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Local Anaesthesia (Including Dental)

The safety of local anaesthetic agents remains a controversial issue due to experimental evidence that some of the local anaesthetic agents are porphyrogenic in either animal models (e.g. lidocaine) or cell culture (e.g. lidocaine, mepivicaine, prilocaine, bupivacaine). However despite this laboratory evidence, clinical experience has shown that most of these agents have been used in patients with acute porphyria without any notable adverse effect.

General Points:

		These drugs are used in small doses, are metabolised slowly and there is no first pass effect.
		To date there are no case reports in the literature ascribing an acute attack to the use of local anaesthesia.

Procedures

Dental Anaesthesia.
By far the commonest requirement for local anaesthesia occurs when patients require dental treatment. In the majority of cases these procedures can be carried out under local anaesthetic.
Suggestions: Bupivacaine (0.25-0.5%) with adrenaline (1:200,000)
Prilocaine (4%)

Regional Anaesthesia; Nerve blocks, epidural anaesthesia, spinal anaesthesia.
Several reports have documented the safe use of bupivacaine and procaine for epidural anaesthesia during labour. This has involved both extradural (bupivacaine, procaine) and spinal (bupivacaine) anaesthesia.

Topical anaesthesia;
There is little to suggest that local anaesthetic agents formulated for surface anaesthesia are associated with any significant risk. Examples of formulations and their uses include;
Lidocaine;

	Gel (2%) for use prior to venepuncture, minor skin procedures or urethral catheterisation .
	Spray (4-10%) for use in procedures on the respiratory tract (intubation, bronchoschopy, ENT procedures)

Tetracaine ; Gel(4%) for anaesthesia prior to venepuncture or minor skin procedures.
Eye drops (0.5-1%)
Oxybuprocaine; Eye drops (0.4%)

Drugs which have been used safely as Local Anaesthetic Agents

	Tetracaine	Oxybuprocaine
	Bupivicaine	Prilocaine
	Lidocaine	Procaine
	Mepivacaine	Tetracaine

REFERENCES

1. James, MFM, Hift RJ. Porphyrias. Br J Anaesth 2000;85:143-53.

2. McNeill, MJ and Bennet A. Use of regional anaesthesia in a patient with acute porphyria. Br. J. Anaesth. 1990;64:371-3.

3. Brown, Welbury. The management of porphyria in dental practice. Br Dent J. 2002; 193: 145-146.

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