Oxycodone

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Oxycodone is an opioid used for background and breakthrough pain.

Indications

  • Pain
  • Dyspnoea

Pharmacokinetics

Oxycodone is well absorbed orally and has an oral bioavailability of usually a little over 50%, thus subcutaneous doses should be about half of oral doses.

Oral immediate release oxycodone beings acting within about 30 minutes of ingestion; subcutaneous injections have an onset of action within about 15 minutes. The peak action is usually 1-2 hours post administration.

Oxycodone is metabolized via the the cytochrome P450 system and many of its metabolites are minimally active, thus it is a little safer than morphine in renal failure, but not ideal in patients with moderate or severe renal impairment.

Pharmacodynamics

Mechanism of action

Oxycodone is an opioid bringing about analgesia through its agonist effect on the mu receptor.

Adverse drug reactions

Like other opioids, oxycodone causes the dose-relate effects of drowsiness and slower respirations.

Other common adverse effects include:

  • Constipation
  • Nausea and vomiting
  • Pruritus
  • Confusion

Dosing and Routes of Administration

Oxycodone can be given orally and subcutaneously. Given its oral bioavailability, a subcutaneous dose of oxycodone should be around half to two-thirds the oral dose.

Doses in opioid naive patients are age related and typical starting doses may be:

Age Type Starting dose
Young and middle-aged adult Oral immediate release 5-10mg for breakthrough pain
Oral modified release Typically 10mg twice daily
SC stat 5-7.5mg for breakthrough pain
CSCI 15mg over 24 hours
Elderly adult Oral immediate release 5mg for brekathrough pain
Oral modified release Typically 5mg twice daily
SC stat 2.5 for breakthrough pain
CSCI 10mg over 24 hours

Equianalgesic Doses

Oxycodone is slightly more potent than morphine and an oral dose of morphine of 15mg is usually equivalent to an oral dose of oxycodone of about 10mg (i.e. oral morphine:oral oxycodone = 3:2).

Specifically:

1mg of SC oxycodone 
= 1mg of SC morphine
= 3mg of oral morphine
= 2mg of oral oxycodone
= 15microgs of SC fentanyl

The table below can be used as a quick reference in converting oxycodone doses to other opioids and vice versa. These are approximate doses and it is always wise to use caution and be conservative in dosing when undertaking a conversion. The table can be used for background pain control and breakthrough doses.

Morphine Oxycodone Fentanyl Buprenorphine
(milligrams) (milligrams) (milligrams) (milligrams) (micrograms)
Oral SC Oral SC Patch SC Patch
5mg 2.5mg 5mg 2.5mg * 25mcg #
10mg 2.5-5mg 10mg 2.5-5mg * 50mcg #
15mg 5mg 10mg 5mg * 75mcg #
20mg 5-7.5mg 15mg 5-7.5mg * 100mcg #
30mg 10mg 20mg 10mg * 150mcg #
45mg 15mg 30mg 15mg * 225mcg #
60mg 20mg 40mg 20mg * 300mcg #
90mg 30mg 60mg 30mg * 450mcg #
120mg 40mg 80mg 40mg * 600mcg #
180mg 60mg 120mg 60mg * 900mcg #
240mg 80mg 160mg 80mg * 1200mcg #
300mg 100mg 200mg 100mg * 1500mcg #
* a 25 microgram/hour patch of fentanyl = a daily dose of 24×25 = 600 micrograms of fentanyl
# a 20mg buprenorphine patch approximately equals a 12microgram/hour fental patch
Table - Opioid Equivalence


Compatibilities in a CSCI

The following combinations have been described as safe in a continuous subcutaneous infusion:

2 Drug Oxycodone Combinations
Diluent
Oxycodone + Cyclizine Water
Haloperidol Water or Saline
Hyoscine butylbromide Water or Saline
Ketamine Water or Saline
Ketorolac Saline
Levomepromazine Water or Saline
Metoclopramide Water or Saline
Midazolam Water or Saline
Octreotide Water or Saline
Ondansentron Water or Saline
Ranitidine Water or Saline
Table - Oxycodone compatibilities
3 Drug Oxycodone Combinations
Diluent
Oxycodone Haloperidol + Cyclizine & Water
Ketamine Saline
Midazolam Water or Saline
Octreotide Water or Saline
Hyoscine butylbromide + Octreotide Water
Ondansetron Water
Ranitidine Saline
Levomepromazine + Hyoscine butylbromide Water or Saline
Ketamine Saline
Metoclopramide Water or Saline
Midazolam Water or Saline
Octreotide Water or Saline
Ondansetron Water or Saline
Ranitidine Saline
Metoclopramide + Ondansetron Water or Saline
Ranitidine Saline
Midazolam + Cyclizine & Water
Hyoscine butylbromide Water or Saline
Ketamine Water or Saline
Metoclopramide Water or Saline
Octreotide Water or Saline
Ondansetron Water or Saline
& Precipitation reported with higher doses of oxycodone >100mg
Table - Oxycodone compatibilities
4 Drug Oxycodone Combinations
Diluent
Haloperidol + Hyoscine butylbromide + Ranitidine % Saline
Midazolam + Cyclizine & Water
Hyoscine butylbromide Water or Saline
Ketamine Saline
Octreotide Water
Levomepromazine + Hyoscine butylbromide + Octreotide Water or Saline
Ranitidine @ Saline
Metoclopramide + Midazaolam Water
Midazolam + Hyoscine butylbromide Water or Saline
Ketamine Saline
Octreotide Water or Saline
Ondansetron Saline
Midazolam + Hyoscine butylbromide + Ondansetron Water
Midazolam + Ondansetron + Octreotide Water
@ Precipitation has been reported with higher doses of oxycodone (>100mg) or levomepromazine (>100mg)
 % Add ranitidine last once all the other drugs and diluent have been combined
Table - Oxycodone compatibilities

Authors

Graham Llewellyn Grove