Codeine used, Side dose, pharmacodynamic & mechanism of action......

 Codeine

Brand name:- Codine 15mgtab, 15mg/5ml lintus.

Codeine is an opioid analgesic (pain reliever) which works by blocking transmission of pain signals to the brain to lower pain perception. It is also used, usually in combination with other medications, to reduce coughing. Codeine is available as a single-ingredient product, or in combination with acetaminophen or aspirin, and in some cough and cold.

Pharmacodynamic:- 

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 Label.

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 .

Effects on blood pressure:-

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

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 18.

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

Mechanism of action:- 

Classically, there are three main opioid receptors, although there are other subtypes. These are all G-protein coupled and originally named mu, delta, and kappa. When opioids bind to these receptors, a series of intracellular events occur, resulting in a decreased intracellular cAMP, hyperpolarization of the cell and neuronal cells, and decreased neurotransmitter release. Within the nervous system, activation of mu receptors in the midbrain is the dominant mechanism of opioid-induced analgesia. The cough reflex is primarily mediated through the opioid receptors in the medulla.

Used:-  

Used for moderate to severe pain and dry cough.

SIDE EFFECTS:- 

Nausea, vomiting, constipation, lightheadedness, dizziness, drowsiness, or sweating may occur.

Dose:- 

10- 30mg ; children 2-6years 2.5-5mg, 6-12 years 5- 10mg , frequently used as syrups codeine phos. As directed by your doctor.