers

The release profile of a novel oral ileocolonic drug delivery technology (ColoPulse-technology) was assessed by a combination of conventional kinetics of a marker substance in blood and site-specific signaling by stable isotope technology. Since ileocolonic delivery involves the drug release in a region in which bacteria are highly present, a prolonged lag time should coincide with proven bacterial enzyme activity. The latter can be tested using 13C-urea as the marker substance. The study was designed as a two period (uncoated versus coated capsule) crossover single dose bioavailability study in healthy subjects. The 13C-recovery data after oral administration of 13C-urea using the ColoPulse delivery system showed a delayed sigmoid release in all subjects with a lag time of > 3 h (median: 330 min.). Release was achieved in a urease-containing intestinal segment in all healthy subjects. Complete release in the ileocolonic region was achieved in 10 of 11 subjects. The ColoPulse-technology therefore enables specific and reliable drug delivery in the ileocolonic region in healthy volunteers.

An open‐label, single‐dose bioavailability study of the pharmacokinetics of CAT‐354 after subcutaneous and intravenous administration in healthy males

To assess the bioavailability and pharmacokinetics of CAT-354, an anti-IL-13 human monoclonal IgG4 antibody, following subcutaneous (s.c.) and intravenous (i.v.) administration. This was a single-dose, randomized, open-label, parallel-group bioavailability study. Healthy male subjects aged 20-54 years were randomly assigned to one of three dose groups (n= 10/group) to receive CAT-354: 150 mg i.v.; 150 mg s.c. or 300 mg s.c. (two 150 mg injections). Serum pharmacokinetics, adverse events (AEs), vital signs, electrocardiograms and laboratory parameters were assessed. CAT-354 showed bioavailability of 62% and 60% after 150 mg and 300 mg s.c. doses, respectively, and linear pharmacokinetics over the dose range tested. Peak serum concentrations in the s.c. groups occurred after 3-9 (median 5) days, with a mean elimination half-life of 19.2 +/- 3.1 days (150 mg) and 19.4 +/- 3.59 days (300 mg) after s.c. and 21.4 +/- 2.46 days after i.v. administration. Volume of distribution at steady state (V(ss)) was 4960 +/- 1440 ml kg(-1) after i.v. (slightly greater than plasma volume). Average apparent clearances (CL/F) were 292 +/- 82.3 and 307 +/- 109 ml day(-1) after 150 and 300 mg s.c., respectively; systemic CL of 188 +/- 84.0 ml day(-1) after i.v. dosing was consistent with endogenous IgG and reticuloendothelial elimination. No severe or serious AEs occurred. Among 40 reported AEs, 25 were headache, sinus disorders/respiratory symptoms and changes in body temperature perception. CAT-354 exhibited bioavailability of approximately 60% when given s.c. to healthy male subjects.

Lutein bioavailability from lutein ester-fortified fermented milk: in vivo and in vitro study

We assessed the bioavailability of lutein from lutein-fortified fermented milk using in vivo and in vitro approaches. Twenty-four volunteers were randomized to take lutein-fortified fermented milk at two levels of fortification. Single-dose bioavailability study (2×100 ml, ca. 8 or 16 mg of lutein) was performed using a three-point approach (baseline, 3.5 and 6.5 h). Multiple-dose study consisted of consuming one serving/day (ca. 4 or 8 mg/100 ml) for 14 days. Blood samples for biochemical, hematological and lutein analysis were drawn at baseline, Day 7 and Day 14. In vitro bioaccessibility was assessed by a static gastrointestinal digestion model. Lutein content, in vitro ester hydrolysis and micellarization, and lutein concentrations achieved in serum were analyzed by HPLC. In vivo, post-prandial response was higher using the high content fermented milk, but the percentage of absorption was not different according to the dose consumed. Net increments at Day 7 and Day 14 were significantly higher on consuming the high-dose milk as well. In vitro, lutein ester hydrolysis was incomplete regardless of the amount initially present. Free lutein released was higher using the high-dose fermented milk, but the percentage of hydrolysis was similar at both levels of fortification. In the micellar phase, the percentage of free and total lutein was not different according to the dose. Our results support the suitability of the fermented milk as a carrier of lutein esters and an in vivo dose-dependent effect upon regular consumption and suggest the usefulness of in vitro models to provide relevant information to predict in vivo responses.

A Quantitative Analysis of Memantine in Human Plasma Using Ultra Performance Liquid Chromatography/Tandem Mass Spectrometry

The aim of this study is to compare the single‐dose oral bioavailability of memantine hydrochloride 10 mg tablets of Ranbaxy Laboratories Limited, with NAMENDA™ tablets (containing memantine hydrochloride 10 mg) of Forest Pharmaceuticals Inc. in healthy, adult, human subjects under fasting condition. The study was carried out as 2‐way crossover design on 8 subjects in fasting and fed conditions. The plasma samples were obtained over a 72 h post dose in each period. Plasma memantine samples were analyzed by liquid chromatography coupled to tandem mass spectrometry (LC‐MS/MS) with positive ion electro spray ionization using multiple reactions monitoring (MRM). A sensitive, reproducible, accurate and validated LC‐MS/MS method with limit of quantification (LOQ) 0.200 ng/mL was used to analyze memantine. Ln transformed AUC0-72 and Cmax were assessed for bioequivalence using 90% confidence interval (CI). 90% confidence intervals for the ratio of test and reference (Ratio of least‐squares mean) for ln‐transformed AUC0-72 and Cmax were within the regulatory acceptance criteria of 80‐125%.

Consumption of Restructured Meat Products with Added Walnuts Has a Cholesterol-Lowering Effect in Subjects at High Cardiovascular Risk: A Randomised, Crossover, Placebo-Controlled Study

Background: Diet and lifestyle are modifiable factors involved in the development and prevention of non-communicable diseases, including cardiovascular disease. Nut consumption, particularly walnut intake, has been inversely related to incident coronary heart disease (CHD) in observational studies and to improved lipid profiles in short-term feeding trials.Objective: To assess the potential functional effect associated with the regular consumption of walnut-enriched restructured meat products in subjects at risk for cardiovascular disease (CVD).Design: A crossover single-dose bioavailability study (n = 3) using γ-tocopherol as exposure marker and a crossover unblinded dietary intervention study (5 weeks) in subjects at risk (n = 25). Dietary intervention consisted of regular consumption of the meat product, with or without walnuts, five times per week for five weeks with a 1-month washout in between. Overnight fasting blood samples were collected on days 0, 12, 21, 28 and 35, coinciding with blood pressure and body weight recordings. Participants were asked to complete a diet record throughout the study. The functional effects were assessed using clinically relevant and related biomarkers of CHD: serum total, HDL and LDL cholesterol, triacylglycerols, homocysteine, vitamins B6 and B12, folic acid, α-tocopherol and platelet function test (obturation time).Results: The regular consumption of walnut-enriched meat products compared with that of the restructured meat products without added walnuts provokes a decrease in total cholesterol of 6.8 mg/dl (CI95%: −12.8, −0.85). Compared to baseline (mixed diet), meat products with walnuts decreased total cholesterol (−10.7 mg/dl, CI95%: −17.1, −4.2), LDL cholesterol (−7.6 mg/dl, CI95%: −2.2, −13.0) and body weight (−0.5 kg, CI95%: −0.1, −0.9) and increased γ-tocopherol (8.9 mg/dl, CI95%: 1.0, 16.8).Conclusions: The restructured meat products with added walnuts supplied in this study can be considered functional foods for subjects at high risk for CVD, as their regular consumption provokes a reduction in total cholesterol of 4.5% with respect to baseline values (mixed diet) and 3% with respect to the restructured meat without walnuts.

In vitro disintegration and dissolution studies of once-weekly copies of alendronate sodium tablets (70 mg) and in vivo implications

ABSTRACTObjective: The aim of this study was to evaluate the in vitro disintegration and dissolution of 26 alendronic acid tablets (70 mg) on the market in Canada, Germany, the Netherlands, and the United Kingdom compared to the branded product (Fosamax).Research design and methods: The disintegration and dissolution times were determined using the methods described in the United States Pharmacopeia 30 (USP 30). The disintegration of four orally disintegrating tablets (non-bisphosphonates) and branded film-coated risedronate sodium tablets were included for comparison.Results: The mean disintegration times of the alendronic acid tablets ranged from 14 s for Pharma­chemie (Netherlands) to 342 s (5.7 min) for Betapharm (Germany). The mean disintegration time of the branded product tablets ranged from 43 to 78 s. Six of the 26 companies market alendronic acid tablets with very rapid disintegration times which are similar to those of orally disintegrating tablets (non-bisphosphonates). The alendronic acid tablets with very rapid mean disintegration times are as follows: Pharmachemie (Netherlands), 14 s; Novopharm (Canada), 13–24 s; GRY-Pharma (Germany), 21 s; Juta Pharma (Germany), 30 s; APS/Teva (United Kingdom), 26 and 37 s; and Teva (UK), 14–29 s. Since there is no established disintegration time for alendronic acid tablets there can be no assurance that the copy tablets are equivalent to the branded product in terms of esophageal drug exposure. However, the in vitro disintegration times have not been correlated with in vivo disintegration and performance. The dissolution of all the bisphosphonate tablets was rapid with greater than 80% dissolved in 15 min and all products conformed to the USP 30 specification.Conclusions: The dissolution of all alendronic acid tablets was rapid and complete and conformed to the established USP 30 specifications which should ensure adequate drug absorption from the copy products. However, copies of alendronic acid tablets are approved based on the results of single-dose bioavailability studies in healthy subjects and this is not adequate to establish similar disintegration characteristics.

Bioavailability of vitamins A and E from whole and vitamin-fortified milks in control subjects

Dairy products fortified with vitamins and minerals represent a growing market that is of interest to those sectors of the population with unbalanced diets and increased needs. However, there is little information on the bioavailability of micronutrients in milk products at dietary intake levels. To evaluate the bioavailability of vitamins A and E in whole milk and fortified whole and skimmed milk in control subjects. A single-dose bioavailability study was performed using three commercially available milks (unfortified whole milk and whole and skimmed milk fortified with vitamins A and E). Nineteen volunteers (10 women and 9 men) ingested 430 ml of each milk on different days. The contents of retinol and alpha-tocopherol provided in the milks and the retinyl esters and alpha-tocopherol in triglyceride-rich lipoprotein fractions (TRL) from plasma collected for 6.5 h postprandially were assayed using a quality-controlled HPLC method. The relative absorption of vitamins A and E from milks was calculated on the basis of area under the curve (AUC) versus time curve estimations, adjusted for plasma volume and expressed as percentage of the amount of nutrient provided. The total amounts of retinol and alpha-tocopherol provided ranged between 0.48 and 4.15 micromol and 0.41 and 32.49 micromol, respectively. The AUC value of retinyl palmitate in TRL was higher for fortified whole milk than for the other two milks (unfortified whole and fortified skimmed milk). The percent relative absorption of vitamin A did not differ among the three types of milk. The AUC for alpha-tocopherol was no different after the ingestion of any of these milks. The mean percentage of retinol absorption was apparently similar for the three types of milk, regardless of the amount of fat ingested with each type of milk and the vitamin A provided.

Single-dose bioavailability of levetiracetam intravenous infusion relative to oral tablets and multiple-dose pharmacokinetics and tolerability of levetiracetam intravenous infusion compared with placebo in healthy subjects

Background: Antiepileptic drugs are usually administere dorally, but alternative routes of drug delivery may be required when oral administration is not feasible. Objective: The purpose of this study was to evaluate the single-dose bioavailability of an IV formulation of levetiracetam relative to oral tablets and the multiple-dose tolerability and pharmacokinetics of this formulation compared with placebo in healthy subjects. Methods: This study consisted of 2 phases. Subjects entered the first phase, which was a single-dose, randomized, open-label, 2-way crossover bioavailability comparison of a 15-minute IV infusion of levetiracetam 1500 mg and three 500-mg oral tablets. Subjects then entered the second phase, a multiple-dose, randomized, double-blind, placebo-controlled (2:1), parallel-group tolerability and pharmacokinetic study, in which they received 9 successive doses of levetiracetam 1500 mg IV or placebo at 12-hour intervals. Plasma levetiracetam concentrations were determined by gas chromatography with nitrogen-phosphorus detection. The comparison of bioavailability was based on the 90% CIs around the geometric mean ratios for AUC and C max (IV/oral). Results: Eighteen subjects (9 men, 9 women) participated in the study. All subjects were white. Their mean (SD) age was 35.0 (9.3) years, mean weight 73.3 (14.2) kg, and mean body mass index 23.9 (2.5) kg/m 2. After a single dose, the IV infusion and oral tablet were similar in terms of C max (50.5 and 47.7 μg/mL, respectively) and AUC (392.4 and 427.9 pg · h/mL). The geometric mean IV/oral ratios were 92.2 (90 % CI, 89.0-95.6) for AUC and 103.7 (90% CI, 91.6-117.4) for C max indicating that the IV and oral formulations were bioequivalent. After multiple twice-daily infusions, steady state was reached within 48 hours. Seventeen (94%) of 18 subjects had ≥1 treatment-emergent adverse event after single-dose administration. During the single-dose phase, the incidence of treatment-emergent adverse events was 89% (16/18) for the IV formulation and 72% (13/18) for the oral tablets; during the multiple-dose phase, the incidence of treatment-emergent adverse events was 67% (8/12) in the IV levetiracetam group and 33% (2/6) in the placebo group. The most common adverse events in the single-dose phase were somnolence (61% IV vs 28% oral) and postural dizziness (17% vs 39%, respectively). The most common adverse events with IV levetiracetam in the multiple-dose phase were also somnolence (33% vs 17% placebo) and postural dizziness (25% vs 0% placebo). Conclusions: In these healthy subjects, single doses of levetiracetam 1500 mg administered as a 15-minute IV infusion and as oral tablets were bioequivalent. General and local tolerability during multiple dosing were good. Steady state was reached within 48 hours. Despite the limitations of a study of short duration and small size conducted in healthy subjects, the findings suggest that use of a 15-minute IV infusion of levetiracetam should be further investigated.

Methylphenidate Bioavailability in Adults When an Extended-Release Multiparticulate Formulation Is Administered Sprinkled on Food or as an Intact Capsule

To determine the single-dose bioavailability of 20-mg Metadate CD (methylphenidate HCI, USP) Extended-Release Capsules sprinkled onto 1 level tablespoon (15 mL) of applesauce relative to an intact capsule under fasted conditions in healthy adults. This was a single-center, open-label, single-dose, randomized, two-way crossover study with a 6-day washout period between doses, in healthy male and female subjects (N= 26), aged 21-40 years. Plasma concentration-time data for methylphenidate were used to calculate the pharmacokinetic parameters for each treatment. The pharmacokinetic profile for Metadate CD exhibited biphasic release characteristics with a sharp initial slope and a second rising portion. For Cmax (maximum observed concentration), AUC(0-infinity) (area under the plasma concentration curve from time 0 to infinity) and AUC(0-infinity) (area under the plasma concentration curve from time 0 to the last measurable time point), the geometric least squares mean ratios and 90% confidence intervals were within the 80% to 125% confidence interval for bioequivalence. Adverse events were similar to those reported for methylphenidate. The bioavailability of methylphenidate was not altered when Metadate CD capsules were administered by sprinkling their contents onto a small amount of applesauce.

Comparative Single-Dose Bioavailability Study of Two Oral Formulations of Ibuprofen in Healthy Volunteers

Objective: To compare the bioavailability of equivalent doses of two oral formulations of ibuprofen: ibuprofen lysinate 1025mg (powder for oral suspension) and ibuprofen free acid 600mg (effervescent granules).

Pharmacokinetic and Pharmacodynamic Comparison of Two Calcium Supplements in Postmenopausal Women

This randomized crossover study compared the single-dose bioavailability and effects on parathyroid function of two commercially formulated calcium supplements containing 500 mg of elemental calcium. Twenty-five postmenopausal women underwent three phases of study wherein they each took a single dose of calcium citrate with a standard breakfast (as Citracal 250 mg + D), calcium carbonate (as Os-Cal 500 mg + D), or placebo at 8 a.m. Blood samples were drawn at baseline and hourly for 4 or 6 hours after each dose. Fasting and postload urine samples were also collected. Compared with calcium carbonate, calcium citrate provided a 46% greater peak-basal variation and 94% higher change in area under the curve for serum calcium and a 41% greater increment in urinary calcium. Moreover, the decrement in serum parathyroid hormone concentration from baseline was greater after calcium citrate. In conclusion, calcium citrate is more bioavailable than calcium carbonate when given with a meal.

Experimental, extrapolated and truncated areas under the concentration-time curve in bioequivalence trials.

The extrapolated area under the concentration-time curve (AUC0-infinity) for any drug is considered by operating guidelines as the primary parameter related to the extent of absorption in single-dose bioavailability and bioequivalence trials. Not more than 20% should be added to the experimental AUC (AUC0-t) in the extrapolating procedure. However, in certain specific cases, it is problematic and, in other cases, impossible to respect the above requirement. It was intended to demonstrate that truncated AUC or AUC0-t would be used in bioequivalence trials when the AUC cannot be extrapolated. AUC0-t and truncated AUC were compared at various time intervals with AUC0-infinity in a series of 19 single-dose bioequivalence trials covering 15 different drugs, each carried out on 12-24 healthy volunteers. Point estimators and 90% confidence intervals in the 0.80-1.25 and 0.70-1.43 ranges were statistically processed using log-transformed parameters. In all the trials considered, overlapping point estimators and 90% confidence intervals were invariably obtained, regardless of the AUC used. The use of AUC0-t or truncated AUC may be considered an ancillary procedure in bioequivalence trials when AUC cannot be extrapolated. This occurs with most extended-release formulations, endogenous substances, and poorly absorbed drugs. It also occurs in trials with one or more poor metabolisers, with drugs possessing very long elimination half-lives, and with bioassays having problems of sensitivity that preclude sufficiently precise plasma concentration measurement over the required sampling period.