haloperidol

introduction

droperidol is a butyrophenone type antipsychotic agent which is similar to droperidol (Droleptan)
it produces marked tranquillization and sedation as well as having an anti-emetic effect
it potentiates other CNS depressants
also produces mild alpha-adrenergic blockade, peripheral vascular dilatation, hypotension, and reduction of the pressor effect of adrenaline
as with all drugs, benefits of using haloperidol should be weighed against the potential risk

known HS
severe CNS depression
Parkinson's disease
phaeochromocytoma - severe hypertension and tachycardia may occur
lactation
prolonged QTc > 450msec (eg. congenital causes, or patients at risk of this such as other medications which cause it, hypokalaemia, hypomagnesaemia, hypocalcaemia, bradycardia, etc)
relative C/I: acute alcohol intoxication

FH sudden death
PH cardiac disease
acute kidney injury (AKI) / acute renal failure (ARF) or chronic renal failure
liver impairment
chronic obstructive pulmonary disease (COPD) or significant respiratory disease
patients at risk of electrolyte disturbances such as those on diuretics
ensure cardiac monitoring and resuscitation facilities are nearby in case the low risk of torsade de pointes VT eventuates, or the patient has a respiratory arrest (more likely to occur withconcurrent sedatives such as opiates and opioids, particularly if these are given rapidly iv)
reduce initial doses of concurrent opiates and opioids to 1/3rd of normal doses
pregnancy in 3rd trimester as risk of neonatal extrapyramidal effects
lactation
safety not established in children under 2yrs
no use of machinery or driving within 24hrs of dose if dose > 5mg (10hrs for 5mg doses)
elderly
glaucoma patients
patients at risk of urinary retention
hyperthyroidism
bipolar disorder as rapid change to depressed state may occur

rapidly absorbed from the gastrointestinal tract following oral administration but appears to undergo first-pass metabolism in the liver
peak plasma levels within 2-6 hours of oral dosing and ~20 minutes after im administration
onset of action is 3-10 minutes following intravenous or intramuscular administration, although maximum effect may be delayed until 30 minutes
plasma half life 12-28hrs

sedation, dizziness
hypotension - can Rx with iv fluids +/- metaraminol (Aramine)
tachycardia
anticholinergic effects including urinary retention may occur
respiratory depression especially with concurrent sedatives or opiates and opioids
extrapyramidal reactions such as oculogyric crisis, dystonic reactions, akathisia - may require Rx with benztropine, etc
neuroleptic malignant syndrome (NMS)
torsade de pointes VT if develops prolonged QTc
seizures may occur in toxic doses
other adverse effects, most are not clinically important in the ED setting when it is used to Rx severe agitation

healthy adults excluding the elderly:
- 2-10mg im or slow iv
- titrated slow iv boluses may be used every 30-60 minutes up to max. 100mg in 24hrs
- ongoing maintenance dose usually at half the total daily dose required to gain control, and gioven at least 4-8hrs after the last controlling dose