Antipsychotic plasma levels

Question 1

How does divalproex affect paliperidone?

Answer 1

Divalproex is an inhibitor, so it can increase the AUC of paliperidone by up to 50% because paliperidone is the metabolite of risperidone, and it is converted into its form by CYP2D6.

Question 2

What side effect does risperidone uniquely have the greatest propensity for?

Answer 2

Hyperprolactinemia, because it binds to efflux pgp transporters more frequently than other APs, and gets circulated towards the anterior pituitary.