nitrophenols and Nervous-System-Diseases

The multiple-dose tolerability, pharmacokinetics, and pharmacodynamics of tolcapone, a novel catechol-O-methyltransferase (COMT) inhibitor, were assessed in healthy elderly volunteers receiving concomitant carbidopa and levodopa.. Thirty-six volunteers from 55 to 75 years old participated in this double-blind, placebo-controlled, ascending multiple-dose study. Tolcapone was studied at dosages of 100, 200, 400, or 800 mg three times daily (t.i.d.) in four sequential groups. Each group consisted of nine participants who had been randomized to receive either placebo (n = 3) or tolcapone (n = 6). Tolcapone or placebo was coadministered with carbidopa and levodopa (25 and 100 mg, respectively) for 7 days. Assessments included tolerability, pharmacokinetics of tolcapone, levodopa, and 3-O-methyldopa, and inhibition of COMT activity in erythrocytes.. By inhibiting COMT, tolcapone reduced levodopa metabolism to 3-O-methyldopa, resulting in a twofold increase in levodopa exposure (area under the curve) and elimination half-life, without changing levodopa peak plasma concentration. These effects were similar on days 1 and 7 of treatment. Development of tolerance to COMT inhibition was not observed. Onset of effect was rapid (day 1 of treatment), and the maximum effect on levodopa pharmacokinetics was already observed with 100 or 200 mg tolcapone t.i.d. At these dosages, tolcapone pharmacokinetics were linear and stable; accumulation occurred with 800 mg t.i.d. The combination of tolcapone and carbidopa-levodopa was generally well tolerated, although more nausea and vomiting were observed at higher dosages (400 to 800 mg t.i.d.), particularly in women.. Tolcapone shows promise as an effective adjunct to levodopa in the treatment of Parkinson's disease. Clinical pharmacology data indicate that the therapeutic regimen should be 100 or 200 mg t.i.d.

Topics: Administration, Oral; Aged; Analysis of Variance; Antiparkinson Agents; Benzophenones; Catechol O-Methyltransferase Inhibitors; Dopamine Agents; Dose-Response Relationship, Drug; Double-Blind Method; Drug Interactions; Enzyme Inhibitors; Erythrocytes; Female; Gastrointestinal Diseases; Humans; Levodopa; Male; Middle Aged; Nervous System Diseases; Nitrophenols; Tolcapone

SL25.1131 [3(S),3a(S)-3-methoxymethyl-7-[4,4,4-trifluorobutoxy]-3,3a,4,5-tetrahydro-1,3-oxazolo[3,4-a]quinolin-1-one] is a new, nonselective, and reversible monoamine oxidase (MAO) inhibitor, belonging to a oxazoloquinolinone series. In vitro studies showed that SL25.1131 inhibits rat brain MAO-A and MAO-B with IC50 values of 6.7 and 16.8 nM and substrate-dependent Ki values of 3.3 and 4.2 nM, respectively. In ex vivo conditions, the oral administration of SL25.1131 induced a dose-dependent inhibition of MAO-A and MAO-B activities in the rat brain with ED50 values of 0.67 and 0.52 mg/kg, respectively. In the rat brain, duodenum, and liver, the inhibition of MAO-A and MAO-B by SL25.1131 (3.5 mg/kg p.o.) was reversible, and the recovery of MAO-A and MAO-B activities was complete 16 h after administration. SL25.1131 (3.5 mg/kg p.o.) increased tissue levels of dopamine (DA), norepinephrine, and 5-hydroxytryptamine and decreased levels of their deaminated metabolites 3,4-dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindolacetic acid. In mice, SL25.1131 induced a dose-dependent potentiation of 5-hydroxytryptophan-induced tremors and phenylethylamine-induced stereotypies with ED50 values of 0.60 and 2.8 mg/kg p.o., respectively. SL25.1131 was able to reestablish normal striatal dopaminergic tone and locomotor activity in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned mice. In addition, when coadministered with L-DOPA, SL25.1131 increased the available DA in the striatum and the duration of L-DOPA-induced hyperactivity. The duration of the effect of L-DOPA on circling behavior in 6-hydroxydopamine-lesioned rats was also increased. The neurochemical profile of SL25.1131 demonstrates that this compound is a mixed, potent, and reversible MAO-A/B inhibitor in vitro, in vivo, and ex vivo. SL25.1131 has therapeutic potential as a symptomatic treatment during the early phase of Parkinson's disease and as an adjunct to L-DOPA therapy during the early and late phases of the disease.

Topics: 3,4-Dihydroxyphenylacetic Acid; Animals; Benzophenones; Brain; Corpus Striatum; Disease Models, Animal; Dopamine; Drug Interactions; Levodopa; Maze Learning; Mice; Mice, Inbred C57BL; Monoamine Oxidase; Monoamine Oxidase Inhibitors; MPTP Poisoning; Nervous System Diseases; Nitrophenols; Oxazoles; Oxidopamine; Prefrontal Cortex; Quinolines; Rats; Rats, Sprague-Dawley; Serotonin; Stereotyped Behavior; Tolcapone; Tremor; Tyramine

O-Ethyl-O-4-nitrophenylphosphoramidate is a short-acting anticholinesterase and a possible candidate for a prophylactic agent against nerve agents since human acetylcholinesterase inhibited by this agent undergoes rapid spontaneous reactivation which can be accelerated further, if necessary, by treatment with oximes. Doses of the agent > 1 mg/kg (s.c.) given to unprotected rats were fatal in a short time but 2 rats and one hen given 0.5 mg/kg survived. Hens given 2.5 or 4 mg/kg s.c. 20 min after prophylactic physostigmine + atropine survived acute effects and were killed 4.5 or 24 h later. Brain and spinal cord neuropathy target esterase levels of these hens were depressed only 4-10% compared with levels in brains from hens given only oxime + atropine or of undosed animals. Clinical signs of neuropathy were not seen in surviving birds observed for 3 weeks. It appears there would be negligible delayed neuropathic hazard associated with administration of O-ethyl-O-4-nitrophenylphosphoramidate at subacute doses.

Topics: Animals; Carboxylic Ester Hydrolases; Chickens; Cholinesterase Inhibitors; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Female; Nervous System Diseases; Nitrophenols; Organophosphorus Compounds; Rats; Rats, Inbred Strains

A series of 105 patients with organophosphate poisoning admitted to Harari Hospital during the past 4 years is described. Poisoning with organophosphate compounds is being seen more frequently in hospital practice in Rhodesia. Many of the cases are attempted suicides, but frequently there is no positive history of contact with the poison. The majority of patients exhibit the classic clinical features of parasympathetic overactivity, but diagnosis may be obscured by atypical presentation. Rapid diagnosis and utilization of the treatment regimen outlined in this article should reduce the mortality to less than 15%.

Topics: Adolescent; Adult; Atropine; Black or African American; Black People; Butyrylcholinesterase; Child; Critical Care; Female; Humans; Insecticides; Male; Nervous System Diseases; Nitrophenols; Organophosphorus Compounds; Oximes; Poisoning; Sex Ratio; Zimbabwe

Topics: Adolescent; Adult; Aged; Autonomic Nervous System; Color; Eye Diseases; Eye Movements; Female; Humans; Insecticides; Liver Function Tests; Male; Middle Aged; Nervous System Diseases; Nitrophenols; Organophosphate Poisoning; Pupil; Refraction, Ocular; Vision Disorders; Visual Acuity; Visual Fields