Side Effects of Typical Anti Psychotic Drugs

8/11/2019 Side Effects of Typical Anti Psychotic Drugs

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Antipsychotics have been classified into2 groups: Typicaland Atypical

Typical antipsychotics are those whichtypically produce EPS at clinicallyeffective doses.

Atypical antipsychotics are those whichare less likely to produce EPS at clinicallyeffective doses.


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Also called neuroleptics due to theirinhibitory effect on locomotion activity.

Their major mode of action is to block

dopamine D2 receptors in the limbicsystem

They vary in affinity for the D2 receptor,

from low affinity drugs which require highdoses for clinical efficacy, to high affinitydrugs which are effective at lower doses


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For typical neuroleptics, the adverse effectsthat are most routinely concerning areextrapyramidal adverse effects (EPS).

High potency drugs (eg haloperidol,fluphenazine) are more likely to produce EPSthan low potency agents (eg chlorpromazine,thioridazine).

The latter may have lower potential for EPSthan other typical neuroleptics because of itsrelatively higher affinity for muscarinicreceptors.


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There are a wide range of EPS producedby typical neuroleptics, including thefollowing: Dystonic reactions (when first administered)

Akathisia (during the first 2-3 weeks)

Parkinsonism (during the first several weeks with

variable persistence) Neuroleptic malignant syndrome (at any time

point )

Tardive dyskinesia


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Characterized by intermittent spasmodic or

sustained involuntary contractions of muscles

in the face, neck, trunk, pelvis, and extremities

They are rarely life threatening, yet are veryuncomfortable and often produce significant

anxiety and distress for patients

Can be treated with parenteral anticholinergicagents or diphenhydramine, an antihistamine

with some anticholinergic properties.


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This may be the most common of the EPSeffects, occurring in up to 70% of patientstreated long term with haloperidol.

It refers to a subjective uncomfortableexperience of motor restlessness which isrelieved my movement. Patients will complainof discomfort, and manifest increases in

psychomotor behavior. These symptoms can be so distressing as to

increase the risk of agitation or even suicidalbehavior.


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Women are believed to be at higher risk

Management:

Reduction in dosage or switching to anatypical antipsychotic drug, or drug less likelyto cause akathisia

If not feasible, symptoms may respond to

anticholinergics usually within 3-7 days. Other options: low doses of benzodiazepines

or beta-blockers


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A neurological syndrome characterized bytremor, hypokinesia, rigidity, and posturalinstability.

Resembles idiopathic parkinsonism Severe neuroleptic induced parkinsonism

may resemble depression or negative

symptoms of schizophrenia However associated motor signs and time

course of symptoms in relation to startingantipsychotic treatment distinguishes it


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Onset and severity of antipsychoticinduced parkinsonism is related tomedication dosage, like akathisia

Hence lowering dosage or switching tomedication that is less likely to cause theeffect may provide significant relief

If not feasible, anticholinergics may providerelief, usually within 3-7 days


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Involuntary movements of the tongue,lips, face, trunk, and extremities

Emerges at various rates depending onage, sex and diagnosis.

It is related to dose, and will be less likely

with lower doses of typical neuroleptics It is ordinarily reversible, although

irreversible/severe forms can occur.


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Management:

There are no definitive treatments fortardive dyskinesia

Best way to minimize the occurrence is touse an atypical antipsychotic instead oftypical agent

These drugs are associated with a muchlower risk of tardive dyskinesia

Periodic screening with a structuredassessment tool (eg AIMS)


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A rare life-threatening side-effect related to anapparent compromise of the neuromuscular andsympathetic nervous system

Usually occurs at the initiation of treatment with ahigh-potency agent

It is characterized by: Muscle rigidity

Breakdown of muscle fibers, leading to large increases in

plasma creatine kinase Fever

Autonomic instability

Changing levels of consciousness

Sometimes death


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Management: Immediate discontinuation of medication is

essential.

Applying external hypothermia

Supporting blood pressure

Administering a direct-acting dopamineagonist (eg. Bromocriptine, Pergolide) whichblocks release of intracellular stored calciumions

After successful treatment, an atypicalantipsychotic should be used


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Typical neuroleptic drugs produce a widevariety of other side-effects including:

Weight gain

Seizures (especially pimozide)

Sedation

Hypotension

Elevated liver enzymes

Retinitis pigmentosa (thioridazine)


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Orthostatic hypotension

Prolongation of QT interval (low potencyphenothiazines, pimozide)

Anticholinergic effects (mesoridazine,chlorpromazine, thioridazine)

All typical neuroleptics produce marked

increases in serum prolactin levels. Theprolactin elevations may affect sexualfunction in both males and females.


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Side Effects of Typical Anti Psychotic Drugs

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