The use of oral topical anaesthetic agents may interfere with swallowing and thus enhance the danger of aspiration of food in the respiratory tract. To this end, overdosage with Covonia Throat Spray (use of 10 ml or more) could produce a slight risk of inducing too great a local anaesthetic effect in the glottis region and consequent reduction in control of the swallowing reflex.
Excessively high blood concentrations of lidocaine may produce CNS and/or cardiovascular effects. Early CNS effects may consist of nervousness, dizziness, tinnitus, nystagmus, restlessness, excitation, paraesthesia, blurred vision, nausea, vomiting, and tremors which may progress to medullary depression and tonic and clonic convulsions. Cardiovascular reactions are depressant and may be characterised by hypotension, myocardial depression, bradycardia and possibly cardiac arrest.
Although the bioavailability of lidocaine is low it may be sufficient to result in significant toxicity when swallowed. CNS toxicity, seizures and death have been reported following the ingestion of topical preparations. However, in the case of Covonia Throat Spray more than one litre would have to be swallowed to be equivalent to the ingestion of sufficient lidocaine (0.5 g or more) to cause significant toxicity.
Systemic toxicity from chlorhexidine is rare. The main consequence of ingestion is mucosal irritation.
Treatment of lidocaine overdosage consists of ensuring adequate ventilation and arresting convulsions. Ventilation should be maintained with oxygen by assisted or controlled respiration as required. Convulsions may be treated with thiopentone, diazepam or succinylcholine. As succinylcholine will arrest respiration it should only be used if the clinician has the ability to perform endotracheal intubation and to manage a totally paralysed patient. If ventricular fibrillation or cardiac arrest occurs, effective cardiovascular resuscitation must be instituted. Adrenaline in repeated doses and sodium bicarbonate should be given as rapidly as possible.
Use in children under 12 years.
Known hypersensitivity to the product or any of its components, especially in those with a history of possible chlorhexidine-related allergic reactions.
Not applicable.
Chlorhexidine and lidocaine are usually well tolerated and no unwanted effects have been reported for the product during local short term use.
In extremely rare cases local anaesthetic preparations have been associated with allergic reactions. Hypersensitivity reactions to lidocaine hydrochloride following local injection have presented as localised oedema with slight difficulty in breathing or as a generalised rash.
Chlorhexidine may sometimes produce discoloration of the teeth and tongue. This is not permanent and disappears after treatment when chlorhexidine is discontinued. Occasionally, a dental scale and polish may be necessary to remove the stain completely. Skin sensitivity to chlorhexidine has occasionally been reported, and severe hypersensitivity reactions, including anaphylactic shock, have been reported on rare occasions following the topical use of chlorhexidine. Chlorhexidine may cause transient taste disturbances, a burning sensation of the tongue, and occasional parotid gland swelling.
Skin disorders
Frequency not known: Allergic skin reactions such as dermatitis, pruritus, erythema, eczema, rash, urticaria, skin irritation, and blisters.
Immune disorders
Frequency not known: Hypersensitivity including anaphylactic shock.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme: www.mhra.gov.uk/yellowcard
There are no further relevant data.
Covonia Throat Spray is indicated for the symptomatic relief of painful, irritated sore throats.
It is a sugar free preparation and can be used by diabetics.
Additional therapy is required in the event of bacterial infection accompanied by fever.
Lidocaine is a local anaesthetic of the amide type. Like other local anaesthetics, lidocaine impairs the generation and conduction of the nerve impulses by slowing depolarisation. This results from blocking of the large transient increase in permeability of the cell membrane to sodium ions that follows initial depolarisation of the membrane. Lidocaine also reduces the permeability of the resting axon to potassium and to sodium ions.
Chlorhexidine is a bisbiguanide antiseptic and disinfectant which is bactericidal or bacteriostatic against a wide range of Gram-positive and Gram-negative bacteria. It is more effective against Gram-positive than Gram-negative bacteria and some species of Pseudomonas and Proteus have low susceptibility. It is relatively ineffective against mycobacteria. It inhibits some viruses and is active against some fungi.
Covonia Throat Spray is applied topically for local action in the throat. On swallowing the spray solution or saliva, small amounts may reach the digestive system and some may be absorbed from the oral and pharyngeal mucosa.
Lidocaine is readily absorbed from oral mucous membranes, the gastrointestinal tract and through damaged skin. Absorption through intact skin is poor. Presystemic metabolism is extensive and bioavailability is only about 35% after oral administration. Following absorption, lidocaine is rapidly distributed to all body tissues. It crosses the placenta and blood-brain barrier. Approximately 65% is bound to plasma protein. It has a plasma half-life of 1.6 hours. Lidocaine is largely metabolised in the liver. Any alteration in liver function or hepatic blood flow can have a significant effect on its pharmacokinetics and dosage requirements. Metabolism in the liver is rapid and approximately 90% of a given dose is dealkylated to form monoethylglycinexylidide (MEGX) and glycinexylidide (GX); both of which may contribute to its therapeutic and toxic effects. Further metabolism occurs and metabolites are excreted in the urine with less than 10% of unchanged lidocaine.
Chlorhexidine is poorly absorbed from mucous membranes, intact skin and the gastrointestinal tract. It is only minimally metabolised by the liver and is excreted through bile. Urinary excretion is very low.
Treatment with Covonia Throat Spray should be limited to the relief of existing pain and irritation when strictly necessary. It is not intended for prolonged use, either continuously or repeatedly.
This medicine contains 42.5 vol % ethanol (alcohol), i.e. up to 168mg per application (5 sprays), equivalent to 0.85ml beer or 0.35ml wine per dose.
Each 10 ml of the throat spray contains 3.5 g of ethanol.
Covonia Throat Spray contains chlorhexidine. Chlorhexidine is known to induce hypersensitivity, including generalised allergic reactions and anaphylactic shock. The prevalence of chlorhexidine hypersensitivity is not known, but available literature suggests this is likely to be rare. Covonia Throat Spray should not be administered to anyone with a potential history of allergic reaction to chlorhexidine-containing compound.
Do not use and consult your doctor if you have difficulty in swallowing. Do not use without consulting your doctor if sore throat is severe or has lasted for more than 2 days or is accompanied by high fever, headache, nausea or vomiting.
Avoid contact with eyes.
No significant effects are known.
Adults and children over 12 years
The dose is 3 to 5 sprays (0.3 - 0.5 ml). This can be repeated 6 to 10 times per day.
Children under 12 years
Not recommended.
Not applicable.
