BP 2025 (Ph. Eur. 11.6 update)
Action and use
Antituberculosis drug.
DEFINITION
Isoniazid Injection is a sterile solution of Isoniazid in Water for Injections.
The injection complies with the requirements stated under Parenteral Preparations and with the following requirements.
Content of isoniazid, C6H7N3O
95.0 to 105.0% of the stated amount.
IDENTIFICATION
- Using a rotary evaporator, evaporate a volume of the injection containing 50 mg of Isoniazid to dryness, extract the residue with two 10 mL quantities of ethanol (96%), filter and evaporate the combined ethanol extracts to dryness. The infrared absorption spectrum of the residue, Appendix II A, is concordant with the reference spectrum of isoniazid (RS 196).
- To a volume containing 25 mg of Isoniazid add 5 mL of ethanol (96%),1 g of sodium tetraborate and 5 mL of a 5.0% w/v solution of 1-chloro-2,4-dinitrobenzene in ethanol (96%), evaporate to dryness on a water bath, heat for a further 10 minutes and dissolve the residue in 10 mL of methanol. A reddish purple colour is produced.
TESTS
Acidity
pH, 5.6 to 6.0, Appendix V L.
ASSAY
Dilute a quantity containing 0.4 g of Isoniazid to 250 mL with water. To 25 mL of the solution in a glass-stoppered flask add 25 mL of 0.05m bromine VS and 5 mL of hydrochloric acid, shake for 1 minute, allow to stand for 15 minutes, add 1 g of potassium iodide and titrate with 0.1M sodium thiosulfate VS using starch mucilage as indicator. Repeat the operation without the injection. The difference between the titrations represents the amount of bromine required. Each mL of 0.05M bromine VS is equivalent to 3.429 mg of C6H7N3O.
STORAGE
Isoniazid Injection should be protected from light.
