Chapter 5: Antipsychotics Flashcards
which dopamine pathway has a major role in motivation/reward and why
mesolimbic pathway
dopamine neurons target the nucleus accumbens (pleasure center) in the ventral emotional striatum
conventional antipsychotics
haloperidol (Haldol)
chlorpromazine (Thorazine)
fluphenazine (Prolixin)
perphenazine (Trilafon)
thioridazine (Mellaril)
trifluoperazine (Stelazine)
Loxapine (Loxitane)
thiothixene (Navane)
pimozide (Orap)
the pines
clozapine
olanzapine
quetiapine
asenapine
zotepine
many dones and a rone
risperidone
paliperidone
ziprasidone
iloperidone
lurasidone
lumateperone
two pips and a rip
aripiprazole
brexpiprazole
cariprazine
Explain how secondary negative symptoms happen with drugs that target MESOLIMBIC/MESOSTRIATAL dopamine D2 receptors and how to treat it
dopamine neurons target nucleus accumbens (pleasure center) in the PFC. When dopamine is hyperactive here it causes positive symptoms of psychosis. Blocking D2 receptors here improves positive symptoms but can cause secondary negative symptoms. Treatment is reduce D2 blocker, switch to one that is better tolerated or use adjunctive meds (especially ones that treat depression)
explain how seconday negative symptoms happen by drugs that target MESOCORTICAL D2 receptors
in schizophrenia mesocortical pathway in the PFC is hypoactive which leads to negative symptoms. D2 blockers in this pathway make it more hypoactive worsening negative symptoms
Explain how targeting tuberoinfundibular dopamine D2 receptors causes prolactin elevation and what are some side effects of hyperprolactinemia
when dopamine binds to D2 receptors in this pathway it inhibits release of prolactin. When dopamine cant bind to these receptors prolactin is not inhibited and levels rise. Associated side effects are galactorrhea, gynecomastia, weight gain, sexual dysfunction
explain how targeting NIGROSTRIATAL D2 receptors cause motor side effects and what are some of these motor side effects
affects the reciprocal relationship between dopamine and acetylcholine which is important for normal movement. Causes drug-induced Parkinsonism, dystonia, akathisia, NMS, tardive dyskinesia
what happens with acute and chronic blockade of D2 receptors in the nigrostriatal pathway
Normal: dopamine binds to D2 and inhibits release of acetylcholine.
Acute: DIP, akathesia, dystonia
Chronic: Tardive dyskinesia
how does DIP occur from acute blocking D2 receptors in the nigrostriatal pathway and what are symptoms of DIP
when dopamine cant bind to its receptors it cant inhibit acetylcholine release. The excess acetylcholine causes increased excitation of postsynaptic M1 receptors on GABA neurons, which causes even more acetylcholine release which inhibits movements. You get akinesia, bradykinesia, rigidity, and tremor
how do you treat drug-induced Parkinsonism and how does the treatment work
anticholinergics (benztropine) Blocks the postsynaptic M1 receptors which restores the balance of dopamine and acetylcholine.
peripheral and central side effects of anticholinergics
peripheral: dry mouth, blurred vision, urinary retention, constipation
central: sedation and cognitive dysfunction
what happens when there is too high of net anticholinergic action
paralytic ileus
what is amantadine used for and how does it work
treat drug-induced parkinsonism without anticholinergic side effects
weak antagonism of NMDA glutamate receptors leading to downstream changes in dopamine activity in the indirect and direct striatal motor pathways
what is drug-induced acute dystonia, how does it occur, and how do you treat it
twisty-jerkys caused by D2 blockers often with first exposure. treatment with IM anticholinergic injection. Late onset is typically from tardive dyskinesia and anticholinergics actually make this type of dystonia worse
what is drug-induced akathesia and how do you treat it
internal and motor restlessness. Treated with benzodiazepines and B-adrenergic blockers blockers
what is neuroletpic malignant syndrome, what are the symptoms, and how do you treat it
potentially fatal complication of D2 blockade. Symptoms are extreme muscle rigidity, high fever, coma, death. Treatment is withdrawal of D2 blocker, use of muscle relaxers, and intense supportive treatments
pathophysiology of tardive dyskinesia
when there is chronic blockade of D2 receptors in the nigrostriatal pathway it causes upregulation of D2 receptors that are supersensitive to dopamine allowing way too much dopamine in which tells the stop pathway to go go go leading to tardive dyskinesia
How does D2 inhibition of the stop pathway regulate normal movement
dopamine in nigrostriatal pathway binds to postsynaptic D2 on GABA neurons. This inhibits the stop pathway, essentially telling it to go
pathophysiology of drug-induced parkinsonism
when D2 receptors are blocked, dopamine cant get in to tell the stop pathway to go, so it stops. Too much stop leads to DIP
treatment for tardive dyskinesia
VMAT inhibitors reserpine and tetrabenazine-like drugs
how does reserpine work
irreversibly binds to VMAT1 and VMAT2 so that dopamine cant get into presynaptic vesicles. Then it is rapidly destroyed by enzyme MAO intracellularly