Excessive dosage, or short intervals between doses, can result in high
levels of lignocaine or its metabolites and serious adverse effects. Patients
should be instructed to strictly adhere to the recommended dosage and
administration guidelines (the management of serious adverse reactions
may require the use of resuscitative equipment, oxygen and other
The lowest dose that results in effective anaesthesia should be used to avoid high
plasma levels and serious adverse effects. Tolerance to elevated blood levels
varies with the status of the patient.
Debilitated, elderly and/or acutely ill patients and children should be given reduced
doses commensurate with their age and physical status.
Absorption from wound surfaces and mucous membranes is relatively high,
especially in the bronchial tree. Because of the possibility of significant systemic
absorption, Xylocaine Jelly should be used with caution in patients with
traumatised mucosa and/or sepsis in the region of the proposed application.
If the dose or site of administration is likely to result in high blood levels,
lignocaine, in common with other local anaesthetics, should be used with caution
in patients with epilepsy, impaired cardiac conduction, bradycardia, impaired
hepatic function, severe shock and patients with severe renal dysfunction.
"Carcinogenic and Mutagenic Potential
Genotoxicity tests with lignocaine are inconclusive. In genotoxicity studies, a
metabolite of lignocaine, 2,6 xylidine, showed evidence of activity in some tests
but not in other tests. This metabolite has been shown to have carcinogenic
potential (nasal and subcutaneous tumours) in preclinical toxicological studies
evaluating chronic exposure. "
I appreciate that it's possible to be too cautious, but I'm inclined to avoid anything with carcinogenic potential if there's an alternative.