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Biomedical subjects

R J Royer

Publications and source records attributed to R J Royer.

At least 73 records · Page 4Linked to original sources
PubMed1979

Pharmacokinetics of salicylates in elderly.

In order to study changes in the pharmacokinetics of salicylates in old people, we used two groups of inpatients without hepatic or renal impairment: the first comprised 15 patients more than 65 years old, mean age 77 years; the second, 7 patients of mean age 21 years. Each patient was given 1 g of acetylsalicylic acid orally in the morning while fasting. Blood samples were subsequently taken after 30, 60 and 90 min and 2, 3, 4, 6, 8, 10, and 24 h. Fluorimetric assay results were analyzed kinetically with a mathematical model corresponding to a single diffusion compartment model. The results showed only a slight increase in the absorption half-time in old subjects, and a marked increase in elimination half-time (3.71 and 2.38 h in old and young subjects, respectively; t = 2.33: p less than 0.05) and in the volume of distribution (5.51 and 3.83 liters respectively; t = 3.20: p less than 0.1). On the other hand, bioavailability varied little, as did metabolic clearance. This study confirms that intestinal absorption of this drug is not much impaired in old people, while hepatic and/or renal elimination functions are changed. This finding agrees with results found for aminopyrine, antipyrine, and digoxin.

Adult↗
PubMed1978

Drug interference in clinical chemistry: studies on ascorbic acid.

The expert group "Drug Interference in Clinical Chemistry" of the Bureau of Reference, Directorate General for Research, Science and Education of the Commission of the European Communities, consisting of one participant of each member of the European Communities, presents this first report on the final results of its activities. Within the framework of a first stage basic program, the paper describes interferences of therapeutic and elevated doses of ascorbic acid on commonly used clinical chemical methods. This is the result of a bipartite study that was jointly planned, carried out and evaluated. Local and personal influences have been eliminated, as have variations due to methodology, measurement equipment and reagents, in order to be able to present distinct causal effects of ascorbic acid. No definite influence of ascorbic acid on analytical values for urea, cholesterol, calcium, protein, bilirubin, aspartate aminotransferase and alkaline phosphatase could be detected. At therapeutic concentrations, ascorbic acid distinctly interferes with the analysis of glucose, uric acid, creatinine and inorganic phosphate. The extent and direction of interferences vary, depending on the type of reaction, kit and apparatus. In some cases the influence of ascorbic acid results in severe disturbance of the analytical methods leading to useless values.

Ascorbic Acid↗
PubMed1978

[Effect of diphenylhydantoin administered during gestation and lactation on the motor development and cerebellar histology of the young rat].

Rattus norvegicus females were treated by diphenylhydantoin (D.P.H.), all along pregnancy and lactation. 4 groups were constituted: a 100 mg DPH/kg/day group, a 50 mg DPH/kg/day group; a placebo group (treated with pure water), and control group. D.P.H. was given twice a day by a gastric tube. The cerebellar Purkinje cells studied through light microscopy and transmission electron microscopy in young rats (25 days old) showed no visible alteration. 2 motorcoordination tests were applied to the young rats, during their 2nd and 3rd weeks of post-natal life. Young rats of DPH 100, DPH 50 and placebo groups showed a backwardness relatively to control. This backwardness may be attributed to the maternal forced feeding stress, but not to a specific action of the DPH.

Animals↗
PubMed1978

[Pharmacology of morphine and its derivatives (review)].

Morphine, the principal alkaloid of "papaver somniferum" is the reference substance of central analgesics, the parmacodynamic constants of which are: analgesia and the possibility of addiction. Respiratory depression is, for many of them, a grave side-effect. At the present time, no substance in this category is fully satisfactory and all may result in dependence. Equi-analgesic doses of dextromoramide, phenoperidine and Fentanyl are less than those of morphine, whilst those of pethidine and pentazocine are higher. Study of the pharmacokinetics of these various substances indicates no common elements, and it is difficult to consider that the analgesic action is proportional to blood levels. Clinical assessment of the mean duration of action makes it possible to divide morphine derivatives into substances with a very short action (20 to 45 minutes) such as Febtanyl and phenoperidine, and those with a longer action (1 to 4 hours) which includes the majority of the other substances. The analgesic activity of Methoadone lasts for 4 to 6 hours. Morphine antagonists such as Methadone, nalophine, naloxone and naltrexone possess specific problems in terms of their utilization. Pharmacological data concerning theses substances are described.

Biotransformation↗
PubMed1977

[Interactions of salicylates and other nonsteroid anti-inflammatory agents].

The salicylates are frequently associated in every day treatment with other non-steroid anti-inflammatory drugs, which justifies a study of their interactions. Animal pharmacodynamics, although interesting, is of little practical interest. Pharmacokinetic research seems to indicate that aspirin reduces the bio-availability of other non steroid anti-inflammatory drugs, which has not yet been confirmed clinically. It is still premature to conclude, but the already established facts suggest the continuation of such studies.

Animals↗
PubMed1976

[Pharmacokinetic data on phenobarbital. Study on the influence of gestational age and dysmaturity].

Blood levels of barbiturate after a single intramuscular injection of 10 mg of phenobarbiitone have been plotted against time in 15 neonates at term of whom five were normal and 10 were dysmature, and 15 pre-term infants between 32 and 34 wesks gestation, of whom 12 had a satisfactory weight and 3 were dysmature. The analysis of the experiments according to a mathematical model gave the following results. Half life of absorption +/- 1 S.D. 9.55 HR +/- 6.97 for the term neonates and 11.12 hr +/- 7.61 for the pre-term infants. The difference is not significant. Half life of elimination +/- 1 S.D. 118.06 hours +/- 64.79 for the neonates of term and 110.49 hr +/- 37.19 for the pre-term infants. The half life of elimination is much shorter in the pre-term dysmature infants 74.10 hrs +/- 40.12. The individual variations are important but the differences between the groups of neonates studied are not great. This permits re-grouping and calculation of a half life of elimination for the whole group of 114.28 hr +/- 28.05. The risk of over dosage and the large individual variation in the metabolism of phenobarbitone in the new born lead us to recommend checking the blood levels when giving repeated doses.

Birth Weight↗
PubMed1976

[Interaction of salicyl compounds and other non-steroidal anti-inflammatory agents: pharmacokinetic study of phenylbutazone-aspirin combination in man].

The pharmacodynamic interaction between phenybutazone and aspirin was studied in 9 patients. The levels of phenylbutazone were estimated by gas-chromatography and verified by mass-spectrometry. When phenylbutazone was administered together with salicylates a decrease in the bioavailability of phenylbutazone was demonstrated, but there was no significant variation in the absorption and elimination constants or in the half-life. The variations were much less than those observed with other nonsteroid anti-inflammatory drugs (indometacine, naproxen, fenoprofen). These interactions must be taken into account in the long-term treatment of cases of inflammatory rheumatism.

Adult↗
PubMed1976

[Pediatric pharmacology. Practical ideas of kinetics and metabolism of drugs].

After administration, a drug does not exert immediately all its actions. Rates of diffusion, fixation and excretion of drugs are depending from their nature as well as from the condition of the body to which they are given. The resultant of these mechanisms control the blood level of a drug, level which varies in function of time. The blood level reflects the pharmacodynamic activity of a drug. Information on kinetics and significance of the status of drug equilibrium are of major importance for rational drug administration.

Biological Availability↗