Pharmacology of Anitpsychotics Flashcards
Define Psychosis
the inability to distinguish between the internal experience (mind) and the external experience of the environment (reality)
What are the signs/symptoms of psychosis?
delusions and hallucinations, but may also include disorganized speech, disorganized behavior, or gross distortions of reality
What are the diagnosis requirements for schizophrenia?
- two or more of the following: delusions, hallucinations, disorganized speech, grossly disorganized or catatonic behavior, negative symptoms
- social and/or occupational dysfunction
- continuous signs of disturbances persist at LEAST 6 MONTHS
- rule out drugs or medical conditions as cause
What are positive symptoms of schizophrenia?
-hallucinations: sensory perceptions unconnected to external stimuli (typically auditory)
-delusions: fixed false belief that is not shared by others in culture
-disorganized thoughts and speech: rambling, mutism, etc.
-abnormal motor behavior: strange posture or catatonic
What drugs may induce similar psychotic symptoms to schizophrenia?
-cocaine, amphetamine (dopamine agonist, NE agonist)
-hallucinogenic drugs (serotonin agonist)
-anticholinergic drugs (Ach antagonism)
-dissociative anesthetic (glutamate N-methyl-D-aspartate antagonism)
Describe the Glutamate hypothesis in Schizophrenia
antagonists of the NMDA glutamate receptor, such as PCP and ketamine, produce behavioral changes in humans (psychosis, hallucinations, etc) resulting in hypofunction of NMDA receptors are hypothesized to be involved in schizophrenia
What are the 2 classes of DA receptors?
-D1 (and D5) are Galpha(s) receptors that increase cAMP and are located post synaptically
-D2 (and D3 and D4) are Galpha(i) receptors that decrease cAMP and are located both pre- and post synaptically
What neurotransmitters are implicated in Psychosis/Schizophrenia?
dopamine, serotonin, glutamate
What drugs are first generation antipsychotics?
chloropromazine and haloperidol
What first generation antipsychotic is considered low potency?
chlorpromazine
What first generation antipsychotic is considered high potency?
haloperidol
What are the side effects of low potency first generation antipsychotics?
low incidence of neurological side effects (ACh block, D2 block, and serotonin (5HT) block), but high incidence of autonomic side effects (sedation, alpha1 block)
What are the side effects of high potency first generation antipsychotics?
fewer autonomic side effects (alpha1 block) but higher frequency of neurological and endocrinological side effects (D2 block, serotonin (5HT) block)
How do antipsychotics treat positive symptoms of schizophrenia?
overactive mesolimbic dopamine neurotransmission induces positive symptoms so antagonism of D2 dopamine receptors normalize dopamine neurotransmission to treat positive symptoms
How do antipsychotics induce Parkinsonism (extrapyramidal symptoms)?
dopamine receptors in the nigrostriatal system are also blocked and blockade of D2 receptors in the striatum causes imbalance of dopamine and produces parkinsonian-like effects