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PubMed1999

Effect of the gene dosage of CgammaP2C19 on diazepam metabolism in Chinese subjects.

OBJECTIVE: To determine whether the gene dosage of CYP2C19 affects the metabolism of diazepam and desmethyldiazepam in healthy Chinese subjects. SUBJECTS AND METHODS: Eighteen unrelated adult men were recruited for the study from a total of 101 healthy Chinese volunteers who had been screened for CYP2C19 phenotype and genotype. All subjects received a single oral dose (5 mg) of diazepam, and the pharmacokinetics of diazepam and desmethyldiazepam were compared in six ml homozygotes (ml/ml), six ml heterozygotes (wt/ml), and six wild-type homozygotes (wt/wt). RESULTS: The plasma elimination half-life values of diazepam (84.0 +/- 13.7 hours) and desmethyldiazepam (176.0 +/- 28.9 hours) in subjects of ml/ml were significantly longer than those (62.9 +/- 9.8 hours for diazepam; 132.1 +/- 24.9 hours for desmethyldiazepam; both P < .01) in subjects of wt/ml or those (20.0 +/- 10.8 hours for diazepam; 99.2.+/- 21.7 hours for desmethyldiazepam; both P < .01) in subjects of wt/wt. A significant difference in the corresponding half-life values existed between the wt/ml and wt/wt subjects (P < .01). As expected, the slowest mean clearance of diazepam was observed in the ml/ml subjects (2.8 +/- 0.9 mL/min) and the fastest in the wt/wt subjects (19.5 +/- 9.8 mL/min), with the wt/ml heterozygotes having an intermediate value (7.2 +/- 2.6 mL/min). CONCLUSION: The presence of a single-nucleotide polymorphism (G681A) of the CYP2C19 gene cosegregates with the impaired metabolism of diazepam and desmethyldiazepam among Chinese subjects in a gene-dosage effect manner.

Adult↗

PubMed2003

Long-lasting behavioral changes induced by pre- or neonatal exposure to diazepam in rats.

Prenatal treatment with small doses of diazepam may counteract the effect of physical stress in rats, normalizing the time course of neonatal reflexes and the behavioral responses in adulthood. However, prenatal administration of diazepam in greater doses may induce desensitization of gamma-aminobutyric acid A (GABA(A)) receptors and induce hypersensitivity to convulsants. This study was designed to examine in rats the influence of prenatal or neonatal diazepam treatment on development of neonatal reflexes, as index of brain maturation, and susceptibility to pentylenetetrazol-induced convulsions in adulthood. Pregnant Wistar rats were injected with diazepam 2.5 mg/kg/day, intraperitoneally (i.p.) on days 14-21 of pregnancy. Offspring showed a delay in the appearing of neonatal reflexes (cliff aversion, forelimb placing, forelimb grasping and bar holding) except for righting and startle reflexes. At 50 days of age, male rats showed a greater sensitivity to pentylenetetrazol compared to controls. In contrast, females showed a decreased susceptibility to convulsions. The appearance of reflexes in pups exposed to diazepam during neonatal life appeared to be similar to that of controls. Only the appearance of cliff aversion and startle reflexes appeared to be delayed in animals exposed neonatally to diazepam as compared to controls. In adulthood, female rats exposed in early neonatal life to diazepam again showed a resistance to pentylenetetrazol-induced convulsions as compared to male animals. These data suggest that prenatal exposure to diazepam induces long-lasting behavioral changes, which may be influenced by sex-dependent factors.

Animals↗

PubMed1996

Chronic treatment with diazepam or abecarnil differently affects the expression of GABAA receptor subunit mRNAs in the rat cortex.

Diazepam and abecarnil produce their overt effects by interaction with the GABAA receptor. Chronic treatment with abecarnil, however, does not induce diazepam-like tolerance. This study investigates the effects of chronic diazepam and abecarnil treatment on expression of GABAA receptor alpha 1-6 beta 1-3 and gamma 1-3 subunit isoform mRNAs in rat cortex. Male Sprague-Dawley rats were injected subcutaneously once daily for 7 or 14 days with 15 mg/kg diazepam or 6 mg/kg abecarnil in sesame-oil vehicle, and steady-state levels of GABAA receptor subunit mRNAs were quantified by solution hybridization. The levels of alpha 4- and alpha-, beta 1- and gamma 3-subunit mRNAs were significantly increased after 7 days of diazepam treatment, and this effect was maintained at 14 days. A significant increase in alpha 3-subunit mRNA was apparent only after 14 days of diazepam treatment and a significant decrease in beta 2-subunit mRNA was seen only after 14 days of abecarnil treatment. Gamma 2-Subunit mRNA was significantly decreased after 14 days of either diazepam or abecarnil exposure. A degree of association between a particular drug treatment and changes in the levels of mRNAs arising from a given gene cluster was noted. Our results are consistent with a model of diazepam dependence based on GABAA receptor subunit isoform switching.

Animals↗

PubMed1987

Endotracheal diazepam: absorption and pulmonary pathologic effects.

We conducted a study to evaluate the absorption of endotracheally administered diazepam and the pulmonary pathologic changes induced by its administration. Six cats received diazepam and five cats received saline endotracheally. Serial blood gases and serum diazepam levels were drawn at intervals for 90 minutes after the administration of diazepam. The cats were sacrificed after two days and their lungs were examined by a pathologist. Mean diazepam levels reached a peak two minutes after the administration of diazepam and remained elevated above therapeutic levels for 90 minutes. There was no significant change in pH, PO2, or PCO2 for either group. Histologic examination of the lungs showed a significantly increased incidence of pneumonitis in the diazepam group as compared to the saline group. This study demonstrates that although diazepam is well absorbed when administered endotracheally, it has adverse effects on the lungs that may preclude endotracheal use in the currently available commercial form.

Absorption↗

PubMed1997

Diazepam attenuation of restraint stress-induced corticosterone levels is enhanced by prior exposure to repeated restraint.

Prior research has demonstrated that diazepam decreases hypothalamic-pituitary-adrenal cortex (HPA) axis activity in stressful contexts but, paradoxically, acts as a stimulator of basal axis activity. Also, several investigators have reported that low doses of diazepam are not effective in reducing stress-induced corticosterone (CORT) levels, yet similar doses typically produce anxiolytic effects on behavioral measures of fear and anxiety. We have examined the effects of diazepam on plasma CORT levels in male Sprague-Dawley rats utilizing a repeated restraint paradigm. Consistent with most literature, diazepam administered IP (1.5, 3.0, or 6.0 mg/kg) 1 h prior to restraint increased non-stress, baseline plasma CORT levels in a dose-dependent fashion. During the first exposure to the 1 h restraint-stress procedure, CORT levels of diazepam-injected rats did not differ from the stress levels of controls except at the 60-min stress time point in those subjects receiving 6.0 mg/kg. However, diazepam at all three doses was able to attenuate the stress-induced increase in CORT following 5 days of diazepam+restraint treatment. Using the 3.0 mg/kg dose as a probe, it was found that this effect was not dependent on the repeated administration of diazepam, but rather on repeated exposure to restraint. These results suggest that repeated restraint produces a change in neural sensitivity to benzodiazepines.

Animals↗

PubMed2007

Molecularly imprinted solid-phase extraction of diazepam and its metabolites from hair samples.

An anti-diazepam, molecularly imprinted polymer (MIP) has been synthesized and used to extract diazepam and other benzodiazepines from hair samples via a molecularly imprinted solid-phase extraction (MISPE) protocol. Optimum retention of diazepam on the MIP columns was achieved using an apolar solvent, and the binding capacity of the polymer toward diazepam was found to be 110 ng of diazepam/mg of polymer. The recovery of a 50 ng diazepam standard spiked into blank hair was 93%, with good precision (RSD = 1.5%). The LOD and LOQ of diazepam in spiked hair samples were 0.09 and 0.14 ng/mg, respectively. The MISPE method was demonstrated to be applicable to the analysis of diazepam metabolites and other benzodiazepine drugs, in addition to diazepam itself. The application of the extraction method to postmortem hair samples yielded results that were in good agreement with the corresponding ELISA data (from blood samples) and data arising from the analysis of the same blood samples using a validated in-house SPE-LC-MS-MS method.

Benzodiazepines↗

PubMed1983

Abuse potential of halazepam and of diazepam in patients recently treated for acute alcohol withdrawal.

Thirty men recently treated for alcohol withdrawal were enrolled in a three-way crossover double-blind study with a balanced incomplete block design. Patients received single doses of three of the following: halazepam, 320 mg; halazepam, 160 mg; diazepam, 40 mg; diazepam, 20 mg; and placebo. The doses of the drugs were approximately equivalent in anxiolytic effect. Patients rated themselves at baseline, 30 min after, and 1, 2, 3, 4, 6, and 8 hr after drug on the following: euphoria, sedation, "drug-liking," "feeling the drug," and drug identification. By 30 min both diazepam groups reported increases in euphoria, sedation, and feeling and liking the drug; halazepam groups reported little subjective change at 30 min, and at 1 hr subjective effects did not differ from placebo on any scale. At 2 and 3 hr, both halazepam doses induced subjective effects on several scales, but peak effects were lower than peak effects of high diazepam doses. Unlike diazepam, the higher halazepam dose did not appear to induce greater effects than the lower dose. At peak, more of the diazepam group correctly identified the drug than those in the halazepam groups. More in the halazepam groups identified it as placebo than either diazepam group. To the degree that abuse potential is related to peak intensity and to time of onset of those subjective effects described as pleasant or likable, halazepam should have a lower potential for abuse than diazepam.

Adult↗

PubMed1986

Combined effects of buspirone and diazepam on objective and subjective tests of performance in healthy volunteers.

The combined effects on performance of two anxiolytics with different mechanisms of action were evaluated double-blind and crossover in 12 healthy students. Objective (tracking, divided attention, Maddox wing, etc.) and subjective (visual analogue scales and questionnaires) tests were done before and twice after single oral doses. Diazepam (0.15 and 0.30 mg/kg) impaired performance dose relatedly and rendered the subjects drowsy, calm, mentally slow, and clumsy. Buspirone (15 mg) proved inactive in objective tests but matched diazepam (0.30 mg/kg) subjectively. In combinations, buspirone added to the effects of diazepam in Maddox wing and letter cancellation but tended to counteract diazepam effects on divided attention and learning acquisition. Subjectively buspirone prolonged diazepam-induced sedation. Increased calmness caused by diazepam was not affected by concomitant buspirone. It is suggested that combining small doses of buspirone to diazepam does not cause any additional decrement in psychomotor performance. Possible advantages of the diazepam-buspirone combination in therapeutic use are discussed.

Adult↗

PubMed1990

Effect of omeprazole treatment on diazepam plasma levels in slow versus normal rapid metabolizers of omeprazole.

The effect of omeprazole treatment on diazepam plasma levels was studied in four slow and six rapid metabolizers of omeprazole. Single intravenous doses of diazepam (0.1 mg/kg) were administered after 1 week of oral treatment with omeprazole (20 mg) and placebo. This was a double-blind crossover study with randomized placebo and omeprazole treatments. Blood was collected up to 120 hours after diazepam dosing (still during one-daily omeprazole and placebo administration) for measurement of diazepam and its major metabolite desmethyldiazepam. The slow metabolizers of omeprazole also metabolized diazepam slowly, exhibiting only half the diazepam plasma clearance of the others. The mean clearance of diazepam was decreased 26% after omeprazole in the rapid metabolizers, whereas the slow group showed no apparent interaction. The mean plasma concentrations of desmethyldiazepam showed a more rapid formation in the rapid compared with the slow metabolizers, which is a logical consequence of the rate of diazepam metabolism.

Adult↗

PubMed1990

Diazepam metabolism in native Chinese poor and extensive hydroxylators of S-mephenytoin: interethnic differences in comparison with white subjects.

A single oral 5 mg dose of diazepam was given to 16 healthy native Chinese Han volunteers. Eight volunteers were extensive metabolizers of S-mephenytoin, and eight were poor metabolizers of S-mephenytoin. Plasma levels of diazepam and its demethyl metabolite were determined by HPLC in blood samples drawn during 4 weeks. There was no difference in diazepam disposition between the two phenotypes. However, the plasma half-life of demethyldiazepam was longer in poor metabolizers than in extensive metabolizers of mephenytoin (mean +/- SD: 161 +/- 37 and 116 +/- 29 hours, respectively; p less than 0.02). The plasma concentrations of demethyldiazepam at 7, 14, and 21 days after intake of diazepam were significantly higher in poor metabolizers than in extensive metabolizers. We compared the pharmacokinetic parameters of diazepam in Chinese subjects with our previously reported data from white subjects. The mean plasma half-life values of diazepam in Chinese extensive metabolizers (85.1 hours) and poor metabolizers (88.3 hours) were very similar to those in white subjects who were poor metabolizers (88.3 hours), and more than twice those in white subjects who were extensive metabolizers (40.8 hours). In parallel, the mean clearance of diazepam in Chinese subjects (independent of phenotype) was similar to that in white subjects who were poor metabolizers, but half that in white subjects who were extensive metabolizers. Chinese subjects had a slightly larger volume of distribution of diazepam than white subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed2006

Microinjection of naltrexone into the central, but not the basolateral, amygdala blocks the anxiolytic effects of diazepam in the plus maze.

The amygdala is involved in behavioral and physiological responses to fear, and the anxiolytic properties of several drugs are localized to this region. Activation of endogenous opioid systems is known to occur in response to stress and a growing body of literature suggests that opioid systems regulate the properties of anxiolytic drugs. These experiments sought to elucidate the role of opioid receptors in the central (CeA) and basolateral (BLA) nuclei of the amygdala in regulating the anxiolytic properties of ethanol and diazepam. Male rats fitted with cannula received bilateral microinjections of the nonselective opioid receptor antagonist naltrexone (NAL) immediately followed by systemic delivery of either ethanol (1 g/kg) or diazepam (2 mg/kg) in the elevated plus maze. Both diazepam and ethanol decreased anxiety-like behavior. Delivery of NAL into the CeA blocked the anxiolytic properties of diazepam. Delivery of NAL into the BLA slightly increased open arm avoidance, but had no effect on the anxiolytic properties of diazepam. Microinjection of NAL into either nucleus failed to block the effects of ethanol. These results were specific to the anxiolytic properties of diazepam, since baseline behaviors were unaffected by microinjection of NAL. Microinjection of lidocaine produced results distinct from NAL and failed to block the anxiolytic actions of diazepam. These studies indicate distinct roles for opioid receptor systems in the CeA and BLA in regulating the anxiolytic properties of diazepam in the elevated plus maze. Further, opioid receptor systems in the CeA and BLA do not regulate the anxiolytic properties of ethanol in this test.

Acetylcholinesterase↗

PubMed1977

Ethanol and oral diazepam absorption.

Despite widespread use and abuse of ethanol and diazepam in combination, little is known about the effects of ethanol on diazepam absorption. We administered diazepam (0.07 mg per kilogram of body weight) with water and with 30 ml of 50 per cent ethanol to seven normal volunteers. Plasma diazepam levels were significantly higher at 60 minutes (P less than 0.05), 90 minutes (P less than 0.01), 120 minutes (P less than 0.01), and 240 minutes (P less than 0.01) when diazepam was administered with ethanol than with water alone. Since maximum mean plasma diazepam levels after combined ingestion with ethanol were nearly twice as high than after diazepam and water (373 ng per milliliter versus 197 ng per mililiter at 60 minutes) we conclude that ethanol enhanced diazepam absorption.

Administration, Oral↗

PubMed1993

A controlled trial of diazepam administered during febrile illnesses to prevent recurrence of febrile seizures.

BACKGROUND: Phenobarbital, once widely prescribed to prevent febrile seizures, is now in disfavor because of its side effects and lack of efficacy. Diazepam, administered only during episodes of fever, may be a safe, effective agent to prevent the recurrence of febrile seizures. METHODS: We conducted a randomized, double-blind, placebo-controlled trial among 406 children (mean age, 24 months) who had at least one febrile seizure. Diazepam (0.33 mg per kilogram of body weight) or placebo was administered orally every eight hours during all febrile illnesses. RESULTS: During a mean follow-up of 1.9 years (a period during which 90 percent of febrile seizures recur), our intention-to-treat analysis showed a reduction of 44 percent in the risk of febrile seizures per person-year with diazepam (relative risk = 0.56; 95 percent confidence interval, 0.38 to 0.81; P = 0.002). A survival analysis of the length of time to the first recurrent febrile seizure did not show a significant difference between the treatment groups (P = 0.064 by the log-rank test), but after adjustment for covariates, diazepam was found to have a benefit (P = 0.027 by Cox regression analysis). An analysis restricted to children who had seizures while actually receiving the study medication (7 in the diazepam group and 29 in the placebo group) showed an 82 percent reduction in the risk of febrile seizures with diazepam (relative risk = 0.18; 95 percent confidence interval, 0.09 to 0.37; P < 0.001). Of the 153 children who took at least one dose of diazepam, 39 percent had ataxia, lethargy, or irritability or at least one other moderate side effect that was reversed after a reduction in the dose. There were no severe side effects. CONCLUSIONS: Oral diazepam, given only when fever is present, is safe and reduces the risk of recurrent febrile seizures.

Administration, Oral↗

PubMed2005

Diazepam affects both level and amplitude of rat locomotor activity rhythm but has no effect on core body temperature.

The present study investigates the effects of a chronic administration of diazepam, a benzodiazepine widely used as an anxiolytic, on locomotor activity and body core temperature rhythms in male Wistar rats housed under 12 : 12 light : dark (LD) cycle conditions. Diazepam was administered subcutaneously for 3 wks in a dosage of 3 mg/kg body weight/day, 1 h before the onset of darkness. Diazepam increased the level of locomotor activity from the first day until the end of treatment, and also increased the amplitude of the activity circadian rhythm, but only on the third wk of treatment. Diazepam exerted no effects on the length of the period and did not affect the phase of the locomotor activity rhythm. The body temperature rhythm of rats was affected neither by short-term (a single injection) nor by long-term (every day for 3 wks) diazepam treatment. Diazepam lacked effect on body core temperature even on the first day of administration, thereby ruling out the possibility of drug tolerance development. The fact that diazepam affects locomotor activity, but not core body temperature, suggests that different mechanisms mediate the actions of diazepam on locomotor activity and on core body temperature.

Animals↗

PubMed1975

Recovery and skills related to driving after intravenous sedation: dose-response relationship with diazepam.

Skills related to driving, the ability to discriminate the fusion of flickering light, and hand and foot proprioception, were measured double-blind in 34 healthy volunteers before and after three doses of i.v. diazepam. The effects of diazepam were most harmful to co-ordination. With 0.15 mg/kg, 0.30 mg/kg and 0.45 mg/kg of diazepam the impairment of co-ordinative skills was statistically significant (P less than 0.05) up to 2, 6 and 8 hr respectively. No impairment of performance on any test was measurable at 6 hr after 0.15 mg/kg or at 10 hr after 0.30 or 0.45 mg/kg of diazepam. There were large interindividual variations in serum concentrations of diazepam within each dose level. The increases in serum concentrations of diazepam after the intake of food support the concept of an enterohepatic cycle for diazepam. It was concluded that patients should not drive or operate machinery for at least 6 hr after 0.15 mg/kg of i.v. diazepam and at least 10 hr after 0.30 mg/kg and 0.45 mg/kg.

Amnesia↗

PubMed1976

Plasma diazepam concentrations following prolonged administration.

Plasma diazepam and N-desmethyl diazepam concentrations were measured in patients receiving diazepam 5 mg or 10 mg i.v. at 4-h intervals for periods of 6-22 days. At both doses there was an accumulation of both diazepam and its metabolite, the latter reaching concentrations of up to two to three times that of the parent drug. Plasma diazepam concentrations reached a plateau after 8 days while the concentration of N-desmethyl metabolite continued to increase throughtout the period of drug administration. On discontinuation of diazepam therapy both diazepam and N-desmethyl diazepam concentrations decreased slowly, the former with a half-life of 2-4 days and the latter with a half-life of 4-8 days.

Adult↗

PubMed1997

The direct effects of diazepam and midazolam on myocardial depression in cultured rat ventricular myocytes.

UNLABELLED: We examined the direct myocardial depressant effects of diazepam and midazolam and determined whether a benzodiazepine receptor antagonist, flumazenil, or an L-type Ca2+ channel agonist, Bay K 8644, affects the myocardial depression induced by diazepam and midazolam in cultured rat ventricular myocytes. Ventricular myocytes of neonatal rats were obtained by enzymatic digestion with collagenase and cultured for 6-7 days. The myocytes were stabilized in serum-free medium, and the spontaneous beating rate and amplitude were measured by determining displacement with a fiberoptic sensor. Myocytes were exposed to either diazepam or midazolam at concentrations of 0.1, 1, 10, and 100 microM. The beating rate and amplitude were measured 4 min after diazepam or midazolam administration. In other cells, either diazepam or midazolam was administered at each concentration in the presence of flumazenil or Bay K 8644. Midazolam and diazepam decreased the beating rate and amplitude concentration-dependently. These myocardial depressant effects were prevented by Bay K 8644 and, to a lesser degree, by flumazenil. Thus, the L-type Ca2+ channel is important in the direct myocardial depression caused by diazepam and midazolam. IMPLICATIONS: This study describes the direct effect of midazolam and diazepam on intrinsic myocardial contraction using cultured rat ventricular heart cells. Both of these drugs have a direct myocardial depressant effect at the cellular level, which is mainly mediated by an inhibition of the sarcolemmal L-type Ca2+ channel.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1981

Sedative-hypnotic tolerance testing and withdrawal comparing diazepam to barbiturates.

A study was conducted to assess the feasibility of substituting diazepam for pentobarbital and phenobarbital in sedative-hypnotic tolerance testing and withdrawal of tolerant patients. Nineteen patients potentially dependent on sedative-hypnotics were tolerance tested with either diazepam or pentobarbital and, if tolerant, were withdrawn with diazepam or phenobarbital, respectively. Seventy-eight subjects previously described in the literature with drug dependencies similar to the diazepam and barbiturate groups provided a basis for comparing the diazepam group to untreated patients to determine whether diazepam was able to prevent abstinence symptoms. Withdrawal was successfully completed in all patients. The expected and observed incidence of seizures, delirium, and minor withdrawal for the barbiturate group and seizures and delirium for the diazepam group did not differ significantly, although a large type II error compromised these conclusions. A significant difference was seen between the observed and expected incidence of minor withdrawal symptoms in the diazepam-withdrawn patients.

Adult↗