Ethanol pharmacodynamic effects

The pharmacodynamic effects of ethanol are complex, and any attempt to link its actions to specific neurotransmitters or isolated brain regions is simplistic. A complicated neural network involved in the actions of ethanol accounts for its reinforcing, intoxicating, and abstinence effects. At the present time, use of medications that target neurotransmitters and neuromodulators affected by ethanol represents a reasonable strategy for the development of pharmacotherapies that reduce the reinforcing effects of alcohol and the craving and withdrawal symptoms that commonly occur in the context of alcohol dependence. 

The effects of ethanol on bodily functions, e.g., those of the brain, heart, and liver, are dependent upon the systemic concentrations of ethanol over time. Therefore, the pharmacokinetics of ethanol play a pivotal role in the pharmacodynamic actions of ethanol and of its metabolic product acetaldehyde [6],... 

Interactions between ethanol and other drugs can have important clinical effects resulting from alterations in the pharmacokinetics or pharmacodynamics of the second drug. 

A pharmacodynamic interaction involves either inhibition or enhancement of the clinical effects of the victim drug as a consequence of similar or identical end-organ actions. Examples are the increase or decrease of the sedative-hypnotic actions of benzodiazepine agonist drugs due to coadministration of ethanol or... 

Except for additive effects with other sedative or hypnotic drugs, reports of clinically important pharmacodynamic interactions between benzodiazepines and other drugs have been infrequent. Ethanol increases both the rate of absorption of benzodiazepines and the associated CNS depression. Valproate and benzodiazepines in combination may cause psychotic episodes. 

B. Toxicodynamics Toxicodynamics is a term used to denote the injurious effects of toxins, ie, their pharmacodynamics. A knowledge of toxicodynamics can be useful in the diagnosis and management of poisoning. For example, hypertension and tachycardia are typically seen in overdoses with amphetamines, cocaine, and antimuscarinic drugs. Hypotension with bradycardia occurs with overdoses of calcium channel blockers, beta-blockers, and sedative-hypnotics. Hypotension with tachycardia occurs with tricyclic antidepressants, phenothiazines, and theophylline. Hyperthermia is most frequently a result of overdose of drugs with antimuscarinic actions, the salicylates, or sympathomimetics. Hypothermia is more likely to occur with toxic doses of ethanol and other CNS depressants. Increased respiratory rate is often a feature of... 

Crean CS, Tompson DJ. The effects of ethanol on the pharmacokinetics, pharmacodynamics, safety, and tolerability of ezogabine (retigabine). Clin Ther January 2013 35(l) 87-93. 

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