In estimating the safe dosage of this drug, it is important to take account of the rate at which it is absorbed and excreted as well as its potency. The patient's age, weight, physique and clinical condition, the degree of vascularity of the area to which the drug is to be applied, and the duration of administration are other factors which must be taken into account. The dosage is adjusted according to the response of the patient and site of administration. The lowest concentration and smallest dose producing the required effect should be given.
Adults: For healthy adults, the individual maximum recommended dose should not exceed 7 mg/kg of body weight and in general it is recommended that the maximum total dose not exceed 500 mg.
Children and elderly or debilitated patients: require smaller doses, commensurate with age and physical condition. Dosages in children should be reduced, commensurate with age, body-weight and physical condition.
The following doses have been recommended for individual local anaesthetic procedures in the USA:
- For percutaneous infiltration anaesthesia: 5 to 300 mg (1 to 60 mL of a 0.5% solution or 0.5 to 30 mL of a 1% solution).
- The dosage in peripheral nerve block depends on the route of administration. For brachial plexus block 225 to 300 mg (15 to 20 mL) as a 1.5% solution is used; for intercostal nerve block 30 mg (3 mL) is given as a 1% solution; for paracervical block a 1% solution is used in a dose of 100 mg (10 mL) on each side, repeated not more frequently than every 90 minutes; for paravertebral block a 1% solution may be used in doses of 30 to 50 mg (3 to 5 mL); a 1% solution is recommended for pudendal block in doses of 100 mg (10 mL) on each side; for retrobulbar block a 4% solution may be used in doses of 120 to 200 mg (3 to 5 mL)
- For sympathetic nerve block a 1% solution is recommended; doses are 50 mg (5 mL) for cervical block and 50 to 100 mg (5 to 10 mL) for lumbar block.
- For epidural anaesthesia 2 to 3 mL of solution is needed for each dermatome to be anaesthetised but usual total doses and recommended concentrations are: lumbar epidural 250 to 300 mg (25 to 30 mL) as a 1% solution for analgesia and 225 to 300 mg (15 to 20 mL) as a 1.5% solution or 200 to 300 mg (10 to 15 mL) as a 2% solution for anaesthesia, and for thoracic epidural a 1% solution may be used at doses of 200 to 300 mg (20 to 30 mL). In obstetric caudal analgesia 200 to 300 mg (20 to 30 mL) is used as a 1% solution and in surgical caudal anaesthesia a 1.5% solution may be used in doses of 225 to 300 mg (15 to 20 mL). For continuous epidural anaesthesia, the maximum doses should not be repeated more frequently than every 90 minutes.
- A hyperbaric solution of 1.5% or 5% lidocaine hydrochloride in glucose 7.5% solution is available for spinal anaesthesia; then epinephrine (adrenaline) should not be used. Doses of up to 50 mg (1 mL) as a 5% solution and 9 to 15 mg (0.6 to 1 mL) as a 1.5% solution have been used during labour for a normal vaginal delivery. Up to 75 mg (1.5 mL) as the 5% solution has been used for caesarean section and 75 to 100 mg (1.5 to 2 mL) for other surgical procedures.