First-Generation Antipsychotic Agents | Second-Generation Antipsychotic Drugs
All first-generation antipsychotic drugs are associated with
adverse effects, such as sedation, dystonia and muscle stiffness,
tremors, elevated prolactin levels, and weight gain. Akathisia (motor
restlessness) is particularly unpleasant and is often associated
with drug refusal and outpatient noncompliance. Cogwheeling, a shuffling
gait, pacing, agitation, and excessive leg-swinging may be indications
of acute extrapyramidal side effects. These acute side effects of
antipsychotic agents are usually dose related. In addition to acute
motor side effects, with long-term administration antipsychotic drugs
may also cause tardive dyskinesia, an involuntary movement disorder
most often characterized by puckering of the lips and tongue and/or
writhing of the arms or legs. The incidence of tardive dyskinesia
is about 5% per year of drug exposure among patients taking
first-generation antipsychotic drugs (Kane et al. 1984).
In about 2% of cases, tardive dyskinesia is severely disfiguring.
In some patients, tardive dyskinesia persists indefinitely, even
after the drug is discontinued. Because of the risk of tardive dyskinesia,
patients receiving long-term maintenance therapy should be evaluated
for abnormal involuntary movements at least every 6 months. Rating
instruments such as the Abnormal Involuntary Movement Scale may
be used (Table 20–2). Neuroleptic malignant syndrome, a
rare but potentially fatal adverse effect, is characterized by rigidity,
fever, autonomic instability, and elevated creatinine phosphokinase.