Antipsychotics & Parkinson's Flashcards
What disease is the primary indication for the use of anti psychotics?
Schizophrenia
Describe the positive and negative symptoms of schizophrenia
Schizophrenia consists of positive symptoms such as hallucinations, delusions, disorganized thought or behavior, whereas negative symptoms of the disease are apathy, flat affect and a decrease in energy
What symptoms of shizophrenia are treated with FGA?
Only the positive symptoms
Name high potency FGA
Haloperidol, Trifluoperazine, Fluphenazine
Name low potency FGA
Chlorpromazine and thioridazine
Describe the MOA of FGA
All first generation antipsychotics work by blocking D2 receptors in the CNS, especially in the mesolimbic and striatofrontal system
What are high potency FGA associated with
Trifluroperazine and fluphenazine are high potentcy first generation antipsychotics, which means greater D2 receptor binding (lower EM50); these agents are NOT strongly associated with sedating, waking, or anticholinergic activity but confer a high risk of extrapyramidal side effects
What are low potency FGA associated with
Chloropromazine and Thioridazine are low potency (high EM50) first generation antipsychotics that are associated with low risk of extrapyramidal symptoms but have high histaminic and muscarinic activity with a corresponding increased risk of sedation and anticholinergic effects
What is the hallmark of acute psychotic episodes? What can exacerbate acute psychotic episodes?
Excess of dopamine, dopamine agonist such as levodopa
How are acute psychotic episodes managed?
Acute psychotic episodes, regardless of the underlying condition causing them, are usually managed with high potency 1st generation anti-psychotics
What is a pharmacokinetic property of FGA
are highly lipophilic -> highly tissue and protein bound with large volumes of distribution, giving them a long half-life
What other disease can be treated with FGA?
First generation antipsychotics can be useful in the management of tourettes syndrome, though other dopamine-depleters and α-blockers are more often used
What are the side effects of low potency FGA?
Systemic side effects due to blockade of muscarinic and histamine receptorsAntimuscarinic: dry mouth, hyperthermia, constipation, blurred vision, and urinary retention Anti histamin effect: cause sedation and drowsiness which may be usefulBlock alpha 1 receptors so can cause orthostatic hypotension
What is the hallmark of side effect of high potency FGA?
Extra medullary symptoms due to blockade of D2 receptors in nigro-striatal tract, this causes an excess of cholinergic activity
What drugs can be used to control extra pyramidal side effects of high potency FGA?
Benztropine, diphenhydramine due to their anti muscarinic properties, help re establish dopamine:cholinergic balance
Describe the extra pyramidal side effect
Dystonia (seen within hours; more common with young males), akathisia (restlessness w/ inability to sit still; seen within days) , and cog-wheel rigidity (seen within weeks)
What is the most important long term side effect seen wit FGA?
The most important long-term neurological side effect you need to watch out for when using antipsychotic therapy is tardive dyskinesia
Can we use levodopa to balance out the extra pyramidal side effects instead of using anti muscarinic drugs?
Extrapyramidal Effects due to first generation antipsychotics cannot be treated with levodopa (Dopamine), as too much Dopamine is what we are trying to treat in the first place (their psychosis)
What is another AE due to central D2 receptor blockade
HyperprolactinemiaThe hypothalamus usually secretes dopamine to inhibit prolactin release from the anterior pituitary. Any drugs that block dopamine receptors will block dopamine secretion by the hypothalamus, causing hyperprolactinemia which can cause galactorrhea, amenorrhea, and impotence. Impotence and loss of libido in men due to hyperprolactinemia is due to prolactin inhibiting GnRH release from the anterior pituitary.
CV AE of FGA?
Can cause torsades
What are 2 other CNS diseases caused by FGA?
FGA reduce the threshold for seizuresAll antipsychotics (especially first generation) can cause neuroleptic malignant syndrome (NMS) which occurs to patients who are extra-sensitive to extrapyramidal side effects
What is a side effect of Chlorpromazine specifically
corneal deposits
What is a side effect of Thioridazine specifically
Retinal deposits. Deposits in the retina can cause browning of the vision and advanced cases may look like retinitis pigmentosa
Name SGA
“Quiet please, Only whispering is Appropriate” = Quetiapine, Olanzapine, Risperidone, and Aripiprazole”zipper” - ziprasidone”closet” - clozapine - the prototypical atypical antipsychotic