Biomedical subjects

E Beyssac

Publications and source records attributed to E Beyssac.

22 records · Page 2Linked to original sources

PubMedDate not supplied

The unusual routes of administration.

A wide range of administration routes can be drawn on to optimise drug absorption. Though the oral route remains the favourite one for most drugs in many disease states, other routes are routinely used. Each has its strengths and weaknesses and needs to be selected carefully with full consideration of the drug, its target and the release pattern required. Advances in pharmacology and biopharmaceutics have led to exciting developments in the ways drugs can now be administered. Optimising drug administration means finding answers to a number of questions. These questions include: what, how, when and where to deliver, and how to retain the drug long enough for it to be fully effective. These issues are linked; route of administration, drug and therapeutic systems are interrelated; thus the choice of what to deliver influences how, when and where to deliver. Various definitions of 'usual/unusual' administration routes are presented, depending on the factors that determine the fate of the active ingredients, on the delivery device, and on the therapeutic objectives to be met. The various dosage forms designed for these routes, and the administration strategies developed to achieve the desired effects are described.

Absorption↗

PubMedDate not supplied

Bioinversion of ibuprofen enantiomers after administration in dogs: estimation of a novel index.

This study compares the pharmacokinetics and bioinversion of two chemical forms of ibuprofen administered intravenously or orally. Dogs were given the free acid form of the S(+) isomer p.o. or i.v., or the racemate, as the free acid or sodium salt, p.o., in a cross-over design. The main kinetic parameters were calculated and formation and bioinversion curves plotted. The values of Cmax, Tmax and AUC were higher for the S(+) isomer. The percentage bioinversion averaged between 35-70% according to the form. This study proposes a new index for the calculation of bioinversion, independently of any i.v. administration, and confirms its self-limiting nature.

Animals↗

PubMedDate not supplied

In vitro/in vivo correlations: scientific implications and standardisation.

In vitro/in vivo correlations and the parameters that should be correlated have now been well defined in the USP and FDA working group proposals. Among the three levels of correlation defined, Level A is the most interesting one. In this paper, the Level A correlation is studied from a mathematical and a biopharmaceutical point of view. The conditions that must be met before attempting to establish correlations and the place of in vitro/in vivo correlation in modified release drug dosage form development are discussed. To establish in vitro/in vivo correlations requires a strict development methodology in order to obtain them in the most favourable conditions. In vitro/in vivo correlations should be sought as early as possible during the dosage form development (a priori correlations). If the formulation has been undertaken first and correlations sought on the finished product from subsequent in vitro tests, the predictive power of these correlations (a posteriori correlations) is thus limited and they require additional validation.

Animals↗

PubMedDate not supplied

[Comparative study of pharmacokinetics and effects on urinary secretion of electrolytes of furosemide and furosemide-amiloride in healthy subjects].

A randomized cross over study was carried out in 12 healthy volunteers to investigate simultaneously the pharmacokinetics and the effects on urinary volume and electrolyte excretion after administration of single doses of 40 mg frusemide and a combination tablet containing both 40 mg frusemide and 5 mg amiloride. From a statistical analysis of plasma levels of frusemide and amiloride measured by HPLC methodology, no significant difference between the reference drug alone, frusemide, and the combination tablets was observed in mean peak plasma levels, mean times to peak or mean areas under the plasma concentration-time curves (AUC). Frusemide and the combination tablet both produced a rapid and powerful diuresis in the 0-2 hours postdose period and did not differ significantly in urine output at any time point. However a difference in natriuretic activity was observed between frusemide and the combination with the latter producing a significantly greater sodium excretion in the 0 to 2 hours period (p less than 0.05). Potassium retaining activity throughout the 24 hours was marked after the administration of the combination, the potassium excretion being significantly less (p less than 0.05) than either control of frusemide alone. There was also a significant correlation between plasma levels of frusemide and the time course of urine and electrolyte excretion in healthy subjects.

Adult↗