Clonazepam Injection

Benzodiazepine.

Clonazepam Injection is a sterile solution of Clonazepam. It is prepared immediately before use by diluting Sterile Clonazepam Concentrate with Water for Injections in accordance with the manufacturer's instructions.

The injection complies with the requirements stated under Parenteral Preparations.

Sterile Clonazepam Concentrate is a sterile solution of Clonazepam in a suitable solvent.

The concentrate complies with the requirements for Concentrates for Injections or Infusions stated under Parenteral Preparations and with the following requirements.

95.0 to 105.0% of the stated amount.

A clear, colourless or slightly greenish yellow solution.

Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.

(1) Dilute a volume of the injection containing 3 mg of Clonazepam in a stoppered tube with an equal volume of water, shake with 1 mL of chloroform, allow to separate and use the chloroform layer.

(2) Dissolve 3 mg of clonazepam BPCRS in 1 mL of chloroform.

(a) Use as the coating silica gel F₂₅₄ (Merck silica gel 60 F₂₅₄ plates are suitable).

(b) Use the mobile phase as described below.

(c) Apply 10 µL of each solution.

(d) Develop the plate to 10 cm.

(e) After removal of the plate, dry it in a current of cold air, spray with 2m sodium hydroxide and heat at 120° for 15 minutes.

2 volumes of 13.5m ammonia, 15 volumes of n-heptane, 30 volumes of nitromethane and 60 volumes of ether.

The principal spot in the chromatogram obtained with solution (1) corresponds in position and colour to that in the chromatogram obtained with solution (2). Spots due to excipients may also be observed.

pH, 3.4 to 4.3, Appendix V L.

Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions protected from light.

(1) Dilute, if necessary, a volume of the injection containing 10 mg of Clonazepam to 20 mL with water and extract with three 3-mL quantities of chloroform. Wash each chloroform extract separately with the same 10 mL volume of water, combine the extracts and add sufficient chloroform to produce 10 mL.

(2) 0.0005% w/v of 3-amino-4-(2-chlorophenyl)-6-nitroquinolin-2(1H)-one BPCRS in chloroform.

(3) 0.0002% w/v of 3-amino-4-(2-chlorophenyl)-6-nitroquinolin-2(1H)-one BPCRS in chloroform.

(a) Use as the coating silica gel G.

(b) Use the mobile phases as described below.

(c) Apply 50 µL of each solution.

(d) Develop the plate to 15 cm.

(e) After the first development, remove the plate and dry in a current of cool air. After the second development, remove the plate, heat at a pressure of 2kPa at 120° for 3 hours, allow to cool and spray with a 10% w/v solution of zinc chloride in 0.1m hydrochloric acid. Allow the plate to dry in air and visualise by Method I, Appendix III A, beginning at the words 'expose to nitrous fumes ...'.

For the first development  20 volumes of chloroform and 80 volumes of ether.

For the second development  10 volumes of ether and 90 volumes of nitromethane.

Under the prescribed conditions the Rf value of clonazepam is about 0.35; 3-amino-4-(2-chlorophenyl)-6-nitroquinolin-2(1H)-one (carbostyril impurity), about 0.45; 2-amino-2′-chloro-5-nitrobenzophenone (nitrobenzophenone impurity), about 0.75.

In the chromatogram obtained with solution (1):

any spot corresponding to the nitrobenzophenone impurity is not more intense than the spot in the chromatogram obtained with solution (3) (0.2%);

any spot corresponding to the carbostyril impurity is not more intense than the spot in the chromatograms obtained with solutions (3) (0.2%);

any other secondary spot is not more intense than the spot in the chromatogram obtained with solution (2) (0.5%).

Protect the solutions from light. To a volume of the injection containing 20 mg of Clonazepam add sufficient propan-2-ol to produce 100 mL and dilute 10 mL to 100 mL with propan-2-ol. Measure the absorbance of the resulting solution at the maximum at 310 nm, Appendix II B. Calculate the content of C₁₅H₁₀ClN₃O₃ taking 364 as the value of A(1%, 1 cm) at the maximum at 310 nm.

Clonazepam Injection should be protected from light.

The label states (1) 'Sterile Clonazepam Concentrate'; (2) that the diluted injection is to be given by intravenous injection.