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Phencyclidine analogs and precursors: rotarod and lethal dose studies in the mouse
Abstract:
A series of phencyclidine (PCP) related analogs, carbonitrile synthetic precursors and two monohydroxylated metabolites were compared pharmacologically in mice for their ability to produce ataxia using the rotarod method and toxicologically for their acute 4-hr lethality. The slope of the PCP dose-ataxic response curve was steeper than those of diazepam, pentobarbital, morphine and ketocyclazocine but not the slope of the sigma agonist, N-allylnormetazocine curve. Responses for all analogs, metabolites and precursors produced curves parallel to that of PCP. Ataxia potencies of all PCP-related compounds ranged from 0.05 to 2.15 X PCP and durations of action ranged from 18 to 65 min. N-ethyl-1-phenylcyclohexylamine, 1-[1-(2-thienyl)-cyclohexyl]-piperidine and 1-[1-(2-thienyl)-cyclohexyl]-pyrrolidine were most potent and least potent were 1-(1-phenyl-cyclohexyl)-4-methylpiperidine, the phenyl and thienyl morpholines and 4-phenyl-4-piperidinocyclohexanol. Among the PCP analogs, modifying the piperidine or aromatic ring effected changes only in potency. Seizures and respiratory depression characterized the lethal effects of PCP, its analogs, metabolites and precursors. However, the precursors failed to elicit the stereotyped movements and hyperactivity that preceded seizures produced by the other compounds. Overall potencies for lethality relative to PCP covered a narrow range (0.16-1.83) with the carbonitrile precursors being most potent. Therapeutic indices indicated relatively large margins of safety for 1-[1-(2-thienyl)-cyclohexyl]-piperidine, 1-[1-(2-thienyl)-cyclohexyl]-piperidine, N-ethyl-1-phenylcyclohexylamine and ketamine and the smallest were for 1-(1-phenylcyclohexyl)-4-methylpiperidine, the metabolite 4-phenyl-4-piperidinocyclohexanol and the three precursors.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
This study compared phencyclidine (PCP) analogs, precursors, and metabolites in mice, finding varied potencies for ataxia and lethality. Some compounds showed wider safety margins than others, with precursors exhibiting unique toxicological profiles.
Area of Science:
- Pharmacology
- Toxicology
- Neuroscience
Background:
- Phencyclidine (PCP) and its analogs are known for their psychoactive and toxicological effects.
- Understanding the pharmacological and toxicological profiles of PCP-related compounds is crucial for assessing potential risks.
Purpose of the Study:
- To compare the pharmacological (ataxia) and toxicological (lethality) effects of PCP analogs, carbonitrile precursors, and monohydroxylated metabolites in mice.
- To determine the relative potencies and safety margins of these compounds.
Main Methods:
- Pharmacological assessment of ataxia using the rotarod method in mice.
- Toxicological assessment of acute 4-hour lethality in mice.
- Dose-response curve analysis and comparison of potency and duration of action.
Main Results:
- PCP analogs, precursors, and metabolites exhibited a range of ataxia potencies (0.05-2.15x PCP) and durations (18-65 min).
- Lethality was characterized by seizures and respiratory depression; precursors differed by lacking stereotyped movements and hyperactivity.
- Therapeutic indices varied, with some compounds like N-ethyl-1-phenylcyclohexylamine and ketamine showing larger safety margins, while others like 1-(1-phenylcyclohexyl)-4-methylpiperidine and precursors had smaller margins.
Conclusions:
- Structural modifications of PCP analogs influenced potency but not the nature of the dose-response curves.
- Carbonitrile precursors demonstrated distinct toxicological profiles compared to other PCP-related compounds.
- The study provides valuable data on the relative safety and toxicity of various PCP-related substances.