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In vitro and in vivo assessment of hepatic and extrahepatic metabolism of diazepam in the rat.

Since diazepam is metabolized by many organs in the rat, the microsomal fractions of the liver, kidney, and lung from male Wistar rats were assayed for NADPH-dependent metabolism of diazepam and enzymatic parameters. The predicted extraction ratios were obtained from this in vitro experimental system. The organ clearances of the liver, kidney, and lung were then calculated for the determination of the relative contribution of each eliminating organ to the total body clearance (CLtot) of diazepam in the rat. The liver was the most effective eliminating organ, followed by the kidney and the lung, in that order. The hepatic extraction ratio of diazepam was determined in vivo after portal and femoral vein administrations of diazepam. The validity of the in vitro experimental system for the liver was demonstrated by a good agreement between the calculated hepatic extraction ratio of diazepam from in vitro enzymatic parameters (0.616) and that derived in vivo (0.648). However, the sum of organ clearances of the liver, kidney, and lung did not account for CLtot of diazepam in the rat, suggesting the possible contribution of the metabolism in the other organs or tissues, or an underestimation of the pulmonary and renal metabolism.

Animals↗

Comparison of bisoprolol and diazepam in the treatment of cardiac neurosis.

In order to compare the beta blockers bisoprolol and diazepam in the treatment of cardiac neurosis, 40 patients (16 males and 24 females, mean age: 39 +/- 11 years) were examined in a double-blind, crossover study. Following a 4-week placebo period, patients were randomized to receive either bisoprolol 10 mg daily or diazepam 5 mg twice daily for 4 weeks. After a second 4-week washout period on placebo, patients were switched to the alternative regimen for a further 4 weeks. At the end of the placebo periods and during each phase of treatment, the following parameters were evaluated: somatic symptoms by self-assessment questionnaire, anxiety state by Hamilton rating scale, reaction time to both acoustic and visual stimuli, blood pressure, and heart rate. Both treatments were effective in reducing somatic symptoms of cardiac neurosis, but bisoprolol was significantly more effective than diazepam (p less than 0.01). On the contrary, diazepam was superior to bisoprolol in improving the Hamilton scale related to psychic symptoms. Only diazepam prolonged reaction times. Both treatments were well tolerated; however, 12 patients complained of drowsiness and nine of sedation under diazepam. In conclusion, bisoprolol appeared to be as effective as diazepam in the treatment of cardiac neurosis, but with better effects on somatic symptoms and without affecting patients' psychomotor performance.

Adrenergic beta-Antagonists↗

Protective cardiovascular effects of diazepam in experimental acute chloroquine poisoning.

To assess the effects of diazepam in chloroquine poisoning, we studied pentobarbital anesthetized and mechanically ventilated pigs. All the pigs received 50 mg.kg-1 chloroquine given intravenously for 25 min. Eight pigs acted as control (group C). Another 7 were treated with diazepam given intravenously 5 min after the end of chloroquine infusion: 2 mg.kg-1 of diazepam for 2 min, then 1 mg.kg.h-1 for 25 min (group D). Thereafter, all pigs were sacrificed. In both groups the chloroquine infusion induced a large fall in arterial pressure, a decrease in heart rate, and an increase in QRS duration. No difference was observed between the 2 groups for weight, systolic and diastolic arterial pressures, heart rate, QRS and QT durations before diazepam. After diazepam, systolic and diastolic arterial pressures, heart rate, urine volume, urinary excretion of chloroquine, plasma and blood cell chloroquine levels were higher, whereas QRS duration was lower, in group D compared to group C. No difference was observed between the 2 groups for urinary concentration of chloroquine, the ratio between plasma and blood cell chloroquine levels, hepatic, cardiac, and skeletal muscle chloroquine levels, and QT duration. After diazepam, the slope of the regression curve between QRS duration and plasma chloroquine levels was reversed in group D compared to group C. We conclude that diazepam counteracts some haemodynamic and electrocardiographic changes, and increases urinary excretion of chloroquine, in acute experimental chloroquine poisoning.

Animals↗

Evidence for an involvement of GABA in the mediation of the cerebellar cGMP decrease and the anticonvulsant action diazepam.

Subcutaneous injections of isoniazid or picrotoxin increase the cerebellar content of 3',5'-cyclic guanosine monophosphate (cGMP) without changing the 3',5'-cyclic adenosine monophosphate cAMP. This increase was dose dependent and the threshold for the cGMP increase was lower than that for convulsions. In cerebellum the increase of cGMP content elicited by isoniazid but not that caused by picrotoxin was paralleled by a decrease of GABA content. Diazepam doses starting from 1.74 mumol/kg intraperitoneally produced a dose dependent decrease of cerebellar cGMP concentration without changing cAMP or GABA content. Smaller doses of diazepam (0.5 mumol/kg i.p.)failed to decrease the basal cerebellar content of cGMP. However, this dose of diazepam antagonized the increase of cGMP produced by isoniazid but not that produced by picrotoxin. Higher doses of diazepam were necessary to block the increase of cerebellar cGMP elicited by picrotoxin. Low doses of diazepam (0.14 mumol/kg) antagonized the convulsions in 50% of the rats injected with 3.3 mmol/kg of isoniazid. The doses of diazepam required to block picrotoxin, pentylenetetrazol or strychnine convulsions were 7, 25 and 40 times higher than those required to block isoniazid convulsions, respectively. Desmethyldiazepam, chloridiazepoxide, oxazepam were also several times more potent in antagonizing isoniazid than picrotoxin, pentylenetetrazol, or strychnine convulsions. In contrast, barbiturates were equipotent against all the convulsants studied. These experiments suggest that diazepam may act in the CNS either by altering the disposition of endogenous GABA or by mimicking the action of GABA at specific synaptic receptors.

Aminobutyrates↗

Diazepam increases GABA mediated inhibition in the olfactory cortex slice.

The effect of diazepam on inhibition has been examined using an in vitro preparation of the guinea-pig olfactory cortex. Diazepam (0.03-30 mumol/l) doubled the intensity and duration of the recurrent inhibitory conductance. Diazepam had no effect on single evoked excitatory post-synaptic potential (e.p.s.p.) nor any effects on the action potential or membrane electrical constants. Diazepam (0.003-100 mumol/l) also reduced the multisynaptic e.p.s.p. generated through a recurrent pathway directed at the soma when elicited during the time-course of the inhibitory conductance. Diazepam had a comparitively small effect on the monosynaptic e.p.s.p. generated on the distal dendrite. Pentobarbitone had a similar though more intense effect over a narrow concentration range (10-200 mumol/l). The inhibitory coductance is thought to be GABA-mediated. Diazepam doubled the potency of the GABA analogue, muscimol, when applied via the bathing solution, whereas a modest 50 mumol/l pentobarbitone increased muscimol potency by about four-fold. The mild but selective effect of diazepam contrasts with the more intense and general effects of pentobarbitone and supports the idea that these drugs act through different mechanisms at the GABA receptor/channel complex.

Animals↗

[Frequency of positive diazepam-screening in post-mortem examinations (author's transl)].

The post-mortem blood specimens of 389 forensic autopsies were analyzed for diazepam. The age of the cases investigated was above 10 years and the survival time was less than 12 hours. Eighteen samples corresponding to 4.6% were found to be diazepam-positive. These 18 samples were distributed equally between men and women. The proportion of diazepam-positive samples was increased in the groups of suicide and poisoning (alcohol and opiates). The association between diazepam intake and poisoning was statistically highly significant. No correlation was found between diazepam intake and age. Alcohol was found to occur significantly more often in the group of the diazepam positive cases as compared to the diazepam negative group.

Adolescent↗

Pharmacologic profile of a new anxiolytic, DN-2327: effect of Ro15-1788 and interaction with diazepam in rodents.

In order to characterize the pharmacologic profile of DN-2327, an isoindoline benzodiazepine (BZD) receptor ligand, its interactions with Ro15-1788 and diazepam were analyzed in rodents. The anti-conflict action of DN-2327 in two conflict tests using rats, the punished water-lick conflict (Vogel conflict) and the punished bar-pressing conflict test, was completely attenuated by treatment with Ro15-1788. The anti-convulsive (pentylenetetrazol [PTZ] induced convulsion) effect of DN-2327 was also reduced by Ro15-1788. These results suggest that the anti-conflict and anti-convulsive actions of DN-2327 may be mediated via BZD receptors. On the other hand, DN-2327 only slightly affected the motor coordination in mice and rats, as estimated by the inclined screen test and the climbing test, respectively; however, the compound attenuated the motor incoordination produced by diazepam. Furthermore, the pentobarbital potentiating effect of diazepam was reduced by pretreatment with DN-2327 in mice. In the Vogel conflict test, additive effects were observed upon the conflict test, additive effects were observed upon the concomitant administration of subeffective doses (5 mg/kg, PO) of DN-2327 and diazepam. DN-2327 at 20 mg/kg, PO, did not reduce but slightly potentiated the anti-conflict effect of the maximum effective dose of diazepam. For PTZ-induced convulsions, DN-2327, 0.5 and 20 mg/kg, PO, doses which produced partial and complete anti-convulsive effects, respectively, in rats did not reduce but increased additively the effects of diazepam. DN-2327 at 10 and 20 mg/kg, PO, doses which both produced partial anti-convulsive effects in mice, showed an additive effect with the partial effects of diazepam.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Pharmacological dissociation between the spatial learning deficits produced by morphine and diazepam.

This study sought to determine whether the place learning deficits produced by diazepam are a secondary result of opioid release. Rats pretreated with diazepam (3 mg/kg) or morphine (15 mg/kg) were trained in the Morris water maze. Diazepam impaired place learning-slowing acquisition and preventing the formation of a quadrant preference. Morphine also slowed acquisition, but did not prevent place learning, and impaired escape to a visible platform. Flumazenil blocked the deficits produced by diazepam, but not morphine. Naloxone (2 mg/kg) blocked the deficits produced by morphine, but not diazepam. A high dose of naloxone (10 mg/kg) slowed acquisition, and exacerbated the deficit produced by diazepam. These results demonstrate that diazepam interferes with mnemonic processes through endogenous benzodiazepine receptors, independently of opioidergic systems. Further, they suggest that morphine interferes with motivational processes through opioidergic systems, independently of endogenous benzodiazepine systems.

Animals↗

Enhancement of acetylcholine release by flumazenil in the hippocampus of rats chronically treated with diazepam but not with imidazenil or abecarnil.

The effects of long-term treatment (three times a day for 3 weeks) with pharmacologically active doses of the novel anxiolytics and anticovulsants abecarnil (0.5 mg/kg, IP) and imidazenil (0.5 mg/kg, IP) on basal hippocampal acetylcholine release in freely moving rats were compared with those of diazepam (3 mg/kg, IP). Challenge doses of diazepam, abecarnil, and imidazenil decreased the extracellular acetyl-choline concentration in the hippocampus by the same extent in animals chronically treated with the respective drug or vehicle. Moreover, the abrupt discontinuation of long-term treatment with diazepam, abecarnil, or imidazenil failed to affect hippocampal acetylcholine release during the first 5 days of withdrawal. In contrast, the acute administration of the benzodiazepine receptor antagonist flumazenil (1 mg/kg, IP) 2 days after diazepam withdrawal elicited a marked increase (65%) in acetylcholine release in the hippocampus. Flumazenil failed to induce the same effect 5 days after diazepam withdrawal or 2 or 5 days after discontinuation of long-term treatment with abecarnil or imidazenil. These results indicate that (i) the inhibitory effects of full (diazepam), partial (imidazenil), and selective (abecarnil) benzodiazepine receptor agonists on acetylcholine output in rat hippocampus are not affected by repeated drug administration; (ii) discontinuation of long-term treatment with each type of agonist does not affect hippocampal cholinergic mechanisms; and (iii) flumazenil increases acetylcholine release only in the hippocampus of rats chronically treated with diazepam. Together, these data further differentiate the pharmacology of benzodiazepine receptor full agonists from that of partial and selective agonists.

Acetylcholine↗

Effects of diazepam on behavioural and antinociceptive responses to the elevated plus-maze in male mice depend upon treatment regimen and prior maze experience.

Recent studies have shown that brief exposure to an elevated plus-maze (EPM) produces non-opioid antinociception in male mice. The present experiments were designed to assess the effects of diazepam on this phenomenon. When acutely administered, low doses (0.5-1.0 mg/kg) of diazepam failed to produce an anxiolytic profile and exerted rather inconsistent effects on EPM-induced elevations in tail-flick latencies. In EPM-experienced mice, chronic treatment with higher doses of diazepam (2-4 mg/kg, 8 days) produced a weak anxiolytic action and inhibited the early phase of EPM antinociception only. However, in EPM-naive mice, 8-day diazepam pretreatment exerted a marked anxiolytic effect and completely eliminated the antinociceptive response to the maze. Together, these data support the view that anxiety is a key factor in certain forms of adaptive pain inhibition and suggest a possible mediational role for benzodiazepine receptors. Our findings also show that prior exposure to the EPM, rather than chronic handling/injection, greatly reduces the anti-anxiety effect of diazepam. Furthermore, since re-exposure to the maze, per se, decreased time spent on the open arms and central platform, a shift in behavioural baseline ("retest anxiogenesis") may have contributed to the weak behavioural effects of diazepam in test-experienced animals. Importantly, as chronic treatment with diazepam did not influence this anxiogenic-like retest profile, our data suggest that a single prior experience of the EPM may radically alter the nature of the anxiety reaction provoked by this test.

Analgesia↗

Intramuscular midazolam vs intravenous diazepam for acute seizures.

OBJECTIVE: To determine effectiveness of intramuscular midazolam to control acute seizures in children as compared to intravenous diazepam. METHODS: 115 children in the age group of 1 month to 12 years who presented with acute convulsions were enrolled in the study. Patients who already had an intravenous access present were treated intravenous diazepam. Patients without an i.v. access at the time of convulsions were randomised into 2 groups and treated with either intramuscular midazolam or intravenous diazepam for control of seizures. Time interval from administration of drug to cessation of seizures was compared. Effectiveness of i.m. midazolam in various age groups, types of convulsions and etiology of convulsions was analyzed. Side effects of both drugs were evaluated. RESULTS: The mean interval to cessation of convulsions with i.m. midazolam was 97.22 seconds whereas in diazepam group without prior i.v. access it was 250.35 seconds and in diazepam group with prior i.v. access it was 119.4 seconds. i.m. midazolam acted faster in all age groups and in patients with febrile convulsions, which was statistically significant. i.m. midazolam was equally effective in various types of convulsions be it GTC or focal convulsions. 7 patients (10.8%) had thrombophlebitis associated with i.v. diazepam administration whereas none of the patients in the midazolam group had any side effects, which was statistically significant. CONCLUSION: i.m. midazolam is an effective agent for controlling acute convulsions in children especially in children with febrile convulsions. It has relatively no side effects as compared to Intravenous diazepam and can be used as a first line agent for treatment of acute convulsions in patients with difficult intravenous access.

Anticonvulsants↗

Cord blood diazepam: clinical effects in neonates of eclamptic mothers.

Diazepam used in the treatment of eclampsia crosses the placental barrier readily, and may cause various clinical effects in the neonates. Twenty-five (25) live born babies of eclamptic mothers receiving diazepam were studied and cord blood diazepam concentration was estimated. Effect of low dose of diazepam is minimal apart from lowering of rectal temperature and the effects lasted for a period of 12 hours. But high dose (> 30 mg) of diazepam and prolonged duration of diazepam therapy in mothers causes significant depression of the newborn and the effects lasted for a period of 36-48 hours. As the clinical condition of the newborn is not related to the diazepam concentration in cord blood, the cord blood estimation is not helpful in the assessment of clinical effects of the drug in newborn. The tissue storage of the drug in newborn appears to be responsible for the clinical effects.

Adult↗

Effects of continuous diazepam administration on GABAA subunit mRNA in rat brain.

Rats treated chronically with diazepam develop tolerance to diazepam effects and show changes in sensitivity of GABAergic systems. In order to investigate possible molecular mechanisms associated with these changes, we have evaluated the effects of acute and chronic diazepam treatment on levels of mRNA for the alpha 1 and beta 1 subunits of the GABAA receptor. Northern blots were hybridized with 32P-labeled GABA alpha 1 and beta 1 cDNA probes, and resulting bands were quantified by autoradiography and densitometry. Levels of alpha 1 mRNA were significantly decreased in cerebral cortex but not in cerebellum or hippocampus of chronic diazepam-treated rats. Acute diazepam treatment did not change levels of alpha 1 mRNA in any of the brain regions. Levels of beta 1 mRNA were examined by Northern blot analysis and also by solution hybridization analysis using a 32P-labeled riboprobe. Both methods showed that beta 1 mRNA was not significantly changed by chronic diazepam treatment. These results demonstrate a specific change in alpha 1 subunit that is associated with a state of altered GABA sensitivity and provide further support for the regional heterogeneity of chronic diazepam effects.

Animals↗

Compared efficacy of diazepam or avizafone to prevent soman-induced electroencephalographic disturbances and neuropathology in primates: relationship to plasmatic benzodiazepine pharmacokinetics.

We performed an experiment to characterize the toxicity of soman in cynomolgus monkeys in which organophosphorus intoxication was followed by treatment with either the current three-drug therapy atropine/pralidoxime/diazepam or a combination of atropine/pralidoxime/avizafone, avizafone being the water soluble prodrug of diazepam. Clinical, electrophysiological, and histological approaches were combined. When benzodiazepines were injected at the similar molar dose of 0.7 micromol/kg, the protection against soman toxicity was better with the atropine/ pralidoxime/diazepam combination than with the atropine/pralidoxime/avizafone one. Pharmacokinetic studies demonstrated that this difference of efficacy could be explained by a lower plasmatic load of diazepam obtained after injection of avizafone at 0.7 micromol/kg, compared to the administration of diazepam at the same molar dose. Moreover, after injection of avizafone, plasmatic levels of diazepam were achieved faster and declined more rapidly than after administration of diazepam. Compared to diazepam given at a dose of 0.7 micromol/kg, injection of 1 micromol avizafone/kg gave a similar plasmatic load of benzodiazepine, but with a lower time to maximum plasma concentration (tmax) and a higher maximum plasma concentration (Cmax) for plasmatic diazepam. We therefore went on to demonstrate that administration of the atropine/pralidoxime/avizafone combination at a dose 1 micromol benzodiazepine/kg to intoxicated monkeys afforded electrophysiological and histological protection similar to that obtained after administration of atropine/pralidoxime/diazepam at a dose of 0.7 micromol diazepam/kg. Reflections on the possible incorporation of avizafone in three-drug emergency treatment are presented.

Animals↗

The effects of diazepam on human self-aggressive behavior.

RATIONALE: Diazepam, a benzodiazepine with a relatively rapid onset of clinical effects, has been associated with suicide and other self-aggressive acts. The evidence for this association, however, comes exclusively from retrospective non-experimental studies. Although suggestive, the results of these studies do not support a cause-and-effect relationship between benzodiazepine consumption and self-aggressive behavior. OBJECTIVE: To experimentally examine the effect of diazepam on human self-aggressive behavior under controlled laboratory conditions. METHOD: Forty-six healthy men and women were randomly assigned to receive placebo, or 5 mg or 10 mg diazepam in a double-blind, between-groups design. Participants were then provided the opportunity to self-administer electric shocks during a competitive reaction-time task (the self-aggression paradigm, SAP). Self-aggression was defined by the intensity of shock chosen. RESULTS: Diazepam (10 mg) was associated with higher average shock self-administered than placebo. Subjects receiving 10 mg diazepam were also more likely to attempt to self-administer a shock that they were led to believe was "severe" and painful. Sedation effects were found, but diazepam consumption did not impair memory, attention, concentration, pain threshold, or reaction-time performance. CONCLUSIONS: Clinically relevant diazepam doses may be associated with self-aggressive behaviors at levels that do not significantly impair basic cognitive processes or psychomotor performance.

Adult↗

Cortisol response to diazepam: its relationship to age, dose, duration of treatment, and presence of generalized anxiety disorder.

OBJECTIVE: Acute diazepam administration has been shown to decrease plasma cortisol levels consistent with decreased activity of the hypothalamic-pituitary-adrenal axis, especially in individuals experiencing stress. However, the effects of chronic diazepam treatment on cortisol have been less studied, and the relationship to age, anxiety, duration of treatment, and dose are not well understood. METHOD: This double-blind placebo-controlled study examined acute and chronic effects of diazepam on plasma cortisol levels in young (19-35 years) and elderly (60-79 years) individuals with and without generalized anxiety disorder (GAD). Subjects received single oral challenges of placebo or diazepam (2.5 mg or 10 mg) in a placebo-controlled cross-over design, followed by 3 weeks of chronic daily treatment with 2.5 mg or 10 mg diazepam or placebo taken at 10 p.m., and then by a final acute challenge with a single oral dose of the same study medication received during chronic treatment. RESULTS: The elderly experienced significant reductions in plasma cortisol levels compared to placebo both in the initial challenge and during chronic treatment, but the young did not. However, cortisol response to drug was comparable in both groups. Final challenge did not produce any significant cortisol effects in either group and the cortisol response in the elderly was significantly reduced compared to the initial challenge. GAD status was not a factor in plasma cortisol responses to diazepam. CONCLUSIONS: Diazepam reduced cortisol both acutely and during chronic treatment, but not during final challenge, consistent with some tolerance development. This effect was most apparent in the elderly compared with the young adults and was not modulated by GAD status or dosage, and was not related to drug effects on performance and on self-ratings of sedation and tension.

Adult↗

Chronic diazepam administration differentially affects melatonin synthesis in rat pineal and Harderian glands.

RATIONALE: Pineal and Harderian gland melatonin production as well as plasma melatonin levels were investigated in male Wistar rats (12 weeks old) after administration of diazepam, a benzodiazepine widely used as anxiolytic. OBJECTIVE: The present study investigates the effects of a chronic administration of diazepam on pineal and Harderian gland melatonin contents. METHODS: Diazepam was administered subcutaneously, for 21 days, at a dosage of 3 mg/kg body weight per day, 1 h before the onset of darkness. RESULTS: Diazepam clearly affected pineal melatonin biosynthesis and plasma melatonin levels. Diazepam reduced the pineal melatonin content (by a factor of 2) and the activity of N-acetyltransferase (NAT) (by a factor of 3.5), as well as plasma melatonin levels (by a factor of 1.5), but had no effects on pineal hydroxyindole-O-methyltransferase activity. By contrast to the pineal gland, diazepam failed to affect the Harderian gland melatonin content. CONCLUSIONS: Our results suggest that the inhibition of melatonin production induced by diazepam in vivo may be due to a direct action of this benzodiazepine on the pineal gland, through its action on NAT, the key enzyme of melatonin synthesis, and that the control of melatonin production in the Harderian glands may be different from that observed in the pineal gland.

Acetylserotonin O-Methyltransferase↗

Prior non-spatial pretraining eliminates sensorimotor disturbances and impairments in water maze learning caused by diazepam.

Diazepam has been reported to impair spatial learning in the water maze. This experiment reexamined this topic using control groups that had first been non-spatially pretrained to familiarize them with the general behavioral strategies required in the water maze task. Naive rats given diazepam (0.5, 3.0, 6.0 mg/kg, IP) displayed dose-related maze acquisition impairments and sensorimotor disturbances (swimming in the periphery of the pool, deflecting off or swimming over the hidden platform, jumping off the platform when placed there after a trial, ataxia on a narrow wooden beam). The sensorimotor disturbances interfered with the acquisition of information about the spatial location of the platform, occurred in the absence of impairments in a subsequent visible platform task or swim speed, and correlated strongly with measures of acquisition. In contrast, the non-spatially pretrained groups did not exhibit sensorimotor disturbances in the water maze and acquired the maze task as rapidly under diazepam as control rats. The non-spatially pretrained groups continued to display diazepam-induced sensorimotor disturbances (ataxia) in a novel beam walking task. CGS8216 (10.0 or 20.0 mg/kg), a benzodiazepine receptor antagonist, attenuated the effect of 3.0 or 6.0 mg/kg diazepam in naive rats, suggesting that the effects of diazepam were mediated by benzodiazepine receptors. Occupancy of benzodiazepine receptors by diazepam does not prevent robust spatial learning in the water maze.

Animals↗