Antipsychotics Flashcards
What is the dopamine hypothesis?
-blocking of dopamine activity in the CNS can improve psychosis
Name 3 Typical Anti-psychotics.
(1st Generation)
- Haloperidol
- Chlorpromazine
- Trifluoperazine
What does activation of D2 receptors result in?
- inhibition of adenylyl cyclase
>reduce cAMP
Where are the D2 receptors found ?
- Limbic system
- Prefrontal cortex
- Basal ganglia
What is the MAIN MOA of Typical Anti-psychotics?
- blockade of D2 receptors
What conditions can be treated with Typical Anti-psychotics? (7)
- Schizophrenia (+)ve symptoms
- Psychosis
- Mania
- OCD
- Delirium (Haloperidol)
- Tourette’s Syndrome
- Huntington’s disease
Which pathway do the typical anti-psychotics act on for it to cause motor dysfxn?
- Nigrostriatal Pathway
What other NTs are affected by the intake of Typical Anti-psychotics?
- Serotonin
- Histamine
- Epinephrine
- Ach
Which typical anti-psychotic is known to block histamine and alpha-1 receptors MORE than D2 r.?
Chlorpromazine
Which typical anti-psychotic blocks the D2 receptors the most?
Haloperidol
What are S.Es Typical Antipsychotics when blocking dopamine?
Parkinsonism (rigidity/bradykinesia/resting tremor) Hyperprolactinemia >Amenorrhea >Galactorea >Gynecomastia
Anti-Emetic (esp. Chlorpromezine)
What occurs as a result of other receptors being blocked?
- Ach Blockade> DRY MOUTH and CONSTIPATION
- A-1 receptors> Hypotension
- Histamine receptor > sedation and CONSTIPATION
What is the pyramidal system?
What occurs if this system is damaged?
- corticospinal system —because it runs through the PYRAMIDS of the medulla
- WEAKNESS when damaged
What is the extrapyramidal system responsible for?
-modulation of the movements
- and it involves the Basal Ganglia Nuclei and the associated tracts
> MOVEMENT DISORDERS occur with damage to the extrapyramidal system
What are EPS?
-Movement S.Es: Akathisia, Bradykinesia, Tardive dyskinesia, dystonia
What is dystonia?
- spasms or stiffness
- occurs within HOURS/days of administering the drug
- jaw is locked/ can’t move arm
How to treat dystonia?
Benztropine
-anticholinergic drug; blocks M1 receptors
What is the most COMMON EPS with Anti-psychotic drugs?
Akathisia- restlessness, URGE to move
- mistaken for worsening of psychotic condition
When does Akathisia usually set in?
- within DAYS
How to treat Akathisia?
- lower the dose
- benzodiazepines
- propanolol
Which EPS kicks in within WEEKS of drug administration?
- Bradykinesia
drug-induced Parkinsonism
How to treat Bradykinesia?
Benztropine
like dystonia- frozen muscles; slow movement
What occurs with Tardive Dyskinesia?
Choreoathetosis
- twisting and writhing, irregular MOTIONs
- mouth, tongue, face limbs
- —sets in months/ years after use of drugs
- permanent!
Name 3 High potent Typical Antipsychotics.
And why are they of high potency?
- haloperidol
- fluphenazine
- trifluoperazine
- the main s.e: EPS with just 1mg dosage
List 2 low potency Typ.Antipsychotics.
- Chlorpromazine
- Thioridazine
—-need 50-100mg for therapeutic effect
What form of S.Es are seen with the low potency drugs?
More NEUROLOGICAL s.es
- sedation
- dry mouth
What is a RARE, dangerous S.E to Typical Antipsychotics?
NMS—Neuroleptic Malignant Syndrome (onset= 7-10 days after administr.)
—-watch out for RIGID MUSCLES (EPS) & FEVER
What 3 other conditions are seen with NMS?
- Mental Status Changes (encephalopathy)
- elevated Creatine Kinase (Muscle Damage)
- Myoglobinuria> acute renal failure (rhabdomyolysis)
How to treat NMS?
- Dantrolene (muscle relaxant)
- bromocriptine (Dopamine Agonist)
Which Anti-psychotic is known to PROLONG the QT interval on the ECG? Dangers of prolonged QT?
- IV Haloperidol
- —Torsades de pointes may turn up
Which Typical antipsychotic results in corneal deposits?
- Chlorpromazine
> will ACCELERATE the ageing of the lens
Which typical anti-psychotic results in RETINAL deposits? How does it present as?
- Thioridazine
- browning of their vision
Main diff. between TYPICAL and ATYPICAL anti-psychotics?
- atypical: LESS EPS s.es
Why are second gen. antipsychotics known to reduce psychotic symptoms more efficiently than typical antispsychotics?
- —d/t its greater Serotonin blocking receptor effect
- increased 5-HT2A receptors activity is said to cause hallucinations
WHat are the 2 main s.e of CLOZAPINE?
-bone marrow toxicity
>AGRANULOCYTOSIS ….therefore should monitor weekly (then monthly later)
-SEIZURES (2-5%)
What to do if pt presents with: Amenorrhea, Galactorhea and Gynaecomastia in men?
- measure prolactin level
- scan head
- check med list
High rates of Hyperprolactinemia is seen in what drugs?
- Haloperidol
- Fluphenazine
- RISPERIDONE
- PALIPERIDONE
What is ARIPIPRAZOLE?
- its a D2 partial AGONIST
- —less dopamine blockade s.e
What is the S.E of ARIPIPRAZOLE?
-akathisia
Risks of use of anti-psychotics on elderly?
- STROKE
- THROMBOEMBOLISM
