Table 1.

APDs and relationship with appetite dysregulation and obesity.

Antipsychotics (SGAs)	Receptors	Activity
•Olanzapine (antagonism) •Clozapine (antagonism) •Quetiapine (antagonism) •Risperidone (antagonism) •Ziprasidone and Aripiprazole (5HT1a agonism, 5HT2a, and 5HT2c antagonism)	5HT1a, 5HT2a, and 5HT2c	Obesity and dysregulated food intake (observed mainly in olanzapine, clozapine, risperidone, and quetiapine treatment) (41–46).
•Olanzapine (antagonism) •Clozapine (antagonism) •Quetipine (antagonism) •Risperidone (antagonism) •Ziprasidone (antagonism)	H1 /H3	Obesity and dysregulated food intake (observed mainly in olanzapine, clozapine, and quetiapine treatment) (56–70).
•Olanzapine (antagonism) •Clozapine (antagonism) •Quetipine (antagonism) •Risperidone (mild antagonism) •Ziprasidone (antagonism with low affinity) •Aripiprazole (partial D2 agonism)	D2	Obesity and dysregulated food intake (observed mainly in olanzapine and clozapine treatment) (71–74).
•Olanzapine (antagonism) •Clozapine (antagonism)	M3	Obesity, dysregulated food intake, and peripheral effects (77–82).

Different APDs are shown in the table in connection with 5HT1a, 5HT2a, 5HT2c, H1/H3, D2, and M3 receptor systems in the regulation of appetite and obesity. Both clozapine and olanzapine demonstrate a strong connection between food intake and weight gain.

5HT1a,2a,2c, Serotonin receptors; H1/H3, Histamine receptor; M3, Muscarinic receptor; D2, Dopamine receptor; SGAs, Second-generation antipsychotics.