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At least 19 recordsLinked to original sources
PubMed1991

Pharmacokinetic profiles of prazepam and 14C-prazepam in rat.

Pharmacokinetics of Prazepam and 14C-Prazepam were studied in rat. Prazepam was measured in blood and plasma by a gas-liquid chromatography assay with an electron capture detector. Its major metabolite, Desmethyldiazepam, was also determined in blood in the same way. Total radioactivity was measured in plasma by scintillation spectrometry. Pharmacokinetic analysis were carried out by two ways; according to compartmental pharmacokinetic models and by statistic moments.

Animals↗
PubMedDate not supplied

[Prazepam drops versus 10 mg prazepam tablets in anxious patients in ambulatory care].

A multicentric study has been conducted with a new prazepam formulation (drop) which has been compared with 10 mg tablets. The aim of the study was to check the clinical equivalence of the two formulations. Nine generalists and 9 psychiatrists participated in this double blind study. One hundred fifty four patients with DSM III generalized anxiety criteria were included in this study and received prazepam at an average dosage of 20 mg per day. There were 11 drop outs: 6 in the tablet group and 5 in the drop group. The statistical analysis was done on 143 patients. Before treatment the two groups were equivalent. There was a very significant decrease (p less than 10(-4) in Hamilton anxiety scale scores, physician visual analogic scale and patient visual analogic scale with no difference between both groups. The vigilance, measured by the Mini-Folstein scale, was significantly increased (p less than 10(-4) in both groups. The tolerance was also similar: 14 patients in the tablet group and 10 in the drop one complained of asthenia and somnolence.

Adult↗
PubMed1991

Comparison of performance of healthy volunteers given prazepam alone or combined with ethanol. Relation to drug plasma concentrations.

The interaction between a single dose of 20 mg of prazepam and 0.5 g/kg body weight ethanol was investigated in 12 healthy male volunteers by nine objective performance tests, eight visual analogue self-rating scales and measurement of prazepam and ethanol plasma concentrations, using a double-blind three-way crossover design. The volunteers were each given three treatments (prazepam+ethanol, placebo+ethanol and prazepam alone), separated by a 2-week interval. They completed the performance tests before treatment and 1.5 and 4 h thereafter, and the self-rating scales before treatment, 1.5, 4 and 8 thereafter. To determine prazepam and ethanol plasma levels, venous blood samples were drawn before drug intake and 0.25, 0.5, 1, 1.5, 3, 4, 5 and 8 h thereafter. In two of the performance tests: auditory reaction time and digit symbol substitution, the combination of prazepam and ethanol was shown to impair performance more than either drug taken alone 1.5 h after their administration. A similar result was found for the drowsiness scored in the self-ratings. The time needed to complete the two-symbol cancellation test was longer when the subjects received prazepam either alone or combined with ethanol. Simultaneous ingestion of prazepam and ethanol did not alter the bioavailability of either drug.

Adolescent↗
PubMed1988

Comparison of sublingual and oral prazepam in normal subjects. II. Pharmacokinetic and pharmacodynamic data.

The pharmacokinetic profiles of oral and sublingual administrations of prazepam 20 mg to 5 normal volunteers were compared in order to explain the clinical observation that sublingual prazepam appears to exhibit sedative properties when compared to the same dose of oral prazepam. Blood samples for pharmacokinetic evaluation were collected just before drug intake and 7.5, 15, 22.5, 30, 45, 60, 90 min, 2, 3, 5, 6, 7, 8, 9, 10 and 24 h after drug intake. The study was performed in double-blind and crossover conditions. Serum levels of prazepam and its major metabolite N-desmethyl-diazepam were measured by HPLC. No prazepam was detected at a concentration higher than 20 ng/ml (limit of detection) whereas N-desmethyl-diazepam reached concentrations around 140 ng/ml. To correlate this observation with the clinical data, the affinity of prazepam and N-desmethyl-diazepam was compared measuring their ability to displace 50% of 3H-flunitrazepam bound to benzodiazepine receptors contained in synaptosomal preparation obtained from rat brain. N-desmethyl-diazepam was 17-fold more potent than prazepam. This data suggests that prazepam is a pro-drug which is transformed to the active compound N-desmethyl-diazepam and that the difference in clinical observation with both administrations could be correlated to N-desmethyl-diazepam concentration-time curves. Nevertheless, the comparison of the area under the N-desmethyl-diazepam serum concentration-time curves, the maximum concentrations, the times when the maximum concentrations were observed and the times needed to detect a significant level after oral and sublingual administration did not show statistical difference.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1984

Comparative single-dose kinetics of oxazolam, prazepam, and clorazepate: three precursors of desmethyldiazepam.

Twelve healthy volunteers received a single 40-mg oral dose of the benzodiazepine derivative oxazolam, which serves primarily as a precursor of the active substance desmethyldiazepam (DMDZ). Concentrations of DMDZ were measured in multiple serum samples drawn for up to two weeks after the dose. Peak serum DMDZ concentrations averaged 115 ng/ml, measured at 8.6 hours after dosage. Mean DMDZ elimination half-life averaged 61 hours. Three of the subjects also received 40 mg each of prazepam and clorazepate, two other DMDZ precursors, on separate occasions. Although DMDZ elimination half-life was similar, total area under the curve (AUC) for DMDZ was larger for clorazepate, known to be completely transformed into DMDZ, than for oxazolam or prazepam the extent of whose conversion to DMDZ has not been previously established. After correcting for the different molar equivalent of DMDZ available from each preparation, the DMDZ ratio averaged 0.22 for oxazolam vs. clorazepate and 0.51 for prazepam vs. clorazepate. Thus, both oxazolam and prazepam lead to slow appearance of DMDZ in the systemic circulation. Furthermore the extent of DMDZ formation from oxazolam and prazepam is either incomplete or the drugs are incompletely absorbed. Equivalent doses of oxazolam, prazepam, and clorazepate should not be interchanged in clinical practice.

Adult↗
PubMed1985

Ranitidine versus ranitidine and prazepam in the short-term treatment of duodenal ulcer--a double-blind controlled trial.

Fifty out-patients with an active, endoscopically proven duodenal ulcer were entered a double-blind trial of ranitidine + prazepam or ranitidine + placebo. Two drop-outs occurred in the prazepam group and 1 in the placebo group. After 28 days of treatment, the ulcer had healed in 95.6% of the patients on ranitidine + prazepam and 75% of the patients on ranitidine + placebo (p = 0.03). Sleepiness was the most frequent side effect, reported by 8 subjects in the prazepam group and by 1 subject in the placebo group. It is concluded that prazepam can be usefully combined with ranitidine in the short-term treatment of duodenal ulcer.

Adult↗
PubMed1978

Quantitative analysis of prazepam and its metabolites by electron capture gas chromatography and selected ion monitoring. Application to diaplacetal passage and fetal hepatic metabolism in early human pregnancy.

Methods have been developed for the determination of the benzodiazepine tranquilizer prazepam and its metabolites desmethyl diazepam, 3-hydroxy-prazepam and oxazepam by electron capture gas chromatography and selected ion monitoring with diazepam as the internal standard. The benzodiazepines were isolated from blood serum or homogenized tissue samples, either by extraction with ethyl acetate or on small Extrelut columns packed with porous silica. The concentrated extracts were directly injected into the gas chromatograph equipped with an electron capture detector. Following trimethylsilylation, analysis on a gas chromatography--mass spectrometry--computer system operated in the selected ion-monitoring mode was performed. Using 50--200 mg (microliter) biological material, concentrations of prazepam and metabolites of 5 ng/g(ml) could be determined with signal-to-noise ratios of greater than 10. Using 1 g(ml) samples, the same signal-to-noise ratios were obtained with 1 ng/g(ml) concentrations. The methods developed were applied to the analysis of the diaplacental transfer of prazepam and desmethyl diazepam in early human pregnancy. Furthermore, prazepam metabolism in human fetal liver and cell cultures was studied.

Cells, Cultured↗
PubMed1983

A multi-centre comparison of prazepam and diazepam in the treatment of anxiety.

A single-blind, parallel group, multi-centre study was carried out in 2009 patients with an anxiety state to compare the efficacy, tolerance and withdrawal effects of prazepam and diazepam in therapeutically equivalent doses. Patients were allocated at random to receive 30 mg prazepam or 15 mg diazepam per day, either in divided dosage (3 times) during the day or as a single large dose at night. After a 2-week treatment period, drug therapy was withdrawn gradually. Patients were followed-up at weekly intervals over the 4-week study period. Hamilton Anxiety Rating Scale scores and physicians' global assessment of response at each visit indicated that whilst both drugs and dosage regimens were effective patients treated with diazepam responded rather less well and had a greater return of anxiety symptoms after therapy was stopped compared to those on prazepam. Moreover, the prazepam-treated patients, especially those on the divided daytime dosage regimen, had fewer and milder side-effects in the early treatment period. Dizziness was least apparent in the prazepam single night time dosage group and it is suggested that this may be an important practical consideration in the treatment of anxiety in the elderly.

Adolescent↗
PubMed1982

[Effect of prazepam on experimental hypertensive models].

Combined effects of prazepam and trichlormethiazide (TCM) which were given simultaneously were studied in renal hypertensive rats (1-kidney type) and DOCA hypertensive rats. In this study the blood pressure was measured by the plethysmographic method. Orally administered prazepam alone did not show any appreciable effect on the blood pressure, while TCM, even when administered alone, exhibited marked and long-lasting hypotensive effects of both hypertensive rats. In addition, the hypotensive effect of TCM was apparently potentiated by the concurrent use of prazepam. In the experiment where conscious and unconstricted spontaneous hypertensive rats (SHR) were used, the pressor response and tachycardia were observed when foot shock (acute stress) was loaded. This pressor response was the "all or none" type and a threshold existed. In contrast to the pressor response, the degree of tachycardia varied depending on the intensity of the stress. The similar responses were also observed in normotensive rats, although the degrees of the responses were significantly weaker than those in SHR. Prazepam given alone obviously suppressed the cardiovascular responses mentioned above. The present results suggest that prazepam is an useful drug for the treatment of hypertension.

Animals↗
PubMed1979

A double-blind comparison of prazepam with diazepam, chlorazepate dipotassium and placebo in anxious out-patients.

The study compared prazepam with diazepam, chlorazepate dipotassium, and placebo in the treatment of anxious out-patients. Patients were screened for participation in the study to be sure they met the criteria for inclusion. Patients were excluded if they had complicating physical or mental problems. All patients signed an informed consent. Seventy-three patients entered the study, thirteen did not complete at least two weeks of treatment and were not used in the data analysis. Of these thirteen, ten did not return and were lost to follow-up, tow entered the hospital for reasons unrelated to the drug study, and one patient on diazepam was terminated because of increased anxiety. Six patients were used in the data analysis, thirty-six males and twenty-four females with an age range of 21-61 years. Side-effects were minimal. Drowsiness was reported by two people in the placebo group, one taking chlorazepate dipotassium, three on prazepam and one on diazepam. One diazepam patient reported nausea and vomitting. Scores on the Zung Self-Rating Scale for Anxiety showed all three drug groups to be superior to placebo. The Hopkins Symptom Check-list found prazepam and diazepam to be superior to placebo and chlorazepate. No differences among the groups were found in the Hamilton Anxiety Scale. Prazepam may offer advantages over the other available benzodiazepines since it may be more readily absorbed than chlorazepate and has less side-effects than diazepam.

Adolescent↗
PubMedDate not supplied

[Value of prazepam drops in the brief treatment of anxiety disorders].

In order to assess the clinical usefulness of benzodiazepine brief therapy with planned tapering, prazepam as drops was administered to 40 psychiatric outpatients suffering from generalized anxiety disorder. After a one-week placebo period, the patients received prazepam 40 mg daily (i.e., 10 drops in the morning, 10 drops at noon and 20 drops in the evening) during 3 weeks, with the possibility to adjust the doses after one week. The doses were then tapered at 4 mg/d (i.e., 1 drop in the morning, 1 drop at noon and 2 drops in the evening) until complete suppression of the treatment. The assessments, performed before the placebo period, at inclusion, after 1 and 3 weeks of active treatment, and after 1 and 2 weeks of tapering, included the Hamilton anxiety scale, the Lader tranquillizer withdrawal rating scale, and the collection of side effects; moreover, the patients completed daily a visual analogue scale. Results showed a very marked anxiolytic effect of prazepam with an already very significant decrease in the scores on the various scales after 1 week of treatment when the daily dose was significantly reduced. Three quarters of the patients were able to take part in the tapering of prazepam doses without exhibiting any reappearance of anxious symptomatology, rebound anxiety, or withdrawal symptoms. The tolerance of the treatment was rated as good or very good in 91.9% of the patients. This study demonstrates the possibility of a brief anxiolytic treatment followed by tapering in a majority of patients with generalized anxiety disorders. For this strategy, the availability of a drop form represents an obvious advantage.

Administration, Oral↗
PubMed1981

[Pharmacokinetics of oral prazepam].

The biotransformation pathways following oral administration of prazepam are characterized. The time course of the active metabolite descyclopropylmethylprazepam (= norprazepam), representing 80-90% of all prazepam metabolites in plasma, can be described by an open one compartment model with a mean elimination half life of 70 h and a plasma clearance of 1.0-1.4 l/h. 3-5 h after single doses of 20 mg prazepam, the corresponding peak levels of norprazepam are 120-160 ng/ml. There is only a slight uptake of norprazepam into red blood cells and a relative low secretion into breast milk. Following repeated doses of daily 20 mg prazepam steady state levels of norprazepam are 600-800 ng/ml. The slow build-up of the active metabolite and the long elimination half life ensure continuous plasma levels with small fluctuations.

Administration, Oral↗
PubMedDate not supplied

Concentrations of N-descyclopropylmethylprazepam in whole-blood, plasma, and milk after administration of prazepam to humans.

After oral doses of 30 mg of prazepam to humans, N-descyclopropylmethylprazepam (desalkylprazepam, N-desmethyldiazepam) is the only major drug-related compound in plasma. Neither the parent drug, nor its major urinary metabolites were detected in plasma. The overall concentration-time profile of desalkylprazepam in the plasma of females was lower than, and significantly different (p less than 0.001) from that in the plasma of males. However, the mean peak desalkylprazepam concentrations in the plasma of females (265 ng ml-1 +/- 60 S.D.) were not significantly different (p greater than 0.05) from those in males (342 ng ml-1 +/- 60 S.D.). Concentrations declined in the plasma of either sex with similar half-lives (mean 60 h, range 37-93 h). Apparent plasma desalkylprazepam clearances were also similar (mean 60 h, range 37-93 h). Apparent plasma desalkylprazepam clearances were also similar (mean 1.09 l h-1), range 0.74-1.84 l h-1). At 12 h after the last of multiple doses of prazepam (60 mg d-1 for 3 days) to lactating women, mean plasma concentrations of desalkylprazepam were 823 ng ml-1 +/- 200 S.D. and declined with a mean half-life of about 60 h over the time-course studied. There was only slight uptake of desalkylprazepam into blood cells; plasma; whole blood concentration ratios were constant at about 1.6. Concentrations of desalkylprazepam in milk were low at about 10 per cent of the corresponding plasma levels (e.g. 86 ng ml-1 +/- 37 S.D. at 12 h). The data suggest that, expressed on a mg kg-1 basis, exposed neonates could receive about 4 per cent of the maternal dose of prazepam as desalkylprazepam.

Administration, Oral↗
PubMed1982

The influence of tilidine and prazepam on withdrawal reflex, skin resistance reaction and pain rating in man.

Pain rating, withdrawal reflex and skin resistance reaction upon electrical skin stimuli were studied on 15 male volunteers under placebo, tilidine and prazepam. Tilidine (Valoron) is an orally applicable narcotic analgesic, with a mode of pain relief presumably similar to morphine; the tranquilizer prazepam (Demetrin) belongs to the benzodiazepine group. Significant reduction in all measured reaction amplitudes was found under tilidine, whereas prazepam reduced significantly only the skin resistance reaction. The relative drug-induced changes in reaction amplitudes, related to the corresponding placebo value, were independent of stimulus intensity for all investigated reactions. Therefore, fitted power functions re = a . Sn between reaction amplitudes re and stimulus intensity S showed a decrease in parameter a under the investigated drugs, whereas the exponent n remained constant. High correlations between parameters a and corresponding reciprocal threshold currents could be shown for all reactions measured. Furthermore the drug-induced changes of withdrawal reflex amplitude and of subjective estimation were found to be correlated over subjects. In contrast, no correlations were found between variations in skin resistance reaction and magnitude estimation due to the selected drugs, i.e., the influence of the drugs on the sensory component of pain sensation and on the skin resistance reaction were independent effects.

Analgesia↗