Management of severe pain

 

Opioids for moderate to severe pain:

 

 Morphine

 Morphine  is the most commonly used strong opioid but requires dose titration for each individual.

•  During dose titration, initially a normal release preparation should be given in the form of a elixir or tablet with fast onset of action but only a short duration of effect is best. Give a 4 hourly 30mg (more dose can be given) for breakthrough pain when needed. 

• After 1-2 days review the dose given and adjust if inadequate relief is provided. Once pain is under control the

  4 hourly immediate release can be converted to the same 24 hour dose of modified release either given as 12 hourly or 24 hourly.

• Morphine is available orally (suspensions and tablet) and rectally as suppositories. The oral

  route is the preferred route, however if this is not possible,the subcutaneous route is

  an alternative. Morphine administered by mouth is divided into 2 preparations;

  immediate release and sustained release. The former exerts effect within an hour of

  ingestion and has effect for up to 4 hours. The latter produces analgesic effect after

  a delay of 2 to 6 hours and provides pain relief for 12 to 24 hours.

 

 

 

 

 

 

 

 

 

 

Diamorphine

 

 Diamorphine is a semisynethetic version of morphine and is a prodrug because it

must be converted into 6-acetylmorphine and morphine in order to produce

analgesic effect.

•  Once it is administered orally, only morphine can be detected in the blood.

• Typical dose ia 5mg every 4 hours (oral). Given diamorphine orally is an inefficient

way of giving diamorphine but for parenteral administration it is advantageous because

it is more soluble than morphine so reduced volume is required.

•  Diamorphine when given by IM or SC injection is three times more potent as

morphine  because it is more soluble and lipophilic than morphine. 

 

 

 

 Oxycodone

 

•  Oxycodone has high oral bioavailability of 60-90% and the potency of this drug is

about twice than that of morphine for pain relief.

•  It is mainly excreted by the

kidneys with a short half life of 2-4 hours and hence needs to be given every 4-6

hours and used with caution in renal impairment.

•  Preparations available is via the

oral route (immediate release 5-30mg 4-6hourly and sustained release of 10mg 12 hourly)

available as capsules,solution, modified release tablets. Dose titration similar to that of morphine.

•  Avoid use in in chronic kidney stages 4-5 where eGFR is less than 30ml.