A new dosage form of oxazepam buccal dispensing. Results of a double-blind premedication test

The Wyeth company has developed a new vehicle for drugs allowing the immediate dissolving of the medication in contact with the saliva. A double-blind test with oxazepam confirms the value of this new vehicle. Moreover, contrarily to our fears, it also confirms that such dispensing had no secondary effects on the alimentary tract.

Self-reports of anxiety level and EEG changes after a single dose of benzodiazepines. Double-blind comparison of two forms of oxazepam

A new formulation of oxazepam especially designed to increase the speed of absorption and eliminate the need to use water (freeze-dried dosage formulation; FDDF) was compared in double-blind and crossover conditions with the standard tablets of the same compound. 5 inpatients with generalized anxiety disorder received at 1-week intervals a single 30 mg dose of one of the compounds. Every 8 min for 96 min after drug intake, they completed a battery of visual analogue scales and had an EEG recording with computerized spectral analysis. Results showed a significantly more rapid onset of activity of FDDF oxazepam for both the self-reports of anxiety level (p less than 0.005) and the specific beta 2 EEG changes (p less than 0.0001), which were significantly correlated (r = -0.73; p less than 0.01). Moreover, all patients rated FDDF oxazepam as having faster onset of action in clinical change than regular tablets (p less than 0.05). This study shows the value of visual analogue scales, pharmaco-EEG, and crossover design in well-selected anxious inpatients in substantiating clinical differences between anxiolytic pharmacotherapies.

Withdrawal after substitution of a short-acting for a long-acting benzodiazepine

A withdrawal syndrome occurred in two patients after substitution of a short-acting benzodiazepine for a long-acting benzodiazepine. Both patients had used long-acting benzodiazepines on a daily basis for many years. In one case, oxazepam was substituted for diazepam, and in the other, temazepam was substituted for flurazepam hydrochloride. In both cases the short-acting benzodiazepine was substituted in a once-daily dosage. Withdrawal symptoms followed and persisted for at least one month. Relative advantages and disadvantages of short-acting and long-acting benzodiazepines are discussed.

Familial paroxysmal dystonic choreoathetosis and response to alternate-day oxazepam therapy

A patient with familial paroxysmal dystonic choreoathetosis (FPDC) who was only transiently improved on daily benzodiazepine therapy showed sustained benefit from a regimen of alternate-day oxazepam therapy. Our findings confirm that FPDC is responsive to benzodiazepine therapy and suggest that an alternate-day dosing schedule, using a short-acting benzodiazepine, may minimize receptor down regulation and thereby sustain the therapeutic effect.

Long v short half-life benzodiazepines in the elderly. Kinetics and clinical effects of diazepam and oxazepam

Oxazepam and diazepam were compared in healthy elderly volunteers. Absorption of diazepam was faster than oxazepam and onset of clinical effects were more profound. Diazepam accumulation was extensive, washout was slow and active compounds were present two weeks after the last dose. Oxazepam accumulation was significantly less and elimination significantly faster than diazepam. There was no difference between oxazepam and diazepam in sedation or fatigue during the drug treatment, but sedative effects persisted for two weeks after diazepam therapy was discontinued. Sedation rapidly returned to baseline in the oxazepam group. Thus, the differing pharmacokinetic profiles of diazepam and oxazepam have clinical consequences during multiple dosage in the elderly.

[Comparative test of the bioavailability and pharmacokinetics of 2 oxazepam preparations using high-pressure liquid chromatography]

The relative bioavailability and pharmacokinetic profile of two oxazepam preparations were evaluated in 12 normal volunteers by a newly developed HPLC-method. After oral application of one tablet of the test (Noctazepam) and reference preparation, respectively, no statistically significant differences of the AUC, Cmax Tmax and t1/2 were found. As compared to the reference preparation the relative bioavailability of the test preparation as 110%; both preparations are therefore bioequivalent.

Renal disease, age, and oxazepam kinetics

Effects of renal insufficiency and age on oxazepam kinetics were assessed in 13 normal subjects (21 to 72 yr old), four patients with renal insufficiency, and eight patients on hemodialysis. Normal intact oxazepam results were: mean elimination half-life (t1/2), 10 hr; area under the curve (AUC), 6.0 microgram.hr/ml; unbound oxazepam fraction (fup), 3.2%; maximum concentration of unbound oxazepam (Cmax,u), 16 ng/ml; and intrinsic (unbound drug) clearance (Clint), 2.9 l/hr/kg. Less than 1% of the dose was excreted intact in urine. Age differences had no influence on results. In renal insufficiency patients, t1/2 was prolonged to 25 hr, fup increased to 7%, and Cmax,u and Clint were unchanged. Volume of distribution of unbound oxazepam (Vu) increased, thereby prolonging t1/2. In dialysis patients, t1/2 was prolonged to 33 hr, fup increased to 6.2%, and Cmax,u and Clint again were unchanged. Oxazepam was undialyzable; since unbound oxazepam disposition kinetics are not altered, no dosage adjustment for patients is necessary.

A comparative study on the clinical effects of flunitrazepam and oxazepam as oral premedication

The clinical effects of flunitrazepam and oxazepam as oral premedicants were tested in a double-blind study of 69 otorhinolaryngologic patients. Flunitrazepam had a somewhat higher sedative effect (p less than 0.10) and moderated the increase in systolic blood pressure significantly (p less than 0.005) more than did oxazepam, but as regards the other parameters tested no significant differences were found (sleep, apprehension, excitement, dizziness, emetic effect, headache, increase in heart rate, venepuncture). In some patients a profuse salivary secretion was observed despite intravenous injection of atropine just before the induction of anesthesia. Our results support earlier claims of flunitrazepam's relatively strong sedative and anxiolytic properties, but on the whole the difference in clinical effects of these benzodiazepine derivatives was not marked.

Oxazepam esters. 3. Intrinsic activity, selectivity, and prodrug effect

Antimetrazol and muscle-relaxant activities of 11 aliphatic esters of oxazepam were studied as a function of time in mice. The esters given intravenously retained antimetrazol activity, while muscle-relaxant activity was generally decreased. The administration of a dose equivalent to the antimetrazol ED50 resulted in constant oxazepam brain levels for most esters; therefore, the intrinsic anticonvulsant activity of the intact ester is insignificant. The dimethylphenylpropionyl ester appeared to antagonize the effect of oxazepam, since it elevated the free oxazepam level required to achieve the ED50 in the antimetrazol assay. The administration of doses equivalent to the muscle-relaxant ED50 values resulted in no correlation with total brain benzodiazepine levels, suggesting that changes in the selectivity of action are the consequence of different sites of action.

Clinical pharmacokinetics of oxazepam and lorazepam

Oxazepam and lorazepam are 3-hydroxy benzodiazepine derivatives used as sedatives and anxiolytics. The major metabolic pathway for both compounds involves conjugation to glucuronic acid at the 3-position, followed by urinary excretion of the inactive glucuronide metabolite. Oxazepam has been administered to humans by the oral route only. Usual ranges for kinetic parameters are: elimination half-life, 5 to 15 hours; volume of distribution, 0.6 to 2.0 L/kg; clearance, 0.9 to 2.0 ml/min/kg. Age and liver disease have a minimal influence on oxazepam kinetics, but renal disease is associated with a prolonged half-life and increased volume of distribution. Typical kinetic values for lorazepam are: elimination half-life, 8 to 25 hours; volume of distribution, 1.0 to 1.3 L/kg; clearance, 0.7 to 1.2 ml/min/kg. Lorazepam clearance is somewhat reduced in old age, but liver disease has a minimal effect on clearance. Oral and intramuscular lorazepam are rapidly absorbed, with systemic availability averaging 90% or more. Both oxazepam and lorazepam are extensively bound to plasma protein, but the free fraction for lorazepam (8 to 12%) is greater than that for oxazepam (2 to 4%).

Improving benzodiazepine prescribing in family practice through review and education

Indications for and dosages of four commonly prescribed benzodiazepines were recorded at a family medicine centre with the aid of a computerized data collection system. Four guidelines were then developed for appropriate prescribing of these drugs: (a) benzodiazepines should be used less frequently with increasing age; (b) short-acting drugs are preferable to long-acting drugs; (c) patients 65 years of age and over should receive half the daily dose prescribed for younger patients; and (d) use of these drugs for more than 1 month should be discouraged. After a year's observation it was evident that none of the guidelines were being followed. The 30 physicians in the practice were then informed of the findings by an educational program. Another 6 months of observation showed a reduction in the prescribing of benzodiazepines to patients 65 years of age and over, a significant shift to the use of short-acting benzodiazepines, and some reduction in the daily dose and duration of administration of diazepam. Thus, such a review of drug prescribing in family practice can be a practical and effective method of improving prescribing patterns.

The effect of melperon on ocular readaptation time, as assessed by a new recording technique

A new simplified technique recording readaptation time after photo stress, RAT, is described. The psychometric properties in terms of internal consistency and retest reliability were tested, and the effect on RAT after intake of melperon at two different dose levels was investigated and correlated to blood plasma levels. The results show that there was a satisfactory consistency of RAT at each occasion but stability over a 1 month period could not be demonstrated. Significantly dose-dependent changes were recorded after intake of melperon but the prolongation of RAT was not significantly correlated to blood plasma levels.

Metabolism of rat brain phospholipids after prolonged treatment with psychotropic drugs

Adult and newborn rats were treated with psychotropic drugs: neuroleptics (fluphenazine, benperidol, pimozide, thiotixen), an ataractic (oxazepam) and an anti-depressant (protriptyline) for periods up to one year or longer. The body weight was monitored, and brain weight, total cerebral lipid content, content of individual phospholipids, incorporation of 32P into individual phospholipids, and the fatty acids composition of phosphatidylethanolamine were measured. The prolonged treatment with neuroleptics and an antidepressant, but not with oxazepam, produced profound, often biphasic or multiphasic changes in the biochemistry of phospholipids. These changes should be taken into account in discussion of the mechanism of action and side-effects of prolonged treatment with antidepressants and neuroleptics.

Massive benzodiazepine requirements during acute alcohol withdrawal

Severe alcohol withdrawal developed in an abstinent chronic alcoholic man. Massive doses of benzodiazepines (2,335 mg of diazepam intravenously, 21,225 mg of oxazepam orally) achieved only marginal control of delirium and agitation. Analysis of multiple blood samples drawn during and after the withdrawal episode indicated, as expected, very high concentrations of diazepam and metabolites and of oxazepam. There was no evidence of an abnormal pharmacokinetic profile. Benzodiazepine resistance in withdrawing alcoholics probably reflects a receptor-site phenomenon rather than an abnormal drug disposition.

Oral oxazepam as a premedicant in minor surgery

The clinical effects of oral oxazepam and placebo as premedicants were tested in a double-blind study in 40 gynaecological patients. The gas chromatographically measured concentrations of the active, unconjugated forms of oxazepam in the plasma were correlated with the clinical effects of oxazepam, assessed both subjectively and objectively. The insertion of an intravenous cannula was significantly more difficult (p less than 0.001) in the placebo premedicated group. However, there was no significant difference between the two groups in the cutaneous temperature of the left forefinger. Of the eleven parameters tested there was a significant difference between the oxazepam and placebo group in the quality of sleep on the night before operation (p less than 0.05) and in the degree of preoperative sedation (p less than 0.01). The combined results of the eleven parameters of the oxazepam group also differed positively significantly from the placebo group (p less than 0.01). There was no obvious relationship between the plasma concentration and clinical effect of oxazepam.

Subjective effects and vigilance after diazepam and oxazepam in normal subjects

Twenty-two normal subjects were given single oral doses of diazepam 5 mg, oxazepam 15 mg and placebo in a double-blind cross-over trial. Subjective effects according to a rating scale and performance on a vigilance task were assessed. The results showed a difference between each of the two drugs and placebo, but none between the drugs, with regard to the vigilance test. The results from the rating of subjective effects showed an increase in "tiredness" for both drugs, and a decreased "well-being" for oxazepam.

The abuse potential of benzodiazepines with special reference to oxazepam

Extensive use of oxazepam, particularly in the abuse-prone population of alcoholic patients, has shown that the dependence-producing potential of this drug is remarkably low, only four cases of dependence having been encountered over many years. Even abrupt withdrawal of oxazepam does not normally precipitate an abstinence syndrome. A computerized literature search retrieved 68 papers on benzodiazepine abuse and/or dependence, only 4 (6%) being concerned with oxazepam. Three reasons are proposed to account for the exceptionally low abuse-potential of oxazepam, the first being considered to be the most important: its onset of central nervous system activity is gradual, so there is no sudden 'intoxication' effect; it tends to cause dizziness at high dosages, discouraging the patient to increase the dose; and because it has a short half-life and no major active metabolites, intermittent therapy (which many patients now practise with all benzodiazepines), periodically allows the complete elimination of the drug from the body.

Pharmacokinetics of oxazepam given during labour

The transfer across the placenta and the maternal and neonatal kinetics of oxazepam and its conjugate was studied in 12 patients and their newborns. Oxazepam was readily absorbed and peak plasma concentrations were similar to those in healthy non-pregnant volunteers. When meperidine was given within one hour of the dose of oxazepam the absorption was delayed but the bioavailability did not decrease. In the newborns the umbilical vein plasma concentration of oxazepam usually exceeded that of the conjugate. The reverse was true for all subsequent plasma samples from the newborn. The half-life of oxazepam in the newborn averaged 22 hours as compared to 6.5 hours in the mothers. A significant rise of the plasma concentration of oxazepam conjugate was noted in three newborns during the first 6-10 hours of extrauterine life. This shows that the newborn is able to conjugate oxazepam. The Apgar score values were normal.

The clinical activity of oxazepam

Over the years, oxazepam has distinguished itself clinically from other benzodiazepines by virtue of its excellent tolerance. Recent research suggests that this is due to metabolic and pharmacokinetic differences rather than an intrinsically more favourable toxic-to-therapeutic dosage ratio. Because of its excellent tolerance, dosage is very flexible, and it is, therefore, possible to utilize oxazepam in a wide spectrum of anxiety-related disorders including the psychoses. The use of oxazepam in anxiety neurosis, depressive neurosis, psychotic disorders, alcoholism, and insomnia is discussed.

The pharmacokinetic profile of oxazepam

Oxazepam has the shortest half life of the benzodiazepines and does not form any active metabolites. Its pharmacokinetic properties in healthy volunteers, uremic patients and dogs are reviewed. In normal man half lives between 6 and 25 hours are obtained. The drug is completely absorbed and steady state concentrations develop after multiple doses. In uremic patients the terminal half life of oxazepam in plasma was prolonged to 24-91 hours. However the clearance of oxazepam was not significantly decreased in this patient group and similar doses as in normal subjects are recommended. There was a marked retention of the water soluble oxazepam conjugate in the uremic patients but no pharmacological effect could be detected. In the uremic patients, as in dogs, secondary plasma concentration peaks were seen after single doses. In uremic patients, fecal excretion of oxazepam was increased. In the dog one third of a single intravenous dose was recovered in the bile. Thus enterohepatic cycling may occur in the dog and in uremic patients.

The clinical pharmacology of oxazepam

The benzodiazepines have been available now for about 15 years but new aspects of their actions are being elucidated all the time. Oxazepam has a short half-life and inactive metabolites and therefore differs from most other benzodiazepines. Some aspects of its clinical pharmacology are reviewed in outline. Firstly, the effects of the drug on psychological functioning is discussed. Next, the controversy regarding benzodiazepines and aggression is examined. Oxazepam appears exceptional here in that it is not associated with paradoxical release of aggression in patients. Finally, the ethical implications of the widespread use of these drugs is commented on, and the problem of dependence, physical and psychological, discussed. It appears that oxazepam is less likely than other benzodiazepines to induce dependence.

High-dose benzodiazepines in the treatment of severe neurotic anxiety

There has been a paucity of research in the use of high-dose benzodiazepines in the treatment of severe neurotic anxiety. The author presents five cases, three with excellent and two with poor outcomes. The English and Fench language literature is reviewed and reveals evidence that high-dose benzodiazepines may be useful in the treatment of certain neurotic patients. However, the lack of controlled studies is noted. The author poses several questions important to the future of research on benzodiazepines.