The pharmacokinetics of sodium oxybate oral solution following acute and chronic administration to narcoleptic patients.

This trial was conducted to evaluate the pharmacokinetics and safety of a sodium oxybate (gamma-hydroxybutyrate [GHB]) oral solution in narcoleptic patients after acute and chronic treatment. An open-label, two-period, two-treatment study design was used. Trial subjects included 13 patients with polysomnographically confirmed narcolepsy.

The influence of gender and food on the pharmacokinetics of sodium oxybate oral solution in healthy subjects.

Sodium oxybate (Xyrem; gamma-hydroxybutyrate) oral solution was recently approved in the United States for the treatment of cataplexy in patients with narcolepsy. Two single-center, randomized, open-label studies in healthy volunteers receiving single oral 4.5-g doses of sodium oxybate evaluated effects of (1) gender on oxybate pharmacokinetics and (2) food on its oral bioavailability.

Azithromycin and terfenadine: lack of drug interaction.

A double-blind placebo-controlled study was conducted in healthy men to determine the effect of coadministration of azithromycin on the pharmacodynamics and pharmacokinetics of terfenadine. Administration of 500 mg azithromycin for 1 day and 250 mg on 4 subsequent days did not affect the pharmacokinetics of the pharmacologically active terfenadine carboxylate metabolite when 60 mg terfenadine was given twice daily for 12 days, starting 7 days before azithromycin administration. Terfenadine alone resulted in a 0.

Comparison of the pharmacokinetics of two nicotine transdermal systems: nicoderm and habitrol.

This randomized, crossover study compared the nicotine and cotinine pharmacokinetic parameters and plasma concentration profiles of two different nicotine transdermal products: Nicoderm (Alza, Palo Alto, CA; and Marion Merrell Dow, Kansas City, MO) and Habitrol (Basel Pharmaceuticals, Summit, NJ). The two treatments were randomly assigned to each of 24 male smokers and worn for 24 hours each day for 5 days, with a 6-day washout between treatments. Plasma nicotine and cotinine concentrations were measured on day 1 and day 5 of each treatment.

Pharmacokinetics of vigabatrin following single and multiple oral doses in normal volunteers.

The pharmacokinetics of vigabatrin were investigated after single and multiple oral doses in two groups of 24 healthy male volunteers. Vigabatrin was well tolerated by the volunteers; headache was the most frequently reported adverse event. There were no clinically remarkable changes in serum chemistry, urinalysis, or hematology attributable to vigabatrin.

Oxidation of the antihistaminic drug terfenadine in human liver microsomes. Role of cytochrome P-450 3A(4) in N-dealkylation and C-hydroxylation.

The antihistaminic drug terfenadine, alpha-[4-(1,1-dimethylethyl)phenyl]-4-(hydroxydiphenylmethyl)-1- piperidinebutanol (Seldane), is of interest because of its lack of sedative properties. Major routes of metabolism include oxidative N-dealkylation to 4-(hydroxydiphenylmethyl)-piperidine (1) and oxidation of a tert-butyl methyl group to a primary alcohol (2), which is subsequently oxidized to a carboxylic acid. Rates of formation of 1 and 2 varied approximately 30-fold in the 17 human liver microsomal samples examined and were highly correlated with each other, suggesting that the same enzyme may be involved in both oxidations.

Single- and multiple-dose pharmacokinetics of Nicoderm (Nicotine Transdermal System).

The pharmacokinetics and tolerability of single and multiple applications of Nicotine Transdermal Systems (NTS), designed to deliver 14 mg of nicotine per 24 hours, were investigated in 20 healthy adult male smokers. After a single application, mean Cmax and tmax for plasma nicotine were 12.2 ng/mL and 4.

Comparison of plasma nicotine concentrations after application of nicoderm (nicotine transdermal system) to different skin sites.

Drug absorption through the skin can vary according to the application site. The nicotine transdermal system, Nicoderm (Alza Corp., Palo Alto, CA) contains a rate-controlling membrane designed to regulate delivery of nicotine to the skin and thus limit variability in nicotine plasma levels.

Absence of food effects on the pharmacokinetics of terfenadine.

Administration of terfenadine (Seldane) immediately after a high fat breakfast slightly affects the rate but not the extent of absorption relative to fasting administration. Mean peak levels of the active metabolite were increased by 13 per cent but delayed by 0.9 h while AUC was virtually the same as when terfenadine was administered while fasting.

Pharmacokinetics of terfenadine in healthy elderly subjects.

The pharmacokinetics of the terfenadine active metabolite, metabolite I, was examined in ten healthy elderly adults and ten younger adults after single-dose oral administration of 120-mg terfenadine. All subjects successfully completed the study without reporting sedation or other adverse events. Absorption was rapid in both the young and elderly.

Direct enantiomeric separation of terfenadine and its major acid metabolite by high-performance liquid chromatography, and the lack of stereoselective terfenadine enantiomer biotransformation in man.

Direct enantiomeric separation of terfenadine and its major acid metabolite was achieved by using two different chiral stationary phase columns with two different mobile phase systems. Further, the enantiomeric composition of the human urinary acid metabolite has been determined, indicating a non-stereoselective biotransformation in man.

Determination of terfenadine and terfenadine acid metabolite in plasma using solid-phase extraction and high-performance liquid chromatography with fluorescence detection.

This work describes the methodology for the analysis of terfenadine and the acid metabolite of terfenadine in plasma using high-performance liquid chromatography. The use of solid-phase extraction allows the use of robotic or manual sample preparation for the efficient clean-up of terfenadine and terfenadine acid metabolite from plasma. Additional selectivity is obtained through the use of fluorescence detection.

Clinical pharmacology of intravenous enoximone: pharmacodynamics and pharmacokinetics in patients with heart failure.

Twenty-one patients with heart failure (New York Heart Association [NYHA] class II to IV) received a 24-hour infusion of enoximone followed by a 12-hour washout period. Patients were randomly assigned to one of four treatment groups. Groups I to III received an 0.

Determination of the metabolites of terfenadine in human urine by thermospray liquid chromatography-mass spectrometry.

Thermospray liquid chromatography-mass spectrometry (TSP LC-MS) was used to determine human urinary metabolites of terfenadine after oral administration of terfenadine tablets. In addition to the two previously identified major metabolites, azacyclonol (MDL 4829) and the 'acid' metabolite (MDL 16,455), three additional metabolites were also detected. One of the additional metabolites was identified as the 'alcohol' metabolite (MDL 17,523) and the other two were proposed to be an 'aldehyde' and a 'ketone-acid' metabolites from their TSP mass spectra.

Pharmacodynamics of enoximone during intravenous infusion.

Twenty-one patients with heart failure (NYHA class II-IV) received a 24-hour infusion of enoximone, followed by a 12-hour washout period. Patients were randomly assigned to one of four treatment groups. Groups I-III received a 0.

Pharmacology and pharmacokinetics of enoximone.

Enoximone is an inotropic vasodilating agent. Its principal effects are positive inotropism and vasodilation, which are not accompanied by changes in myocardial oxygen consumption. An inotropic dose of enoximone increases the level of cyclic AMP in the isolated, blood-perfused dog papillary muscle owing to its selective inhibition of the one isoform of cyclic AMP phosphodiesterase from the dog heart that is inhibited by cyclic GMP.

Human serum and plasma protein binding of enoximone and its sulfoxide metabolite.

Experimental factors and determinants of the protein binding of enoximone (a new cardiotonic agent) were investigated in human serum from healthy, drug-free subjects using a rapid ultrafiltration method; these factors and determinants included nonspecific binding to the apparatus, ultrafiltrate volume, temperature, serum pH, enoximone serum concentration, and enoximone sulfoxide (metabolite) concentration. It was demonstrated from mass balance experiments that nonspecific binding to the apparatus did not occur. Within the range investigated, ultrafiltrate volume did not affect the binding result.

Biotransformation and pharmacokinetic overview of enoximone and its sulfoxide metabolite.

Enoximone possesses both positive inotropic and vasodilatory activities and may be useful in the treatment of patients with congestive heart failure (CHF). In all animal species investigated (rat, dog, monkey and man), the major urinary metabolite is the sulfide oxidation product (sulfoxide); very little unchanged drug appears in urine. Both in vitro and in vivo animal studies indicate reversibility of the sulfoxidation reaction; therefore, it is presumed that sulfoxidation is reversible in man.

Acute hemodynamic effect of oral MDL 17,043 in severe congestive heart failure.

MDL 17,043, when administered intravenously in humans, produces a significant and salutary hemodynamic response. To determine its acute effect when administered orally (3 mg/kg), 10 patients with severe congestive heart failure were studied by right-sided cardiac catheterization for 8 hours. At 4 hours after drug ingestion, there was significant improvement in several hemodynamic measurements.

Dose related induction of the drug metabolizing enzymes of rat liver by cilobamine.

Cilobamine , an antidepressant, was investigated for its influence on the hepatic drug metabolizing enzymes ( DME ) of male Charles River CD rats. Cilobamine doses (3, 10, 30, 100, and 300 mg/kg po, as free base) were compared to sodium phenobarbital (PB) doses (3, 10, 30, 100, and 200 mg/kg po, as free acid). Compounds were given daily for 4 days and all tests were done on Day 5.

Simultaneous analysis of a new cardiotonic agent, MDL 17,043, and its major sulfoxide metabolite in plasma by high-performance liquid chromatography.

MDL 17,043 or 1,3-dihydro-4-methyl-5-[4-(methylthio)benzoyl]-2H-imidazol-2-one, is a new cardiotonic agent being developed for the treatment of congestive heart failure. This communication describes a sensitive and selective analytical procedure for the simultaneous analysis of MDL 17,043 and its major oxidative metabolite in plasma. The method involves addition of internal standard and organic solvent extraction, followed by separation with high-performance liquid chromatography and detection by ultraviolet absorption.