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Median Lethal Dose Of Some Local Anaesthetic Preparations, Prasert Songkittiguna

Chulalongkorn University Dental Journal

The median lethal dose (LD50) of local anaesthetics in mice was determined by the method of Reed & Muench. No statistical difference (P < 0.05) was found in comparing the (LD50) of the four commonly-used local anaesthetic preparations; they were lidocaine 2%, lidocaine 2% with adrenaline 1:80,000, lidocaine 2% with noradrenaline 1:50,000 and prilocaine 3% with felypressin 0.03 IU. It is suggested therefore that, in mice, the (LD50) of these local anaesthetics are comparable. However, lidocaine 2% with noradrenaline 1:50,000 had a wider therapeutic index, therefore it could be the safest local anaesthetic among the other three drugs.