Source: Medicines & Healthcare Products Regulatory Agency (GB) Revision Year: 2020 Publisher: Galen Limited, Seagoe Industrial Estate, Craigavon, BT63 5UA, UK
Pharmacotherapeutic group: Opioids in combination with non-opioid analgesics
ATC code: N02AJ06
Paracetamol has analgesic and antipyretic effects that do not differ significantly from that of aspirin. Its anti-inflammatory action is weak and it has practically no anti-platelet effect. The mechanism of action is unclear although it is believed to exert its action by inhibition of prostaglandin synthesis.
Codeine is a centrally acting weak analgesic. Codeine exerts its effects through µ opioid receptors, although codeine has low affinity for these receptors, and its analgesic effect is due to its conversion to morphine. Codeine, particularly in combination with other analgesics such as paracetamol, has been shown to be effective in acute nociceptive pain.
Paracetamol is readily absorbed from the GI tract with peak plasma concentrations occurring about 30 minutes to two hours after oral administration. 90-100% of administered drug can be recovered in the urine within the first day. Practically none is excreted unchanged, most is conjugated in the liver with glucuronic acid or sulphuric acid.
Codeine and its salts are rapidly absorbed from the GI tract with peak plasma levels occurring about one hour after oral administration. Codeine is metabolised in the liver and excreted in the urine mainly as a conjugate of glucuronic acid. Approximately 10% of administered codeine is demethylated to form morphine.
Concurrent administration of both drugs does not interfere with the normal metabolic processes of each agent.
None stated.
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