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Biomedical subjects

R J Royer

Publications and source records attributed to R J Royer.

At least 19 recordsLinked to original sources
PubMed1992

Determination of zopiclone in plasma using column liquid chromatography with ultraviolet detection.

A reversed-phase liquid chromatographic method with ultraviolet detection for the determination of zopiclone in plasma is described. It is rapid, sensitive, reproducible and linear over a wide range. The method was used to study plasma zopiclone concentrations in a case of acute intoxication after oral ingestion of 300 mg of the drug. The plasma level was 1600 ng/ml 4.5 h after the dose and the elimination half-life was 3.5 h.

Adult↗
PubMed1992

Automated determination of disopyramide and N-monodealkyldisopyramide in plasma by reversed-phase liquid chromatography with a column switching system.

A rapid and simple column liquid chromatographic method involving a column switching system for the determination of disopyramide and its N-monodealkyl metabolite (NMD) in plasma is described. The deproteinized plasma is applied to an automated system. Purification and concentration were performed using a precolumn connected to a six-position valve; analytical separation was done on-line using a cyano reversed-phase column with a mobile phase consisting of 10 mmol/l trimethylamine (pH 2.5, adjusted with phosphoric acid)-acetonitrile-tetrahydrofuran (78:20:2, v/v/v). Absorbance was measured at 265 nm, with a minimum detectable amount of disopyramide and NMD of 0.1 micrograms/ml. The method can be applied to drug monitoring and pharmacokinetic studies.

Chromatography, High Pressure Liquid↗
PubMed1992

Plasma thiamine concentrations after intramuscular and oral multiple dosage regimens in healthy men.

A novel liquid chromatographic method for the determination of thiamine in plasma has been developed and has been used to study plasma thiamine concentrations after multiple dosage regimens for 11 days. The method involves purification, concentration and analytical separation of thiochrome on-line, using a switching column system. Ten healthy men were given 500 mg thiamine i.m. once a day (Group 1) and ten were given 250 mg p.o. every 12 h (Group 2). The times to reach steady state (7 and 5.6 days for Groups 1 and 2, respectively) were not different (P greater than 0.05). The mean elimination half-life was 1.8 days. The mean minimum steady-state concentration after the oral regimen (23 micrograms.l-1) was 78% of that after the intramuscular regime (29 micrograms.l-1).

Administration, Oral↗
PubMed1992

Plasma and cerebrospinal fluid concentrations of paracetamol after a single intravenous dose of propacetamol.

Since the antipyretic and probably the analgesic effects of paracetamol are, at least in part, centrally mediated, its plasma and cerebrospinal fluid (CSF) concentrations were measured in 43 patients with nerve-root compression pain. Each subject was given a short i.v. infusion of 2 g propacetamol, a prodrug which is hydrolysed to paracetamol within 7 min. Single blood and CSF samples were drawn concomitantly in each patient at intervals between 20 min and 12 h. Maximum CSF drug concentrations were observed at the 4th hour, subsequent concentrations exceeding those in plasma. The elimination half-life of paracetamol calculated from pooled data was shorter in plasma (2.4 h) than in CSF (3.2 h). The time-course of paracetamol in CSF may parallel that of analgesic effect.

Acetaminophen↗
PubMed1991

Effect of plasma exchange on flumequine pharmacokinetics: comparison with control kinetics.

The effect of plasma exchange (PE) on the pharmacokinetics of flumequine (Apurone) was studied in eight patients receiving a single oral dose of 800 mg. The maximum concentration (38 micrograms/ml) and time to maximum concentration (2.6 h) values were not significantly altered by PE beginning 3 h after administration of flumequine. There was no change in the terminal elimination half-lives (6.6 h), in the steady-state volume of distribution (29 L), or in the apparent plasma clearance (2.5 L/h). By contrast, PE decreased the mean residence time by 30% (14.3 +/- 4.1 h without PE; 9.88 +/- 1.36 h with PE; p less than 0.05). The amount of flumequine extracted by PE (72 mg) was proportional to the plasma concentration at the beginning of the exchange. The elimination half-life during PE (3.15 +/- 1.23 h) decreased by 40%. Renal clearance (0.3 L/h) was not affected. PE only partially modifies the pharmacokinetics of flumequine administered in a single oral dose before PE.

Administration, Oral↗
PubMed1990

Pharmacovigilance. The French system.

The French system of drug surveillance (pharmacovigilance) is a combination of mandatory reporting and intensive hospital surveillance. The Regional Centres are decentralised but coordinated through a national network. An algorithm index is used to assess the relationship between drugs and adverse effects. The adverse reactions alert system is produced by the compilation and analysis of the cases entered in a data bank (8062 in 1988) and by the analysis of queries from general practitioners (20,000 in 1988). The duties of the centres are also to provide information, analyse data and to improve the safe use of drugs.

Communication↗
PubMed1990

Differences in sodium salicylate protein binding in serum and synovial fluid from patients with a knee effusion.

Protein binding of sodium salicylate in synovial fluid and in serum from 23 inpatients with rheumatic diseases were studied, ex vivo, by equilibrium dialysis. Scatchard model with two classes of sites was used as a mathematical tool. At therapeutic concentrations, protein binding of sodium salicylate was significantly higher in serum than in synovial fluid. The ratio of areas under the curves for bound concentrations for synovial fluid to that for serum was 0.867. This difference was attributed to the hypoalbuminemia observed in the synovial fluid; for a given molar ratio of drug to albumin, or in other words, for the same amount of available drug per mole of albumin. The number of sites occupied was the same in the two biological media.

Adolescent↗
PubMed1989

Identification and simultaneous determination of non-steroidal anti-inflammatory drugs using high-performance liquid chromatography.

An isocratic high-performance liquid chromatographic procedure is presented for the screening of plasma samples for the presence of sixteen non-steroidal anti-inflammatory drugs. Detection was achieved simultaneously at two wavelengths (254 and 370 nm) and the purity of the eluted peaks was tested using absorbance ratios at the two wavelengths; identification could thus be effective without interferences from substances of other pharmacological classes. The drugs were extracted simultaneously with diethyl ether after acidification and separated from each other on an octadecyl reversed-phase column using only one eluent, acetonitrile-0.3% acetic acid-tetrahydrofuran (36:63.1:0.9, v/v). The recovery, precision and reproducibility of the method were satisfactory as it allowed the determination of the drugs from infra- to supratherapeutic concentrations.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1989

Role of ancillary properties of beta-adrenoceptor antagonists in protecting the heart from anoxia.

The mechanism of the cardioprotective action of beta-blocking drugs against anoxia or ischemia is still not clear. We used beta-blockers (5 x 10(-7) M) of various pharmacodynamic profiles in a model of isolated, perfused working guinea pig heart subjected to 20 min of anoxia to study this. The cardioprotective effects were evaluated by measuring the recovery of the flow indices after 15 min of reoxygenation. There was a significant cardioprotective action (as measured by the effect on stroke volume recovery and on recovery of other flow and work indices) of the beta-blocking properties (nadolol, P less than 0.05), of the membrane-stabilizing property [+)-propranolol, P less than 0.05) and of a combination of these two properties with (+/-)-propranolol, which had a significantly greater effect than nadolol (P less than 0.05). The addition of weak (acebutolol) or strong (pindolol) intrinsic partial agonist activity had no clear unfavourable effect, as the degree of cardioprotection was comparable with that obtained with (+/-)-propranolol. The stroke volume recovery (percent recovery after anoxia) in the control hearts was 42.57 +/- 12.75 compared to 54.84 +/- 6.94 in hearts pretreated with nadolol, 62.99 +/- 11.41 with (+)-propranolol, 71.02 +/- 11.36 with (+/-)-propranolol, 72.63 +/- 13.08 with acebutolol and 68.01 +/- 15.42 with pindolol. In vitro heart protection from anoxia with beta-blockers would appear to be related to beta-blocking activity and/or membrane stabilizing property but not a function of partial agonist activity. These ancillary properties of beta-blockers should thus be taken into account in studies on cardioprotection.

Adrenergic beta-Antagonists↗
PubMed1989

Clinical pharmacokinetics of nonsteroidal anti-inflammatory drugs in the cerebrospinal fluid.

The pharmacokinetics of nonsteroidal anti-inflammatory drugs (NSAIDs) in the cerebrospinal fluid (CSF) is of clinical interest as it may be related to some of their properties and side-effects. Two types of NSAIDs can be described with respect to their concentration and time course in CSF: in the first type, the transfer across the blood-brain barrier seems to be controlled by simple physico-chemical factors. These drugs (oxyphenbutazone, indomethacin, ketoprofen) are characterized by a high lipophilicity. At steady state, their free plasma concentrations correspond to their CSF concentrations. The second group consists of more hydrophilic compounds (salicylates); there is no correlation between plasma concentrations and CSF concentration. Further investigation needs to be carried out on CNS side-effects and the antialgesic activity of salicylates in relation on their CSF distribution.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1989

Tianeptine and its main metabolite pharmacokinetics in chronic alcoholism and cirrhosis.

The effect of chronic alcoholism (with or without associated moderate cirrhosis) on the disposition of the antidepressant tianeptine, which is devoid of substantial first-pass metabolism, was examined in 21 patients and 11 age-matched controls. Pharmacokinetic parameters for tianeptine and its C5 acid analogue metabolite (MC5 metabolite) were estimated by non-compartmental analysis. The area under the curve (AUC) for tianeptine, following a 12.5mg single oral dose, was decreased by 31% in chronic alcoholics and increased by only 14% in cirrhotics, compared to controls. These changes did not attain statistical significance. The trend of changes in the AUC for the MC5 metabolite was similar to that observed for the parent drug. No statistical difference was found in the terminal half-life for both tianeptine and its MC5 metabolite between patients and controls. On the basis of this study, it appears unnecessary to modify the proposed dosage regimen used in clinical trials (tianeptine sodium salt 12.5mg 3 times daily) in chronic alcoholics with or without associated moderate cirrhosis.

Adult↗
PubMed1989

[Mechanisms of undesirable effects of drugs].

Better prevention against adverse drug reactions could be obtained by improving our knowledge of pathological mechanisms and particularly risk factors. Because it is a medical act, the diagnosis must be made by a clinician who must then report it to his Drug Control Center.

Dose-Response Relationship, Drug↗
PubMed1988

The effect of food on the systemic availability of ketoprofen.

We have studied the pharmacokinetics of ketoprofen, a non-steroidal anti-inflammatory drug, in 12 patients after a single 100 mg oral dose both in fasting conditions and with a meal. Food significantly affected the peak plasma concentration of ketoprofen and decreased its absorption rate. However, the extent of absorption of ketoprofen, as reflected by the area under the plasma concentration time curve, appeared to be unchanged in the presence of food.

Administration, Oral↗
PubMed1988

Pharmacokinetic and metabolic parameters of tianeptine in healthy volunteers and in populations with risk factors.

Following oral administration in the fasting healthy subject, the mean maximum concentration of tianeptine is 334 +/- 79 ng/ml. Absorption of tianeptine from the tablet form is rapid and complete. Maximum plasma concentration is obtained by the first hour following administration (0.94 +/- 0.47 h). Absolute bioavailability is 99 +/- 29%. Tianeptine is thus rapidly and completely absorbed in the tablet form and is not subject to first-pass effect. Distribution of tianeptine in the body is characterized by the following: its rapidity, the mean distribution half-life being about 0.7 h; its limited extent, the apparent volume of distribution being about 0.8 L/kg (0.77 +/- 0.31 L/kg); and protein binding, which averages 93.8 +/- 2.4%. Elimination of tianeptine is characterized by a short mean half-life of 2 h 30 min (2.5 +/- 1.1 h) and by renal excretion of 0.4 ml/min (0.4 +/- 0.4 ml/min). Tianeptine is extensively metabolized. Major metabolites are analogs of tianeptine with a C5 and C3 lateral chain and a N-demethylated derivative. Studies have shown negligible influence on pharmacokinetic parameters of chronic alcoholism even in case of hepatic cirrhosis. In renal failure, and in the elderly, studies have revealed a 1-h prolongation of elimination half-life which suggests that the dosage should be limited to two tablets per day in such cases.

Administration, Oral↗