Hyoscine Eye Drops

Anticholinergic.

Hyoscine Eye Drops are a sterile solution of Hyoscine Hydrobromide in Purified Water.

The eye drops comply with the requirements stated under Eye Preparations and with the following requirements.

90.0  to 110.0% of the stated amount.

A.  Carry out the method for thin-layer chromatography , Appendix III A, using a silica gel precoated plate (Merck plates are suitable) and a mixture of 10  volumes of diethylamine , 40  volumes of acetone and 50  volumes of dichloromethane as the mobile phase. Apply separately to the plate 5 µl of each of the following solutions. For solution (1) evaporate a volume of the eye drops containing 5  mg of Hyoscine Hydrobromide to dryness on a water bath, triturate the residue with 1  ml of ethanol (96%), allow to stand and use the supernatant liquid. Solution (2) contains 0.5% w/v of hyoscine hydrobromide BPCRS in ethanol (96%). After removal of the plate, heat it at 105° for 20  minutes, allow to cool and spray with potassium iodobismuthate solution R1 . The principal spot in the chromatogram obtained with solution (1) corresponds to that in the chromatogram obtained with solution (2).

B.  In the Assay, the chromatogram obtained with solution (1) shows a peak of similar size and with the same retention time as the principal peak in the chromatogram obtained with solution (2).

Carry out the method for liquid chromatography , Appendix III D, using the following solutions in water. For solution (1) dilute the eye drops, if necessary, to produce a solution containing 0.125% w/v of Hyoscine Hydrobromide. Solution (2) contains 0.125% w/v of hyoscine hydrobromide BPCRS .

The chromatographic procedure may be carried out using (a) a stainless steel column (20  cm × 4.6  mm) and a stainless steel pre-column (1.0  cm × 4.6  mm) both packed with octadecylsilyl silica gel for chromatography (10 µm) (Lichrosorb RP18 is suitable), (b) as the mobile phase with a flow rate of 2  ml per minute a mixture of 1  volume of a 60% w/v solution of perchloric acid , 31  volumes of methanol and 68  volumes of water, adjusted to pH 2.5 with 13.5m ammonia and (c) a detection wavelength of 240  nm. When chlorhexidine is used as a preservative allow the chromatography for solution (1) to proceed until the chlorhexidine has eluted (this may be up to 20  times the retention time of the peak due to hyoscine hydrobromide).

Calculate the content of C₁₇H₂₁NO₄,HBr,3H₂O using the declared content of C₁₇H₂₁NO₄,HBr in hyoscine hydrobromide BPCRS . Each mg of C₁₇H₂₁NO₄,HBr is equivalent to 1.141  mg of C₁₇H₂₁NO₄,HBr,3H₂O.