Adverse experiences following the administration of etidocaine are similar in nature to those observed with other amide local anesthetic agents. These adverse experiences are, in general, dose-related and may result from high plasma levels caused by excessive dosage, rapid absorption or unintended intravascular injection, or may result from a hypersensitivity, idiosyncrasy or diminished tolerance on the party of the patient. Serious adverse experiences are generally systemic in nature. The following types are those most commonly reported:
Central Nervous System
CNS manifestations are excitatory and/or depressant and may be characterized by light-headedness, nervousness, apprehension, euphoria, confusion, dizziness, drowsiness, tinnitus, blurred or double vision, vomiting, sensations of heat, cold or numbness, twitching, tremors, convulsions, unconsciousness, respiratory depression and arrest. The excitatory manifestations may be very brief or may not occur at all, in which case the first manifestation of toxicity may be drowsiness merging into unconsciousness and respiratory arrest.
Drowsiness following the administration of etidocaine is usually an early sign of a high blood level of the drug and may occur as a consequence of rapid absorption.
Cardiovascular manifestations are usually depressant and are characterized by bradycardia, hypotension, and cardiovascular collapse, which may lead to cardiac arrest.
Allergic reactions are characterized by cutaneous lesions, urticaria, edema or anaphylactoid reactions. Allergic reactions may occur as a result of sensitivity either to local anesthetic agents or to the methylparaben used as a preservative in multiple dose vials. The detection of sensitivity by skin testing is of doubtful value.
The incidences of adverse reactions associated with the use of local anesthetics may be related to the total dose of local anesthetic administered and are also dependent upon the particular drug used, the route of administration and the physical status of the patient.
In the practice of caudal or lumbar epidural block, occasional unintentional penetration of the subarachnoid space by the catheter may occur. Subsequent adverse effects may depend partially on the amount of drug administered subdurally. These may include spinal block of varying magnitude (including total spinal block), hypotension secondary to spinal block, loss of bladder and bowel control, and loss of perineal sensation and sexual function. Persistent motor, sensory and/or autonomic (sphincter control) deficit of some lower spinal segments with recovery (several months) or incomplete recovery have been reported in rare instances when caudal or lumbar epidural block has been attempted. Backache and headache have also been noted following use of these anesthetic procedures.
There have been reported cases of permanent injury to extraocular muscles requiring surgical repair following retrobulbar administration.
There have been rare reports of TRISMUS in patients who have received Duranest (etidocaine HCl) for dental anesthesia. Onset of symptoms occurs within hours or days upon resolution of blockade. No correlation has been demonstrated with dosage, administration technique or dental procedure. In most patients, symptoms resolved within days to weeks, although some reports have suggested that symptoms were present for many months. Symptomatic treatment with analgesics, moist heat and physiotherapy was helpful in some cases.