Pharmacology
Effects on the Central Nervous System
The effects of neuroleptanesthetics on human CBF and CMRO2
have not been studied. In dogs, droperidol causes potent cerebral vasoconstriction
that results in a 40% reduction in CBF. No significant change in CMRO2
occurs during droperidol administration.[720]
The
EEG in conscious patients shows some reduction in frequency, with occasional slowing.
[721]
Low-dose droperidol has also been shown to
cause balance disturbances at the time of discharge when administered at doses used
for antiemetic prophylaxis.[722]
Droperidol may
produce extrapyramidal signs and worsens symptoms of Parkinson's disease. It may
also rarely precipitate malignant neuroleptic syndrome.
Effects on the Respiratory System
When used alone, droperidol has little effect on the respiratory
system.[175]
Droperidol (0.044 mg/kg) given to
surgical patients produced a slight reduction in respiratory rate,[723]
and administration of 3 mg intravenously had no significant effect on tidal volume
in volunteers.[176]
More detailed respiratory studies
are not available.
Effects on the Cardiovascular System
Like most antipsychotics, droperidol may prolong the QT interval
by delaying myocardial repolarization and precipitating torsades
de pointes. This effect appears to be dose dependent and may be of clinical
significance when other causes of QT prolongation are also present.[724]
Droperidol may also be associated with some antiarrhythmic effects that are much
like those of quinidine.[552]
[725]
Droperidol produces vasodilation with a decrease in blood pressure (see Table
10-2
). This effect is considered to be a result of moderate α-adrenergic
blockade.[719]
[726]
[727]
Importantly, the dopamine-induced increase
in renal blood flow (renal artery flow meter methodology) is not significantly impaired
by the administration of droperidol.[728]
Droperidol
has little effect on myocardial contractility.[725]
