About Morphine Sulphate®

Actions:
Morphine sulphate is a phenanthrene-derivative opiate agonist. It is the principal alkaloid of opium. Peak analgesia occurs 20 minutes following IV infusion. Maximal respiratory depression occurs within 3 - 7 minutes. Analgesia may be maintained for up to 7 hours. Although sensitivity of the respiratory centre returns to normal within 2 - 3 hours, respiratory minute volumes may remain below normal for 4 - 5 hours.

Pharmacokinetics:
IV morphine sulphate is immediately bioavailable, since no absorption is required. Morphine is metabolised principally in the liver and undergoes conjugation with glucuronic acid at the 3-hydroxyl group. Secondary conjugation may also occur at the 6-hydroxyl group to form 3,6-digluconuride. Morphine is excreted in the urine, mainly as the gluconuride and in smaller amounts as the digluconuride and as unchanged drug. About 90% of the drug is excreted within 24 hours of giving the last dose. About 7 - 10% is excreted in faeces, with a large portion of this excreted via bile.