Management of mild to moderate pain

 

 

Mild to moderate pain

 Codeine is a weak opioid (mainly mu receptor agonist) that helps with cough; provide

analgesia and an antidiarrheal agent.

• Codeine binds to the mu opioid receptor and prevents

the release of substance P and it is thought that codeine is transformed into morphine by the

enzyme P450 2D1 to provide analgesic effect.

•  It is metabolized by the liver cytochrome enzyme (CYP2D6) and it should be noted that some Asians and Caucasians lack effective cytochrome enzymes so metabolize codeine poorly giving suboptimal analgesia.

•  The normal dose is 30-60mg every 4hours, usually lasts for about 4-6 hours (max 240mg per

day). It is available as oral (tablets and syrup) and IM injection.

 

 Tramadol

Alternatively tramadol can be given and has low affinity for kappa and delta opioid receptors.

•  It provides pain relief by 2 pathways; one is acting on the opioid receptors and the other

being that it inhibits the reuptake of serotonin and nor adrenaline.

•  Tramadol is metabolized by hepatic cytochromes CYP2D6 and CYP3A4 to active metabolites. As with codeine,

potential inducers or inhibitors of such cytochrome enzymes will alter effect of analgesia experienced. 

• Typical dose is 50-100mg every 6 hours by oral (capsules, oral dispersible tablets, modified

  release 12 or 24 hourly tablets) or IM or IV infusion. It is not recommended to exceed 400mg

  per day (except in special circumstances) due to elevated risks of experiencing convulsions. 

 

 Dihydrocodeine

Dihydrocodeine is also a weak opioid with similar analgesic efficacy as codeine.

•  Usual dose is 30mg every 4-6 hours and appears to have a narrow dose range of

 beneficial effects. A dose of 60mg or higher is associated with increased risk of adverse side effects.

•  It is available as orally as well as modified release 12 hourly and IM

injection.