TOXICOLOGYEffect is usually local only, but may become systemic with:
■ Inadvertent injection into a blood vessel
■ Use of large volumes
■ Premature release of cuff with intravenous regional anesthesia (Bier block)
Severity is related to dose and route.
MECHANISM/TOXICITY
■ Inhibition of Na++channels→reversible blockade of the initiation and
propagation of action potentials along affected nerve.
■ Methemoglobinemia is possible with exposure to benzocaine or prilocaine.
SYMPTOMS/EXAM
■ Mild overdose
■ Headache, drowsiness, dizziness/lightheadedness
■ Anxiety, tinnitus, numbness of mouth
■ Hypertension, tachycardia
■ Severe overdose
■ Confusion, tremors, seizures and coma
■ Respiratory depression and apnea
■ Hypotension, bradycardia, asystole
■ Widening of PR interval and QRS complex, VT or Vfib
■ Bupivicaine
■ More cardiotoxic than other local anesthetics
■ Not indicated for IV regional anesthesia
DIAGNOSIS
■ Usually clear from history and exam
■ ECG, as needed
■ Co-oximetry if methemoglobinemia is suspected
TREATMENT
■ Supportive care
■ Benzodiazepines for seizures
■ Standard ACLS for cardiac dysrhythmias
■ Discontinue use of agent.
■ No role for decontamination or enhanced elimination
COMPLICATIONS
■ Allergic reactions
■ Ester anesthetics are responsible for most, likely due to metabolite
para-aminobenzoic acid (PABA).
■ Preservativemethylparabenis found in multidose vials of amide anes-
thetics and is chemically related to PABA.
■ Inadvertent IV injection of epinephrine (in “with epi” preparations)
METHYLXANTHINESAgents in this class include:
■ Caffeine: Most commonly used drug in the world; marketed for
increased alertness, weight loss, migraine therapy, and neonatal apnea
and bradycardia
All amide local anesthetics
have two “ i”s in their name.Toxicity is characterized
primarily by neurologic
symptoms, but may include
cardiovascular symptoms in
large overdoses.Pregnant women are
disproportionately affected by
bupivicaine, and it is no
longer indicated for obstetric
anesthesia.