How does Modafinil 200 mg affect the central nervous system?
Modafinil 200 mg is a wake-promoting drug that has been show to reduce excessive sleepiness in patients with narcolepsy, obstructive sleep apnea (OSA), and shift work sleep disorder (SWD).
The medication increases dopamine, norepinephrine, and serotonin in the brain. It also activates the histaminergic and orexinergic systems, which increase wakefulness.
The Central Nervous System
Modafinil 200 mg is a wake-promoting central nervous system (CNS) stimulant. That is use to treat excessive sleepiness due to narcolepsy, obstructive sleep apnea, and shift work disorder. It also is use to increase wakefulness in people with cancer and patients with HIV.
The primary mechanism of action of Modafinil 200 mg is believe to be mediate by the dopaminergic and norepinephrinergic systems. However, a number of other systems are involve in the wake-promoting effect. The histaminergic and orexinergic systems have been identifie as important components of the drug’s effect.
In animal models, modafinil is a potent, selective inhibitor of dopaminergic reuptake in the striatum and the nucleus accumbens. The effects of modafinil on these structures are different from those seen with other CNS stimulants, such as methylphenidate and amphetamine.
Moreover, the effects of modafinil on dopaminergic function have been show to be additive. Suggesting that this compound is an effective and safe treatment for narcolepsy. In addition, the results of the study suggest that modafinil is not a drug of abuse. As it blocks dopamine transporters and does not increase dopamine in the brain.
This result suggests that a new and important mechanism of action for modafinil may be the blocking of dopamine transporters. It is theorize that this mechanism differs from those of methylphenidate and amphetamine, which increase dopamine in the brain by targeting dopamine transporters.
Additionally, it appears that modafinil inhibits the dopamine reuptake in the striatum as well as the norepinephrine reuptake in the nucleus accumbens. In the human striatum, [11C]raclopride BPND decreased significantly in caudate, putamen, and nucleus accumbens after modafinil compared with placebo. Similarly, [11C]cocaine BPND was significantly reduced in caudate after modafinil 200 mg compared with placebo.
Because of the significant dose-relate decrease in dopamine and norepinephrine reuptake, it is not recommend that patients take modafinil with other adrenergic agents. These medications can increase the risk of adverse cardiovascular events. This is especially true in patients with a history of cardiac diseases, such as unstable angina or recent myocardial infarction. It is therefore important to monitor a patient’s condition closely and discontinue the use of modafinil if signs or symptoms of cardiovascular disease or other serious adverse reactions are detected.
The Dopaminergic System
Modafinil 200 mg acts as a wake-promoting agent by increasing dopamine and norepinephrine in the brain. These effects are mediate through a series of receptors and transporters. These include the a2 receptor, which enhances NE release, and the b1 and c1 adrenergic receptors, which increase the activity of n-acetylcholine (NAC), an important precursor of dopamine.
In addition to its arousal and activity-promoting effects, modafinil 200 mg is report to have a number of cognitive-enhancing products. These include increases in working memory, episodic memory, and processes requiring cognitive control. These effects have been observing in various human and nonhuman animal models, including those involving the prefrontal cortex, and are base on evidence from behavioral, electrophysiological, and neuroimaging studies.
One study in healthy adults found that a single dose of modafinil reduced errors on the WCST. And Hayling Sentence Completion Test and decreased impulsive behavior and aggression. In another double-blind, placebo-control trial of 12 patients with schizophrenia, a single dose of modafinil was associate with greater activation of the dorsolateral PFC and anterior cingulate cortex during the performance of a task that required cognitive control of the limbs, measured by fMRI.
Some of the cognitive-enhancing effects of Modvigil Australia are thought to be mediate through its interaction with the DA and a2 receptors. Low doses of the a2 antagonist yohimbine potentiate modafinil’s wake-promoting and activity-promoting effects, whereas higher doses attenuate these effects (Lin et al, 1992).
The majority of the cognitive-enhancing effects of modafinil appear to be mediate through changes in extracellular monoamine levels. This is in contrast to the effects on extracellular glutamate and GABA, which require higher parenteral doses.
These changes in extracellular levels of monoamines may result from the stimulation or inhibition of monoamine oxidase enzymes. The conversion of circulating free amines into cytotoxic reactive oxygen species. Or by changes in neurotransmitter synthesis or release. However, these effects are not likely to account for all of the observed cognitive-enhancing effects of modafinil.
Modafinil also appears to activate some other adrenergic and DA receptors. But these are not currently implicate in the cognitive-enhancing effects of modafinil. It appears to have a limited affinity for the DA receptor. With an IC50 of less than 3 mM in a rodent brain preparation. It does not show specific binding to other monoamine or neuropeptide receptors or transporters. Or to nerve membrane ion channels, suggesting that it is unlikely to have any direct effects on second messenger systems in the brain.
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