Clozapine :: Drugs Science Medical Psychology Essays

Clozapine Clozapine is an atypical anti-psychotic medication that acts as an antagonist (a drug that blocks the effects of a neurotransmitter), thus producing an inhibitory effect, at a variety of neurotransmitter receptors in the brain. The exact site and action by which Clozapine produces its therapeutic effects is difficult to locate due to the complexity of its interactions with several neurotransmitters. It is believed that the two key neurotransmitters that Clozapine interacts with are serotonin (5-HT) and dopamine (DA), particularly at 5-HT2, D2, and D4 receptors (Brenner, H.D., BÃâ€"ker, W., Genner, R., 2001). Serotonin is a biogenic amine derived from tryptophan that generally produces inhibitory postsynaptic potentials (meaning that it causes hyperpolarization of the postsynaptic cell membrane).Functions of serotonin include regulation of sleep and emotions. Dopamine is a monoamine catecholamine derived from the amino acid tyrosine. Receptors that bind dopamine are termed dopaminergic. Dopamine is one of the principal modulatory neurotransmitters in the brain and may have inhibitory or excitatory effects depending upon the response of the postsynaptic receptor (King, www.indstate.edu). Clozapine also has effects at muscarinic M1 receptors, adrenergic receptors, cholinergic receptors, and histamine receptors (Brenner, et al). There are many disputed theories of the biological causes of schizophrenia. One of the most prominent ideas is the "dopamine hypothesis." The dopamine hypothesis attributes hyperdopaminergic function, meaning an excess of dopamine at certain synapses, as a possible cause of schizophrenia (Fann, W.E., Karacan, I., Pokorney, A.D., & Williams, R.L., 1978). Dopamine systems arise from two primary midbrain clusters, the ventral tegmental area and the substantia nigra which have discrete projections to mesolimbic, mesocortical, and striatal regions of the brain. The neurochemical anatomy of dopamine differs in cortical and striatal regions, and it appears that dopamine concentration, receptor regulation, and D2 receptor density varies greatly between striatal and extrastriatal regions (Jones, & Pilowsky, 2002). It is supposed that the therapeutic actions of antipsychotic drugs are exerted via the mesolimbic and mesocortical dopamine pathways in the brain (Hyman et. al., 1995). According to the dopamine hypothesis for schizophrenia, limbic D2 receptor blockade is essential for a drug to have antipsychotic activity. It is believed that the therapeutic actions of antipsychotic drugs are exerted via the mesolimbic and mesocortical dopamine pathways in the brain by acting as D2 receptor antagonists (Hyman et al.)Without exception, effective antipsychotic drugs have at least some degree of antagonism of the dopamine D2 receptors. (Breier, A., Tran, P. Clozapine :: Drugs Science Medical Psychology Essays Clozapine Clozapine is an atypical anti-psychotic medication that acts as an antagonist (a drug that blocks the effects of a neurotransmitter), thus producing an inhibitory effect, at a variety of neurotransmitter receptors in the brain. The exact site and action by which Clozapine produces its therapeutic effects is difficult to locate due to the complexity of its interactions with several neurotransmitters. It is believed that the two key neurotransmitters that Clozapine interacts with are serotonin (5-HT) and dopamine (DA), particularly at 5-HT2, D2, and D4 receptors (Brenner, H.D., BÃâ€"ker, W., Genner, R., 2001). Serotonin is a biogenic amine derived from tryptophan that generally produces inhibitory postsynaptic potentials (meaning that it causes hyperpolarization of the postsynaptic cell membrane).Functions of serotonin include regulation of sleep and emotions. Dopamine is a monoamine catecholamine derived from the amino acid tyrosine. Receptors that bind dopamine are termed dopaminergic. Dopamine is one of the principal modulatory neurotransmitters in the brain and may have inhibitory or excitatory effects depending upon the response of the postsynaptic receptor (King, www.indstate.edu). Clozapine also has effects at muscarinic M1 receptors, adrenergic receptors, cholinergic receptors, and histamine receptors (Brenner, et al). There are many disputed theories of the biological causes of schizophrenia. One of the most prominent ideas is the "dopamine hypothesis." The dopamine hypothesis attributes hyperdopaminergic function, meaning an excess of dopamine at certain synapses, as a possible cause of schizophrenia (Fann, W.E., Karacan, I., Pokorney, A.D., & Williams, R.L., 1978). Dopamine systems arise from two primary midbrain clusters, the ventral tegmental area and the substantia nigra which have discrete projections to mesolimbic, mesocortical, and striatal regions of the brain. The neurochemical anatomy of dopamine differs in cortical and striatal regions, and it appears that dopamine concentration, receptor regulation, and D2 receptor density varies greatly between striatal and extrastriatal regions (Jones, & Pilowsky, 2002). It is supposed that the therapeutic actions of antipsychotic drugs are exerted via the mesolimbic and mesocortical dopamine pathways in the brain (Hyman et. al., 1995). According to the dopamine hypothesis for schizophrenia, limbic D2 receptor blockade is essential for a drug to have antipsychotic activity. It is believed that the therapeutic actions of antipsychotic drugs are exerted via the mesolimbic and mesocortical dopamine pathways in the brain by acting as D2 receptor antagonists (Hyman et al.)Without exception, effective antipsychotic drugs have at least some degree of antagonism of the dopamine D2 receptors. (Breier, A., Tran, P.