Pharmacodynamic response profiles of anxiolytic and sedative drugs.

AIM: Centrally-acting acutely anxiolytic drugs, such as benzodiazepines, barbiturates and gabapentinoids, affect various central nervous system (CNS) functions, which reflects not only their anxiolytic effects but also neuropsychological side-effects. To validate the pharmacodynamic biomarkers for GABA-ergic anxiolytics, this study determined the pharmacodynamics of two anxiolytics and a nonanxiolytic control, and linked them to their anxiolytic and sedative effects, during an anxiety-challenge study day. METHODS: Twenty healthy volunteers were randomized in this placebo-controlled, double-blind, four-way cross-over study with single-dose alprazolam (1 mg), diphenhydramine (50 mg), pregabalin (200 mg) or placebo. The Neurocart was used between repeated fear-potentiated startle assessments. Thus, the potential influence of anxiety on CNS pharmacodynamic markers could be examined. RESULTS: Compared to placebo, VAScalmness increased with alprazolam (2.0 mm) and pregabalin (2.5 mm) but not with diphenhydramine. Saccadic peak velocity (SPV) declined after alprazolam (-57 ° s-1 ) and pregabalin (-28 ° s-1 ), more than with diphenhydramine (-14 ° s-1 ); so did smooth pursuit. The average responses of SPV and smooth pursuit were significantly correlated with the drug-induced increases in VAScalmness . The SPV-relative responses of VASalertness , body-sway and adaptive-tracking also differed among alprazolam, pregabalin and diphenhydramine. CONCLUSIONS: Compared with the antihistaminergic sedative diphenhydramine, alprazolam and pregabalin caused larger SPV reduction, which was correlated with simultaneous improvement of subjective calmness, during a study day in which anxiety was stimulated repeatedly. The different effect profiles of the three drugs are in line with their pharmacological distinctions. These findings corroborate the profiling of CNS effects to demonstrate pharmacological selectivity, and further support SPV as biomarker for anxiolysis involving GABA-ergic neurons. The study also supports the use of prolonged mild threat to demonstrate anxiolytic effects in healthy volunteers.

Pharmacokinetics of PC-SOD, a lecithinized recombinant superoxide dismutase, after single- and multiple-dose administration to healthy Japanese and Caucasian volunteers.

To study the pharmacokinetics of single increasing intravenous doses (40-160 mg) and repeated doses (80 mg for 7 days) of lecithinized superoxide dismutase (PC-SOD) in Japanese volunteers and to compare the pharmacokinetics of PC-SOD between Caucasians and Japanese. The Japanese study consisted of 2 parts: a single-dose, open-label, dose-escalation part and a multiple-dose, single-blind, placebo-controlled part. The pharmacokinetics of PC-SOD were determined using noncompartmental and compartmental methods. Pharmacokinetic data from a study with PC-SOD in Caucasians were reanalyzed using the same methodology. The mean (SD) terminal half-life of PC-SOD in Japanese subjects was 25 (4) hours for the 40-mg and 80-mg doses and 31 (15) hours for the 160-mg dose. There was nonlinearity between dose-normalized C(max) and clearance (P values .002 and .022). After multiple dosing, steady state was reached after 5 days. The observed accumulation ratio was 2.6 (0.5). The pharmacokinetics of the single 80-mg dose were similar for Japanese and Caucasians. The pharmacokinetics of PC-SOD was shown to be nonlinear with dose, which may be attributable to a saturable clearing mechanism. The relatively long half-life of PC-SOD (>24 hours) suggests that it is worthwhile to study the compound as a protective agent in clinical conditions with free radical overload.

Neuronal intranuclear and neuropil inclusions for pathological assessment of Huntington's disease.

To evaluate the usefulness of neuronal intranuclear inclusions and neuropil inclusions for the pathological assessment of Huntington's disease (HD), their presence in neocortex was assessed by ubiquitin and N-terminal huntingtin immunohistochemistry in a consecutive series of 195 autopsy brains of individuals with a positive or tentative clinical diagnosis of, or at risk for, HD. The findings were correlated with striatal pathology (n = 190), CAG repeat length (n = 85) and original pathological diagnosis (n = 186). The antibodies detected both these inclusions in 181 patients with HD pathology > or = Vonsattel et al's grade I, five patients lacking striatal tissue for review, and two at-risk individuals with grade 0 and grade I HD pathology, respectively. One patient with HD-like pathology and two patients and four at-risk individuals without HD pathology lacked HD inclusions. In the genetically analyzed cases, the inclusions were exclusively and consistently observed in association with repeat expansion [(CAG)(n) > or = 39, n = 81]. Thirteen inclusion-positive cases, including the grade 0 at-risk individual, had a false negative original pathological diagnosis of HD and four had an unjustly questionable diagnosis. A false positive diagnosis was made in the inclusion-negative case with HD-like pathology. These results indicate that immunohistochemical analysis for HD inclusions facilitates the pathological evaluation of HD and enhances its accuracy.