Thornton and Ross codeine linctus



Thornton and Ross codeine linctus

Qualitative and quantitative composition

Codeine Phosphate 25mg per 5ml

Each 5ml of syrup contains 4.25g of sucrose

Each 5ml of syrup contains 2.1 vol% of ethanol (alcohol)

Special warnings and precautions for use

CYP2D6 metabolism

Codeine is metabolised by the liver enzyme CYP2D6 into morphine, its active metabolite. If a patient has a deficiency or is completely lacking this enzyme an adequate analgesic effect will not be obtained. Estimates indicate that up to 7% of the Caucasian population may have this deficiency. However, if the patient is an extensive or ultra-rapid metaboliser there is an increased risk of developing side effects of opioid toxicity even at commonly prescribed doses. These patients convert codeine into morphine rapidly resulting in higher than expected serum morphine levels.

General symptoms of opioid toxicity include confusion, somnolence, shallow breathing, small pupils, nausea, vomiting, constipation and lack of appetite. In severe cases this may include symptoms of circulatory and respiratory depression, which may be life-threatening and very rarely fatal.

Fertility, pregnancy and lactation

The product should not be used during pregnancy unless considered necessary by the physician and should be avoided in the first trimester. Opioid administration in the third trimester may cause respiratory depression in the new born, withdrawal effects in neonates of dependent mothers, gastric stasis and risk of inhalation pneumonia in the mother during labour.

Codeine should not be used during breastfeeding

At normal therapeutic doses codeine and its active metabolite may be present in breast milk at very low doses and is unlikely to adversely affect the breast fed infant. However, if the patient is a CYP2D6 ultra-rapid metaboliser, higher levels of the active metabolite, morphine, may be present in breast milk and on very rare occasions may result in symptoms of opioid toxicity in the infant, which may be fatal.


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