Lidocaine Injection

Local anaesthetic; Class I antiarrhythmic.

Lidocaine Injection is a sterile solution of Lidocaine Hydrochloride in Water for Injections.

The injection complies with the requirements stated under Parenteral Preparations and with the following requirements.

95.0 to 105.0% of the stated amount.

A. Make a volume containing 0.1 g of Lidocaine Hydrochloride alkaline with 5m sodium hydroxide, filter, wash the residue with water, dissolve it in 1 mL of ethanol (96%), add 0.5 mL of a 10% w/v solution of cobalt(ii) chloride and shake for 2 minutes. A bluish-green precipitate is produced.

B. To a volume containing 0.1 g of Lidocaine Hydrochloride add 10 mL of picric acid solution R1. The melting point of the precipitate, after washing with water and drying at 105°, is about 229°, Appendix V A.

C. Yields the reactions characteristic of chlorides, Appendix VI.

To a volume of the injection containing 25 mg of Lidocaine Hydrochloride add water if necessary to produce 10 mL, add 2m sodium hydroxide until the solution is just alkaline and extract with three 5 mL quantities of chloroform. Dry the combined chloroform extracts over anhydrous sodium sulfate, filter, wash with a further 5 mL of chloroform and evaporate the filtrate to dryness at a pressure of 2 kPa. Dissolve the residue in 2 mL of methanol, add 1 mL of a 1% w/v solution of 4-dimethylaminobenzaldehyde in methanol and 2 mL of glacial acetic acid and allow to stand at room temperature for 10 minutes. Any yellow colour produced is not more intense than the colour obtained by repeating the operation using 10 mL of a solution of 2,6-dimethylaniline in water containing 1 µg per mL in place of the injection (400 ppm).

Make a quantity containing 0.1 g of Lidocaine Hydrochloride alkaline with 2m sodium hydroxide and extract with three 20 mL quantities of chloroform, washing each extract with the same 10 mL of water. Filter the washed extracts through a filter paper moistened with chloroform and wash the filter with 10 mL of chloroform. Add the washings to the filtrate and carry out Method I for non-aqueous titration, Appendix VIII A, using 0.02m perchloric acid VS as titrant and crystal violet solution as indicator. Each mL of 0.02m perchloric acid VS is equivalent to 5.776 mg of C₁₄H₂₂N₂O,HCl,H₂O.