Quetiapine vs Olanzapine: what is the difference?

How they differ

Both are atypical antipsychotics that block dopamine D2 and serotonin 5-HT2A receptors, and they differ most in how tightly they hold on. Quetiapine binds D2 loosely and comes off quickly, which is why it causes relatively few movement side effects and why it is heavily sedating at lower amounts through its antihistamine activity. Olanzapine binds more firmly and is the more reliably antipsychotic of the two, at the cost of a stronger association with weight gain and metabolic change. Both carry sedation, and both are prescription only. Quetiapine is a dibenzothiazepine at 383.5 and olanzapine a thienobenzodiazepine at 312.4, so they are structural cousins rather than the same skeleton.

Side by side

Common questions

What is the difference between Quetiapine and Olanzapine?

Both are atypical antipsychotics that block dopamine D2 and serotonin 5-HT2A receptors, and they differ most in how tightly they hold on. Quetiapine binds D2 loosely and comes off quickly, which is why it causes relatively few movement side effects and why it is heavily sedating at lower amounts through its antihistamine activity. Olanzapine binds more firmly and is the more reliably antipsychotic of the two, at the cost of a stronger association with weight gain and metabolic change.

Is Quetiapine bigger than Olanzapine?

Quetiapine is the heavier molecule, 383.5 g/mol against 312.4 g/mol for Olanzapine. Quetiapine is C21H25N3O2S and Olanzapine is C17H20N4S.