Modulation of hippocampal ACh release by chronic nicergoline treatment in freely moving young and aged rats.

The effects of nicergoline on basal and K(+)-stimulated release of ACh in the hippocampus of 3- and 19-month old rats has been studied by microdialysis. A significant decrease of basal ACh release (59%) was found in aged vehicle treated rats in comparison to young rats. High-K+ (100 mM) in the perfusate strongly increased the release of ACh by up to 6-fold over the baseline of both young and aged rats. Chronic oral administration of nicergoline to aged rats (5 mg/kg b.i.d. for 6 weeks) significantly reversed (93%) the age-related decrease of basal release of ACh, leaving the increase due to K+ depolarization unchanged. In young animals, nicergoline did not affect the basal output of ACh, but enhanced the K(+)-evoked release of ACh by 39%. Results from this study demonstrate that nicergoline treatment increases the ability of hippocampal cholinergic terminals to release ACh, and suggest that this drug can reset the cholinergic impairement associated with aging.

Increased susceptibility to the anticoagulant effect of warfarin in mice bearing the Lewis lung carcinoma. Role of vitamin K deficiency.

This study reports an increased susceptibility to warfarin anticoagulation in mice bearing an experimental tumour, the Lewis lung carcinoma. In these animals, following a single i.v. injection of warfarin, the prothrombin complex activity decreased normally but recovered far slower than in controls, while the rate of degradation of the clotting factors was not modified. At the level of the vitamin K-dependent liver carboxylase, it was possible to demonstrate an increase in the endogenous substrate (reflecting an impairment of the carboxylase vitamin K dependent system). This abnormality was reversed by vitamin K administration and can be reasonably ascribed to a vitamin K deficiency in association with tumour growth.

Kinetics of virus-specific IgG and IgM antibody response in patas monkeys experimentally infected with Delta herpesvirus by enzyme-linked immunosorbent assay.

The kinetics of virus-specific IgG and IgM antibody response in patas monkeys experimentally infected with Delta herpesvirus (DHV), was studied using enzyme-linked immunosorbent assay (ELISA). An indirect ELISA (IE) test was used for DHV IgG determination, whereas a "double sandwich" (triple antibody layer) ELISA (DSE) test was found to be very sensitive for DHV IgM detection. In DSE test DHV IgG appeared to interfere with IgM determination only in sera containing DHV IgG levels at least 100 times higher than IgM. IgM antibodies appeared 5-8 days after monkey infection, reached a peak titer in 5-7 days, and after 7 days started to drop in titer and disappeared within two months. IgG antibodies appeared 5 days later than IgM, reaching the plateau in the following 7 days and then remaining stable for at least 2 months. Experimental infection of the patas monkey with DHV appears to be a good animal model for human varicella. IE for IgG and DSE for IgM detection are sensitive ELISA tests for determination of the immune response to DHV infection in patas monkeys.

A pharmacokinetic and platelet function study of the combined administration of metoprolol and sulfinpyrazone to healthy volunteers.

In a double-blind study on healthy subjects who underwent three 3-week periods of treatment with metoprolol (M) + sulfinpyrazone (S), M + placebo, and S + placebo, pharmacokinetics and plasma levels of M were not affected by concurrent administration of S. Analysis of variance change-over demonstrated a significant difference between treatments only for serum uric acid levels. Analysis of post-treatment and baseline data within each treatment showed: decreased platelet count by M, lowered serum 6-keto PGF1 alpha by all three treatments, decreased serum TXB2 generation and arachidonic acid-induced platelet aggregation by S + M. No negative interaction between S + M was found.

Typing of herpes simplex virus isolates by enzyme-linked immunosorbent assay: comparison between indirect and double-antibody sandwich techniques.

Indirect and double-antibody sandwich enzyme-linked immunosorbent assay techniques were compared for serotyping 42 herpes simplex virus isolates. Both procedures gave similar results, which were in complete agreement with those obtained by inhibition of the indirect hemagglutination test. The indirect technique proved to be as specific as the double-antibody sandwich enzyme-linked immunosorbent assay, but simpler and cheaper.

Pharmacokinetics of amiodarone in man.

We studied the kinetics of amiodarone in three healthy volunteers after single oral (400 mg) and intravenous (150 mg) doses and in six patients with supraventricular tachycardia. Three patients were studied after the first oral dose (400 mg) and during subsequent therapy (200 mg/day); the other three after 5 mg/kg of amiodarone intravenous. Blood was drawn at intervals for 24 h in patients and up to 32 h (i.v.) and 50 h (p.o.) from healthy volunteers. The drug was measured by high pressure liquid chromatography (HPLC). No difference in kinetic parameters was found between healthy subjects an patients. The pharmacokinetic parameters, calculated on the intravenous data using a two-compartment open model, indicate a very large volume of distribution (9.26-17.17 L/kg in healthy volunteers and 6.88-21.05 L/kg in patients). The elimination half-life ranged from 12.09 to 20.70 h in volunteers and from 11.60 to 19.60 h in patients. Oral absorption was slow an erratic, with fourfold individual variations in systemic bioavailability (22-86%). A slight accumulation of amiodarone was observed in patients under chronic treatment.

Pharmacokinetics of amiodarone in rats.

We studied the kinetics of amiodarone in the rat. After an intravenous dose of 50 mg/kg, the time-course of the drug concentrations was assessed by high-pressure liquid chromatography in blood and tissues up to 16 h. The drug disappeared from the blood with an elimination half-life (t1/2beta) of 514 min and distributed extensively into tissues [apparent volume of distribution (Vd)= 29.51 L/kg]. Concentrations were highest in liver, kidney, and heart, and lowest at all times in the brain. The highest concentrations were found within 5-30 min of administration. Amiodarone accumulated extensively in adipose tissue and reached a fat/blood concentration ratio of about 1,000 at 16 h. Single-pass rat liver perfusion experiments gave an hepatic extraction ratio of 0.49 and an intrinsic clearance of 5.48 ml/min. Amiodarone disappearance in rat liver recirculation experiments was biexponential, with a half-life of 58 min.

Antigenic and biological relationships between human coronavirus OC43 and neonatal calf diarrhoea coronavirus.

Monospecific antisera were prepared in mice to human coronavirus OC43 and neonatal calf diarrhoea coronavirus (NCDCV) which had been previously adapted to growth in suckling mouse brain. Brain suspension from infected suckling mice was used as immunogen. The antigenic relationship between OC43 and NCDCV was studied by the indirect immunoperoxidase antibody technique, by the haemagglutination-inhibition (HI) test and a new infectious centre-reduction neutralization test. In mouse immune sera, a two-way cross-reaction between OC43 and NCDCV was detected. However, the antigenic relationship appeared to be closer for internal (as shown by immunoperoxidase staining) as compared to surface antigens (as shown by HI and neutralization). In primary infections of natural hosts there was a high degree of cross-reactivity between the two coronavirus strains for both surface and internal antigens, and homologous and heterologous titres were consistently within an eightfold dilution difference by all tests. Most human adults and calves had antibody to both OC43 and NCDCV and geometric mean titres of homologous antibody were higher than titres of heterologous antibody. Although OC43 and NCDCV share antigenic determinants, they possessed several different biological properties, including plaque morphology by the infectious centre assay, agglutination of 1-day-old chick erythrocytes and resistance of haemagglutinin to physical and chemical treatments.

Antibody to early antigens of varicella-zoster virus during varicella and zoster.

IgG antibody to the early antigens of varicella-zoster virus (VZV) was studied during both varicella and zoster by the indirect immunoperoxidase antibody technique. In parallel, complement-fixing, immune-adherence hemagglutinating, IgG, and IgM antibodies to VZV were studied. In both varicella and zoster infections, antibody to the early antigens of VZV appeared three to five days after onset of infection, reached a peak during the second week, and progressively decreased in titer until it disappeared, usually within two months. This antibody usually appeared slightly later than IgG or IgM antibody and grossly correlated with IgM antibody in varicella. In zoster infections, IgM antibody to VZV was not found by the immune-adherence hemagglutination assay at a titer of greater than or equal to 1:4, whereas antibody to the early antigens showed a curve similar to that found in varicella. It is suggested that antibody to the early antigens of VZV be considered as a marker of acute VZV infection, which is associated with a specific and significant IgM antibody response in varicella but not in zoster.

Kinetics and efficacy of theophylline in the treatment of apnea in the premature newborn.

Aminophylline (theophylline-ethylenediamine) was administered to 27 premature newborns to prevent apneic spells. Of the 22 patients monitored for theophylline concentration, a therapeutic blood level was reached in 19 in 1--2 days, and 3 stayed below it. "Toxic" blood levels (less than or equal to 20 microgram/ml) were reached in 3 cases, one of whom showed signs of toxicity. Theophylline treatment was not efficient in the prevention of apnea when a serious underlying disease was present. Theophylline blood half-life (mean:27.0 h) and clearance (mean 12.9 ml/h/kg) confirmed the slow elimination pattern of the drug in the premature infant.

Bioavailability and platelet aggregation inhibitory activity of solufenum. A comparison with ibuprofen.

Bioavailability and platelet aggregation inhibitory activity of the lysine salt of ibuprofen (solufenum) were compared with those of the parent molecule in 5 healthy male volunteers. The study had a randomized, cross-over design. The average peak plasma level and the area under the curve were higher when solufenum was administered orally as compared to the same preparation given i.m. or as compared to oral ibuprofen. However, the bioavailability of the 3 preparations studied was not significantly different. In contrast, the inhibitory effect on adrenaline-induced platelet aggregation appeared significantly different. In contrast, the inhibitory effect on adrenaline-induced platelet aggregation appeared significantly earlier after the administration of both solufenum than after ibuprofen. The clinical relevance of these findings is discussed.

Carbamazepine and carbamazepine-10, 11-epoxide concentrations in human brain.

1 Carbamazepine (CBZ) brain and plasma concentrations were measured in twenty-one patients undergoing brain surgery for tumour removal. The drug was administered prophylactically at doses ranging from 6.9 to 14.8 mg/kg for 4-5 days before the intervention. 2 In seventeen cases where sample were collected 10-14 h after dosing, CBZ brain levels ranged from 2.2-14.5 microgram/g. A significant linear relationship (p less than 0.01) was observed between brain and plasma concentrations with a brain/plasma ratio of 1.1 +/- 0.1. 3 Carbamazepine 10,11-epoxide (CBZ-Epox), present in all samples, could be quantified in three brain specimens. Its brain concentrations ranged from 1.5-2.7 microgram/g with a brain/plasma ratio of 1.1-1.2. 4 Parieto-occipital areas tended to show higher CBZ concentrations while lower values were found in temporal regions. Very low CBZ levels were found in two gliomas while in meningiomas CBZ levels were similar to those observed in normal tissue. 5 The data, showing a linear relationship between brain and plasma concentrations of both CBZ and its epoxide, give additional significance to the plasma level monitoring of antiepileptic drugs.

Plasma levels of di-no-propylacetate and clonazepam in epileptic patients.

Plasma levels of DPA and CNP and associated antiepileptic drugs were measured in groups of respectively 106 and 30 epileptic patients aged from 3 to 49 years. A poor correlation between daily oral dose and plasma levels of both drug was observed when the whole group of patients was considered. A better correlation was seen in a group of adult patients who received DPA and PB. Children below 10 years of age disposed both drugs faster than adults and the difference was significant (p less than 0.01) in groups receiving PB as associated drug. Patients medicated with PB and DPA or CNP showed lower plasma levels of both drugs; on the other hand DPA appeared to cause a decrease of PB clearance which was more marked in children. The clinical significance of the fluctuations of daily plasma levels of both drugs are discussed in relationship to the schedule of administration and plasma sampling. Observations on the therapeutic ranges and adverse effect of the drugs are reported.

Further observations on carbamazepine plasma levels in epileptic patients. Relationships with therapeutic and side effects.

Plasma levels of carbamazepine, phenytoin and phenobarbital were monitored weekly over a period of 9 weeks in 20 epileptic patients unresponsive to treatment. No attempts were made to modify phenytoin and/or phenobarbital plasma levels; emphasis was on achieving carbamazepine plasma levels of 4 to 10 mug per milliliter. A remarkable drop in seizure frequency was attained within 2 to 3 weeks of monitoring, with carbamazepine plasma and concentrations within the desired range. Children disposed of the drug faster than adults. No effects of phenytoin and phenobarbital on carbamazepine plasma levels could be observed, while phenobarbital on carbamazepine plasma levels fluctuated remarkably without any relationship to carbamazepine levels. Transient leukopenia was present in most of the patients, while a significant reversible drop in red blood cells was observed in eight patients. The data reported confirm that with a careful monitoring of drug plasma levels, carbamazepine may exert a definite passive effect on seizure frequency in epileptic patients poorly responsive to therapy.

Carbamazepine pharmacokinetics in young, adult and pregnant rats. Relation to pharmacological effects.

Adult, male, female and pregnant rats were treated with single and repeated doses of carbamazepine (CBZ). The time course of the drug concentrations in plasma and tissues was followed. In all cases, data on plasma levels were subjected to pharmacokinetic analyses. Attempts were made to relate pharmacokinetic properties of carbamazepine to its effect on pentobarbital sleeping time and on protection against electroshock, after acute and repeated administration: --it was found that male rats eliminate carbamazepine faster than females: the total body clearance (TBC) was 16 ml/min/kg and 9.4 ml/min/kg, respectively. Two dose levels (25 and 50 mg/kg) had the same pharmacokinetic properties in young rats. Pregnant rats clear CBZ to a lesser extent than controls. --CBZ was found to accelerate its own elimination after repeated administration in both adult and young rats as revealed by the shortening of its half-life and an increase of 50% in clearance. Moreover, the protection against electroshock was significantly reduced after repeated administration, compared with a single-dose administration. Repeated administration of CBZ in rats shortens pentobarbital sleeping time and decreases the pentobarbital brain level significantly.

A simple and sensitive gas chromatographic method for the determination of clonazepam in human plasma.

A simple gas chromatographic method for the determination of clonazepam in human plasma has been developed. After solvent extraction, the compound is measured by an electron capture detector on an OV-17 column. The electron-capture response is linear for 5-120 ng/ml of plasma. There is no interference from other commonly used anti-epileptic drugs or endogenous substrates. Preliminary data from routin monitoring of epileptic patients shows a 10-fold variation in their clonazepam plasma levels.

CSF concentrations and serum protein binding of carbamazepine and carbamazepine-10,11-epoxide in epileptic patients.

Serum and CSF samples of patients receiving chronic carbamazepine treatment were analysed. Daily fluctuations in serum levels of carbamazepine and carbamazepine-10,11-epoxide did not appear to be related to the dosage schedule, but some patients tended to have lower fluctuations when the carbamazepine was given more frequently. The epoxide/carbamazepine serum ratios varied greatly from patient to patient, and also fluctuated during the day for the same patient. Carbamazepine and carbamazepine-10,11-epoxide were present in CSF in concentrations ranging from 19 to 34% and 26 to 71% of the serum concentrations, respectively. There was a significant relationship between the free fraction of both drugs evaluated in vivo and the CSF/serum ratios. The need for a careful evaluation of the possible clinical effect of the epoxide is stressed.

Bioavailability of two carbamazepine preparations during chronic administration to epileptic patients.

Two preparations of carbamazepine, as tablets and in syrup, were given for 8 weeks to 20 patients with epilepsy in a randomized crossover study. Weekly plasma levels were 3-21 mg/1 on dosages of 5-24 mg/kg/day. There was no difference in absorption or steady-state level between the two preparations. Carbamazepine 10, 11-oxide was constantly present when the level of carbamazepine was over 5 mg/l, and tended to be lower with the syrup.