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Biomedical subjects

G Olive

Publications and source records attributed to G Olive.

At least 91 records · Page 5Linked to original sources
PubMed1984

Pharmacokinetics of buflomedil after intravenous administration in patients with chronic renal failure.

The pharmacokinetics of single intravenous doses of buflomedil were studied in nine patients with chronic renal failure. The mean buflomedil half-life was 5.38 h (range 1.78-11.8 h); the mean buflomedil total clearance was 11.8 l/h (range 2.67-37.2 l/h). Comparisons of buflomedil kinetic parameters between the uraemic patients and healthy subjects revealed significant decreases in the renal elimination percentage u, the renal clearance Clr; significant increase in elimination half-life from the central compartment and no significant differences in the other parameters. Chronic renal failure is associated with a significant alteration in buflomedil elimination. This study suggests to reduce the usual dosage to half its value in the renal disease.

Adult↗
PubMed1983

Desensitization of the isolated guinea pig ileum to antihistaminic agents.

Guinea pig ileum developed in vitro a progressive desensitization to the antihistaminic agents mepyramine and benadryl. This desensitization had uncommon characteristics: (1) at the 6.5-9 h period of the experiments, it consisted only of a decreased rate of action of the drugs (1.66 fold and 2 fold increases in the 2 min Kb value of mepyramine and benadryl respectively), without variation in the equilibrium Kb values; (2) it was not a drug effect since control strips (strips exposed to the first dose of antihistaminic agent after 5.5 h in vitro) also showed a decreased rate of action of the drugs (1.58 fold and 1.6 fold increases in the 2 min Kb value of mepyramine and benadryl respectively), without variation in the Kbe values. The desensitization also did not depend on the bathing medium or on the amount of available histamine receptors. The only explanation of the desensitization is a slowing in the antihistaminic agent-receptor reaction either in its access stage or less probably in its interaction stage.

Animals↗
PubMed1983

Pharmacological interaction between nitroglycerin and aspirin after acute and chronic aspirin treatment of healthy subjects.

The interaction between nitroglycerin (NTG) and aspirin was investigated in 7 healthy subjects in order to test whether aspirin could block the haemodynamic response to NTG; the doses used were NTG 0.8 mg, and aspirin 0.5 g for chronic and 1 g for acute treatment. The plasma levels of NTG and various physiological parameters (heart rate, diastolic arterial pressure, end diastolic diameter, and end systolic diameter) were measured during the 30 minutes after the administration of NTG. An increase in NTG Cmax and AUC was observed after both aspirin treatment. The changes in physiological parameters produced by NTG were enhanced by the two treatments, although the differences were not statistically significant. The results indicate complex pharmacokinetic and pharmacodynamic interactions between NTG and aspirin.

Adult↗
PubMed1983

Metabolism of the human placenta perfused in vitro: glucose transfer and utilization, O2 consumption, lactate and ammonia production.

Oxygen consumption, glucose transfer and utilization, and lactate and ammonia release were studied in the human full term placenta using an in vitro perfusion technique. D-Glucose was the only substrate added to the perfusion fluid. On the maternal side, oxygen and glucose were taken up at a constant rate during perfusion. On the fetal side, a lower oxygen uptake was observed. Glucose was steadily released into the fetal perfusate as a result of the downhill concentration gradient established between maternal and fetal circulations. By contrast, lactate and ammonia release took place only into the maternal circulation and decreased rapidly during perfusion. No significant change in tissue glucose content was observed between the onset and the end of the experiment. Placental lactate and ammonia concentrations were shown to diminish significantly during perfusion.

Ammonia↗
PubMed1983

[Benzodiazepines and pregnancy. Transplacental passage, labor and lactation].

Benzodiazepines (BZD) are lipophilic molecules, undissociated agents which easily penetrate membranes. Pharmacokinetics of BZD arises from these chemico-physical properties. Thus BZD show a rapid placental transfer with significant uptake of the drug, in both early and late pregnancy. The changes in the placental structures and in the circulation of the uterus during pregnancy are responsible in the greater placental passage in late pregnancy. After repeated doses in pregnant women, BZD tend to accumulate on the fetus, and the " flappy infant" syndrome may occur. The disposition of diazepam in women to the end of the pregnancy is altered. The terminal half-life is about twice as in non pregnant control, the distribution volume is increased but the total plasma clearance is not changed. In neonate child and particularly in premature infant, elimination of the BZD is slower in relation with immaturity of the hepatic enzymes systems metabolising drugs. BZD appear in human milk, but only high clinical doses might be expected to exert an effect on the nursing newborn. In the first trimester of pregnancy use of BZD has to be exceptional; the safety of these products in early pregnancy has not yet been definitively established. In the late pregnancy and at the parturition, there are more clear indications. Generally high single doses and repeated and prolonged administrations have to be avoided.

Anti-Anxiety Agents↗
PubMed1982

[Comparative pharmacokinetics of benzodiazepines].

The pharmetabolism properties allow to guide the therapeutic use of benzodiazepines. The authors have studied these two aspects in relation with absorption, routes of administration, protein binding, distribution, métabolism, excretion, long-term use. The paper also deals extensively with pharmacokinetics and metabolic modifications under the influence of drug interaction, age, physiologic condition (pregnancy, new-born, elderlies) and pathological condition. These data are useful to guide the choice according to indication and to adapt the dosage.

Adult↗
PubMed1982

Transfer of ritodrine and norepinephrine in human placenta: in vitro study.

The placental transfer from maternal to fetal circulation of ritodrine, a tocolytic agent used in obstetrics and of a structurally related physiologic catecholamine, norepinephrine was studied in vitro using dual perfusion of isolated human placental lobules. The clearances of ritodrine and norepinephrine represent 34 and 24% respectively of tritiated water clearance taken as reference. The relatively low ritodrine clearance may be explained by its small molecular weight and hydrosoluble nature, but not that of norepinephrine. For the latter, a strong membrane limitation and efficient placental catabolism may be implicated. We conclude that some of the fetal effects of maternal infusion of these amines are the result of the method in which the drug is transferred.

Biological Transport, Active↗
PubMed1982

[3H]-Salbutamol placental transfer in pregnant rats on the 19th day of gestation.

[3H]-salbutamol added in tracer doses (approximately equal to 250 nmol per animal) to the carrier solution (20 mg/kg) was injected intraperitoneally to pregnant rats on the 19th day of gestation. Some experiments were performed with intravenous administration (approximately equal to 2.5 microCi in 300 microliters 9 g/l NaCl). Drug distribution was studied in the maternal and fetal plasma, lung and liver, and in the placenta and amniotic fluid. 10% of the maternal salbutamol plasma radioactivity was recovered in the fetal plasma, in accordance with earlier findings reported from our laboratory using human placental lobules in vitro.

Albuterol↗
PubMed1982

Maternofetal transfer of two benzodiazepines. Effect of plasma protein binding and placental uptake.

The influence of plasma protein binding on the maternofetal transfer of diazepam was studied in the perfused human placental lobule. Substitution of buffered salt perfusate in both maternal and fetal circuits for a perfusate with plasma proteins did not alter diazepam transfer significantly. Diazepam placental uptake was shown to be important in perfusion, with both types of perfusates. Comparison with the less liposoluble and less protein-bound benzodiazepine, fosazepam, revealed a marked difference in placental uptake but not in maternofetal transfer. In incubation studies, the kinetics of placental uptake confirmed this difference.

Blood Proteins↗
PubMed1982

Pharmacokinetics of tiapride and absolute bioavailability of three extravascular forms.

The pharmacokinetic properties of a single 200-mg dose of tiapride were studied in eight healthy volunteers (four males and four females). The drug was administered by i. v., i. m., and p. o. routes (solution and tablets). Plasma and urine concentrations were determined by a high-performance liquid chromatography. The results were compatible with a linear two-compartment model. The half-life in the disposition phase ranged from 2.19 h to 4.55 h (mean 3.23 h). Peak plasma concentrations were always reached within 2 h. The percentage of absorption of the i. m. and the two p. o. formulations varied from 49.3 to 98.9%. The renal clearance varied from 11.8 to 24.9 l/h. The drug was mainly eliminated in unmetabolized form in the urine (75.6%).

Absorption↗
PubMed1981

Transfer of Salbutamol in the human placenta in vitro.

The maternal-fetal transfer of Salbutamol was studied in vitro, in dual perfusion of isolated human placental lobules. The fraction of drug transferred to the fetal side was compared to reference substances:((14)C)-antipyrine and ((3H)-inulin. Salbutamol transfer (12%) represents about 39% of antipyrine and five times of inulin transfer. Studies with varying Salbutamol concentrations in the maternal arterial perfusate revealed that the drug transfer to the fetal side was effected by a flow-dependent diffusion process. We conclude that the reported effects on the fetus following a maternal drug infusion are mediated by the drug transferred across the placenta.

Albuterol↗
PubMed1981

[The pattern of cerebrospinal fluid proteins in infants and children. Determination of normal values (author's transl)].

Cerebrospinal fluid (CSF) protein values were measured in 652 children between the ages of 1 day and 17 years, allowing the authors to define the dynamics of the blood-brain barrier under normal conditions and during inflammation of the nervous system. The ratio of CSF albumin/serum albumin (whose upper limit was 0.65 in the study) was the best sign of alteration of blood-brain barrier permeability. The CSF IgG level, whose upper limit was 0.85 (for serum IgG between 10 and 14 g/l) is the most useful criterion for detecting an intra-thecal synthesis of IgG. Six patterns of CSF proteins are defined on the basis of immunochemical and electrophoretic studies. The ratio of CSF albumin/serum albumin and the CSF IgG level must be compared to the electrophoretic pattern of CSF proteins in order to better characterize one aspect of the blood-brain barrier under normal and pathologic conditions of the central nervous system.

Adolescent↗