Search PubMed⌕ Search

Biomedical subjects

M Guyot

Publications and source records attributed to M Guyot.

89 records · Page 5Linked to original sources
PubMedDate not supplied

Diurnal variations in steady-state plasma concentrations of valproic acid in epileptic patients.

Patients on long term valproate treatment exhibit unusual fluctuations in steady-state plasma levels of valproic acid. In order to delineate the underlying mechanisms of these fluctuations, 2 studies were undertaken. In the oral study, 6 epileptic patients received enteric-coated sodium valproate tablets (on a bid regimen for at least 1 month) and plasma levels were monitored on an hourly basis during 24 hours. In the intravenous study, 5 patients received first an intravenous bolus dose (800mg) of sodium valproate followed a week later by a combination intravenous loading dose/constant rate infusion for 36 hours. Plasma valproic acid concentrations were monitored hourly during the infusion study. In the oral study, valproic acid concentrations in all subjects continued to decay for 5 to 6 hours following the 8pm dose. The mean fluctuation in concentrations during 24 hours was 112.8 +/- 31.6%. Consecutive fasting levels were not reproducible. In the intravenous study, small but significant oscillations were present at steady-state; fluctuations ranged from 22 to 34%. However, no circadian rhythm was apparent. On the basis of these findings, it appears that the value of a single fasting sample during therapeutic monitoring of valproic acid is questionable. For an accurate evaluation of valproic acid plasma levels, an average concentration based upon several daily determinations should be performed.

Administration, Oral↗
PubMedDate not supplied

[Artificial blood: the future of blood transfusion? I. Hemoglobin solutions].

To palliate certain drawbacks in blood transfusion, some preparations are studied as oxygen-transporting erythrocytic substitutes; these are preparations of a biological origin such as hemoglobin solutions, or synthetic preparations such as fluorocarbon emulsions. Part 1 studies solutions of purified, pyridoxylated and/or polymerized hemoglobin of human or animal origin.

Blood Substitutes↗
PubMedDate not supplied

[Artificial blood: the future of blood transfusion? II. Blood substitutes other than hemoglobin solutions].

Part 2 discusses the state-of-the-art in oxygen-transporting blood substitutes other than hemoglobin solutions (Part 1); these are the fluorocarbon emulsions, the hemoglobin liposomes and other products such as oxygen-chelating agents. The substitutes reviewed here may play an important future role; before then, their stability, ease of administration, innocuity and value in human clinical medicine must be ensured.

Animals↗
PubMedDate not supplied

Analysis of parent drug-metabolite relationship in the presence of an inducer. Application to the carbamazepine-clobazam interaction in normal man.

An increase in drug metabolic clearance results in a decrease in concentration of parent drug but the effect on concentration of metabolite has been unclear. The effect of increases in the clearance of parent drug and/or metabolite upon the metabolite concentration, metabolite-to-parent drug concentration ratio, and fraction metabolized is described theoretically. It is shown that several combinations of increases in specific clearances can lead to qualitatively similar effects on steady state concentration of metabolite. The effect of increases in metabolic clearances of the clobazam-norclobazam system caused by carbamazepine treatment was studied in normal volunteers. The steady state concentration of metabolite (norclobazam) increased 1.4-fold and the ratio of metabolite to parent drug increased 4-fold. These effects of carbamazepine on clobazam-norclobazam pharmacokinetics could be a result of five theoretical cases. It is concluded that at least the formation clearance of norclobazam was increased. Carbamazepine treatment caused at least a 4-fold increase in the N-demethylation clearance of clobazam. It was also deduced that, in the baseline state, no more than 70% of the clobazam dose was metabolized to norclobazam, even though the norclobazam concentration was more than twice the clobazam concentration.

Adult↗
PubMedDate not supplied

[Present and future choices of vaginal drug dosage forms. I. Classical forms].

The anatomy and physiology of vagina play a major role in the formulation of vaginal products. In this review, many classical dosage forms (tablets, suppositories, creams, gels, foams...), used either for local or systemic treatment are described and discussed. Formulation and essay are briefly reviewed. But emphasis is layed on the problems associated with the administration of these dosage forms, their advantages with regard to other vaginal products and the use of these products as contraceptive devices.

Administration, Intravaginal↗
PubMedDate not supplied

[Present and future choice of pharmaceutical forms for intravaginal administration. II. Barrier systems and vaginal rings].

In part I of this review, various vaginal products for local and systemic treatment have been described and discussed. Part II is reserved to other intravaginal contraceptive systems. Some devices as diaphragms, sponges, ... have a mechanical contraceptive advantage associated or not with a spermicidal activity and can or cannot protect against venereal diseases. Other devices like intravaginal rings allow a long-acting and controlled release of contraceptive hormones and it is quite possible that they replace orale contraceptive dosage forms. Various approaches in designs, safety, effectiveness, inconvenience and advantages are discussed.

Administration, Intravaginal↗