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Biomedical subjects

C Harvengt

Publications and source records attributed to C Harvengt.

At least 19 recordsLinked to original sources
PubMed1997

Pharmacokinetics and pharmacodynamics of cetirizine in infants and toddlers.

The pharmacokinetics of the second generation H1-receptor antagonist cetirizine were studied in 15 infants and toddlers (mean +/- SD age, 12.3 +/- 5.4 months) who were treated with a single 0.25 mg/kg dose of cetirizine solution. The infants and toddlers were hospitalized for recurrent respiratory infections or other hypersensitivity-related diseases. Blood samples were collected at 1/2, 1, 11/2, 2, 4, 6, 8, 12, and 24 hours, and a 24-hour urine sample was obtained. A peak plasma level of 390 +/- 135 ng/ml was observed after 2.0 +/- 1.3 hours. The elimination half-life was 3.1 +/- 1.8 hours, the apparent oral body clearance was 2.13 +/- 1.15 ml/min/kg, and the apparent volume of distribution was 0.44 +/- 0.19 L/kg. The excretion of unchanged cetirizine in six complete urinary collections was 62.7% +/- 13.2% of the administered dose. An additional pharmacodynamic study (inhibition of the histamine-induced wheal and flare) was performed in 10 of these infants and toddlers, after the intake of 0.25 mg/kg cetirizine twice a day for at least 4 days. A 90% +/- 12% inhibition of the wheal and a 87% +/- 17% inhibition of the flare were still observed 12 hours after the last intake. The duration of the H1-inhibition by cetirizine at the cutaneous level is thus longer in infants and toddlers than could be inferred from its pharmacokinetics; the level of inhibition at 12 hours was the same as in older age groups.

Administration, Oral↗
PubMed1996

Pharmacodynamic activity of lipoprotein lipase and hepatic lipase, and pharmacokinetic parameters measured in normolipidaemic subjects receiving ciprofibrate (100 or 200 mg/day) or micronised fenofibrate (200 mg/day) therapy for 23 days.

The activities of lipoprotein lipase (LPL) and hepatic lipase (HL) were investigated after 23 days of ciprofibrate (100 mg or 200 mg) therapy or fenofibrate (200 mg) therapy. In a double-blind, double-placebo, cross-over study, three groups of six healthy volunteers received either 100 mg ciprofibrate/day followed by 200 mg fenofibrate 'high bioavailability' (HB)/day, or vice versa (group A), 200 mg ciprofibrate HB/day followed by 200 mg fenofibrate HB/day, or vice versa (group B), or 100 mg ciprofibrate/day followed by 200 mg ciprofibrate/day, or vice versa (group C). Fasting plasma lipid levels and safety parameters were evaluated before and after treatment. One hundred milligrams ciprofibrate/day therapy was found to be approximately as effective as 200 mg fenofibrate HB/day therapy in altering the lipid profile. The highest activation of LPL was obtained after treatment with 200 mg ciprofibrate/day. A modest, but statistically significant, increase in HL activity was found after 100 or 200 mg ciprofibrate treatment. Investigation of the pharmacokinetics of ciprofibrate and fenofibric acid revealed a shorter time to reach peak plasma levels, but a longer elimination half life for the ciprofibrate preparations in comparison with fenofibrate. A dose of 200 mg ciprofibrate/day is more effective than 100 mg ciprofibrate/day at increasing LPL and HL activity; however, 200 mg ciprofibrate/day is also associated with a potential detrimental change in safety parameters. Two hundred milligrams fenofibrate HB/day therapy may represent an alternative therapy to 100 mg ciprofibrate/day for hyperlipidaemic patients.

Adult↗
PubMed1994

D-propoxyphene and norpropoxyphene kinetics after the oral administration of D-propoxyphene: a new approach to liver function?

In an attempt to design a liver function test which takes into account both portal-systemic shunting and hepatocellular dysfunction, we investigated a group of patients with cirrhosis with or without surgical porta-caval shunt for d-propoxyphene and its major metabolite, norpropoxyphene kinetics. A small dose of d-propoxyphene (0.7 mg/kg body weight) was given orally to seven normal subjects, 15 patients with cirrhosis and seven patients with cirrhosis and surgical portacaval shunt. D-propoxyphene and norpropoxyphene areas under the plasma concentration-time from 0 to 4-h (AUC) were determined by the trapezoidal method. As d-propoxyphene is a high extraction drug and since the production of norpropoxyphene should reflect the amount of d-propoxyphene available to the hepatocytes, we tested the hypothesis that norpropoxyphene/d-propoxyphene AUC ratios should reflect both the degree of portal-systemic shunting and the severity of hepatocyte dysfunction. Norpropoxyphene/d-propoxyphene AUC ratios were significantly lower in patients with cirrhosis (mean +/- S.D.: 0.92 +/- 0.59) than in controls (2.51 +/- 0.45) and also significantly lower in patients with cirrhosis and a surgical shunt (0.53 +/- 0.23) than in patients with cirrhosis but without surgical shunt (1.10 +/- 0.63). Moreover, there was an overall statistically significant correlation between norpropoxyphene/d-propoxyphene AUC ratios and branched to aromatic amino acids ratios (rs = 0.91) and fasting venous NH4 (rs = -0.63). On the other hand, there was only a weak correlation between norpropoxyphene/d-propoxyphene AUC ratios and the 14C-aminopyrine breath test (rs = 0.43). These data suggest that the norpropoxyphene/d-propoxyphene AUC ratio reflects both shunting and reduced hepatocellular function.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1993

Single-dose pharmacokinetics of cetirizine in patients with chronic liver disease.

The pharmacokinetics of the H1-receptor antagonist cetirizine were studied from 0 to 72 hours after a single dose of 20 mg in 5 patients with chronic hepatocellular liver disease (group A), in 5 patients with chronic cholestatic liver disease (group B), and in 16 healthy volunteers. The renal function of patients and volunteers was normal (creatinine clearance > or = 70 mL/min). Cetirizine pharmacokinetics were similar in the two groups of patients. The elimination t1/2 was prolonged in patients (mean +/- standard deviation; group A: 14.32 +/- 2.30 hours; group B: 13.86 +/- 3.14 hours) in comparison with the values observed in volunteers (9.42 +/- 2.4 hours). A reduced apparent oral body clearance also was observed in patients (group A: .48 +/- .23 mL/min/kg; group B: .41 +/- .09 mL/min/kg) in comparison with volunteers (.74 +/- .19 mL/min/kg). No differences were observed in the mean cumulative urinary excretion between patients (group A: 69 +/- 15%; group B: 69 +/- 13%) and volunteers (70.7 +/- 7.8%).

Adult↗
PubMed1993

Scoparone O-demethylase assay is not useful to differentiate the effects of model inducers of cytochrome P-450 in rabbit and guinea pig liver.

Coumarin derivative, scoparone (6,7-dimethoxycoumarin), is regioselectively O-demethylated into isoscopoletin (I) and scopoletin (S). This oxidation is inversely influenced by cytochrome P-450 inducers in the rat such as 3-methylcholantrene (3-MC) and phenobarbital (PB). The I/S ratio is higher than 1.5 with 3-MC treatment whereas it is lower than 0.5 with PB treatment. With regards to this contrasting effect, it has been suggested that the I/S ratio should be useful to differentiate between the effects of these types of inducers. We studied the consequences of in vivo PB and 3-MC treatment on scoparone biotransformation in guinea pig and rabbit. In these two species, at the basal state, scoparone biotransformation was enhanced in comparison to the rat. Moreover, in these untreated animals, two other metabolites were formed. After 3-MC or PB treatment, scoparone metabolism is, in contrast to the rat, inappropriate to differentiate between the P-450 profile of other animals.

Animals↗
PubMed1993

A pharmacokinetic evaluation of the second-generation H1-receptor antagonist cetirizine in very young children.

The pharmacokinetics of the second-generation H1-receptor antagonist cetirizine was studied in eight children younger than 4 years of age who were treated with a single dose of cetirizine solution (5 mg). These children were hospitalized with suspected allergic respiratory problems or recurrent respiratory tract infections. Blood samples were collected at 1/2, 1, 1 1/2, 2, 4, 6, 8, 12, and 24 hours, and a 24-hour urine collection was performed in five of the samples. The findings obtained in children were compared with those obtained in 16 healthy young adults (mean +/- SD, 24.6 +/- 4.1 years) who received a single 20 mg dose. Cetirizine was absorbed more slowly in children (p = 0.006; mean +/- SD, 1.44 +/- 1.12 hours) than in adults (0.62 +/- 0.22 hours). The plasma elimination half-life of cetirizine was significantly shorter in children (p < 0.001; 4.91 +/- 0.6 hours) than in adults (8.6 +/- 2.1 hours), and the clearance rate was significantly higher in children (p < 0.001; 1.48 +/- 0.41 ml/min/kg) than in adults (0.80 +/- 0.17 ml/min/kg). Urinary excretion of unchanged cetirizine was significantly lower in children (p < 0.001; 37.8% +/- 5.2%; n = 5) than in adults (57.7% +/- 11.8%). Therefore the metabolism of cetirizine is faster in young children than in adults. This effect must be taken into account in future pharmacodynamic studies in this age group.

Absorption↗
PubMed1993

The effect of cimetidine on the pharmacokinetics of single oral doses of alfuzosin.

Alfuzosin is a new alpha 1-adrenoceptor antagonist particularly effective in the symptomatic treatment of benign prostatic hypertrophy (BPH). The elimination of alfuzosin being almost entirely metabolic, the potential pharmacokinetic interaction with cimetidine (H2-receptor antagonist) was investigated in 10 healthy young subjects. Pharmacokinetics of alfuzosin were appraised as a 5 mg oral dose before, after one day and after 20 days of cimetidine (1 g/d) administration. An inhibition of the hepatic mixed function oxidase system by cimetidine was established by the oral antipyrine clearance test. Under these conditions, alfuzosin pharmacokinetics were only marginally affected by concomitant cimetidine administration. Surprisingly, a significantly shorter elimination half-life was found after 20 days on cimetidine (from 5.1 +/- 0.4 h to 4.4 +/- 0.5 h). This fact must be attributed to the large inter-individual variation in pharmacokinetic parameters reported for alfuzosin. Cmax and AUC increased up to 20% after cimetidine but without statistical significance. No side-effects on the association cimetidine-alfuzosin were reported. In conclusion, there is a lack of pharmacokinetic interaction on cimetidine-alfuzosin co-administration.

Administration, Oral↗
PubMed1992

Effects of combined bezafibrate-simvastatin appraised in healthy subjects.

The occurrence of clinical and biochemical side effects of bezafibrate (400 mg daily) or simvastatin (20 mg daily) alone or combined was appraised in 13 healthy male normolipidemic subjects according to a single blind design. Each period of 2 weeks of treatment with bezafibrate or simvastatin or bezafibrate plus simvastatin was followed by a period of placebo (1 week). No subjects experienced myalgia or muscle weakness. Plasma creatine kinase (CK) elevations, particularly skeletal muscle CK (CK-MM), were observed in 6 subjects: 11 times during different placebo periods, 5 times on bezafibrate, 4 times on simvastatin, and 4 times on combined bezafibrate-simvastatin, but never reached 1,600 IU/L. Only a trend to an increase of CK mean values on combined bezafibrate-simvastatin was shown. The hepatic transaminase and gamma-glutamyltransferase activities remained unmodified throughout the trial, unlike alkaline phosphatase activity, which fell on bezafibrate and on bezafibrate plus simvastatin. The low-density lipoprotein cholesterol level was more reduced with simvastatin than with bezafibrate. The addition of bezafibrate to simvastatin did not decrease it further. Lecithin:cholesterol acyltransferase activity expressed as fractional esterification rate was enhanced only on simvastatin and bezafibrate-simvastatin.

Adult↗