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The possible interaction of a steady-state cetirizine treatment, a nonsedating H(1) antihistamine, on the disposition of a single I.V. infusion of theophylline was studied in six healthy male volunteers. As a corollary, it was checked whether this single theophylline administration modified the steady-state condition of cetirizine. A three-period, two-treatment, crossover design was used, each period being separated by a washout of 1 week. Each period consisted of the oral administration of 10 mg cetirizine or of a matching placebo every 12 h for 3½ days, the last intake being followed, 1 hour later, by a single 1-h I.V. infusion of 240 mg theophylline or of placebo. The sequence of treatments (A = cetirizine + theophylline placebo, B = cetirizine placebo + theophylline, C = cetirizine + theophylline) was alloted by a double Latin-square randomization. The repeated administration of cetirizine induced a 3% decrease of the urinary elimination of unchanged theophylline; the total body clearance of theophylline was marginally (+5%) and not significantly modified. Theophylline slightly lengthened the elimination half-life of cetirizine (from 8.3 to 9.9 h), without modification of its apparent total body clearance; the half-life of cetirizine remaining in the normal range. These subtle modifications are not clinically relevant and it may, thus, be considered that cetirizine exerts no pertinent interaction on theophylline disposition.

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)

The influence of two inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase, simvastatin and pravastatin, on the level of urinary 6 beta-hydroxycortisol/17-hydroxycorticosteroids (6 beta-OHC/17-OHCS) ratio was determined in two groups of normolipidemic Caucasian subjects (n = 18 and n = 14, respectively). The 6 beta-OHC/17-OHCS ratio increased significantly after simvastatin administration (20 mg day-1 for 17 days) (P = 0.0125) whereas no modification was observed after pravastatin administration (20 mg day-1 during 17 days). As the level of 6 beta-OHC/17-OHCS ratio is a function of cytochrome P-450 3A activity, these results suggest that in Caucasian subjects, simvastatin but not pravastatin could be a weak inducer of cytochrome P-450 3A. This contrasting effect could be related to the major pharmacological differences existing between these two drugs.

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.

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.

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.

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.

A previous study has demonstrated that the urinary level of 6 beta-hydroxycortisol is a marker of liver CYP3A content after induction by rifampicin. To put in evidence an eventual genetic polymorphism for this cytochrome, the frequency distribution of 6 beta-hydroxycortisol excretion was investigated in 102 healthy Caucasians before and after 6 days of oral rifampicin administration (600 mg daily). After rifampicin treatment, a wide interindividual distribution was observed but no clear bimodality. Moreover the mean 6 beta-hydroxycortisol level was higher in women (n = 38) than in men (n = 64). These observations do not favour the existence of a CYP3A genetic polymorphism based on 6 beta-hydroxycortisol excretion but evoke a sexual dimorphism. However, CYP3A is composed of at least four enzymes and as the enzyme(s) responsible for cortisol 6 beta-hydroxylation is (are) not perfectly known, it can not be excluded that a genetic polymorphism does exist for one enzyme of this family.

Combined estrogen-progestin high-dose oral contraceptives increase the risk of impaired glucose tolerance which is estimated at approximately 12% of oral contraceptive current users. Glucose tolerance is adversely affected by the chemical structure of the progestins contained in oral contraceptives such as estrane (norethindrone, ethynodiol) and particularly gonane (norgestrel). The women at high risk to develop an impaired glucose tolerance on high-dose, oral contraceptives are those with previous gestational diabetes, with a positive family history of diabetes mellitus in a first-degree relative, or who are obese or older. Low-dose oral contraceptives with a reduced content of estrogen and progestogen such as levonorgestrel or desogestrel as well as the triphasic oral contraceptives containing a low daily dose of levonorgestrel or gestodene, are associated with a significantly lower risk of impaired glucose tolerance, even in women with previous gestational diabetes. Noteworthy however is the ability of low-dose progestogen containing oral contraceptives, such as low dose gonane or estrane oral contraceptives, to induce glucose intolerance by increasing the plasma insulin response to oral glucose. Impaired glucose tolerance is often reversible within 6 months of discontinuing oral contraceptives, except for oral contraceptive users with previous gestational diabetes. Development of diabetes mellitus in high-dose oral contraceptive users is rare.

We studied changes of atrial natriuretic factor (ANF) and catecholamines in three patients with pheochromocytoma occurring in the familial syndrome of multiple endocrine neoplasia type IIa. Previous studies have suggested a stimulating effect of catecholamines on ANF release. In pheochromocytoma, we observed normal basal ANF levels despite increased catecholamine secretion. In contrast, a rise in plasma ANF was observed when a hypertensive paroxysm occurred. Also during surgery, dissection of pheochromocytoma led to a rise in plasma ANF and catecholamines associated with an increase in blood pressure (in the 3 cases) and in pulmonary artery pressure (in 2 cases). We concluded that chronic elevation of basal catecholamines are without effect on plasma ANF but that manipulation of pheochromocytoma leads to a stimulation of ANF release, possibly mediated by either a direct effect of endogenously released catecholamines and/or an increase in atrial pressure.

A link between debrisoquine oxidation phenotype and lung cancer susceptibility has been evoked by some authors but not confirmed by others. For this reason, we compared the frequency of debrisoquine poor metabolizer phenotype in 91 Belgian patients with lung cancer to that studied in 167 healthy Belgian subjects. No significant difference was observed in our study. These results do not support the existence of this link.

This article summarizes our present knowledge concerning drug-induced cholestasis by lesions of the bile ducts. Acute or chronic ductular and ductal cholestasis are induced by a few drugs. The acute form may mimick viral hepatitis or biliary tract obstruction. The outcome is generally good. The mechanism may be immunoallergic. The clinical presentation of the chronic form resembles that of primary biliary cirrhosis or sclerosing cholangitis. Its prognosis is generally good and characterized by a complete recovery. However, an evolution to biliary cirrhosis is sometimes possible. The mechanism could also be immunoallergic. Extrahepatic cholestasis is frequently observed after intra-arterial infusion of floxuridine. The prognosis is generally poor. The mechanism of this sclerosing cholangitis may be ischaemic.

[Sensitivity and specificity of the determination of urinary catecholamines and their acid metabolites in the diagnosis of neuroblastoma in children] A retrospective comparison of urinary excretion of norepinephrine, epinephrine, dopamine and/or their acidic metabolites, HVA and VMA, in 36 children with neuroblastoma versus 360 hospitalized children without neuroblastoma showed a sensibility of 72% and a specificity of 98% for HVA and 80% and 97% for VMA respectively. Consequently, the sensibilities and specificities of these 2 determinations confirm their useful purpose for the biochemical diagnosis of neuroblastoma in preference to the determinations of norepinephrine, epinephrine and dopamine.

Alpidem is a new imidazopyridine derivative acting as an anxiolytic which may be prescribed with H2 receptor antagonists in patients with peptic ulcer. An open trial design (cimetidine, 1 g daily for 22 days) was carried out in eight healthy subjects. Alpidem, 50 mg was administered orally at 09:00 prior to any treatment and on days 2 and 18 of the cimetidine treatment period. Antipyrine clearance was also determined before and on day 21. Under these experimental conditions, the inhibitory effect of cimetidine on the cyt. P-450 monooxygenase system has been demonstrated (reduced clearance of antipyrine and its three main urinary metabolites) but the plasma pharmacokinetics of alpidem and its three main plasma metabolites did not appear to be modified. Alpidem induced no sedative effect but there was an insignificant trend to impair slightly the psychometric tests 1 h post-drug by the combination with cimetidine. Pharmacokinetic and pharmacodynamic evaluations did not show significant interactions with cimetidine following alpidem 50 mg administration.

The bioavailability of a new film-coated tablet of ticlopidine hydrochloride was compared in 12 healthy male subjects to that of the older sugar-coated tablet. Plasma levels of ticlopidine were measured by gas-liquid chromatography up to 120 h after a single 500 mg dose of each preparation. Drug intake was separated by a four-week interval. No statistically significant differences could be found between the pharmacokinetic parameters for these two preparations. Bioequivalence was confirmed when applying the test of Westlake to the area under the curves (calculated difference: 8.3%; upper limit: 20%). No unwanted effect was reported during the study.