|Potency||Examples||Adverse effect profile|
|high-potency||fluphenazine and haloperidol||more extrapyramidal side effects (EPS) and less histaminic (e.g. sedation), alpha adrenergic (e.g. orthostasis) and anticholinergic effects (e.g. dry mouth)|
|low-potency||chlorpromazine||less EPS but more H1, α1, and muscarinic blocking effects|
Some of the high-potency antipsychotics have been formulated as the decanoate ester (e.g. fluphenazine decanoate) to allow for a slow release of the active drug when given as a deep, intramuscular injection. This has the advantage of providing reliable dosing for a person who doesn't want to be drugged. Depot injections can also be used for involuntary community treatment patients to ensure compliance with a community treatment order when the patient would refuse to take daily oral medication. Depot preparations were limited to high-potency antipsychotics so choice was limited. It is therefore preferable to use oral medications if the cooperation and compliance of the patient can be assured.
The oldest depots available were haloperidol and fluphenazine, with flupentixol and zuclopenthixol as more recent additions. All have a similar, predominantly extrapyramidal, side effect profile though there are some variations between patients. More recently a long acting preparation of the atypical antipsychotic risperidone has become available, offering a new choice. Risperidone still has a higher incidence of extrapyramidal effects than some other drugs available however.
Side effects vary among the various agents in this class of medications, but common side effects include: dry mouth, muscle stiffness, muscle cramping, tremors, EPS and weight-gain. EPS is a cluster of symptoms consisting of akathisia, parkinsonism, dystonias, Anticholinergics such as benztropine and diphenhydramine are commonly prescribed to treat the symptoms of EPS.
There is a significant risk of the serious condition tardive dyskinesia developing as a side effect of typical antipsychotics. The risk of developing tardive dyskinesia after chronic typical antipsychotic usage varies on several factors, such as age and gender. The commonly reported incidence of TD among younger patients is about 5% per year. Among older patients incidence rates as high as 20% per year have been reported. The average prevalence is approximately 30%. There are no treatments that have consistently been shown to be effective for the treatment of tardive dyskinesias, however branched chain amino acids, melatonin, and vitamin E have been suggested as possible treatments. The atypical antipsychotic clozapine has also been suggested as an alternative antipsychotic for patients experiencing tardive dyskinesia. Tardive dyskinesia may reverse upon discontinuation of the offending agent or it may be irreversible.
Neuroleptic malignant syndrome, or NMS, is a rare, but potentially fatal side effect of antipsychotic treatment. NMS is characterized by fever, muscle rigidity, autonomic dysfunction, and altered mental status. Treatment includes discontinuation of the offending agent and supportive care.
The role of typical antipsychotics has come into question recently as studies have suggested that atypical antipsychotics may increase the risk of death in elderly patients. A retrospective cohort study from the New England Journal of Medicine on Dec. 1, 2005 showed an increase in risk of death with the use of typical antipsychotics that was on par with the increase shown with atypical antipsychotics. This has led some to question the common use of antipsychotics for the treatment of agitation in the elderly, particularly with the availability of alternatives such as mood stabilizing and antiepileptic drugs.
Effects of clozapine and typical antipsychotic drugs on plasma 5-HT turnover and impulsivity in patients with schizophrenia: A cross-sectional study
Sep 01, 2000; Objective: To compare the efficacy of clozapine with typical antipsychotic drugs in controlling impulsivity and to explore the...
Effects of typical antipsychotic drugs and risperidone on the quality of sleep in patients with schizophrenia: A pilot study
Sep 01, 1999; Objective: To investigate the effects of a newer antipsychotic drug, risperidone (a potent serotonin 5HT^sub 2A/2C^- and dopamine...
Assessing Residual Confounding of the Association between Antipsychotic Medications and Risk of Death using Survey Data
Feb 01, 2009; Abstract Background: Nonrandomised studies on the causal effects of psychotropic medications may be biased by patient...