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Biomedical subjects

B Dubinsky

Publications and source records attributed to B Dubinsky.

18 recordsLinked to original sources
PubMed1999

gamma-Aminobutyrate-A receptor modulation by 3-aryl-1-(arylsulfonyl)- 1,4,5,6-tetrahydropyridazines.

A series of 3-aryl-1-(arylsulfonyl)-1,4,5,6-tetrahydropyridazine allosteric modulators of the GABAA receptor was synthesized, and biological activity was examined in vitro and in vivo. Beginning with 1a, stepwise modification of the substituents and conservation of the scaffold yielded a chemical series in which the modulatory activity was enhanced by the presence of GABA. The SAR suggests, but does not establish, that the compounds bind to the steroid binding site on the GABAA receptor. The GABA shift for each compound indicates that all compounds in this series are either agonists or partial agonists.

Animals↗
PubMed1999

Potential anxiolytic agents. 3. Novel A-ring modified pyrido[1,2-a]benzimidazoles.

A variety of pyrido[1,2-a]benzimidazoles (PBIs) modified on the A-ring were prepared and evaluated for affinity to the benzodiazepine binding site on the GABA-A receptor and in animal models predictive of anxiolytic activity in humans. A-ring benzo-fused derivative 7 exhibited potent activity, as did the 6- and 7-pyrido compounds 3 and 4.

Animals↗
PubMed1999

New directions in anxiolytic drug research.

Agents to treat anxiety have gained in acceptance and importance in the fast pace of life in the second half of this century. The discovery and refinement of the benzodiazepines represented a quantum leap in therapy from early compounds which were essentially sedatives. With the advent of molecular biology, an understanding of the basic mechanism by which the benzodiazepines exert their effects was revealed through the discovery and isolation of the GABAA receptor and its benzodiazepine binding site. This, in turn, has enabled benzodiazepines to be classified into a broad spectrum of pharmacological types ranging from agonist to inverse agonist, thus allowing fine tuning with respect to side-effects. Consequently, newer, more promising agents have emerged which bind at the GABAA BZD site and have reduced side-effects. An example of this is RWJ-51204 (92), a member of a novel structural type which is superior to several marketed benzodiazepines in animals in terms of efficacy and side-effects. The cost-conscious environment of managed health care presents continuing challenges to the discovery and development of safe, highly efficacious, and cost-effective anxiolytic agents.

Anti-Anxiety Agents↗
PubMed1988

Synthesis of (aryloxy)alkylamines. 2. Novel imidazo-fused heterocycles with calcium channel blocking and local anesthetic activity.

A series of imidazo-fused heterocycles substituted with an aryloxy)alkylamine side chain were prepared as modifications to butoprozine (I) and found to possess calcium channel blocking activity similar in potency to that of bepridil in trachea smooth muscle and similar to that of verapamil in nitrendipine binding affinity in rabbit cardiac muscle. Of the various imidazo-fused heterocycles prepared, the imidazo[1,2-a]pyridines were also found to be potent local anesthetic agents. While most compounds in this series were equipotent to lidocaine in our initial screen, compounds 2 and 35 showed local anesthetic activity approximately 100 times more potent than lidocaine in our preliminary assays. These compounds represent a novel structural class of local anesthetic agents, and compound 2 is under further investigation.

Amines↗
PubMed1987

The antialgesic drugs: human therapeutic correlates of their potency in laboratory animal models of hyperalgesia.

This survey discusses the correlation between the oral potency of antialgesic drugs in several pharmacology laboratories and their human oral dose in clinical practice. We also present a brief overview of a few biological assays that have been successfully used to direct the synthesis of newer antialgesic drugs. The laboratory assay that our analysis showed to be most predictive of the clinical analgesic dose is based upon the response of rats to flexion of an arthritic joint. Laboratory ED50 values from the ACh-induced abdominal constriction assay in mice are nearly as predictive while the predictive power of the yeast-induced hyperalgesia assay in rats is somewhat less. Probably because of the small number of experiments, the correlation between the efficacy of these agents in a canine model of synovitis and their clinical doses only reached borderline statistical significance (p = 0.0651). Regression equations are presented that permit calculations of single clinical analgesic doses from efficacy data in individual tests. Calculation of stepwise multiple regression showed that the clinical dose could be best predicted when efficacy data obtained in the joint flexion assay in rats and the ACh-induced constriction assay in mice are both taken into account. We have concluded that the effective doses are highly predictive of clinical efficacy because these animal assays have been designed to reflect the action of drugs upon prostanoid-induced hyperalgesia.

Acetylcholine↗
PubMed1984

Flunarizine and verapamil: effects on central nervous system and peripheral consequences of cytotoxic hypoxia in rats.

Flunarizine is a calcium entry blocking drug possessing antihypoxic activity in animal models of cerebral and peripheral ischemia-anoxia and has clinical usefulness in circulatory disorders of both central and peripheral origin. This report compares the activity of flunarizine and verapamil, another calcium entry blocking drug, on the central nervous system (CNS) and peripheral consequences of cytotoxic hypoxia induced by high and low doses of KCN. The lethal effect of KCN (6 mg/kg, i.p.) in rats was prevented by orally administered flunarizine (ED50 = 12 mg/kg with four-hr pretreatment) but not by verapamil (at oral doses up to 80 mg/kg with one-hr pretreatment). Since the lethal effect of KCN involves failure of respiration at the CNS level, these results suggest that flunarizine protects against the hypoxic effect of the cyanide ion by an action in brain tissue. We found also that the stimulant effect of low intravenous doses (0.5 mg/kg/min) of KCN upon respiration rate was not altered in pentobarbital- and chloralose-anesthetized rats treated with oral doses of flunarizine up to 80 mg/kg (with four hr pretreatment). In contrast, KCN-stimulated respiration rate in pentobarbital anesthetized rats was significantly attenuated by verapamil (20 and 40 mg/kg, p.o. with one hr pretreatment). Since low doses of the cyanide ion render respiration quicker and deeper by an action on chemoreceptive cells in peripheral arteries, the effect of verapamil against the hypoxic effect of KCN is mediated by an action in the periphery. In summary, we have shown that the physiological consequences of cytotoxic hypoxia can be affected by calcium entry blocking drugs having site-specific activities. Based on our results, flunarizine is more effective than verapamil against cellular anoxia involving the CNS.

Animals↗
PubMed1984

Mechanism of action of suprofen, a new peripheral analgesic, as demonstrated by its effects on several nociceptive mediators.

Suprofen is a new potent, orally effective non-narcotic analgesic agent having a potent inhibitory action on prostaglandin (PG) biosynthesis. Recent experiments have shown that suprofen inhibits uterine hyperactivity induced by the physiological substances, arachidonic acid, bradykinin (BK) and PGF2 alpha. The present study explores the possibility that the analgesic activity of suprofen may involve multiple mechanisms of interaction with PGs, inhibiting synthesis at low doses and with higher doses possibly directly interacting with PGs and other physiological mediators of nociception at a common site. Experiments in mice have shown that suprofen antagonizes abdominal stretching induced by the physiological precursor of PG release, arachidonic acid (ED50 = 0.07 mg/kg, p.o.), and by the nociceptive agents acetylcholine (ACh) (ED50 = 1.7 mg/kg, p.o.), BK (ED50 = 65 mg/kg, p.o.) acetic acid (HAC) (H+ ion; ED50 = 4.6 mg/kg, p.o.), and PGE2, itself (ED50 = 20.2 mg/kg, i.p.). In rabbits, i.a. administered suprofen (ED50 = 0.98 mg/kg) blocked the reflex discharge of spinal sensory neurons evoked by BK (2 to 8 micrograms, i.a.). The analgesic activity of suprofen may involve multiple mechanisms of interaction with PGs and other mediators, including BK; suprofen blocks the nociceptive actions of PGs by inhibiting their formation, via the cyclooxygenase pathway, and possibly at PG sites of action, probably at peripheral nerve endings.

Acetates↗
PubMed1982

Bromperidol, a new butyrophenone neuroleptic: a review.

This review compares and contrasts the preclinical pharmacology of bromperidol with another butyrophenone neuroleptic, haloperidol, and the phenothiazine neuroleptic chlorpromazine. Its pharmacokinetics, biotransformation, and safety in several laboratory animal species are also summarized. These preclinical data support its use as an antipsychotic agent and show that it is well absorbed following oral administration with an apparent elimination half-life of approximately 24 h, supporting a once-daily dose regimen. Animal toxicity (including acute- and multiple-dose toxicology and reproductive and mutagenicity studies) show that bromperidol is well tolerated.

Animals↗
PubMed1975

Effects of selected drugs on an auditory or thalamic conditioned stimulus eliciting recruitment in the cat.

Minimally effective oral doses of chlorpromazine, imipramine, and pentobarbital necessary to block a discrete trial (bar-press) conditioned avoidance response were compared in cats chronically implanted with electrodes over the cerebral cortex and in the nucleus centralis medialis of the thalamus. Three conditioned stimulus contingencies consisting of tone and low or high voltage thalamic stimulation were presented. Minimal conditioned response blocking doses of these agents produced only slight qualitative changes in cortically recorded recruitment. Drug treatment affected the conditioned stimulus contingencies differentially, and the rank order in terms of ease of disruption of the conditioned avoidance response was high voltage thalamic conditioned stimulus greater than low voltage thalamic conditioned stimulus greater than auditory conditioned stimulus. The differential effect of these drugs might have been due to the additive inhibition of these agents and the thalamic conditioned stimulus on performance. With the exception of chlorpromazine, the behavioral effects of these drugs and their effects on recruitment were dissociated.

Acoustic Stimulation↗