Paliperidone (9-OH-risperidone) is the primary active metabolite of the older antipsychotic risperidone. While its specific mechanism of action is unknown, it is believed that paliperidone and risperidone act via similar if not the same pathways. It has been proposed that the drug's therapeutic activity in schizophrenia is mediated through a combination of central dopamine Type 2 (D2) and serotonin Type 2 (5HT2A) receptor antagonism. Paliperidone is also active as an antagonist at alpha 1 and alpha 2 adrenergic receptors and H1 histaminergic receptors, which may explain some of the other effects of the drug. Paliperidone was approved by the FDA for treatment of schizophrenia on December 20, 2006. Very common adverse effects are: headache, tachycardia, somnolence and insomnia.

Aripiprazole is the first next-generation atypical antipsychotic. The unique actions of aripiprazole in humans are likely a combination of "functionally selective" activation of D(2) (and possibly D(3))-dopamine receptors and serotonin 5-HT(1A) receptors, coupled with inhibition of 5-HT(2A) receptors. Aripiprazole was approved by FDA (Abilify trade name) for the treatment of schizophrenia; manic and mixed episodes associated with bipolar I disorder; major depressive disorder; irritability associated with autistic disorder; Tourette’s disorder and agitation associated with schizophrenia or bipolar mania.

Ziprasidone is atypical antipsychotic, approved by the U.S. Food and Drug Administration for the treatment of schizophrenia, and acute mania and mixed states associated with bipolar disorder. Intramuscilar injections of Ziprasidone are indicated for rapid control of the agitation in schizophrenic patients. Ziprasidone is used off-label for treatment of major depressive disorder, anxiety, obsessive compulsive disorder, borderline personality disorder. Ziprasidone functions as an antagonist at the D2, 5HT2A, and 5HT1D receptors, and as an agonist at the 5HT1A receptor.

Dexmethylphenidate is the dextrorotary form of methylphenidate. Dexmethylphenidate is marketed under the trade name Focalin. Focalin (dexmethylphenidate hydrochloride) is the d-threo-enantiomer of racemic methylphenidate hydrochloride, which is a 50/50 mixture of the d-threo and l-threoenantiomers. Focalin is a central nervous system (CNS) stimulant, available in three tablet strengths. Each tablet contains dexmethylphenidate hydrochloride 2.5, 5, or 10 mg for oral administration. Dexmethylphenidate is used as a treatment for ADHD, ideally in conjunction with psychological, educational, behavioral or other forms of treatment. Methylphenidate blocks dopamine uptake in central adrenergic neurons by blocking dopamine transport or carrier proteins. Methylphenidate acts at the brain stem arousal system and the cerebral cortex and causes increased sympathomimetic activity in the central nervous system. Methylphenidate is a catecholamine reuptake inhibitor that indirectly increases catecholaminergic neurotransmission by inhibiting the dopamine transporter (DAT) and norepinephrine transporter (NET), which are responsible for clearing catecholamines from the synapse, particularly in the striatum and meso-limbic system.

Armodafinil is the R-enantiomer of modafinil, a wake-promoting agent, that primarily affects areas of the brain involved in controlling wakefulness. Armodafinil is an indirect dopamine receptor agonist; both armodafinil and modafinil bind in vitro to the dopamine transporter and inhibit dopamine reuptake. Armodafinil tablets are indicated to improve wakefulness in adult patients with excessive sleepiness associated with obstructive sleep apnea (OSA), narcolepsy, or shift work disorder (SWD). Once-daily armodafinil was generally well tolerated in adult patients with excessive sleepiness associated with OSA (despite treatment of the underlying condition), narcolepsy or SWSD.

Quetiapine, marketed as SEROQUEL XR, is an atypical antipsychotic approved for the treatment of schizophrenia, bipolar disorder, and along with an antidepressant to treat major depressive disorder. The mechanism of action of SEROQUEL XR in the treatment of schizophrenia, bipolar disorder and major depressive disorder (MDD), is unknown. However, its efficacy in schizophrenia could be mediated through a combination of dopamine type 2 (D2) and serotonin type 2A (5HT2A) antagonism. The active metabolite, N-desalkyl quetiapine (norquetiapine), has similar activity at D2, but greater activity at 5HT2A receptors, than the parent drug (quetiapine). Quetiapine’s efficacy in bipolar depression and MDD may partly be explained by the high affinity and potent inhibitory effects that norquetiapine exhibits for the norepinephrine transporter. Antagonism at receptors other than dopamine and serotonin with similar or greater affinities may explain some of the other effects of quetiapine and norquetiapine: antagonism at histamine H1 receptors may explain the somnolence, antagonism at adrenergic α1b receptors may explain the orthostatic hypotension, and antagonism at muscarinic M1 receptors may explain the anticholinergic effects. Quetiapine and norquetiapine have affinity for multiple neurotransmitter receptors including dopamine D1 and D2, serotonin 5HT1A and 5HT2A, histamine H1, muscarinic M1, and adrenergic α1b and α2 receptors. Quetiapine differs from norquetiapine in having no appreciable affinity for muscarinic M1 receptors whereas norquetiapine has high affinity. Quetiapine and norquetiapine lack appreciable affinity for benzodiazepine receptors.

Ropinirole (INN; trade names Requip, Repreve, Ronirol, Adartrel) is a dopamine agonist of the non-ergoline class of medications, used in the treatment of Parkinson's disease and restless legs syndrome. Although the precise mechanism of action of ropinirole as a treatment for Parkinson's disease is unknown, it is believed to be related to its ability to stimulate dopamine receptors in the striatum. This conclusion is supported by electrophysiologic studies in animals that have demonstrated that ropinirole influences striatal neuronal firing rates via activation of dopamine receptors in the striatum and the substantia nigra, the site of neurons that send projections to the striatum. Ropinirole is a nonergot dopamine agonist with high relative in vitro specificity and full intrinsic activity at the D2 subfamily of dopamine receptors, binding with higher affinity to D3 than to D2 or D4 receptor subtypes. The relevance of D3 receptor binding in Parkinson's disease is unknown. The mechanism of ropinirole-induced postural hypotension is presumed to be due to a D2 -mediated blunting of the noradrenergic response to standing and subsequent decrease in peripheral vascular resistance. Ropinirole can cause nausea, dizziness, hallucinations, orthostatic hypotension, and sudden sleep attacks during the daytime. Unusual side effects specific to D3 agonists such as ropinirole and pramipexole can include hypersexuality, punding, and compulsive gambling, even in patients without a history of these behaviors.

Pramipexole is a nonergot dopamine agonist with high relative in vitro specificity and full intrinsic activity at the D2 subfamily of dopamine receptors, binding with higher affinity to D3 than to D2 or D4 receptor subtypes. The relevance of D3 receptor binding in Parkinson's disease is unknown. The precise mechanism of action of Pramipexole as a treatment for Parkinson's disease is unknown, although it is believed to be related to its ability to stimulate dopamine receptors in the striatum. This conclusion is supported by electrophysiologic studies in animals that have demonstrated that Pramipexole influences striatal neuronal firing rates via activation of dopamine receptors in the striatum and the substantia nigra, the site of neurons that send projections to the striatum. Pramipexole is used for the treatment of signs and symptoms of idiopathic Parkinson's disease.

Fenoldopam (marketed under the brand name Corlopam) is a drug and synthetic benzazepine derivative which acts as a selective D1 receptor partial agonist. Fenoldopam is a rapid-acting vasodilator. It is an agonist for D1-like dopamine receptors and binds with moderate affinity to α2-adrenoceptors. It has no significant affinity for D2-like receptors, α1 and β adrenoceptors, 5HT1 and 5HT2 receptors, or muscarinic receptors. Fenoldopam is a racemic mixture with the R-isomer responsible for the biological activity. The R-isomer has approximately 250-fold higher affinity for D1-like receptors than does the S-isomer. Fenoldopam Mesylate Injection, USP is indicated for the in-hospital, short-term (up to 48 hours) management of severe hypertension when rapid, but quickly reversible, emergency reduction of blood pressure is clinically indicated, including malignant hypertension with deteriorating end-organ function.

Cabergoline is a long-acting dopamine receptor agonist with a high affinity for D2 receptors. Results of in vitro studies demonstrate that cabergoline exerts a direct inhibitory effect on the secretion of prolactin by rat pituitary lactotrophs. It is FDA approved for the treatment of hyperprolactinemic disorders, either idiopathic or due to pituitary adenomas. Common adverse reactions include constipation, nausea, dizziness, headache and fatigue. Cabergoline should not be administered concurrently with D-antagonists, such as phenothiazines, butyrophenones, thioxanthenes, or metoclopramide.