Single Dose Comparative Bioavailability Study of Lisdexamfetamine Dimesylate as Oral Solution Versus Reference Hard Capsules in Healthy Volunteers.

Lisdexamfetamine is an inactive prodrug of dexamfetamine that is used for the second-line treatment of attention-deficit/hyperactivity disorder (ADHD) and moderate to severe binge eating disorder (BED). Once in the blood, the prodrug is hydrolyzed in erythrocyte cytosol, thus releasing the active dexamfetamine. We here present a fully validated HPLC-MS/MS analytical method for simultaneous determination of lisdexamfetamine and dexamfetamine in human plasma and the first published comparative bioavailability study of lisdexamfetamine including a GMP finished product formulated as oral solution. The Test (T)/Reference (R) ratios for the geometric means (%) of the primary pharmacokinetic (PK) parameters and their corresponding two-sided 90% confidence intervals (CIs) were contained within the predefined regulatory limits of 80.00-125.00% for both lisdexamfetamine and dexamfetamine. While for the lisdexamfetamine prodrug, PK results for the two formulations were slightly different due to the distinct dissolution state at administration, the PK parameters calculated for dexamfetamine were almost identical. A potential explanation of this phenomenon, already described in literature, is that biotransformation of lisdexamfetamine by red blood cells (rather than its release within the gastrointestinal tract) is the process controlling the rate of dexamfetamine delivery.

Single Dose Study Assessing the Pharmacokinetic and Metabolic Profile of Alverine Citrate in Healthy Volunteers.

Alverine citrate is a spasmolytic commonly prescribed in conditions such as irritable bowel syndrome, painful diverticular disease of the colon, and primary dysmenorrhea. While clinical efficacy data on alverine alone or in combination with simethicone is freely available, surprisingly little information regarding the pharmacokinetics and metabolism of alverine can be found in literature. The first HPLC-MS/MS analytical protocol for determination of alverine parent, 4-hydroxy alverine, N-desethyl alverine and 4-hydroxy alverine glucuronide in human plasma was developed and validated. The two validated methods were used for analyzing plasma samples collected during an open label, non-comparative, single dose, one-period, one-treatment, pharmacokinetic and metabolic profile study of Spasmonal® Forte 120 mg hard capsule, conducted in 12 fasting healthy male and female volunteers of Caucasian descent. The study confirmed previous suspicions that parent alverine is subject to high pharmacokinetic variability and also revealed that the metabolic process most susceptible to outlying performance in Caucasians is hydroxylation to the active metabolite 4-hydroxy alverine. Another interesting observation made is that alverine parent accounts for only 3%, whereas total 4-hydroxy alverine (free and conjugated) accounts for 94% of alverine-related moieties in circulation (based on comparisons of total exposure).

The Effect of Food on the Single-Dose Bioavailability and Tolerability of the Highest Marketed Strength of Duloxetine.

Duloxetine is a combined serotonin and norepinephrine reuptake inhibitor indicated in adults for the treatment of major depressive disorder, diabetic peripheral neuropathic pain, and generalized anxiety disorder. The aim of these studies was to evaluate the effect of food on the pharmacokinetics and safety of duloxetine 60-mg gastroresistant hard capsules following single-dose administration. The data were obtained from 2 phase 1 bioequivalence studies, 1 in a fasting state and the other under fed conditions. Both studies have shown that, when administered as a single dose in the same prandial state, the test and reference duloxetine treatments were bioequivalent and exhibited similar safety profiles. The mean fed and fasting pharmacokinetic parameters and drug-related adverse events from the 2 studies were compared in order to assess the effect of food on the duloxetine bioavailability and respectively, tolerability. Administration of duloxetine in fed conditions increased peak plasma concentration by up to 30% and delayed mean time to peak concentration by an average of 1.15 hours while having an insignificant effect on extent of absorption (area under the plasma concentration-time curve in fed state within ±6% as compared with fasting conditions). Even though peak plasma levels were substantially higher in the fed state, there was no negative impact on the drug's safety profile. Actually, administration with food resulted in a lower average number of adverse events per single dose exposure. The negligible variation in overall systemic exposure suggests that efficacy remains unchanged irrespective of administration conditions; however, a better tolerability of the 60-mg dose is expected when the drug is taken with food.

Single-Dose Pharmacokinetic Properties and Relative Bioavailability of Different Formulations of Posaconazole Oral Suspension in Healthy Volunteers.

The rate and extent of absorption of drugs belonging to Biopharmaceutics Classification System class II are rate-limited by dissolution and highly dependent on the performance of the formulated product. The purpose of the present study was to investigate the potential impact of a surfactant and the particle size of the active substance on the in vitro drug dissolution profiles and in vivo pharmacokinetics of the poorly soluble drug posaconazole. A comparative physicochemical evaluation was conducted, and 3 formulations of posaconazole oral suspension were tested in various dissolution media compared with the reference product. In addition, a comparative bioavailability study was conducted in healthy volunteers under high-fat fed conditions. Bioequivalence was assessed based on plasma concentrations of the parent drug (posaconazole) measured by a validated high-pressure liquid chromatography-tandem mass spectrometry method. The 90% confidence intervals for Cmax and AUC0-72 least-squares mean T/R ratios of all 3 posaconazole formulations were within the bioequivalence acceptance range of 80.00% to 125.00%. The study was useful in the formulation development process and demonstrated that neither surfactant type nor particle size of the active substance within the studied range affected the extent or rate of absorption of posaconazole under the tested fed conditions.

Pharmacokinetic study for the establishment of bioequivalence of two inhalation treatments containing budesonide plus formoterol.

OBJECTIVES: The aim of this study was to compare lung deposition and assess the bioequivalence of two formulations containing budesonide and formoterol and being delivered via Elpenhaler and Turbuhaler, respectively. A pharmacokinetic (PK) study was conducted. METHODS: An open, randomized, two-sequence, two-period, crossover, single-dose study in 100 asthmatic patients under fasting conditions was performed. Wash out period was 6 days. Equivalence in lung deposition was assessed after a single inhalation of each treatment with concomitant oral administration of activated charcoal (40 g) to prevent gastrointestinal absorption of the drugs. Several PK parameters were estimated, the area under the drug concentration in plasma versus time curve (AUC0-t ) and the maximum drug concentration in plasma (Cmax ) being the primary response variables. Equivalent lung deposition was concluded if the 90% confidence interval (CI) for the Elpenhaler/Turbuhaler geometric mean ratio of AUC0-t and Cmax , for both drug substances fell within the regulatory limits (0.80-1.25). KEY FINDINGS: Acceptance criteria were met. Equivalent lung deposition can be concluded. No statistically significant differences between treatments in the incidence of adverse events were found. CONCLUSIONS: The formulations are bioequivalent regarding both rate and extent of absorption. The treatments were also well tolerated by the participating subjects.

Confirmation of diosmetin 3-O-glucuronide as major metabolite of diosmin in humans, using micro-liquid-chromatography-mass spectrometry and ion mobility mass spectrometry.

Diosmin is a flavonoid often administered in the treatment of chronic venous insufficiency, hemorrhoids, and related affections. Diosmin is rapidly hydrolized in the intestine to its aglicone, diosmetin, which is further metabolized to conjugates. In this study, the development and validations of three new methods for the determination of diosmetin, free and after enzymatic deconjugation, and of its potential glucuronide metabolites, diosmetin-3-O-glucuronide, diosmetin-7-O-glucuronide, and diosmetin-3,7-O-glucuronide from human plasma and urine are presented. First, the quantification of diosmetin, free and after deconjugation, was carried out by high-performance liquid chromatography coupled with tandem mass spectrometry, on an Ascentis RP-Amide column (150 × 2.1 mm, 5 µm), in reversed-phase conditions, after enzymatic digestion. Then glucuronide metabolites from plasma were separated by micro-liquid chromatography coupled with tandem mass spectrometry on a HALO C18 (50 × 0.3 mm, 2.7 µm, 90 Å) column, after solid-phase extraction. Finally, glucuronides from urine were measured using a Discovery HSF5 (100 × 2.1 mm, 5 µm) column, after simple dilution with mobile phase. The methods were validated by assessing linearity, accuracy, precision, low limit of quantification, selectivity, extraction recovery, stability, and matrix effects; results in agreement with regulatory (Food and Drug Administration and European Medicines Agency) guidelines acceptance criteria were obtained in all cases. The methods were applied to a pharmacokinetic study with diosmin (450 mg orally administered tablets). The mean C max of diosmetin in plasma was 6,049.3 ± 5,548.6 pg/mL. A very good correlation between measured diosmetin and glucuronide metabolites concentrations was obtained. Diosmetin-3-O-glucuronide was identified as a major circulating metabolite of diosmetin in plasma and in urine, and this finding was confirmed by supplementary experiments with differential ion-mobility mass spectrometry.

Development and validation of an HPLC-MS/MS method to quantify clopidogrel acyl glucuronide, clopidogrel acid metabolite, and clopidogrel in plasma samples avoiding analyte back-conversion.

A new sensitive and fast quantitative analytical method for the simultaneous determination of clopidogrel, its main metabolite clopidogrel carboxylic acid, and the newly described acyl glucuronide metabolite, in human plasma samples, is presented. The analytical procedures (plasma storage, handling, and extract storage in the autosampler) were optimized in order to avoid back-conversion; a known drawback in measurements of clopidogrel. Clopidogrel acyl glucuronide was confirmed as a major source of back-conversion to the parent drug in the presence of methanol, and thorough stability experiments were carried out to find the most appropriate conditions for an accurate analysis of clopidogrel and the two metabolites. The method was validated by assessing selectivity, sensitivity, linearity, accuracy, and precision for all three analytes, in accordance to Food and Drug Administration guidelines. Spiked quality controls in plasma as well as incurred samples were used to verify back-conversion in the selected conditions, with results meeting European Medicines Agency acceptance criteria (concentrations within 80-120% of the first reading). The method was then applied to a pharmacokinetic study, and for the first time, a pharmacokinetic curve of clopidogrel acyl glucuronide in human plasma is presented. The concentrations ranged up to 1,048.684 ng/mL, with a mean of 470.268 ng/mL, while clopidogrel had a mean C(max) of 1.348 ng/mL; these orders of magnitude show how much the back-conversion of this metabolite may influence clopidogrel quantification if it is not properly controlled.

Adhesion inhibition "in vitro" by heparin derivatives correlates with their activity on angiogenesis in mice.

Heparin (HEP) play an important role in angiogenesis. Inhibition of matrix degrading enzymes and binding to adhesion molecules are some of the interaction mechanism. The bleeding risk and the need of parenteral administration, restrict the therapeutic use of HEP as angiogenesis modulator; presently derivatives, with different pharmacokinetic and anticoagulant properties, are available. In this study the "in vitro" anti-adhesion activity, tested with PMNs and endothelial cells, was compared with the effect on angiogenesis, evaluated in Matrigel implanted mice. Some HEP derivatives, with low anticoagulant activity, showed a significant angiogenesis inhibition. A positive correlation between adhesion inhibition in vitro and anti-angiogenesis effect in vivo was found suggesting that the interaction with adhesion molecules by HEP derivatives play a relevant role in the angiogenesis control.

Intra-plaque production of platelet-activating factor correlates with neoangiogenesis in human carotid atherosclerotic lesions.

Platelet-activating factor (PAF) is a phospholipid mediator synthesized by activated inflammatory and endothelial cells. Recently PAF has been shown to contribute to neoangiogenesis in several experimental models. Here we evaluated the presence of PAF and its potential role in neovascularization within human atherosclerotic plaques. The amount of PAF extracted from 18 carotid plaques (266.65+/-40.07 pg/100 mg dry tissue; mean +/- SE) was significantly higher than that extracted from 18 normal arterial specimens (6 from carotid artery and 12 from aorta) (4.72+/-2.31 pg/100 mg dry tissue; mean +/- SE). The levels of PAF significantly correlated with the infiltration of CD68-positive monocytes and the extent of neovascularization, detected as von Willebrand Factor-positive cells. The amount of PAF also correlated with the area occupied by TNF-alpha-expressing cells. The absence of enhanced level of PAF in the circulation of atherosclerotic patients suggests a local production of this mediator within the plaque. The lipid extracts of atherosclerotic plaques containing high levels of PAF-bioactivity, but not those of control arteries, were angiogenic in a murine Matrigel model. WEB 2170, a specific PAF receptor antagonist, significantly prevented angiogenesis induced by the lipid extracts of atherosclerotic plaques. Our results indicate a local production of PAF within the atherosclerotic plaques and suggest that it may contribute to intra-plaque neoangiogenesis.