| Ingestion of the complete contents of the marketed pack would not be expected to cause any adverse effects.Lidocaine: Systemic features: CNS Symptoms: Increasing restlessness, visual disturbances, agitation, tinnitus, confusion, hallucinations, drowsiness, weakness, shivering, paraesthesia, and muscle twitching lead to convulsions, which are the major feature of toxicity. Coma and apnoea may develop.Cardiac Symptoms: Possibly transient hypertension and tachycardia followed by arrhythmias (including sinus bradycardia, AV nodal or ventricular arrhythmias, asystole). The incidence of torsade de pointes is less than with other groups of antiarrhythmics. Hypotension may result from depressed myocardial contractility and peripheral vasodilation.GI Symptoms: Nausea and vomiting.Allergic reactions occur rarely and may include urticaria, angioedema, contact dermatitis and pruritis. Acute respiratory distress syndrome (ARDS) has been reported in severe allergic reactions.Rarely methaemoglobinaemia may occur with excessive exposure to some local anaesthetics. This is much more commonly seen with benzocaine and prilocaine (due to its metabolite o-toluidine) than with lidocaine.Serious toxicity is usually due to inadvertent intravenous overdosage. It is much less likely after oral administration because of extensive first pass metabolism but has been reported after ingestion of large amounts. Lidocaine is readily absorbed across mucous membranes and through damaged skin. Systemic toxicity and death have been reported in children and adults following ingestion or aspiration of topical solutions or viscous preparations. The effect may also be due to absorption of high concentrations across the buccal mucosa causing systemic toxicity (see Section 4.4). Potential toxic doses range from 800mg of gargled lidocaine solution (death), 1200mg ingestion (agitation and confusion) and 6g ingestion (death). Toxicity may also arise from rectal or urethral instillation. Anaphylaxis or an anaphylactoid reaction has been reported following administration of 1% lidocaine solution for topical anaesthesia prior to fiberoptic bronchoscopy.Signs of serious toxicity may occur at plasma concentrations greater than 5-8 microgram/mL (5-8mg/L).Following ingestion bioavailability of lidocaine is 30-35% and peak levels occur within 40 minutes. The elimination half-life is about 1-2 hours. Metabolites of lidocaine have longer half-lives than lidocaine itself as well as antiarrhythmic activity.All patients who have taken a deliberate overdose should be referred for assessment. Children and adults who have ingested 6mg/kg or more lidocaine, or those who are symptomatic, should be referred for medical assessment.Children and adults who have accidentally ingested less than 6mg/kg lidocaine and who have no new symptoms since the time of ingestion do not need to be referred for medical assessment. Patients should be advised to seek medical attention if symptoms develop.Chlorocresol:Systemic features: Nausea, vomiting, diarrhoea, hypotension, tachycardia, cardiac arrhythmias, metabolic acidosis, pallor, sweating and shock. CNS stimulation is followed by drowsiness, respiratory depression, cyanosis, convulsions, coma, bronchospasm and rapid onset pulmonary oedema and death. Methaemoglobinaemia is recognised. Phenol may also cause renal and hepatic injury.Chronic exposure is rare but has been associated with nausea, vomiting, diarrhoea, anorexia, weight loss, hypersalivation, headache, fainting, mental disturbances, weakness, muscle aches and pain, mouth sores, renal and hepatic injury.Exposure by any route can cause irritation, burns and systemic effects.Ingestion causes irritation of mucous membranes, and of the GI tract. Significant ingestion is said to cause white/brown skin and mucosal burns which may be painless as phenol destroys the nerve endings. Laryngeal oedema can occur, and oesophageal stricture may be a late complication.Skin contact – even dilute solutions (1%) can cause irritation, dermatitis and burns to the skin following prolonged contact. Often presents as relatively painless white or brown necrotic lesions; the brown colouration may remain after healing.Management: 1. Wash area with soap and water.2. Maintain a clear airway and ensure adequate ventilation. Give oxygen if clinically indicated.3. Observe for at least 4 hours after exposure. Perform 12 lead ECG. Monitor pulse, blood pressure and cardiac rhythm continuously for 4 hours if the ECG is abnormal or the patient is symptomatic. Measure urea and electrolytes, arterial blood gases, liver and renal function in symptomatic cases and monitor in a critical care facility.4. If cardiotoxicity is unresponsive to the above consider the use of a lipid emulsion. It is thought lipid may reduce free concentrations of active drug and therefore improve myocardial function, although other mechanisms are also postulated.5. Correct acid base and metabolic disturbances as required.6. Institute drug treatment of seizures as per local protocol.Paediatric populations: Lidocaine:In children up to 6mg/kg lidocaine (with chlorhexidine in mouth paint) produced only minor symptoms. A 5 month old child had a seizure after ingestion of 100mg (14mg/kg). Severe toxicity in children is unlikely at doses less than 15mg/kg. | |
