What is Codeine

Codeine sulfate is a form of this drug that is commonly used. It is available in tablet form ^Label and indicated for the relief of mild to moderately severe pain, where the use of an opioid analgesic is appropriate ^Label.

The solution form is used by itself or combined in a syrup with other drugs and is used as a cough suppressant in adults aged 18 and above ¹¹, ¹².

Associated Conditions

• Coughing
• Mild pain
• Pain
• Severe Pain
• Moderate Pain

Pharmacodynamics

General effects

Codeine is a weak narcotic pain reliever and cough suppressant that is similar to morphine and hydrocodone. A small amount of ingested codeine is converted to morphine in the body. Codeine increases tolerance to pain, reducing existing discomfort. In addition to decreasing pain, codeine also causes sedation, drowsiness, and respiratory depression .

Antitussive activity

This drug has shown antitussive activity in clinical trials  and has been effective in cough secondary to tuberculosis and insomnia due to coughing . Codeine suppresses the cough reflex through a direct effect on the cough center in the medulla .

Effects on intestinal motility

Codeine may reduce intestinal motility through both a local and possibly central mechanism of action  This may possibly lead to constipation . The chronic use of opioids, including codeine sulfate, may lead to obstructive bowel disease, particularly in patients with underlying disorders of intestinal motility .

Effects on the central nervous system

Codeine phosphate is an opioid analgesic with uses similar to those of morphine, but is much less potent as an analgesic. Its primary site of action is at the mu opioid receptors distributed throughout the central nervous system. The sedative activities of codeine are less potent than those of morphine . Codeine may cause respiratory system depression by the activation of μ-opioid receptors at specific sites in the central nervous system ⁸.

Effects on blood pressure

This drug poses an increased risk of compromised ability to maintain blood pressure due to peripheral vasodilation and other mechanisms 

Effects on chronic cancer pain and other types of pain

Codeine is an opioid analgesic with similar indications to those of morphine, however, is much less potent in its pain alleviating properties. Its primary action takes place at the mu opioid receptors, which are distributed throughout the central nervous system. The average duration of action is about 4 hours 

Regular dosing of opioid analgesics such as codeine in patients with severe cancer pain has been well documented to improve symptoms .

Mechanism of action

Codeine is a selective agonist for the mu opioid receptor, but with a much weaker affinity to this receptor than morphine, a more potent opioid drug. Codeine binds to mu-opioid receptors, which are involved in the transmission of pain throughout the body and central nervous system ^Label, . The analgesic properties of codeine are thought to arise from its conversion to Morphine, although the exact mechanism of analgesic action is unknown at this time ^Label,