Ecological effects of pharmaceuticals in aquatic systems--impacts through behavioural alterations

The study of animal behaviour is important for both ecology and ecotoxicology, yet research in these two fields is currently developing independently. Here, we synthesize the available knowledge on drug-induced behavioural alterations in fish, discuss potential ecological consequences and report results from an experiment in which we quantify both uptake and behavioural impact of a psychiatric drug on a predatory fish (Perca fluviatilis) and its invertebrate prey (Coenagrion hastulatum). We show that perch became more active while damselfly behaviour was unaffected, illustrating that behavioural effects of pharmaceuticals can differ between species. Furthermore, we demonstrate that prey consumption can be an important exposure route as on average 46% of the pharmaceutical in ingested prey accumulated in the predator. This suggests that investigations of exposure through bioconcentration, where trophic interactions and subsequent bioaccumulation of exposed individuals are ignored, underestimate exposure. Wildlife may therefore be exposed to higher levels of behaviourally altering pharmaceuticals than predictions based on commonly used exposure assays and pharmaceutical concentrations found in environmental monitoring programmes.

Reinforcement of irritability during therapy with benzodiazepines

BACKGROUND

Often, long-term treatment with benzodiazepines is a subject of discussion due to potential side effects, with dependence on benzodiazepines as the most serous one. After longer period of benzodiazepines tolerance on their anxiolytic effects develops. Discontinuation is usually beneficial as it is followed by improved psychomotor and cognitive functioning, particularly in the elderly. Previous studies confirmed occurrence of physical dependence in high percentage of patients in long term treatment with benzodiazepines at therapeutic dosages. Benzodiazepines are relatively well-tolerated medicines but can induce serious problems of addiction and that is why their use is regulated. The aim of this article is to report a case of a patient who was taking 15 tablets of oxazepam daily for a period of time, during which reinforcement of irritability occurred.

CONCLUSION

It is necessary to warn patients who take benzodiazepines in therapy that reinforcement of irritability may occur in case of higher dosage of benzodiazepines, which may be misinterpreted as worsening in mental condition.

Comparison of mirtazapine and fluoxetine in the treatment of major depressive disorder: a double-blind, randomized trial

BACKGROUND

Depression is an international public health problem. The aim of this study was to compare the efficacy and tolerability of mirtazapine and fluoxetine treatment in a sample population consisting of Iranian patients suffering major depressive disorder.

METHODS

Thirty-six inpatients and outpatients with a diagnosis of major depressive disorder (Diagnostic and Statistical Manual of Mental Disorders-IV) and a score > or = 18 on the 17-item Hamilton Rating Scale for Depression (HAM-D-17) were randomly assigned to 6 weeks of treatment with mirtazapine (30 mg/day) or fluoxetine (20 mg/day). Efficacy was assessed by HAM-D-17. Information about adverse events was obtained by questioning of participants and/or their examination. Assessments were performed at weeks 0, 1, 2, 3, 4 and 6.

RESULTS

Sixteen of mirtazapine-treated patients and fifteen of fluoxetine-treated patients completed the 6-week study period. Both treatment groups were well matched at baseline with respect to demographic and disease characteristics. Both drugs showed a significant improvement over the 6 weeks of treatment (P < 0.001). There was no statistically significant difference between the mean +/- SEM HAM-D scores of two groups at weeks 1, 2, 3, 4, and at the end point. There were no significant differences between two groups in terms of response to treatment (> or = 50% decrease from baseline in HAM-D-17 total score) and remission (HAM-D-17 score of < or = 7). None of the differences in reported adverse events was statistically significant.

CONCLUSION

In this study, mirtazapine and fluoxetine were equally effective and well tolerated after 6 weeks of treatment in patients with major depressive disorder.

Effects of additional oxazepam in long-term users of oxazepam

Although additional dosages of benzodiazepines in long-term users of benzodiazepines are common, it is unknown whether these additional dosages resort any effect. The effects of an additional 20-mg dosage oxazepam were assessed in a double-blind, balanced-order, crossover randomized study comparing 16 long-term users of oxazepam (patients) with 18 benzodiazepine-naive controls (controls). The effects of 10 and 30 mg oxazepam were assessed at pretest and 2.5 hours after drug administration on: (a) saccadic eye movements as proxy for the sedative effect, (b) acoustic startle response (ASR) as proxy for the anxiolytic effects, (c) memory, (d) reaction time tasks, and (e) subjective measurements. Dose-related effects were found in patients on the peak velocity of saccadic eye movement and on response probability, respectively peak amplitude of the ASR. Comparison with controls, however, suggests that in patients the sedative effects might be mixed up with suppression of sedative withdrawal symptoms, whereas patients were as sensitive as benzodiazepine-naive controls for the effects of an additional dosage on the ASR. Neither 10 nor 30 mg oxazepam challenge affected the reaction time tasks in patients, whereas controls show a dose-related impairment. The memory impairing effects, however, did not differ significantly between patients and controls. In contrast to controls, patients could not discriminate between a 10- and 30-mg dosage as assessed by visual analogue scales and the STAI-DY-1, which might indicate a placebo effect in the 10-mg challenge in patients. We conclude that additional dosages of oxazepam still exert pronounced effects after daily use for more than 10 years.

Idiopathic recurrent stupor: a warning

A proposal that an endogenous benzodiazepine-like agent named endozepine-4 might be responsible for presentations of recurrent stupor has gained wide acceptance. A case of recurrent stupor over two decades is presented with many similarities to previous cases of "endozepine stupor". This case, however, was caused by exogenous benzodiazepine administration and serves as a warning to clinicians to beware of this diagnosis.

[Investigation of a fetal heart-rate pattern that shows a reduced oscillation amplitude]

A fetal heart-rate pattern that has a reduced oscillation amplitude may indicate a physiological fetal dormant period but could also be an indication of fetal hypoxemia. In some rare cases such a fetal heart rate-pattern can be an indicator of cerebral or cardial fetal malformation or of an intoxication caused by sedative drugs. Our patient is a 32-year-old Para III in the phase of 29 weeks and 3 days gestation. Upon admission to the clinic, the fetal heart-rate pattern showed a reduced oscillation amplitude, and there were no signs of fetal movement. The ultrasound examination gave us no reason to suspect fetal malformation, and the results of the Doppler ultrasonography were also normal. However, although the patient had denied taking any medication at all, the results of an toxicological blood test confirmed our suspicion of benzodiazepine intoxication. Throughout the night the fetal heart-rate pattern was continuously measured, and in the early hours of the morning, after breaking down of the oxazepam medication, a normalization of the fetal heart-rate pattern was observed. This case report definitively demonstrates that Doppler ultrasonography is a valuable method for assessing any uncertainty regarding a fetal heart-rate pattern.

Efficacy and tolerability of valerian extract LI 156 compared with oxazepam in the treatment of non-organic insomnia--a randomized, double-blind, comparative clinical study

Patients aged 18 to 73 years and diagnosed with non-organic insomnia according to ICD-10 (F 51.0) were treated in a multicentre, double-blind, randomised parallel group comparison with either 600 mg/die valerian extract LI 156 (Sedonium) or 10 mg/die oxazepam taken for 6 weeks. A total of 202 outpatients with a mean duration of insomnia of 3.5 months at baseline were included at 24 study centres (general practices) in Germany. - Sleep quality (SQ) after 6 weeks measured by the Sleep Questionnaire B (SF-B; CIPS 1996) showed that 600 mg/die valerian extract LI 156 was at least as efficacious as a treatment with 10 mg/die oxazepam. Both treatments markedly increased sleep quality compared with baseline (p <0.01). The other SF-B subscales, i.e. feeling of refreshment after sleep (GES), psychic stability in the evening (PSYA), psychic exhaustion in the evening (PSYE), psychosomatic symptoms in the sleep phase (PSS), dream recall (TRME), and duration of sleep confirmed similar effects of both treatments. Clinical Global Impressions scale (CGI) and Global Assessment of Efficacy by investigator and patient, again, showed similar effects of both treatments. Adverse events occurred in 29 patients (28.4%) receiving valerian extract LI 156 and 36 patients (36.0%) under oxazepam, and were all rated mild to moderate. No serious adverse drug reactions were reported in either group. Most patients assessed their respective treatment as very good (82.8% in the valerian group, 73.4% in the oxazepam group). During the 6 week treatment phase Valerian extract LI 156 (Sedonium) 600 mg/die showed a comparable efficacy to 10 mg/die oxazepam in the therapy of non-organic insomnia.

Intravenous flumazenil versus oxazepam tapering in the treatment of benzodiazepine withdrawal: a randomized, placebo-controlled study

Flumazenil (FLU), a benzodiazepine (BZD) partial agonist with a weak intrinsic activity, was previously found unable to precipitate withdrawal in tolerant subjects submitted to long-lasting BZD treatment. The potential use of FLU to treat BZD withdrawal symptoms has also been evaluated tentatively in clinical studies. In the present experiment, FLU (treatment A) was compared with oxazepam tapering (treatment B) and placebo (treatment C) in the control of BZD withdrawal symptoms in three groups of BZD dependent patients. Group A patients (20) received FLU 1 mg twice a day for 8 days, and oxazepam 30 mg in two divided doses (15 mg + 15 mg) during the first night, oxazepam 15 mg during the second night and oxazepam 7.5 mg during the third night. FLU was injected i.v. in saline for 4 hours in the morning and 4 hours in the afternoon, in association with placebo tablets. Group B patients (20) were treated by tapering of oxazepam dosage (from 120 mg) and with saline solution (as placebo) instead of FLU for 8 days. Group C patients (10) received saline instead of FLU and placebo tablets instead of oxazepam for 8 days. FLU immediately reversed BZD effects on balance task and significantly reduced withdrawal symptoms in comparison with oxazepam and placebo on both self-reported and observer-rated withdrawal scales. The partial agonist also reduced craving scores during the detoxification procedure. In addition, during oxazepam tapering, group B patients experienced paradoxical symptoms that were not apparent in FLU patients. Patients treated with FLU showed a significantly lower relapse rates on days 15, 23 and 30 after the detoxification week. Our data provide further evidence of FLUs ability to counteract BZD effects, control BZD withdrawal and normalize BZD receptor function. The effectiveness of FLU may reflect its capacity to upregulate BZD receptors and to reverse the uncoupling between the recognition sites of BZD and GABA, on the GABA(A) macromolecular complex, that has been reported in tolerant subjects.

Symptom-triggered vs fixed-schedule doses of benzodiazepine for alcohol withdrawal: a randomized treatment trial

BACKGROUND

In alcohol withdrawal, fixed doses of benzodiazepine are generally recommended as a first-line pharmacologic approach. This study determines the benefits of an individualized treatment regimen on the quantity of benzodiazepine administered and the duration of its use during alcohol withdrawal treatment.

METHODS

We conducted a prospective, randomized, double-blind, controlled trial including 117 consecutive patients with alcohol dependence, according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, entering an alcohol treatment program at both the Lausanne and Geneva university hospitals, Switzerland. Patients were randomized into 2 groups: (1) 56 were treated with oxazepam in response to the development of signs of alcohol withdrawal (symptom-triggered); and (2) 61 were treated with oxazepam every 6 hours with additional doses as needed (fixed-schedule). The administration of oxazepam in group 1 and additional oxazepam in group 2 was determined using a standardized measure of alcohol withdrawal. The main outcome measures were the total amount and duration of treatment with oxazepam, the incidence of complications, and the comfort level.

RESULTS

A total of 22 patients (39%) in the symptom-triggered group were treated with oxazepam vs 100% in the fixed-schedule group (P<.001). The mean oxazepam dose administered in the symptom-triggered group was 37.5 mg compared with 231.4 mg in the fixed-schedule group (P<.001). The mean duration of oxazepam treatment was 20.0 hours in the symptom-triggered group vs 62.7 hours in the fixed-schedule group (P<.001). Withdrawal complications were limited to a single episode of seizures in the symptom-triggered group. There were no differences in the measures of comfort between the 2 groups.

CONCLUSIONS

Symptom-triggered benzodiazepine treatment for alcohol withdrawal is safe, comfortable, and associated with a decrease in the quantity of medication and duration of treatment.

Benzodiazepines differently modulate EAAT1/GLAST and EAAT2/GLT1 glutamate transporters expressed in CHO cells

It has been described recently that low concentrations of benzodiazepines stimulate the transport activity of the neuronal glutamate transporter EAAT3, whereas high concentrations inhibit it. The present study is aimed to investigate whether benzodiazepines have similar effects on the two glial glutamate transporter, EAAT1 and EAAT2. To this end, the transporters were transiently expressed in CHO cells and transport activity was determined by isotope fluxes using D-aspartate as non-metabolizable homologue of L-glutamate. At low D-aspartate concentrations (1 micromol/l) EAAT1-mediated uptake was reduced significantly by low concentrations of oxazepam (1 micromol/l) and diazepam (1 and 10 micromol/l). At 100 micromol/l D-aspartate oxazepam stimulated EAAT1-mediated uptake up to 150% in a dose dependent manner, whereas the inhibition by low concentrations of diazepam was attenuated. In contrast, a significant effect of diazepam on EAAT2-mediated uptake was only observed at 1000 micromol/l where uptake was inhibited by 60%. A similar inhibition was observed for EAAT1. These studies demonstrate a different modulation of EAAT1 and EAAT2 by benzodiazepines. Furthermore the glial transporters differ from the neuronal glutamate transporter. Thus, a complex in vivo response of the various transporters to benzodiazepines can be expected.

Divalproex sodium in alcohol withdrawal: a randomized double-blind placebo-controlled clinical trial

BACKGROUND

Divalproex sodium, an anticonvulsant and antikindling agent and gamma-aminobutyric acid enhancer, has been proposed as an alternative to benzodiazepines for treating alcohol withdrawal. This study reports on a randomized, double-blind, placebo-controlled trial of divalproex sodium in acute alcohol withdrawal.

METHODS

Thirty-six hospitalized patients experiencing moderate alcohol withdrawal as measured by a score of at least 10 on the revised Clinical Institute Withdrawal Assessment for Alcohol Scale (CIWA-Ar) were randomized to receive either divalproex sodium 500 mg three times per day for 7 days or matched placebo in a double-blind manner. All subjects received a baseline dose of oxazepam and had additional oxazepam available as a rescue medication in accordance with a standard, symptom-triggered detoxification protocol. Mean total milligrams of oxazepam received, progression of withdrawal symptoms, psychological distress as measured by the Symptom Checklist-90, side effects, and adverse outcomes were compared between groups.

RESULTS

Use of divalproex sodium resulted in less use of oxazepam (p < 0.033). Group differences seemed primarily driven by those subjects who experienced symptoms above threshold level (CIWA-Ar >or=10) after 12 hr. The progression in severity of withdrawal symptoms (increase in CIWA-Ar above baseline) was also significantly greater in the placebo group (p < 0.05).

CONCLUSIONS

This placebo-controlled pilot study suggests that divalproex sodium significantly affects the course of acute alcohol withdrawal and reduces the need for treatment with a benzodiazepine. A more aggressive loading dose strategy may demonstrate a more robust or earlier response.

Routine hospital alcohol detoxification practice compared to symptom triggered management with an Objective Withdrawal Scale (CIWA-Ar)

Charts of patients hospitalized for uncomplicated alcohol withdrawal were examined and detoxification practices compared. Patients detoxified using a Clinical Institute Withdrawal Assessment for Alcohol-revised (CIWA-Ar) based PRN protocol on the addiction unit received significantly fewer chlordiazepoxide milligram equivalents over shorter duration than patients managed by other detoxification methods on other hospital units. Significantly fewer patients received benzodiazepines in the CIWA-Ar protocol managed group, but inter-group differences (p < 0.01) remained when only medicated patients were compared. Differences between the protocol and non-protocol groups did not reach statistical significance when PRN only strategies were examined, suggesting that the use of a symptom-triggered strategy may account for the noted effects.

[Tramadol and oxazepam. Effect on pulmonry function in elderly patients with chronic obstructive lung disease]

Many patients with chronic obstructive pulmonary disease (COPD) suffer from osteoporotic pain as a result of glucocorticoid treatment and nervous symptoms partly related to their lung disease. There seems to be som reluctance to treat these patients with an opioid or benzodiazepine. Upon request, the Drug Information Centre in Odense made an extensive literature search on the subject. No documentation was found that tramadol additionally depresses the respiration in patients with COPD, nor has oxazepam in clinically relevant doses been found to exacerbate their lung disease. The clinical effect is subject to large interindividual variability, and the use of these drugs should, to a greater extent, rest on experience with the individual patient. There seems to be no reason to maintain a priori this rigoristic reluctance to use tramadol and/or oxazepam in patients with COPD.

Night eating syndrome. Preliminary results

Clinical aspects of the "night eating syndrome" (NES) are described. Recent studies, also referred to in the present report, have revealed certain triggering factors of this syndrome, but do not reveal the nature of the relationship between awakening and compulsory need for food. According to the psychodynamic interpretation, these subjects eat at night to replace dreaming, to which they offer strong resistance, whilst according to the psychobiological interpretation, motivational stimuli develop the irresistible and repeated desire for food. Within a post-rational cognitive theoretical model, the compulsion to food would be the mode through which subjects obtain a modified conscious state necessary to appease the suffering due to an experience of emptiness and incapacity. Psychological support associated with pharmacological treatment (benzodiazepine, gamma-hydroxybutyric acid) has been shown, in a personal series, to be effective both upon the sleep disorder and craving.

Valproate prophylaxis for migraine induced by selective serotonin reuptake inhibitors

We report the successful use of valproate in a 44-year-old woman with migraine induced by selective serotonin reuptake inhibitors. Valproate should be considered for those patients who develop serious migraine for the first time, or worsening of previous migraine, after the initiation of treatment with selective serotonin reuptake inhibitors and for whom continued treatment with this class of drugs is important.

Rapid opiate detoxication in outpatient treatment: relationship with naltrexone compliance

A variety of detoxification methods have been utilized for the treatment of heroin withdrawal before individuals begin long-term opiate-free and naltrexone programs. While methadone in decreasing doses is still widely used for detoxication procedures, rapid and ultrarapid protocols including clonidine and opiate receptors antagonists have been proposed. This study compares the efficacy of different detoxification methods and investigates possible changes in naltrexone compliance. Ninety-eight heroin-addicted individuals were studied to evaluate withdrawal symptoms, craving, mood, urine toxicologic screens, and drop-out rate during therapy with: Group A: clonidine only (5 days); Group B: clonidine, oxazepam, baclofen, and ketoprofene with naloxone and naltrexone (2 days); and Group C: methadone in decreasing doses (10 days). Naltrexone compliance and relapse rates were evaluated during a 6-month follow-up period. Rapid detoxification with opiate antagonists (Group B) induced slight and transient withdrawal symptoms, and resulted in a significantly lower percentage of heroin catabolites in urine controls during the detoxification procedure, lower negative and positive craving, less mood problems, and higher compliance in extended naltrexone treatment. In comparison with clonidine only (Group A) and methadone (Group C), the early use of naltrexone during detoxification in combination with benzodiazepines and clonidine facilitated extended naltrexone acceptance and improved the recovery outcome in outpatients.

Considerations for the use of oral sedation in the institutionalized geriatric patient during dental interventions: a review of the literature

Some institutionalized elderly persons need a sedative prior to a dental examination or treatment because they have a disturbance due to physical illnesses, degenerative changes in the brain, and/or psychiatric disorders, associated with advanced aging. Oral administration is one of the safest methods of delivery of a sedative drug. It is almost universally acceptable, easy to administer, costs little, has a low incidence and severity of adverse reactions, and requires no additional formal specialized training for the dentist. However, theoretical and practical knowledge of sedation is essential. This paper reviews the literature on oral sedation for the geriatric patient. Benzodiazepines are most often used for oral sedation of geriatric patients. The properties of these drugs were reviewed, and recommendations were made with respect to the drugs of choice and their dosage. Generally, fast-acting benzodiazepines of short duration, with rapid rate of elimination and no active metabolites, are recommended. The drug of choice, and the dosage, may vary according to the medical history and physical condition of the patient.

Benzodiazepines alter cochleo-cochlear loop in humans

By using otoacoustic emission, we looked for change in outer hair cell (OHC) motile activity and medial olivocochlear (MOC) system inhibition due to benzodiazepine administration, a drug that is known to produce a pharmacological effect by interacting with GABAergic inhibitory neurotransmission. No effect was observed on OHC motile activity, in contrast benzodiazepines decreased MOC system effectiveness suggesting the existence of GABAergic fibers projecting onto the MOC system.

An anxiolytic-like effect of ondansetron disappears in oxazepam-tolerant rats

In our experiments a drug from the group of 5-HT3 antagonists--ondansetron (OND)--has been used in rats developing tolerance to oxazepam (OXZ). After 7 days of oxazepam administration (5 mg/kg i.p.) a significant decrease in the anxiolytic behavior was observed in the Crawley test. In the rats already partly tolerant to oxazepam, an undiminished anxiolytic-like effect of ondansetron (single injection of 0.1 mg/kg i.p., seventh day) was observed. After 14 days of oxazepam administration its anxiolytic activity was even more diminished. A single injection of ondansetron 0.1 mg/kg restored the anxiolytic behavior: rise of BWT (black-white transition) and WSE (white square entrance). After 21 days the anxiolytic activity of oxazepam was totally abolished and the single injection of ondansetron did not restore the state of anxiolysis. The results show that the anxiolytic effects of ondansetron were not influenced in the first stages of tolerance development to oxazepam, but the drug was not able to produce an anxiolytic effect in the state of full tolerance to oxazepam (after 3 weeks).

The effect of chronic benzodiazepines exposure on body weight in rats

Changes in body weight (BW) in female rats treated for 5 weeks (wk) with weekly subcutaneous implantation of silastic capsules containing different benzodiazepines (BZs): diazepam (DZ) 90, 180, 360 and 540 mg wk-1; nordiazepam (ND) 600 mg wk-1; oxazepam (OX) 600 mg wk-1 and flunitrazepam (FN) 540 mg wk-1 and in male rats exposed to DZ (540 mg wk-1) were evaluated herein. Rats (female and male) implanted with empty capsules served as controls. The BW gain was significantly higher in male than in female rats (both DZ-treated and controls). The BW gain increased with increasing doses of DZ but slowed with time of exposure. In comparison to control rats, the BW gain was significantly higher in DZ-(540 mg wk-1) and OX- but not in ND- and FN-treated female rats. However, the differences between BZs were not of statistical significance. In rats exposed to empty capsules (male, female); DZ (male); ND and OX (female) the BW gain increased with time (1-4 wk) while in rats exposed to DZ and FN (female) the BW stabilised within 2 wk. Acute injection of the central BZ receptor antagonist, flumazenil (40 mg kg-1, i.v., 5th wk of chronic exposure), tended to inhibit the time-related BW gain in rats exposed to empty capsules (male, female), DZ (male), ND and OX (female) but did not affect the BW in DZ- (540 mg wk-1) and FN-exposed rats (female) where BW stabilised prior to FLU injection. Repeated administration of flumazenil (30 mg kg-1 wk-1, i.p.) did not affect the BW gain in DZ- and ND-treated female rats. The present data indicate that different BZs have different effects on BW gain in the rat suggesting that different subtypes of BZ receptors are involved.

Outpatient non-opioid detoxification for opioid withdrawal. Who is likely to benefit?

The authors examined characteristics of successful completers of an outpatient clonidine/oxazepam detoxification procedure for opioid dependence. Of 215 initial applicants, 167 received medication, and 65 successfully completed by taking a dose of naltrexone. Those who completed were more likely to have last used an opioid other than heroin, to be heroin smokers, rather than intravenous users, to have used benzodiazepines in the 30 days before treatment, and to have abstained from opioids for a longer time before presenting for treatment. New users (for less than 2 years) did no better than those using longer than 2 years. These findings may help in the continued refinement of patient placement criteria.

A protocol to switch high-dose, methadone-maintained subjects to buprenorphine

Buprenorphine (BUP) is an alternative to methadone (METH) maintenance. However, there are few studies on the switching of patients from METH to BUP. Eighteen volunteers who had been maintained on METH for 1-19 years were recruited for a residential cocaine self-administration study. All subjects were maintained on 60 mg METH for up to 1 1/2 weeks before the 7-day changeover (60, 40, 30, 30, 0 mg METH; 4, 8 mg BUP). Fifteen subjects successfully completed the transfer from METH to BUP, experiencing moderate withdrawal symptoms, as measured by the Subjective Opiate Withdrawal Scale (SOWS). Withdrawal symptoms were the highest during the first assessment of the day, at the time of BUP administration. SOWS scores returned to baseline 4 days after the switchover. This study demonstrates that within a supportive inpatient setting, research volunteers can be rapidly switched from high-maintenance doses of METH to BUP with an acceptable degree of tolerability.

Activity of hepatic drug metabolizing enzymes following oxazepam-dosed feed treatment in B6C3F1 mice

Oxazepam has been determined to be a potent hepatocarcinogen in mice. Evidence in the literature indicates that oxazepam is capable of inducing drug metabolizing enzymes in rodents and an association between enzyme induction and carcinogenesis has been proposed for other compounds such as phenobarbital. We examined the pattern of enzyme induction that occurs under bioassay conditions in male B6C3F1 mice. The results indicate that oxazepam is capable of inducing multiple drug metabolizing enzymes under bioassay conditions. Closer examination of the most induced samples suggests that oxazepam is a phenobarbital-type enzyme inducer.

Precipitated withdrawal in squirrel monkeys after repeated daily oral administration of alprazolam, diazepam, flunitrazepam or oxazepam

The lowest dose of alprazolam, diazepam, flunitrazepam and oxazepam consistently to induce loss of righting reflex in squirrel monkeys or vehicle was orally administered to monkeys on 18 consecutive days: 2 mg/kg alprazolam (n = 4), 30 mg/kg diazepam (n = 4), 1 mg/kg flunitrazepam (n = 4), 280 mg/kg oxazepam (n = 5), or vehicle (n = 4). Tolerance developed rapidly for loss of righting reflex, more slowly for sleep and only minimally for muscle relaxation observed during the period immediately following daily oral administration. Injection of the specific benzodiazepine receptor antagonist flumazenil (10 mg/kg i.v.) 5 h after the ninth daily oral treatment produced signs of precipitated withdrawal (tremor, vomiting and/or convulsions) in one alprazolam-, four diazepam-, one flunitrazepam- and four oxazepam-treated monkeys, but not in the vehicle-treated monkeys. Physiological saline injected intravenously several days later under these same experimental conditions failed to provoke a precipitated withdrawal reaction. When flumazenil-induced precipitated withdrawal was again evaluated after the 18th daily oral treatment, withdrawal signs were observed in all alprazolam- and all diazepam-treated monkeys, as well as in three flunitrazepam- and three oxazepam-treated monkeys, but not in the vehicle-treated monkeys (convulsions were observed in one alprazolam-, two diazepam-, one flunitrazepam- and two oxazepam-treated monkeys). No signs of spontaneous withdrawal were observed in any of the monkeys during a subsequent 3-week drug-free period. Thus, repeated administration of approximately equieffective doses of these four benzodiazepines resulted in a similar development of tolerance and physical dependence (indicated by the occurrence of a precipitated withdrawal reaction).

Early responses of the liver of B6C3F1 mice to the hepatocarcinogen oxazepam

Oxazepam has recently been shown to induce hepatocarcinogenicity in B6C3F1 mice. Due to the widespread human exposure to this anxiolytic compound and other structurally similar benzodiazepines, we conducted toxicity and cell proliferation studies on oxazepam to determine possible mechanisms whereby this nonmutagenic chemical may have exerted a carcinogenic effect. Male B6C3F1 mice (10 per dose-time group) received diets containing oxazepam at 0, 25, 125, 2500, and 5000 ppm. Mice were treated for 15, 30, 45, or 90 days, at which time they were evaluated for feed consumption, liver/body weight ratios, clinical pathology, serum oxazepam levels, and histopathology of the liver. During the final 7 days before sacrifice, the mice were exposed to BrDU via osmotic minipump to quantify hepatocellular replicative DNA synthesis. Few effects were observed resulting from chronic exposure to oxazepam other than statistically significant, dose-related increases in liver/body weight ratios. Replicative DNA synthesis was significantly increased in a dose-related manner at the 15-day time point in the 125, 2500, and 5000 ppm dose groups, and attained levels of four- to five-fold above control levels which returned to control levels by 30 days. The lack of significant toxicity, sustained increased liver/body weight ratios, and the rapid and transient induction of replicative DNA synthesis are similar to the effects reported for exposure to another widely used therapeutic agent shown to be a nongenotoxic carcinogen, phenobarbital.

Pain sensation in transurethral microwave thermotherapy for benign prostatic hyperplasia: the rationale for prophylactic sedation

Transurethral microwave thermotherapy (TUMT) can be painful. Pain sensation limits treatment tolerance and consequently also treatment efficacy. Of our population of patients treated with TUMT, 22% (63/288) needed intravenous analgesia and, nevertheless, 6% (17/288) needed definitive treatment interruption. The aim of this study was to identify the mechanism of pain sensation during TUMT and to verify whether the prophylactic use of a sedative drug would improve treatment tolerance. Eighty-three patients undergoing TUMT treatment for benign prostatic hyperplasia at our department entered a prospective, randomized, single-blinded study. Thirty minutes before treatment, 40 patients (group A) received 960 mg cotrimoxazole orally while 43 patients (group B) received 960 mg cotrimoxazole and 10 mg oxazepam, both orally. Statistically significant improvement in treatment tolerance in group B in comparison with group A was found. Pain sensation during TUMT seemed to be mostly due to anxiety. It is concluded that the prophylactic use of a sedative drug is advisable in patients undergoing TUMT in order to improve treatment tolerance.

An investigation of micronucleus and mutation induction by oxazepam in mammalian cells

The benzodiazepines are a class of drugs that are widely used in the treatment of various psychiatric disorders. One member of this class, oxazepam, is also a common metabolite of several other benzodiazepines. Since the evidence for the genetic toxicity and carcinogenic properties of these compounds is inconsistent, we investigated the oxazepam-induced formation of micronuclei in Syrian Hamster embryo fibroblast (SHE) cells, human amniotic fluid fibroblast-like (AFFL) cells and L5178Y mouse cells. A dose-dependent increase in micronucleus fractions was found in all three cell lines. The time course of micronucleus induction in L5178Y cells showed a maximum at 5 h after treatment, suggesting that the micronuclei were formed in the first mitosis after treatment. Kinetochore staining (CREST-antiserum) revealed the presence of kinetochores in approximately 50% of the micronuclei in all three cell types. This result was further confirmed by in situ hybridization in L5178Y cells and indicates the presence of whole chromosomes or centric fragments as well as acentric fragments in the oxazepam-induced micronuclei. The L5178Y cells did not show a mutagenic response to oxazepam at any of the doses or expression times used.

Modeling blood/plasma concentrations in dosed feed and dosed drinking water toxicology studies

A computer model for predicting blood/plasma concentrations of test chemicals in dosed feed and dosed drinking water toxicology studies was developed. The model was constructed based on linear theory. The animal's feeding and drinking habits and the linear disposition kinetics of the test chemical obtained after a bolus gavage dose were built into the model. Blood/plasma concentrations of oxazepam and pentachlorophenol in dosed feed and dosed drinking water studies were predicted and compared with the experimentally determined data. The model proved highly reliable in predicting the blood/plasma concentrations of test chemical in dosed feed and dosed drinking water studies. The results suggest that if the kinetics of test chemicals fit a one-compartment model then bioaccumulation of the test chemical will occur in dosed feed or in dosed drinking water studies when absorption half-lives are less than 1.38 hr and elimination half-lives are longer than 5 hr. The extent of accumulation is mainly dependent on the elimination half-lives. For chemicals with absorption half-lives less than 1.38 hr and elimination half-lives less than 2 hr, the extent of bioaccumulation will be minimal. Blood/plasma concentrations of test chemicals in rats and mice will fluctuate daily and a quasi-steady state will be achieved after ad libitum exposure to dosed feed or dosed drinking water for approximately 4 days. If a daily 12-hr light cycle is used with the light cycle starting at 7:00 AM, the expected peak and trough blood concentrations in dosed feed studies will occur approximately in the early morning (5:00 AM) and in the late afternoon (4:00 PM), respectively. Similar results were obtained for dosed drinking water studies. The model should be applicable to dosed feed and dosed drinking water studies using other species.

Oral benzodiazepines and conscious sedation: A review

A large number of benzodiazepines have been studied for use as sedatives and for their anxiolytic potential as premedicants for outpatient surgery. Potent, new, orally-administered drugs with short half-lives, rapid onset, and minimal residual effects have been developed. Dose-dependent amnesia is also produced by some of these agents. Advances in understanding receptor physiology have shed light on specific pharmacologic activities and aided the discovery of benzodiazepine antagonists with antidote properties. While these drugs have relatively low toxicity, dose-related oversedation remains a risk in susceptible patients, especially when combined with other sedatives.

Pharmacodynamics of the anticonvulsant effect of oxazepam in aging BN/BiRij rats

1. The purpose of this investigation was to examine the influence of increasing age on the pharmacokinetics and the time course of the anticonvulsant response of oxazepam in BN/BiRij rats as an animal model of aging. 2. Oxazepam was administered intravenously in a dose of 12 mg kg-1 body weight and the anticonvulsant effect intensity was measured as elevation above baseline of a threshold for induction of localized seizure activity (TLS). Direct cortical stimulation with ramp shaped electrical pulse trains of increasing intensity was used to determine this threshold. 3. The pharmacological effect vs. time profile showed in young rats an anticonvulsant component followed by proconvulsant component which is suggestive for the occurrence of acute tolerance and/or withdrawal syndrome. With increasing age the proconvulsant component disappeared, resulting in a monophasic effect profile (anticonvulsant effect only) at the age of 35 months with significantly higher anticonvulsant effect intensity immediately following drug administration. No age-related changes in the pharmacokinetic parameters of oxazepam were observed. 4. In five animals of each age group, benzodiazepine receptor binding characteristics were determined in vitro with [3H]-flunitrazepam as a ligand. Both receptor density and affinity did not show age-related changes. Available literature data on post-receptor events do not indicate conclusive age-related changes. 5. It is concluded, that the observed change in the pharmacodynamics of anticonvulsant effect of oxazepam can be explained by the disappearance of the tolerance/withdrawal phenomenon. This is compatible with a decreased efficiency of homeostatic control mechanisms in the elderly.

Correlation between doses of oxazepam and their effects on performance of a standardised test battery

Ten different doses of oxazepam (ranging from 7.5 to 50 mg) or placebo were administered to a total of 28 female subjects in three separate studies. Subjects completed a battery of psychometric tests at 1 and 2 h postdose. The tests included critical flicker fusion, choice reaction time and a tracking task. Following separate analyses of variance, effect sizes (Cohen's d) were calculated for each dose at each dependent variable. These effect sizes were then correlated with the dose of drug administered, using regression analyses. It was found that the doses correlated highly with most of the psychometric variables determined, implying that the test battery is sensitive to drug effects.

Neurodevelopment in late infancy after prenatal exposure to benzodiazepines--a prospective study

Growth and neurodevelopment at 6, 10 and 18 months of age have been studied prospectively and longitudinally in a series of 17 children born to mothers who used benzodiazepines (BZD) in therapeutic doses as their only psychotropic drug throughout pregnancy. The results were compared with a group of 29 children born to mothers without any known use of psychotropic drugs. The BZD-exposed children caught up their low mean birth-weight, at an early stage, whereas the slightly decreased head circumference at birth remained at the same low level. In five infants, a pattern of craniofacial anomalies was found. Deviating neurodevelopmental and clinical symptoms and signs were common. The gross motor development was retarded at 6 and 10 months, but was nearly normal at 18 months. Impaired fine motor functions were found on all follow-up occasions. At 18 months, the most prominent finding was a delayed development of pincer grasp. The BZD-exposed children showed deviations in muscle tone and pattern of movements more frequently than children in the reference group. The study suggests that the use of BZD in therapeutic doses throughout pregnancy can have negative effects on the development of children up to 18 months of age. The long-term hazards cannot be evaluated from these results. A further follow-up at early school age is needed and is in progress.

Mortality in Swiss albino mice after i.p. injection of oxazepam in dimethyl sulphoxide

Twenty percent of the Swiss albino mice administered with a single dose (60 mg/kg) of oxazepam dissolved in dimethyl sulphoxide (DMSO) died within 7 days. Similarly high mortality rate (37%) was observed in diazepam sensitive mice derived from a Swiss albino stock. In contrast, zero mortality was observed in Swiss albino mice administered with DMSO or diazepam (35 mg/kg). Mortality at 60 mg/kg diazepam was only 10%. The high mortality caused by oxazepam in Swiss albino mice seemed to be strain-related as only 7% mortality was observed with identically treated BALB/c mice. Since DMSO is the only convenient vehicle for the administration of oxazepam by injection, it is suggested that a suitable strain must be selected for experimentation in order to avoid unnecessary loss of animals.

Single dose pharmacokinetics and pharmacodynamics of oral oxazepam in very elderly institutionalised subjects

The effect of extreme old age on the pharmacokinetics and pharmacodynamics of orally administered oxazepam 15 mg was studied in 10 healthy elderly (age 80-94 years) institutionalised subjects and 10 healthy young controls (age 26-42 years). The total oxazepam clearance was 1.24 (0.91-1.80) ml min-1 kg-1 (median and range) and 1.44 (0.88-2.13) ml min-1 kg-1 in the elderly and young, respectively (NS), and the elimination half-lives were 8.1 (5.5-10.8) h and 5.7 (4.9-6.2) h. respectively (P less than 0.01). The percent of unbound oxazepam was greater in the elderly; 9.8 (8.1-13.3)% as opposed to 5.1 (3.7-5.9)% in the young (P less than 0.0001). Clearance of unbound oxazepam was lower in the elderly, median values being 13.8 (7.1-21.1) ml min-1 kg-1 compared with 30.3 (18.3-41.5) ml min-1 kg-1 in the young (P less than 0.0001). A single 15 mg dose oxazepam decreased the ability of the elderly to perform a finger tapping test at 3 h but not 8 h after drug administration, whereas placebo had no effect at either times. No effect was observed in the young subjects.

Prenatal oxazepam enhances mouse maternal aggression in the offspring, without modifying acute chlordiazepoxide effects

In the rat, behavioral changes during lactation are in several ways similar to those produced by benzodiazepines (BDZ). Moreover, an increased activity at the GABA/BDZ receptor complex has been found in both conditions. We tested the hypothesis that early manipulation of this neurochemical system by prenatal BDZ exposure should affect typical responses of lactating dams, such as maternal aggression. Outbred CD-1 mice were treated with either oxazepam (15 mg/kg PO twice/day on days 12-16 of fetal life) or vehicle and fostered at birth to untreated dams. Female offspring were subsequently mated at the young-adult stage and used to assess maternal aggressive responses towards a male intruder. In a first 5-min test on postpartum day 6, the prenatal oxazepam animals showed a reduced Latency to the First Attack, a markedly enhanced frequency of several offensive scores (such as Fighting Episodes, Attacks, and Offensive Upright, On Top, and Kicking Postures), a decrease of Submissive Postures and a reduced duration of time spent lying still (Out of the Nest). The tests were repeated 48 h later after IP treatment by either chlordiazepoxide (10 mg/kg) or saline. The drug significantly enhanced locomotor activity as well as the frequency of Fighting Episodes and of Attacks, while decreasing the number of Submissive Postures and the time spent On Nest. These effects were not significantly modified by prenatal oxazepam exposure. This suggests that long-term and acute effects of benzodiazepines are produced either by changes in different regulatory systems or by different types of changes in the same system.

[Perioperative subjective emotional state]

The aim of adequate preoperative medication is to minimize the patient's anxiety level. Preoperative anxiety can be consciously and specifically orientated or it can be masked. This double-blind study was performed to evaluate the effects of an anxiolytic drug in comparison with a placebo perioperatively and to assess the post-operative course of the important factors anxiety, depression and asthenia. The Mannheim inventory for subjective state and STAI (State-Trait-Anxiety-Inventory) were offered. The study was undertaken in 60 female patients, who were operated for suspected carcinoma of the breast. We conclude that in such a specific group of patients extensive preoperative psychological preparation must be backed up by the administration of an anxiolytic drug.

A double-blind, controlled trial in primary care patients with generalized anxiety: a comparison between buspirone and oxazepam

Two hundred thirty patients with generalized anxiety and Hamilton Rating Scale for Anxiety (HAM-A) scores greater than or equal to 18 were subdivided at random, according to a double-blind design, into one group treated with 5-10 mg of oral buspirone t.i.d. or one group treated with 10-20 mg of oral oxazepam t.i.d. for 6 weeks. No anxiolytic treatment was allowed 3 months prior to trial entry. Analysis of demographic variables revealed no significant imbalance between the two treatment groups. Twenty patients were excluded from efficacy analysis because of treatment withdrawal before the first efficacy evaluation on Day 7. Another 4 patients were excluded because they were taking concomitant psychotropic medication. The remaining 206 patients displayed a decrease in HAM-A scores (mean +/- SD) from 23.9 +/- 4.1 to 10.6 +/- 7.7 in the buspirone group and from 23.9 +/- 4.2 to 11.5 +/- 8.0 in the oxazepam group. The two treatment groups were also found to be virtually identical in an "intent to treat" analysis of all 230 patients as well as in other ratings (Hamilton Rating Scale for Depression, Raskin Depression Scale, Covi Anxiety Scale, Physicians Questionnaire, global ratings, and Hopkins Symptom Checklist [HSCL]-56). However, oxazepam was never superior to buspirone in any of the efficacy analyses. Of the 230 patients, 127 spontaneously reported adverse events, including drowsiness, dizziness, headache, nausea, and nervousness. Adverse events were relatively similar in the two groups. In conclusion, buspirone and oxazepam appear to be equally effective in the treatment of generalized anxiety encountered by general practitioners. This outcome, in addition to a previously documented absence of any dependency liability, makes buspirone a clinically important anxiolytic drug.

The effects of flumazenil-precipitated abstinence on the pharmacokinetics of chronic oxazepam in dogs

The pharmacokinetics of oxazepam was studied in naive dogs and in oxazepam-dependent dogs without and with administered flumazenil (6 mg/kg). Oxazepam is eliminated with a relatively short elimination half life (ca. 150 min) in both acutely and chronically treated dogs. It exhibits only a modest first pass metabolism (ca. 10%) and its bioavailability following oral administration is about 22%. The steady state concentration of oxazepam in chronically treated dogs was lower than was predicted from single dose studies. Flumazenil did not change the rate of absorption or elimination of oxazepam-dependent dogs. The total steady state plasma concentration of oxazepam was significantly reduced by flumazenil administration suggesting a displacement interaction between flumazenil and oxazepam.

Comparative effectiveness and costs of inpatient and outpatient detoxification of patients with mild-to-moderate alcohol withdrawal syndrome

We compared the effectiveness, safety, and costs of outpatient (n = 87) and inpatient (n = 77) detoxification from alcohol in a randomized, prospective trial involving 164 male veterans of low socioeconomic status. The outpatients were evaluated medically and psychiatrically and then were prescribed decreasing doses of oxazepam on the basis of daily clinic visits. The inpatient program combined comprehensive psychiatric and medical evaluation, detoxification with oxazepam, and the initiation of rehabilitation treatment. The mean duration of treatment was significantly shorter for outpatients (6.5 days) than for inpatients (9.2 days). On the other hand, significantly more inpatients (95 percent) than outpatient (72 percent) completed detoxification. There were no serious medical complications in either group. Outcome evaluations completed at one and six months for 93 and 85 percent of the patients, respectively, showed substantial improvement in both groups at both follow-up periods. At one month there were fewer alcohol-related problems among inpatients and fewer medical problems among outpatients. However, no group differences were found at the six-month follow-up, nor were differences found in the subsequent use of other alcoholism-treatment services. Costs were substantially greater for inpatients ($3,319 to $3,665 per patient) than for outpatients ($175 to $388). We conclude that outpatient medical detoxification is an effective, safe, and low-cost treatment for patients with mid-to-moderate symptoms of alcohol withdrawal.

The use of benzodiazepine hypnotics in the elderly

An epidemiologic study was conducted to observe patient-reported use and effects of triazolam, flurazepam, and oxazepam taken at bedtime among 2260 outpatients age 65 years or older in Canada. The study used pharmacy-based enrollment, with participant follow-up through a 3-day diary and a telephone interview. The study also evaluated how the three benzodiazepine hypnotics were prescribed. Prescription information showed that 66% of the flurazepam prescriptions were for the highest strength, compared to 39% and 35% for triazolam and oxazepam, respectively. As patient age increased, the highest strength of each agent was prescribed less frequently. For all drugs, 53% of prescriptions were written for use as necessary (prn), and the proportion who received such prescriptions increased with age. Patient reports, however, revealed that 57% were using a hypnotic every day, and this regular use increased with advancing age. Regular daily use was more common among those who used triazolam and oxazepam (62%) than those who took flurazepam (42%).

[Drug interaction between imipramine hydrochloride and benzodiazepines when administered orally for 15 days]

The effects of daily oral administration of imipramine (IM) hydrochloride (50 mg/kg) and/or oxazepam (OZ, 20 mg/kg) or diazepam (DZ, 5 mg/kg) in a 1% aqueous solution of carboxymethylcellulose sodium salt (CMC) on the activities of drug metabolizing enzyme systems and steady state plasma levels of IM, desmethylimipramine (DIM), DZ, desmethyl-diazepam (DDZ) and OZ were investigated in rats during a 15-day period. In addition, the effect of a single intravenous administration of IM hydrochloride (5 mg/kg), DZ (0.5 mg/kg) and OZ (2 mg/kg) on plasma concentration-time profiles of IM, DIM, DZ, DDZ and OZ was investigated in rats given the same drug treatments by the oral route for 14 days. The group treated with IM hydrochloride plus OZ group showed a great increase in drug-metabolizing enzyme activities, but the difference for the group given IM hydrochloride was not statistically significant. The steady-state plasma levels of DZ after oral administration for 15 days suggested that the group given IM hydrochloride plus DZ did show accumulated DZ. In terms of the area under the concentration-time curve of IM, DZ and OZ after intravenous administration of IM hydrochloride, DZ and OZ, there were significant differences between each of the mono-treatment groups and the IM hydrochloride plus DZ or OZ treatment groups. In conclusion, we have found that the drug interaction for IM hydrochloride by OZ is markedly lower than that by DZ.

Bioavailability and pharmacokinetics of oxazepam

Six healthy volunteers received oxazepam 15 mg i.v. and orally at an interval of at least one week. The kinetic variables of i.v. oxazepam were: elimination half-life (t1/2 beta) 6.7 h, total clearance (CL) 1.07 ml.min-1.kg-1, volume of distribution (Vc) 0.27 l.kg-1 (0.21-0.49) and volume of distribution at steady-state (Vss) 0.59 l.kg-1. The intravenous disposition of unbound oxazepam was characterized by a clearance of 22.5 ml.min-1.kg-1 and a distribution volume of 12.3 l.kg-1. After oral oxazepam the peak plasma level was reached in 1.7 to 2.8 h. The plasma t1/2 beta at 5.8 h was not significantly different from the i.v. value. Absorption was almost complete, with a bioavailability of 92.8%. Urinary recovery was 80.0 and 71.4% of the dose after intravenous and oral administration, respectively. Renal clearance (CLR) of the glucuronide metabolite was 1.10 ml.min-1.kg-1 (0.98-1.52). Oxazepam was extensively bound to plasma protein with a free fraction of 4.5%.

Pentobarbital-like discriminative stimulus properties of halothane, 1,1,1-trichloroethane, isoamyl nitrite, flurothyl and oxazepam in mice

Volatile inhalants represent a diverse group of chemicals which pose a public health problem because of their abuse potential and neurobehavioral toxicity. Although relatively little is known about their pharmacology, they share certain pharmacological properties with classic central nervous system depressants. Drug discrimination procedures were used to compare the effects produced by pentobarbital (PB), oxazepam and several inhalants. Mice were trained to discriminate PB from saline injections in a two-lever operant task. Stimulus generalization was examined after 20-min inhalation exposures to halothane (500-8000 ppm), 1,1,1-trichloroethane (500-12000 ppm), isoamyl nitrite (150-1050 ppm), flurothyl (562-1300 ppm) and injections of oxazepam (0.1-20 mg/kg). Halothane, 1,1,1-trichloroethane and oxazepam produced discriminative stimulus effects similar to those produced by PB. Isoamyl nitrite and flurothyl, while decreasing rates of responding, were not consistently generalized from PB. Differences are apparent in the PB-like discriminative effects of inhalants. Toluene, as shown in a previous study, as well as halothane and 1,1,1-trichloroethane have PB-like discriminative effects which are also shared by oxazepam and may be another common effect of central nervous system depressants. Other chemicals, like isoamyl nitrite and flurothyl, are representative of qualitatively different classes of behaviorally active inhalants.

Kinetics and dynamics of single doses of oxazepam in the elderly: implications of absorption rate

Five healthy elderly volunteers aged 64 to 67 years and 12 healthy young subjects aged 23 to 44 years received single 30 mg oral doses of oxazepam in two different dosage forms (two 15 mg tablets or one 30 mg capsule) on two occasions in a random crossover sequence, with at least 1 week elapsing between trials. In both age groups, rate of oxazepam absorption of the capsule form of the drug was significantly slower than that of the tablets. Peak plasma concentrations were lower and were delayed longer with the capsule form; however, the relative extent of oxazepam absorption did not differ between preparations in either age group. Clinical self-ratings in the elderly group, based on visual analog scales, were consistent with the delayed onset of sedative effects that is associated with the capsule form of administration. Kinetic comparisons in the two groups indicated a significantly prolonged oxazepam elimination half-life with the tablet (p less than .001) and with the capsule (p less than .06) and a trend (p less than .08) toward reduced oxazepam clearance in the elderly. The delayed absorption of oxazepam from the capsule was found in both the young and elderly groups.

Disposition of oxazepam in patients on maintenance hemodialysis

The pharmacokinetics of a single 30-mg oral dose of oxazepam was evaluated in seven patients with chronic renal failure on maintenance hemodialysis and in seven healthy controls matched for age and sex. Based on total (free plus bound) serum oxazepam concentrations, elimination half-life was prolonged in renal patients compared to controls (22 vs 8 h, p less than 0.001) and volume of distribution increased (3.0 vs 1.4 1/kg, p less than 0.02). However, total clearance was similar between groups (1.8 vs 1.9 ml/min per kilogram). These findings were confounded by the increased oxazepam free fraction in serum of renal failure patients (10.3%) as compared to healthy controls (4.3%). Correction for differences in binding indicates similar distribution of unbound oxazepam between groups, but reduced clearance of pharmacologically active unbound oxazepam in renal patients (18 vs 45 ml/min per kilogram). Oxazepam dosage, therefore, may require downward adjustment for renal failure patients on hemodialysis.