Effects of olanzapine and ziprasidone on glucose tolerance in healthy volunteers.

Atypical antipsychotics have been linked to a higher risk for glucose intolerance, and consequentially the development of type 2 diabetes mellitus (DM2). We have therefore set out to investigate the acute effects of oral administration of olanzapine and ziprasidone on whole body insulin sensitivity in healthy subjects. Using the standardized hyperinsulinemic euglycemic clamp technique we compared whole body insulin sensitivity of 29 healthy male volunteers after oral intake of either olanzapine 10 mg/day (n = 14) or ziprasidone 80 mg/day (n = 15) for 10 days. A significant decrease (p<0.001) in whole body insulin sensitivity from 5.7 ml/h/kg ( = mean, SM = 0.4 ml/h/kg) at baseline to 4.7 ml/h/kg ( = mean, SM = 0.3 ml/h/kg) after oral intake of olanzapine (10 mg/day) for 10 days was observed. The ziprasidone (80 mg/day) group did not show any significant difference (5.2+/-0.3 ml/h/kg baseline vs 5.1+/-0.3 ml/h/kg) after 10 days of oral intake. Our main finding demonstrates that oral administration of olanzapine but not ziprasidone leads to a decrease in whole body insulin sensitivity in response to a hyperinsulinemic euglycemic challenge. Our finding is suggestive that not all atypical antipsychotics cause acute direct effects on glucose disposal and that accurate determination of side effect profile should be performed when choosing an atypical antipsychotic.

Reduced serotonin-1A receptor binding in social anxiety disorder.

BACKGROUND: Results from studies in serotonin-1A (5-HT1A) knockout mice and previous positron emission tomography (PET) studies in humans imply a role for 5-HT1A receptors in normal state anxiety as well as in certain anxiety disorders. The objective of this study was to investigate 5-HT1A receptor binding potential (BP) in social anxiety disorder (SAD). METHODS: Using PET and [carbonyl-11C]WAY-100635, we compared a homogeneous group of 12 unmedicated, male SAD patients with 18 healthy control subjects (HC). A multivariate ANOVA with all regional BP values as dependent variables, age and four radiochemical variables as covariates was performed. RESULTS: We found a significantly lower 5-HT1A BP in several limbic and paralimbic areas but not in the hippocampus (p = .234) of SAD patients. The difference in 5-HT1A binding was most significant in the amygdala (-21.4%; p = .003). There was also a more than 20% lower 5-HT(1A) BP of SAD patients in the anterior cingulate cortex (p = .004), insula (p = .003), and dorsal raphe nuclei (p = .030). CONCLUSIONS: The lower 5-HT1A binding in the amygdala and mesiofrontal areas of SAD patients is consistent with 1) preclinical findings of elevated anxiety in 5-HT1A knockout mice, 2) a previous PET study in healthy volunteers showing an inverse correlation between 5-HT1A BP and state anxiety, and 3) another human PET study in patients with panic disorder showing reduced 5-HT1A binding, thus corroborating the potential validity of 5-HT1A receptors as targets in the treatment of human anxiety disorders.

Higher serotonin transporter occupancy after multiple dose administration of escitalopram compared to citalopram: an [123I]ADAM SPECT study.

OBJECTIVES: Previous studies have investigated the occupancy of the serotonin reuptake transporter (SERT) after clinical doses of citalopram and other selective serotonin reuptake inhibitors. In the present study, the occupancies of SERT after multiple doses of escitalopram and citalopram were compared using the radioligand [(123)I]ADAM and single photon emission computed tomography (SPECT). METHODS: Fifteen healthy subjects received escitalopram 10 mg/day (n = 6) or citalopram 20 mg/day (n = 9) for a total of 10 days. SERT occupancies in midbrain were determined with SPECT and [(123)I]ADAM at three different time points: at baseline (no medication) and at 6 and 54 h after last drug intake. RESULTS: At 6 h after the last dose, mean SERT occupancies were 81.5 +/- 5.4% (mean+/-SD) for escitalopram and 64.0 +/- 12.7% for citalopram (p < 0.01). At 54 h after the last dose, mean SERT occupancies were 63.3 +/- 12.1% for escitalopram and 49.0 +/- 11.7% for citalopram (p < 0.05). The plasma concentrations of the S-enantiomer were of the same magnitude in both substances. For both drugs, the elimination rate of the S-enantiomer in plasma was markedly higher than the occupancy decline rate in the midbrain. CONCLUSION: The significantly higher occupancy of SERT after multiple doses of escitalopram compared to citalopram indicates an increased inhibition of SERT by escitalopram. The results can also be explained by an attenuating effect of R-citalopram on the occupancy of S-citalopram at the SERT.

Striatal D(2) receptor occupancy in bipolar patients treated with olanzapine.

We explored the relationship between striatal dopamine-2 (D(2)) receptor occupancy and extra-pyramidal symptoms (EPS) in bipolar patients receiving olanzapine. Seventeen patients with a DSM-IV diagnosis of bipolar disorder were treated with 5-45 mg/day olanzapine for at least 14 days. After that period, D(2) receptor occupancy was determined using Iodobenzamide (IBZM) and SPECT. EPS were assessed by the Simpson-Angus Scale (SAS) and Barnes-Akathisia Scale (BAS). We found a dose-dependent increase in occupancy: 5 mg led to 28-50%, 10 mg to 40-68%, 15 mg to 69%, 20 mg to 57-66%, 30 mg to 66% and 45 mg to 80% D(2) receptor occupancy; and a significant correlation between plasma levels and occupancy (R(2)=.55, P=.001). Similar to schizophrenic patients, bipolar patients did not exhibit EPS at D(2) occupancy levels of 28 to 80%. Although we did not find an increased vulnerability for acute EPS in bipolar patients receiving olanzapine at clinical relevant doses, this needs to be replicated with larger sample sizes.

Therapy of treatment resistant depression: focus on the management of TRD with atypical antipsychotics.

Treatment-resistant depression (TRD) represents a significant challenge for physicians. About one third of patients with major depressive disorder fail to experience sufficient symptom improvement despite adequate treatment. Despite this high occurrence of TRD there was no general consensus on diagnosis criteria for TRD until 1997 when researchers proposed a model of defining and staging TRD. In 1999, others defined operational criteria for the definition of TRD. Treatment of TRD is commonly separated into pharmacologic and nonpharmacologic methods. This review gives a short overview of these two methods. The nonpharmacologic methods include psychotherapy, electroconvulsive therapy, and vagus nerve stimulation. Pharmacologic methods include switching to another antidepressant monotherapy, and augmentation or combination with two or more antidepressants or other agents. This review especially focuses on the augmentation of the antidepressant therapy with atypical antipsychotics.

Lipid-induced insulin resistance is not mediated by impaired transcapillary transport of insulin and glucose in humans.

Increased lipid availability reduces insulin-stimulated glucose disposal in skeletal muscle, which is generally explained by fatty acid-mediated inhibition of insulin signaling. It remains unclear whether lipids also impair transcapillary transport of insulin and glucose, which could become rate controlling for glucose disposal. We hypothesized that lipid-induced insulin resistance is induced by inhibiting myocellular glucose uptake and not by interfering with the delivery of insulin or glucose. We measured changes in interstitial glucose and insulin in skeletal muscle of healthy volunteers during intravenous administration of triglycerides plus heparin or glycerol during physiologic and supraphysiologic hyperinsulinemia, by combining microdialysis with oral glucose tolerance tests and euglycemic-hyperinsulinemic clamps. Lipid infusion reduced insulin-stimulated glucose disposal by ~70% (P < 0.05) during clamps and dynamic insulin sensitivity by ~12% (P < 0.05) during oral glucose loading. Dialysate insulin and glucose levels were unchanged or even transiently higher (P < 0.05) during lipid than during glycerol infusion, whereas regional blood flow remained unchanged. These results demonstrate that short-term elevation of free fatty acids (FFAs) induces insulin resistance, which in skeletal muscle occurs primarily at the cellular level, without impairment of local perfusion or transcapillary transport of insulin and glucose. Thus, vascular effects of FFAs are not rate controlling for muscle insulin-stimulated glucose disposal.

Differences in the dynamics of serotonin reuptake transporter occupancy may explain superior clinical efficacy of escitalopram versus citalopram.

Escitalopram the S-enantiomer of the racemate citalopram, is clinically more effective than citalopram in the treatment of major depressive disorder. However, the precise mechanism by which escitalopram achieves superiority over citalopram is yet to be determined. It has been hypothesized that the therapeutically inactive R-enantiomer competes with the serotonin-enhancing S-enantiomer at a low-affinity allosteric site on serotonin reuptake transporters (SERTs), and reduces the effectiveness of the S-enantiomer at the primary, high-affinity serotonin-binding site. This study summarizes the results of two recent single-photon emission computerized tomography studies measuring SERT occupancy in citalopram-treated and escitalopram-treated healthy volunteers, after a single dose and multiple doses (i.e. under steady-state conditions). The single-dose study showed no attenuating effect of R-citalopram. After multiple dosing, however, SERT occupancy was significantly reduced in the presence of R-citalopram. Under steady-state conditions, R-enantiomer concentrations were greater than for the S-enantiomer because of slower clearance of R-citalopram. A pooled analysis suggests that build-up of the R-enantiomer after repeated citalopram dosing may lead to increased inhibition of S-enantiomer occupancy of SERT. This review adds to the growing body of evidence regarding differences in the dynamics of SERT occupancy, that is, molecular mechanisms underlying the often-observed superior clinical efficacy of escitalopram compared with citalopram in major depressive disorder.

Binding kinetics of 123I[ADAM] in healthy controls: a selective SERT radioligand.

[123I]ADAM (2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine) is a promising radioligand for in-vivo quantification of serotonin transporters (SERT) using single photon emission computed tomography (SPECT) in man. We performed tracer kinetic analysis in various brain regions to determine the optimum equilibrium time for SERT quantification with [123I]ADAM and SPECT. Radiosyntheses of [123I]ADAM were performed at MAP Medical Technologies Oy, Tikkakoski, Finland. Thirty healthy male volunteers (21-41 yr) received between 104 and 163 MBq [123I]ADAM intravenously as a bolus. Consecutively, multiple SPECT scans were performed between 14 and 420 min post-injection (p.i.) using a Siemens Multispect 3 camera. Reconstruction was performed applying filtered back projection with a Butterworth filter (cut-off 0.7, order 7) in 128x128 matrices. Regions of interest (ROI) were drawn manually on the individual T1-weighted magnetic resonance image (MRI) comprising midbrain/hypothalamus for specific binding to SERT, and the cerebellum as reference region. After re-orientation to the MRI, the ROI template was applied to SPECT studies. We generated time-activity curves for the ROI and calculated the ratio countstarget/countscerebellum minus 1 (=V3'') as a measure for specific SERT binding. Counts were corrected for applied activity, acquisition time and body-weight. Peak uptakes were observed between 14 and 50 min after bolus injection. Counts per voxel were highest in the midbrain/hypothalamus, 798 (max. 872, min. 728), whereas 462 counts per voxel (max. 599, min. 412) were measured in the cerebellum at a mean time of 31 min p.i. Stable values for V3'' reached 205-320 min p.i. Mean peak V3'' value was 1.43 (95% CI 171-230) for the midbrain/hypothalamus at 205 min p.i. [123I]ADAM is a useful ligand for in-vivo quantification of human SERT by means of SPECT, with a comparatively better signal-to-noise ratio compared to beta-CIT. Our data suggest that the acquisition time for the SPECT scan is optimally, under pseudo-equilibrium conditions, between 205-320 min post-bolus injection of the tracer.

Gender differences in the psychopathology of depressed inpatients.

In the last few years there has been increased scientific effort to describe the gender-specific psychopathological features of depression. Until now these studies have not been entirely conclusive, which could be the result of methodological difficulties. This report investigates sex differences in the symptom presentation in an inpatient population: 104 female and 113 male patients suffering from a depressive episode according to ICD-10 were admitted to the inpatient treatment at the Department of General Psychiatry in Vienna. A psychopathological rating according to the standardized documentation system of the AMDP (Association for Methodology and Documentation in Psychiatry) was performed at admission and discharge. At admission into the hospital women tended to show more affective lability (p = 0.025), whereas men had higher scores in affective rigidity (p = 0.032), blunted affect (p = 0.002), decreased libido (p = 0.028), hypochondriasis (p = 0.016) and hypochondriac delusions (p = 0.039). At discharge from the hospital women had significantly higher scores in dysphoria (p = 0.010), while men were more prone to have compulsive impulses (p = 0.030). Although our results were obtained in a selected sample of inpatients at a university hospital, they are indicative of psychopathological differences between men and women in the core symptoms of depression. These differences may influence diagnostic practice and gender specific treatment of depression.

Target site penetration of fosfomycin in critically ill patients.

OBJECTIVE: The present study was undertaken to investigate the target site penetration properties of fosfomycin, an antibiotic particularly suitable for treatment of soft tissue infections (STIs) in critically ill patients. METHODS AND RESULTS: The study population included nine patients with sepsis. Penetration of fosfomycin into the interstitial space fluid of skeletal muscle was measured using the microdialysis technique, following a single intravenous administration of 8.0 g of fosfomycin to patients. The median (range) fosfomycin area under the concentration versus time profile for plasma and skeletal muscle were 673 (459-1108) and 477 (226-860) mg x h/L (P < 0.011), respectively. Interstitial maximum concentrations were lower than plasma values (P < 0.029). Median fosfomycin concentrations in the interstitium and plasma exceeded 70 mg/L throughout the observation period of 4 h and covered MICs for Streptococcus pyogenes, Staphylococcus aureus and Pseudomonas aeruginosa. Simulation of bacterial growth inhibition of S. pyogenes, based on tissue concentration data, confirmed the bactericidal properties of fosfomycin described in previous studies. CONCLUSION: Fosfomycin concentrations in muscle interstitium and plasma exceeded the MICs for a range of clinically relevant pathogens in critically ill patients. Thus, fosfomycin exhibits a tissue pharmacokinetic profile, which appears to offer an alternative to other broad-spectrum antibiotics in intensive care patients suffering from STI.

Plasma and tissue pharmacokinetics of cefpirome in patients with sepsis.

OBJECTIVE: Broad initial antibiotic treatment is crucial for patients experiencing septic shock or severe sepsis. Fourth-generation beta-lactam antibiotics, such as cefpirome, are frequently favored in these conditions because of their low toxicity and wide antimicrobial coverage. From recent data, however, there is circumstantial evidence that one reason for the high mortality rate of patients with sepsis might be an impaired penetration of antimicrobial agents from the central compartment to the infectious focus. Thus, the present study aimed at describing penetration properties of cefpirome to the target site of many bacterial infections, which is the extracellular space fluid of soft tissues. DESIGN: Prospective comparative study of two groups. SETTING: An intensive care unit and research ward in a university hospital. SUBJECTS: The study population included 12 patients with septic shock or severe sepsis and a control group of six overall age-matched healthy volunteers. INTERVENTIONS: To measure cefpirome penetration into the interstitial space fluid of skeletal muscle, we employed microdialysis after single intravenous administration of 2.0 g of cefpirome to patients and healthy volunteers. MEASUREMENTS AND MAIN RESULTS: Maximum concentration and area under the concentration vs. time values in interstitium were significantly lower in patients compared with the control group (p <.004). Cefpirome area under the concentration time values for plasma were 16.0 +/- 1.1 mg.min/mL (mean +/- sem) and 18.8 +/- 1.1 mg.min/mL in patients and healthy volunteers, respectively (p =.075, not significant). In both study groups, mean cefpirome concentrations in interstitium and plasma exceeded 28 microg/mL throughout the observation period of 240 mins and covered completely minimal inhibitory concentration values for a range of clinically relevant pathogens. CONCLUSION: Cefpirome concentrations reached in tissue interstitium and plasma exceeded minimal inhibitory concentrations of most clinically relevant pathogens in patients with sepsis. Thus, cefpirome exhibits a tissue pharmacokinetic profile, which seems to be particularly valuable for the empirical therapy of patients with sepsis.

Closed-chest microdialysis to measure antibiotic penetration into human lung tissue.

The majority of bacterial lung infections are localized to the interstitial space fluid, which is therefore an important target site for antimicrobial chemotherapy. Direct measurement of interstitial concentrations of antimicrobial agents in human lung tissue would allow for a more informed approach to appropriate dosing of antimicrobial agents, but until now this was beyond technical reach. In this exploratory pharmacokinetic study, we measured the time versus concentration profile of cefpirome after a single intravenous dose administration of 2 g in the lung interstitial fluid by flexible microdialysis catheters, which were implanted during lung surgery for pulmonary tumors in five patients. Cefpirome concentrations in lung interstitial fluid were 66% of corresponding plasma values within the first 240 min, and exceeded minimal inhibitory concentrations of most relevant bacteria. The experimental procedure was well tolerated by the patients and no adverse events were observed. The present study provides evidence for the first time that closed chest microdialysis of the human lung is a feasible and safe method to measure lung concentrations in patients in vivo. The present data also corroborate the use of cefpirome as a valuable agent in the treatment of lung infections with most extracellular bacteria.