High correlation between serum and cerebrospinal fluid olanzapine concentrations in patients with schizophrenia or schizoaffective disorder medicating with oral olanzapine as the only antipsychotic drug.

The primary aim of the present study was to investigate the relationship between steady state serum and cerebrospinal fluid (CSF) concentrations of olanzapine (OLA) and its metabolite 4'-N-desmethylolanzapine (DMO) in patients with schizophrenia or schizoaffective disorder treated with oral OLA as the only antipsychotic drug. The influence of smoking, gender, age, as well as polymorphisms in cytochrome P450 CYP2D6, CYP1A2, and ABCB1 genes on the serum and CSF drug levels was also analyzed. Thirty-seven white outpatients (10 smokers and 27 nonsmokers) were included. From 29 of them, CSF was collected successfully. A strong correlation (Spearman rank correlation [rs] = 0.93; P < 0.05) was found between serum and CSF concentrations of OLA and a somewhat weaker correlation (rs = 0.5; P < 0.05) between those of DMO. The CSF concentrations of OLA and DMO were on average 12% and 16% of those in serum. Extensive metabolizers of CYP2D6 had higher (P < 0.05) daily doses than poor metabolizers when the influence of smoking was taken into account. Smokers had lower (P < 0.01) concentration-to-dose ratios of OLA in serum (mean, 2.23 ng/mL per mg vs 3.32 ng/mL per mg) and CSF (0.27 ng/mL per mg vs 0.41 ng/mL per mg) than nonsmokers. The concentration-to-dose ratio for serum DMO decreased with increasing age (rs = -0.41; P < 0.05). Carriers of ABCB1 1236T/2677T/3435T haplotype had higher serum (mean, 37.7 ng/mL vs 22.5 ng/mL; P = 0.035) and CSF (4.7 ng/mL vs 2.6 ng/mL; P = 0.018) OLA concentrations than patients without this haplotype. The present study shows a strong correlation between serum and CSF concentrations of OLA, indicating that concentrations of OLA in serum reflect those in CSF.

Liquid chromatography/tandem mass spectrometry method for determination of olanzapine and N-desmethylolanzapine in human serum and cerebrospinal fluid.

A validated, accurate and sensitive LC-MS/MS method for determination of olanzapine and its metabolite N-desmethylolanzapine has been developed. The analytes were quantified by tandem mass spectrometry operating in positive electrospray ionization mode with multiple reaction monitoring. Olanzapine and desmethylolanzapine were extracted from serum or cerebral spinal fluid samples, 200 microl, with tert-butyl methyl ether using olanzapine-D3 as internal standard. Calibrations for olanzapine and desmethylolanzapine were linear within the selected range of 0.2-30 ng/ml (6-96 nM) in cerebral spinal fluid and for olanzapine in plasma, in the range of 5-100 ng/ml (16-320 nM). The method was successfully used for the analysis of samples from patients treated with olanzapine in the dose range of 2.5-25mg/day.

Comparison of drug concentrations in postmortem cerebrospinal fluid and blood specimens.

The concentration of drugs and metabolites in cerebrospinal fluid (CSF) and blood were determined in 282 autopsied cases using liquid-liquid extraction techniques and gas chromatographic analyses. All drugs were confirmed in one matrix by gas chromatography-mass spectrometry. CSF/blood ratios were used to compare the two biological fluids. Classes of drugs evaluated in this study included: benzodiazepines, anticonvulsants, sedatives, opioids, antidepressants, anesthetics, and antihistamines. The majority of the drugs tested were readily detected in CSF specimens. The average CSF/blood ratio for most drugs was in the range of 0.05-0.50. Interpretation of these results is difficult because protein binding, half-life, hydrophobic properties, and pKa of a drug, in addition to survival time after drug use, influence the CSF/blood ratio. While CSF specimens do provide a viable alternative testing matrix when blood specimens are not available, they should not be used to estimate blood drug concentrations.

CR 2945: a novel CCKB receptor antagonist with anxiolytic-like activity.

The effects of CR 2945, an antranilic acid derivative member of a novel family of non-peptide CCKB receptor antagonists, have been compared with those of CAM-1028, an analogue of the CCKB receptor antagonist CI-988, L-365,260 a benzodiazepine derivative CCKB antagonist, CR 1795, an analogue of the CCKA receptor antagonist lorglumide and diazepam, a benzodiazepine receptor agonist, in several rodent screens sensitive to conventional anxiolytics. CR 2945 displayed nanomolar affinity for rat CCKB receptors and showed a selectivity ratio of about 9000 for the CCKB over the CCKA receptor. In ex-vivo binding studies, CR 2945, after i.v. and s.c. administration, inhibited the binding of [125I] (BH)-CCK8 in rat cortex homogenate with ID50s of 10.9 mg/kg and 13.5 mg/kg, respectively. In four rodent tests of anxiety (mouse black/white box, rat elevated plus-maze, rat elevated zero-maze and punished licking test in the rat) CR 2945 (0.1-10 mg/kg s.c. or orally) showed significant dose-dependent anxiolytic-like effects. The reference CCKB antagonist compounds CAM-1028 and L-365,260 showed an anxiolytic-like activity less robust than that of CR 2945 in the elevated zero-maze after s.c. administration, and these compounds were inactive in the elevated plus-maze after oral administration. The magnitude of the activity of CR 2945 was comparable to that of diazepam, but without signs of sedation and ataxia. Furthermore, a 7-day repeated treatment with CR 2945 at 10 mg/kg/day s.c. did not induce tolerance or withdrawal anxiety in rats. CR 1795 showed anxiolytic-like activity with a bell-shaped dose-response curve in the elevated zero-maze model in rats (0.1-10 mg/kg, orally and s.c.), whereas in the mouse black/white box test and in the rat elevated plus-maze test it was less effective. The results suggest that CR 2945 might be a promising alternative to the existing therapy of anxiety-related disorders.

Plasma and CSF benzodiazepine receptor ligand concentrations in cirrhotic patients with hepatic encephalopathy: relationship to severity of encephalopathy and to pharmaceutical benzodiazepine intake.

Increased plasma and CSF concentrations of substances which bind to brain benzodiazepine receptors have previously been reported in cirrhotic patients with hepatic encephalopathy (HE). However, their relationship to previous intake of pharmaceutical benzodiazepines has not been clearly established. In the present study, plasma levels of benzodiazepine receptor ligands (BZRLs) were measured using a sensitive radioreceptor assay in 12 control subjects with no evidence of hepatic, neurological or psychiatric illness, 11 cirrhotic patients without HE, 24 cirrhotic patients with moderate (grade I-II) HE and in 45 cirrhotic patients with severe (grade II-IV) HE. In addition, CSF concentrations of BZRLs were measured in 8 cirrhotic patients with HE and an equal number of age-matched controls. Recent intake (within 10 days) of pharmaceutical benzodiazepines was assessed by detailed review of medical files, and interviews with the patient, at least one family member as well as the pharmacist. Significantly increased plasma concentrations of BZRLs were observed in cirrhotic patients with severe encephalopathy (p < 0.02) compared to controls and to cirrhotic patients without (or with mild) neurological impairment. Increased plasma BZRLs could be accounted for by prior exposure to benzodiazepine medication in all cases. CSF concentrations of BZRLs in cirrhotic patients were not significantly different from control values. These findings do not support a role for "endogenous" benzodiazepines in the pathogenesis of HE in chronic liver disease but suggest that pharmaceutic benzodiazepines administered to cirrhotic patients as sedatives or as part of endoscopic work-up could have contributed to the neurological impairment in some patients.

Idiopathic recurring stupor: a case with possible involvement of the gamma-aminobutyric acid (GABA)ergic system.

A patient had recurrent spontaneous episodes of stupor or coma in the absence of toxic, metabolic, or structural brain damage. Ictal electroencephalography showed fast 14 Hz background activity; sleep studies excluded narcolepsy. Flumazenil (Anexate), a benzodiazepine antagonist, promptly resolved the episodes and normalized the electroencephalogram. Radioreceptor binding studies showed the presence of a ligand to the central benzodiazepine receptor in plasma and cerebrospinal fluid during the episodes, suggesting a gamma-aminobutyric acid (GABA)ergic system involvement in the origin of the attacks.

Relationships between CSF drug concentrations, receptor binding characteristics, and pharmacokinetic and pharmacodynamic properties of selected 1,4-substituted benzodiazepines.

Pharmacokinetic profiles of the 1,4-substituted benzodiazepines are defined by their absorption, distribution, metabolism, and excretion characteristics. An ability to cross the blood-brain barrier and the onset of pharmacological activity have been associated with the physiochemical properties of the benzodiazepines. In addition, drug concentrations in the CSF correlate with the unbound drug concentrations in blood or plasma. Duration of pharmacological activity of the benzodiazepines in humans is associated with the affinity of these compounds for the benzodiazepine receptors in human brain. Therefore, benzodiazepines with high affinity for the benzodiazepine receptor sites in human brain tend to exhibit prolonged half-lives of elimination from the CSF which correlate with the prolonged duration of clinical and pharmacological effects and lower therapeutic doses of these drugs in vivo.

Radioreceptor assay of benzodiazepines in cerebrospinal fluid during chronic flurazepam treatment in cats.

A radioreceptor assay was used to measure benzodiazepine-like activity in cerebrospinal fluid (CSF) of cats during chronic flurazepam treatment. Benzodiazepine-like activity was measured by the displacement of [3H]flunitrazepam from benzodiazepine receptors in homogenates of rat cerebral cortex. Cats were given 5 mg/kg flurazepam daily, and tolerance was measured by rating several indicators of neurological impairment. CSF was sampled 1 h after flurazepam administration, when drug actions were greatest. Ataxia and muscle relaxation were greatest on the first treatment day, then decreased despite increasing CSF benzodiazepine-like activity. By day 11, CSF activity was 3 times that measured 1 h after the first chronic dose. CSF benzodiazepine-like activity declined slowly after treatment and approached zero by the 10th day after treatment. This residual activity, probably due to active flurazepam metabolites, correlates with the observation that physical dependence is present in these cats up to 7 days after the end of chronic treatment. The rapid loss of drug effect despite increasing active drug levels shows that the nervous system is capable of a rapid and profound adaptation to the presence of benzodiazepines.

Endogenous benzodiazepine ligands in human cerebrospinal fluid.

Human cerebrospinal fluid was chromatographed on Bio-Gel P-4. Fractions containing material with molecular weights less than 4000 Dalton were pooled and further fractionated by high pressure liquid chromatography on an UltroPack TSK column G 2000 SW. At least three peaks, which were free of salt and GABA, were shown to displace (3H)-diazepam in the receptor-binding assay. Two of these peaks inhibited diazepam-binding competitively as shown by Lineweaver-Burke and displacement analysis. Their activity could be enhanced by the addition of GABA to the assay mixture. Incubation of these two peaks with various enzymes indicated that at least part of the activity of the second peak is due to a peptide.