Minims Tetracaine HCL

Percutaneous local anaesthetic to produce anaesthesia of the skin prior to venepuncture or venous cannulation.

Adults (including the elderly) and children over 5 years: A maximum of 5 tubes (approximately 5g) can be applied.

Children over 1 month of age and under 5 years: No more than 1 tube should be applied.

Apply the contents of the tube to the centre of the area to be anaesthetised and cover with an occlusive dressing. The contents expellable from 1 tube (approximately 1 gram) are sufficient to cover and anaesthetise an area of up to 30 sq.cm. (6x5cm). Smaller areas of anaesthetised skin may be adequate in infants and small children. Each tube is intended for use on a single occasion only.

Adequate anaesthesia can usually be achieved following a thirty minute application time for venepuncture, and a forty-five minute application time for venous cannulation, after which the gel should be removed with a gauze swab and the site prepared with an antiseptic wipe in the normal manner.

It is not necessary to apply Minims Tetracaine HCL gel for longer than 30-45 minutes and anaesthesia remains for 4-6 hours in most patients after a single application.

Application of Minims Tetracaine HCL gel can be repeated after a minimum of 5 hours if necessary.

The maximum cumulative dose in a 24 hour period should not exceed 7 tubes for adults and 2 tubes for children.

Not recommended for infants under 1 month of age.

Use in premature babies or in full term infants less than 1 month of age, where the metabolic pathway for Tetracaine may not be fully developed. For premature babies use of Minims Tetracaine HCL is not recommended before 1 month after the expected delivery date (44 weeks 'gestation');

Known hypersensitivity to any of the ingredients or to local anaesthetics of the ester type.

Do not apply Minims Tetracaine HCL gel to broken skin, mucous membranes or to the eyes or ears.

Only apply to intact, normal skin.

Not to be taken internally.

Minims Tetracaine HCL gel, like other local anaesthetics may be ototoxic and should not be instilled into the middle ear or used for procedures which might involve penetration into the middle ear. Repeated exposure to Minims Tetracaine HCL gel may increase the risk of sensitisation reactions to Tetracaine.

Although the systemic availability of Tetracaine by percutaneous absorption of Minims Tetracaine HCL gel is low, caution should be exercised in patients with epilepsy.

No adverse effects on the ability to drive or to use hazardous machinery are expected following use of Minims Tetracaine HCL Gel.

Slight erythema is frequently seen at the site of application and is due to the pharmacological action of Tetracaine in dilating capillary vessels. This may help delineating the anaesthetised area.

Slight oedema or itching are less frequently seen at the site of application.

This may be due to the local release of histamine and 5-HT.

More severe erythema, oedema and/or itching confined to the site of application have rarely been reported.

In very rare instances, blistering of the skin at the site of application may be apparent - in these cases, remove the gel immediately and treat the affected area symptomatically

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 at: www.mhra.gov.uk/yellowcard

Overdosage with Minims Tetracaine HCL gel is unlikely to result from application to intact skin. If accidentally ingested systemic toxicity may occur, and signs will be similar to those observed after administration of other local anaesthetics. These signs have been described as: signs of inebriation, tingling, numbness of the tongue, tinnitus, nystagmus, nausea or vomiting, twitching and ultimately convulsions. Oxygen is recommended as the first line treatment for systemic toxicity.

Tetracaine is a local anaesthetic and is believed to act by blocking nerve conduction mainly by inhibiting sodium ion flux across the axon membrane.

Tetracaine achieves this by acting upon specific receptors that control gating mechanisms responsible for conductance changes in specialised proteinaceous sodium channels.

Blocking sodium ion flux prevents the setting up of an action potential in the nerve axon, thus preventing pain receptors signalling to the central nervous system.

Tetracaine additionally has vasodilatory effects, which commonly results in a localised erythema.

The ester type 'caine' anaesthetics are rapidly metabolised in blood mainly by plasma pseudocholinesterase. A 3.33μM (1μg/ml) concentration of tetracaine was fully metabolised in human plasma within 20 seconds.

In vivo data has demonstrated that Minims Tetracaine HCL gel is 15 ± 11% bioavailable when administered to intact normal skin, with a mean absorption and elimination half life of 1.23 ± 0.28 hours.

Peak plasma levels of p-(n-butylamino) benzoic acid (BABA), the major metabolite of tetracaine are between 3-6 hours post dose.

None stated.

None known

As tetracaine can cause contact sensitisation reactions, particularly with repeated contact, healthcare professionals should take care to minimise contact with Minims Tetracaine HCL gel during application and removal.