Drug	Evidence for use in patients with Alzheimer's disease?	Evidence for use in patients with Parkinson's disease?	Dosage in the elderly	Common or major side effects*	Cytochrome P450 system	Cost per month†
Clozapine (Clozaril)	Limited	Yes	6.5 to 75 mg per day	Agranulocytosis, hypotension, seizures, sialorrhea, weight gain, tachycardia, hyperthermia, hyperglycemia	1A2‡	$11 to $132
					2D6§
Olanzapine (Zyprexa)	Yes	No	1.25 to 5 mg per day	Weight gain, hypotension, seizures, hyperglycemia	1A2‡	$78 to $184
Quetiapine (Seroquel)	No	Yes	12.5 to 200 mg per day	Hypotension, headache, weight gain, cataract formation	3A4ll	$22 to $151
Risperidone (Risperdal)	Yes	No	0.25 to 3 mg per day	Extrapyramidal symptoms, hypotension, hyperprolactinemia, insomnia, weight gain	2D6§	$84 to $164
Ziprasidone (Geodon)	No	No	Not studied	QT prolongation, rash, hypertension	3A4ll	N/A