Question

Describe ten types of Central Nervous System Agents and their mechanism of action on neurotransmitters

Answer 1

Central nervous system agents are medicines that affect the central nervous system (CNS). There are many different types of drugs that work on the CNS, including anesthetics, anticonvulsants, antiemetics, antiparkinson agents, CNS stimulants, muscle relaxants, narcotic analgesics (pain relievers), nonnarcotic analgesics (such as acetaminophen and NSAIDs), and sedatives.

Narcotic analgesics principally act on the sigma and mu receptors in the body to decrease the patient’s perception of pain. Non-narcotic agents reduce the level of prostaglandin synthesis to decrease the inflammatory response. The cholinergic agents act by either increasing or decreasing the amounts of available acetylcholine or acetylcholinesterase. Adrenergic agents affect the sympathetic nervous system by promoting or depressing the alpha and/or beta responses. Most of these adrenergic agents are site specific (e.g., Metoprolol is beta1 specific). The CNS stimulants act by increasing the available amount of the neurotransmitter norepinephrine which will increase cellular impulse transmission. Anti-convulsants act in several ways such as either increasing Na+ evacuation or preventing its entry into the cell, elevating GABA levels, or decreasing acetylcholine levels. Sedatives and hypnotics reduce the activity in the thalamus and the cortex (the thalamus receives sensory input from the brain). Two major actions predominate for the anti-depressants, they either increase the norepinephrine and serotonin levels in the brain or they inhibit the production of monoamine oxidase (MAO) which breaks down the neurotransmitters. Antipsychotics block the dopamine receptor sites in the brain or decrease the responsiveness of the medulla. Finally, anxiolytics alter the responses in the limbic center or they increase GABA levels.