Antipsychotics

Question 1

Quetiapine

Answer 1

• atypical

- risk for QT interval prolongation

Question 2

Haloperidol

Answer 2

• typical
• strongest D2 blockade, lightest alpha 1 blockade, no muscarinic blockade (therefore weakest autonomic effects)
• extrapyramidal effects: parkinson-like syndrome, bradykinesia, rigidity, tremor

Question 3

Thioridazine

Answer 3

• typical antipsychotic
• moderate D2 blockade, strongest alpha 1 and muscarinic blockade (strongest autonomic effects)
• postural hypotension and failure to ejaculate
• atropine-like effects
• urinary retention

Question 4

Fluphenaine and trifluoperazine

Answer 4

• atypical
• more potent piperazine sidechains
• extrapyramidal effects

Question 5

Clozappine

Answer 5

• atypical
• D4 antagonist with alpha 1, serotonin, and M blockade
• unique tox: agranulocytosis
• reserved for tx-resistant schizophrenia

Question 6

Aripiprazole

Answer 6

• atypical
• partial agonist at D2
• metabolized by CYP3A4, which is inhibited by grapefruit, azoles, and protease inhibitors and induced by bupropion, fluoxetine, and paroxetine

Question 7

Pharmacokinetics of antipsychotics

Answer 7

• high 1st pass
• lipid soluble, can cross placenta
• extensively protein bound
• metabolized by P450s
• mesoridazine is a metabolite of thioridazine, which is more active than parent compound
• usually dose once/day (except quetiapine and ziiprasidone)