Lidocaine Other names: Lignocaine

If the dose or site of administration is likely to result in high blood levels, lidocaine, in common with other local anaesthetics, should be used with caution in patients with impaired hepatic function, who will require special attention to prevent potentially dangerous side effects.

If the dose or site of administration is likely to result in high blood levels, lidocaine, in common with other local anaesthetics, should be used with caution in patients with severe renal dysfunction, who will require special attention to prevent potentially dangerous side effects.

Patients treated with antiarrhythmic drugs class III (e.g. amiodarone) should be under close surveillance and ECG monitoring considered, since cardiac effects may be additive.

Diuretics antagonize the action of lidocaine due to hypokalaemia.

Drugs that reduce the clearance of lidocaine (e.g. beta-blockers) may cause potentially toxic plasma concentrations when lidocaine is given in repeated high doses over a long time period. Such interactions should therefore be of no clinical importance following short-term treatment with lidocaine at recommended doses.

Lidocaine as a potent inhibitor of CYP1A2 reduces the metabolism of CYP1A2 substrates.

If the dose or site of administration is likely to result in high blood levels, lidocaine, in common with other local anaesthetics, should be used with caution in patients with epilepsy, who will require special attention to prevent potentially dangerous side effects.

Co-administration of lidocaine with atazanavir increases the risk of cardiotoxicity and arrhythmias.

Drugs that reduce the clearance of lidocaine (e.g. cimetidine) may cause potentially toxic plasma concentrations when lidocaine is given in repeated high doses over a long time period. Such interactions should therefore be of no clinical importance following short-term treatment with lidocaine at recommended doses.

Darunavir may increase lidocaine levels in blood serum.

Co-administration of lidocaine with quinupristine increases the risk of toxicity.

Lidocaine may reduce the therapeutic effect of tamoxifen by reducing the production of its active metabolites.

Telithromycin may reduce the clearance of lidocaine.

Terbinafine may reduce the metabolism and clearance of lidocaine.

Voriconazole may increase lidocaine levels in blood serum by reducing its metabolism.

If the dose or site of administration is likely to result in high blood levels, lidocaine, in common with other local anaesthetics, should be used with caution in patients with atrioventricular block, who will require special attention to prevent potentially dangerous side effects.

Lidocaine should not be used on cuffs of endotracheal tubes (ETT) made of plastic. Lidocaine base in contact with both PVC and non-PVC cuffs of endotracheal tubes may cause damage of the cuff. This damage is described as pinholes, which may cause leakage that could lead to pressure loss in the cuff.

Lidocaine is probably porphyrinogenic and should only be prescribed to patients with acute porphyria on strong or urgent indications. Appropriate precautions should be taken for all porphyric patients.

If the dose or site of administration is likely to result in high blood levels, lidocaine, in common with other local anaesthetics, should be used with caution in patients with cardiovascular disease and heart failure, who will require special attention to prevent potentially dangerous side effects.

There is no, or inadequate evidence of safety of the drug in human pregnancy but it has been in wide use for many years without apparent ill consequence, and animal studies have shown no hazard. If drug therapy is needed in pregnancy, this drug can be used if there is no safer alternative.

Lidocaine enters the mother’s milk, but in such small quantities that there is generally no risk of the child being affected at therapeutic dose levels.

Lidocaine has minor influence on the ability to drive and use machines. Depending on the dose, local anaesthetics may have a very mild effect on mental function and may temporarily impair locomotion and co-ordination.

In extremely rare cases amide-type local anaesthetic preparations have been associated with allergic reactions (in the most severe instances anaphylactic shock).

Local irritation at the application site has been described. Following application to laryngeal mucosa before endotracheal intubation, reversible symptoms such as “sore throat”, “hoarseness” and “loss of voice” have been reported. The use of Xylocaine pump spray provides surface anaesthesia during an endotracheal procedure but does not prevent post-intubation soreness.

Systemic adverse reactions are rare and may result from high plasma levels due to excessive dosage or rapid absorption (e.g. following application to areas below the vocal chords) or from hypersensitivity, idiosyncrasy or reduced tolerance on the part of the patient. Such reactions involve the central nervous system and/or the cardiovascular system.

CNS reactions are excitatory and/or depressant and may be characterised by nervousness, dizziness, convulsions, unconsciousness and possibly respiratory arrest. The excitatory reactions may be very brief or may not occur at all, in which case the first manifestations of toxicity may be drowsiness, merging into unconsciousness and respiratory arrest.

Cardiovascular reactions are depressant and may be characterised by hypotension, myocardial depression, bradycardia and possibly cardiac arrest.