Category. Opioid analgesic.

Additional information. Strength in the current WHO Model list of essential medicines: 10mg.

Requirements

Comply with the monograph for "Tablets".

Morphine sulfate tablets contain not less than 90.0% and not more than 110.0% of the amount of (C₁₇H₁₉NO₃)₂,H₂SO₄,5H₂O stated on the label.

Identity tests

• Either tests A and D or tests B, C, and D may be applied.

A. To a quantity of the powdered tablets equivalent to about 0.1g of Morphine sulfate add 10ml of ethanol (~750g/l) TS and shake for 15 minutes. Centrifuge and decant the supernatant liquid. Extract the remaining liquid with two further 10-mL quantities of ethanol (~750g/l) TS and evaporate the combined extracts to dryness. Carry out the examination with the residue as described under 1.7 Spectrophotometry in the infrared region. The infrared absorption spectrum is concordant with the reference spectrum of morphine sulfate.

B. To a quantity of the powdered tablets equivalent to about 20mg of Morphine sulfate add 5ml of water, shake, and filter. To the filtrate add 0.05ml of ferric chloride (25g/l) TS; a blue colour is produced.

C. To a quantity of the powdered tablets equivalent to about 20mg of Morphine sulfate add 5ml of sulfuric acid (0.05mol/l) VS, shake, and filter. To the filtrate add 0.5ml of a saturated solution of potassium iodate R; an amber colour is produced which reaches maximum intensity after 5 minutes. Add 0.5ml of ammonia (~260g/l) TS; the colour darkens almost to black.

D. To a quantity of the powdered tablets equivalent to about 20mg of Morphine sulfate add 5ml of water, shake, and filter. The filtrate yields the reactions described under 2.1 General identification tests as characteristic of sulfates.

Assay. Weigh and powder 20 tablets. To a quantity of the powdered tablets equivalent to about 0.4g of Morphine sulfate add 25ml of water, 5ml of sodium hydroxide (1mol/l) VS, and 1g of ammonium sulfate R, swirl to dissolve. Add 20ml of ethanol (~750g/l) TS and extract with successive quantities of 40ml, 20ml, 20ml, and 20ml of a mixture of 3 volumes of chloroform R and 1 volume of ethanol (~750g/l) TS. Wash each extract with the same 5ml of water, filter, and evaporate the solvent. Dissolve the residue in 10ml of hydrochloric acid (0.05mol/l) VS, boil, cool, add 15ml of water and a few drops of methyl red/ethanol TS. Titrate the excess acid with sodium hydroxide (0.05mol/l) VS.

Each mL of hydrochloric acid (0.05mol/l) VS is equivalent to 18.97mg of (C₁₇H₁₉NO₃)₂,H₂SO₄,5H₂O.