Physicochemical aspects of drug release. XV. Investigation of diffusional transport in dissolution of suspended, sparingly soluble drugs

The dissolution rates of sparingly soluble, fine particulate, suspended drugs have been studied using a Coulter Counter Model TAII. For two sieve fractions of oxazepam the dissolution rates were monitored in media with varying viscosities brought about by the addition of glycerol, while for griseofulvin the change in the medium's viscosity was induced by changing the temperature. By calculating the dissolution rate, and compensating for differences in particle surface area and media solubility, it was shown that the dissolution rate was diffusion controlled. After additional normalization for the diffusion coefficient, it was suggested that the so-called apparent diffusional distance decreased substantially with particle size. The effect of particle size was more limited above approx. 15 μm.     

Disposition of oxazepam in patients on maintenance hemodialysis

Summary 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<0.001) and volume of distribution increased (3.0 vs 1.4 1/kg,p<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.Supported in part by grant OC 10/6-3 from the Deutsche Forschungsgemeinschaft, and by grant MH-34223 from the United States Public Health Service     

Detoxifikation polytoxikomaner Patienten mit Buprenorphin Auswirkungen auf Affektivität, Angst und Entzugssymptomaik

We used an open-labeled, 21-day inpatient detoxification treatment to compare the short-term effects of a 10-day buprenorphine plus 19-day carbamazepine regimen (n = 15) to a 14-day oxazepam plus 19-day carbamazepine regimen (n = 12) during rapid detoxification from opioids and other abused drugs. Somatic and psychopathological changes were assessed using the following rating scales: ASI, HAMD, SCL-90-R, and SOWS. Eighteen of 27 patients (67%) completed the study. Four dropouts (27%) were treated with buprenorphine/carbamazepine (BPN/CBZ) and the other five dropouts (42%) were treated with oxazepam/carbamazepine (OXA/CBZ). Repeated measures analysis of variance showed that SOWS scores were significantly less pronounced with BPN-CBZ than with OXA/CBZ. On the first day of admission, no significant difference in HAMD scores was detected (BPN/CBZ 11.6, BPN/CBZ 1.0). On day 14, HAMD was significantly less pronounced in BPN/CBZ (3.0) than in OXA/CBZ (6.1). BPN/CBZ showed a significant improvement in the ASI score on days 7 and 14 compared with OXA/CBZ. Three of nine items of the SCL-90-R showed a trend toward less pronounced outcome in BPN-CBZ. No severe side effects occurred during treatment in either group. The buprenorphine/carbamazepine regimen provided significantly more effective relief from affect disturbances and withdrawal syndromes than the oxazepam/carbamazepine regimen. The pharmacological basis of these effects of buprenorphine (kappa-antagonism activity,mu-agonism activity) are discussed.     

Evidence of strain differences in GABA-benzodiazepine coupling

The effects of a single dose of oxazepam on seizure threshold, receptor occupancy and brain oxazepam concentration were investigated at several time points after drug treatment in two inbred strains of mice (NIH and C3H/HE). The C3H/HE strain showed a greater sensitivity to the effects of both pentylenetetrazol and oxazepam. Furthermore, the C3H/HE strain showed decreases in both receptor occupancy and seizure threshold across time, whereas the NIH strain showed no change in either measure. Although within-strain correlations were observed between seizure threshold and receptor occupancy, the C3H/HE strain had similar seizure thresholds to the NIH strain throughout but lower percentage receptor occupancies, thus a between-strain correlation was not observed. The C3H/HE strain had a higher number of specific benzodiazepine binding sites and these results may reflect a strain difference in GABA-benzodiazepine receptor coupling. In a further experiment, the development of acute tolerance to the effects of oxazepam was investigated. Brain concentrations of oxazepam and receptor occupancies were determined for each strain of mouse, at two different time points (1.5 and 7.5 h after drug treatment), at which equivalent seizure thresholds were obtained by manipulating the starting dose of oxazepam. For each strain, when equivalent seizure thresholds were observed at different time points, equivalent receptor occupancies were also observed. However, a trend towards higher brain concentrations of oxazepam at the later time point was detected for the two strains, suggesting that there may be some decrease across time in the affinity of the receptor for oxazepam.     

奥沙西泮与劳拉西泮治疗老年人广泛性焦虑症有效性和安全性研究

目的探讨奥沙西泮与劳拉西泮治疗老年人广泛性焦虑症的临床效果以及安全性。方法选择本院收治的焦虑综合征老年患者72例,将其随机分为奥沙西泮组和劳拉西泮组,每组36例,劳拉西泮组使用劳拉西泮片治疗,奥沙西泮组使用奥沙西泮治疗,比较两组治疗后的临床效果以及统计两组治疗期间发生的并发症。结果奥沙西泮组患者显效率为83.3%,劳拉西泮组显效率为58.3%,奥沙西泮组患者显效率高于劳拉西泮组（P〈0.05）,两组患者不良反应发生率差异均无统计学意义（P〉0.05）。结论奥沙西泮治疗老年人广泛性焦虑症,临床疗效优于劳拉西泮,更加适合在老年人中应用。     

Impaired acquisition of swimming navigation in adult mice exposed prenatally to oxazepam

Prenatally administered oxazepam (OX) impairs adult radial maze performance in mice, possibly by permanent hippocampal changes. CDI mice were tested in swimming navigation, a sensitive indicator for hippocampal damage. Ten males and ten females were exposed to OX on fetal days 12–16 by maternal administration PO of 30 mg/kg/day and fostered at birth to untreated dams, while control mice received vehicle solution. All mice were tested at 8–9 weeks for ability to find a submerged platform in a fixed location (acquisition: 18 trials, 6 trials per day) and for capacity to re-orient towards a new platform position (reversal: 12 trials, 6 trials per day). OX mice showed a slight but significant impairment of swimming navigation during the initial part of training, as indicated by longer swimming paths during the fourth and fifth trial (day 1), an impairment due both to delayed habituation to the novel stressfull condition and acquisition of platform climbing but unrelated to navigational abilities. No treatment-dependent differences were observed in the reversal phase. During reversal, both OX and control females spent significantly more time in swimming across the location of the old platform. Unrelated to navigational performance, females showed a slightly but significantly higher swimming speed than males. Due to the absence of any navigational impairment, data suggest that prenatal exposure to oxazepam exerts long-term influence on adult learning capacities primarily through interaction with brain systems located outside the hippocampus.     

Influences of benzodiazepines on hypothalamically elicited emotional responses in the rabbit

Tranquilizers of the benzodiazepine group (oxazepam and diazepam) enhanced the rate of self-stimulation elicited from the lateral hypothalamus. Both tranquilizers induced reversal of escape and avoidance behaviors elicited from the medial hypothalamus to a high rate self-stimulation. The reversal effect persisted for two days and the initial negative emotional responses returned later as the drugs were depleted in the organisms. Thus the effect of minor tranquilizers substantially mimics the ventral hippocampus ablation effect which also produced the reversal of the medial hypothalamus responses in earlier experiments.     

Oxazepam induced mouse killing by rats

Oxazepam (2.5-80 mg/kg) induced significant mouse killing among large samples (N = 100/dose) of Holtzman strain albino rats. Meprobamate (2.5-80 mg/kg) and Chlorpromazine (0.5-4 mg/kg) did not induce killing. Despite its lesser tendency to induce aggression in humans, Oxazepam is as potent as Chlordiazepoxide for inducing killing by rats. Induction of mouse killing by rats appears to the predict clinical potency rather than the aggressive side-effects of anxiolytic benzodiazepines.