Typical antipsychotics (sometimes referred to as conventional antipsychotics or conventional neuroleptics) are a class of antipsychotic drugs first developed in the 1950s and used to treat psychosis (in particular, schizophrenia), and are generally being replaced by atypical antipsychotic drugs. Typical antipsychotics may also be used for the treatment of acute mania, agitation, and other conditions.
Traditional antipsychotics are broken down into low-potency and high-potency classifications. Fluphenazine and haloperidol are examples of high-potency typical antipsychotics, and chlorpromazine is an example of a low potency antipsychotic. High-potency typical antipsychotics tend to be associated with more extrapyramidal side-effects (EPS) and less histaminic (e.g. sedation), alpha adrenergic (e.g. orthostasis) and anticholinergic (e.g. dry mouth) side effects, while low-potency typical antipsychotics tend to be associated with less EPS but more H1, alpha1, and muscarinic side effects.
Some of the high-potency antipsychotics, particularly haloperidol and fluphenazine, 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 has trouble with compliance. 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. For practical reasons, depot preparations are limited to high-potency antipsychotics so the treating physician has a limited choice. It is therefore preferable to use oral medications if the cooperation and compliance of the patient can be obtained.
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 parkinsonism, dystonias, and akathisia. Anticholinergics such as benztropine and diphenhydramine are commonly prescribed to treat the symptoms of EPS.
Risks of serious side-effects
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 than 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.
- Fluphenazine (Prolixin®)
- Haloperidol (Haldol®)