Sunday 3 December, 2006

Opioid analgesic dose conversions

Posted in General Practice, Medicine, Michael Tam, Wards at 19:37 by Michael Tam

Original article by: Michael Tam :: Printer friendly

morphine

Opioid analgesics are the cornerstone to treatment and control of severe pain. Equivalence of dose potency is not absolute and care must be taken in changing analgesics. In general, it is safer to use a lower regular dose with breakthrough analgesia rather than to convert immediately to the “equivalent” dose.

It is important nevertheless to know the approximately dosage conversions.

Equivalence to morphine 30 mg oral (1)
Drug Dosage Ratio
morphine (subcutaneous) 10 mg 1:3
morphine (intramuscular) 6 mg 1:5
morphine (intravenous) (2) 5 mg 1:6
oxycodone (oral) (3) 15 mg 1:2
hydromorphone (oral) (4) 6.5-7.5 mg 1:4-5
hydromorphone
(subcutaneous/intramuscular)
1.3-2.0 mg 1:15-25
fentanyl (transdermal patch) 50 mcg/hr (*) complex
codeine (oral) 180 mg (**) 6:1
codeine (intramuscular) 120 mg (**) 4:1
(*) Assuming morphine 30 mg (PO) q4-hourly dosing. Dose conversions to and from fentanyl transdermal patches are complex. Please refer to the prescriber guidelines, product information or a pain specialist.
(**) There is usually little benefit in using doses of codeine phosphate above 60 mg per dose. Higher doses may lead to agitation and eu/dysphoria (5)

Conversion to oral slow release formulations

Conversion to oral dosing is usually fairly simple.

DO:

  1. Calculate total dose of opioid analgesia taken over 24 hours;
  2. convert to oral equivalent dose;
  3. split the total daily oral dose into twice daily dosing (round down);
  4. don’t forget to prescribe short acting analgesia for breakthrough pain (usually 50-100% of the regular dose per unit time).

An example:

A patient has received morphine 5 mg subcutaneously q4-hourly regularly and in the past 24 hours, received an additional three 5 mg subcutaneous bolus breakthrough doses. To convert into and regimen of oral morphine:

(Step One): Calculate total dose over 24 hours

  • regular doses: 5 mg x 6 doses = morphine 30 mg (s/c)
  • bolus doses: 5 mg x 3 doses = morphine 15 mg (s/c)
  • Total: morphine 45 mg (s/c) per 24 hours

(Step Two): Conversion to equivalent oral morphine

  • subcutaneous morphine to oral morphine ~ 1:3
  • Thus: 45 mg/day x 3
  • Oral equivalent daily dose: morphine 135 mg (PO) per 24 hours

(Step Three): Split into divided doses

  • Split dose (2 per day): morphine 135 mg (PO) / 2
  • Thus: morphine SR 67.5 mg per dose twice daily
  • Rounded down: morphine SR 60 mg (PO) twice daily

(Step Four): Breakthrough analgesia

  • Regular dose: morphine SR 60 mg (PO) per 12 hours
  • Breakthrough dose: (60 mg /12) x 50-100% = morphine 2.5-5.0 mg (PO) per hour
  • Given that oral (short acting) morphine is given every fourth hourly: 2.5-5.0 mg/hr x 4 hr
  • Breakthrough dose: morphine (immediate release) 10-20 mg (PO) q4-hourly PRN

Summary:

morphine SR 60 mg PO twice daily

+

morphine (imm. release) 10-20 mg PO q4-hourly PRN

After 24 hours, review the breakthrough (PRN) requirements. If a significant amount of breakthrough analgesia was required, this should be added to the regular analgesia.

Reference articles

(1) Examples of approximate equivalent doses when changing from morphine to another opioid (Table 10.7). Therapeutic guidelines: Analgesic, version 4, 2002.

(2) Morphine Sulfate Injection BP (DBL). MimsOnline. Last updated: 20 October 2005.

(3) OxyContin (oxycodone hydrochloride). MimsOnline. Last updated: 29 October 2004.

(4) Dilaudid (hydromorphone hydrochloride). MimsOnline. Last updated: 9 July 2004.

(5) Codeine Phosphate. MimsOnline. Last updated: 6 September 2001.

Please read the disclaimer

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28 Comments

  1. Name removed by request said,

    Hello Michael,
    A very helpful website. I have got a couple of questions to ask you.
    1. If a patient is taking oxycodone for pain relief, but they are experiencing a lot of breakthrough pain, could they use Ordine or should they use Oxycontin (conventional tablets) as the breakthrough pain medicine?

    If you can use oxycodone as the principal pain relieving agent and use ordine as a breakthough medicine, that would be quite difficult to convert the breakthrough medicine to the total daily dose?

    I was wondering what would the breakthrough medicine be if patients were taking hydromorphone or durogesic patches?

    2. Suppose that a patient is taking Oxycontin 20mg bd, and they need to be converted back to Morphine, is the dosage simply 40mg bd or 80mg worth of morphine?

    3. In terms of formulation issues, capsules are best to be swallowed whole, right? I think an underlying prinicple would be that tablets which are scored (i.e. anything that is not modified release, sustained release, slow release) can be crushed WHEREAS all capsules should be swallowed whole; is the principle correct?

    I hope you can let me know your thoughts. A very helpful website.
    Kind regards
    Name removed by request

    P.S. Given that you are a doctor, I was wondering whether all nasal sprays have to be primed prior to be using them; does this include imiigran nasal sprays right down to nasonex nasal sprays.

    How about the normal Ventolin puffers; do they have to be primed??? Are the only ones that need to be primed nasal sprays and the GTN spray?

  2. Michael Tam said,

    Firstly: Please read the disclaimer

    (1) If a patient is using oxycodone for pain control, then it is best to stick with one strong opiate analgesic. That is, using slow-release oxycodone (e.g., OxyContin) with immediate-release oxycodone (e.g., Endone or OxyNorm) for breakthrough pain. Where possible, I would avoid mixing oxycodone with morphine (“Ordine”).

    Although I would not use slow-release oxycodone with morphone, it would not be difficult to convert it to a total daily dose. You simply have to convert it to the oral morphine equivalent.

    I have no experience with hydromorphone, but with fentanyl (Durogesic) patches, you could use any of the immediate acting strong opioid analgesics as breakthrough analgesic (e.g., oxycodone or morphine).

    (2) Slow-release oxycodone 20 mg bd (i.e., 40 mg total daily) is equivalent approximately to slow-release morphine 40 mg bd (i.e., 80 mg total daily). Realistically, I would more likely start with morphine SR 30 mg bd with morphine breakthrough analgesia as there is a danger in overestimating the new dose.

    (3) Basically yes – you should swallow capsules whole, you can crush tablets as long as they are not enteric coated or a slow release / modified release formulation.

    (4) Not all nasal sprays need to be primed and metered dose inhalers for the most part do not need to be primed. I would always recommend following the manufacturer’s instructions.

  3. Name removed by request said,

    Dear Michael,
    Some of the common issues that I have come across in community practice is patients requesting for products without a prescription for neuropathic pain. I often inform patients to go and see a doctor. However, as far as the litreature is concerned, anti-inflammatory agents have been shown to do very little in pain relief in patients in neuropathic pain. Is the best option often giving them regular paracetamol or panadeine (paracetmaol 500mg + codeine 9.6 mg) given around the clock?

    Additionally, many patients request for treatment of sciatic nerve pain. Would the above mentioned medications (perhaps with the addition of doxylamine to paracetamol and codeine) be more effective than the non-steroidal anti-inflammatory agents?

    Finally, regarding my query about priming of nasal sprays – I am not completley sure which nasal sprays would not be primed. I feel all nasal sprays have to be primed, so you get the even distribution of the dose. However, as you rightfully state, metered dose inhalers do not need to be primed.

    Kind regards
    Name removed by request

  4. Michael Tam said,

    Most analgesics do not work well for neuropathic pain. Regular paracetamol is not an unreasonable option, especially with the extended release version. There is very little evidence that the small amounts of codeine phosphate in “Panadeine” preparations have any substantial therapeutic benefit.

    Depending on the severity of the pain, multimodal therapy (e.g., paracetamol + low dose NSAID + opiate analgesic + anticonvulsant) can be useful.

    Insofar as sciatica, it is best to treat the underlying cause of the pain. That may be through physiotherapy all the way to surgery depending on the underlying pathology. For the treatment of acute pain, then paracetamol + codeine (500 mg + 30 mg) or tramadol appropriate. I do not generally recommend the use of doxylamine for pain.

    Regards.

  5. Florence said,

    Hi Michael,
    In palliative care for patient on regular hydromorphone, we use hydromorphone oral liquid or injection for breakthrough pain.
    Regards,

  6. lynette farnham said,

    hello, i have seen ordine ordered for a palative care patient with empysema,trachy.patient has no pain but breathless at times. ordine prn is not for pain but coad.is this normal practise and what doesage is recommended
    lynette

  7. Michael Tam said,

    Firstly: Please read the disclaimer

    Morphine (Ordine is morphine hydrochloride elixir) can be effectively used for symptomatic relief of refractory dyspnoea (shortness of breath). This may be both in the palliative care setting and in severe chronic obstructive pulmonary disease. There is a certain degree of historical irony. The first effective antibiotics (the sulphonamides) were not available until the mid- to late-1930s and penicillin was not commercially produced until the 1940s. Before the advent of antibiotics, pneumonia was a severe and deadly disease. Often, it could only be treated symptomatically and morphine was typically used to relieve dyspnoea.

    Nevertheless, care must be exercised when using strong opiates in respiratory illness, and the potential gains must be weighed against the risk of potentially life-threatening respiratory depression.

    Australian researchers, Abernethy, Currow, Frith, et. al (2003) published in the British Medical Journal their findings on a randomised, double-blinded placebo controlled cross-over trial on the use of morphine for refractory dyspnoea in hospital outpatient clinics. Their conclusion is as follows (1):

    “Sustained release, oral morphine at low dosage provides significant symptomatic improvement in refractory dyspnoea in the community setting.”

    The Australian Therapeutic Guidelines Group has published in their guidelines from palliative care (last revised August 2005 at this time) the use of opiates in dyspnoea in palliative care patients. Their recommendations (2):

    For opioid-naive patients, who have an acute episode of dyspnoea, use:

    immediate-release morphine 2.5 to 5 mg orally, OR, morphine 1 to 2.5 mg SC

    For opioid-naive patients, if breathlessness is continuous, use:

    sustained-release or controlled-release morphine 10 to 20 mg per 24 hours orally, regularly. If ineffective (but tolerated), the dose can be titrated up.

    For patients currently receiving opioids who have an acute episode of dyspnoea, give:

    morphine at approximately one-twelfth to one-sixth of the total daily dose (or the alternative opioid at the appropriate dose), as necessary (not more frequently than every 30 minutes; review after 3 doses if symptoms are not relieved).

    If breathlessness is continuous in a patient currently receiving opioids:

    increase maintenance dose of opioid by 30% to 50%

    References
    (1) Abernethy AP, Currow DC, Firth P, Fazekas BS, McHugh A, Bui C. Randomised, double blind, placebo controlled corssover trial of sustained release morphine for the management of refractory dyspnoea. BMJ 2003;327:523-528 (6 September), doi:10.1136/bmj.327.7414.523. [Link]

    (2) Symptomatic relief of dyspnoea in palliative care patients, in Palliative Care, version 2 (2005). Therapeutic Guidelines Limited.

  8. Rita Mic said,

    If a patient is on 60mg oral morphine, what is the dosage equivalent for Oxycontin q12h and also what dosage of Endone should she get to relieve breakthrough pain? How do you calculate that?

  9. Michael Tam said,

    Dear Rita,

    Just follow the instructions in the article.

    1. Calculate total dose of opioid analgesia taken over 24 hours;
    morphine (oral), 60 mg per 24 hours

    2. convert to oral equivalent dose;
    oxycodone : morphine (oral) is 1:2
    So, morphine (oral) 60 mg per 24 hour is equivalent to oxycodone 30 mg per 24 hour

    3. split the total daily oral dose into twice daily dosing (round down);
    oxycodone 30 mg per 24 hour = oxycodone SR 15 mg twice daily

    4. don’t forget to prescribe short acting analgesia for breakthrough pain (usually 50-100% of the regular dose per unit time).
    50-100% of oxycodone 15 mg per 12 hour
    = oxycodone 0.625 – 1.25 mg per hour
    = oxycodone (immediate release) 2.5 mg – 5 mg per 4 hours

  10. Robert K said,

    Hi DR. Mike
    I am a 29 year old male at 5’11” and 180lbs I have scoliosis and a 1&3/4 inch hip displacement at the age of 22 I was perscribed oxycontin 20mg 8times daily with 180 percocet every 20-30 days as a breakthrough during rehab and corrective surgery at age 25 I failed in several attempts at tapering at which time Methadone was provided as an alternative now almost 5 years later I have tapered from 80mg daily to 15mg daily but with recent government limitation and laws in canada it has become very hard to maintain my career as I travel for long periods so my physician and I are starting a morphine sr taper to allow me to continue to work my question is what ratio should I start at 15mg methadone daily to ? morphine sr … My doctor has started me at 15mg morphine sr 3xdaily 1 week 2xdaily second week and so on for 7 weeks … am I to low as I still need to function at work but I am willing and aware that some discomfort will occour BUT I can’t show symtoms or loose my ability to make decisions or think… please respond so i can advise my DR. as he is uncertain and open to any suggestions I can find or offer.. thanks

  11. Michael Tam said,

    Dear Robert,

    Firstly: read the disclaimer

    My experience with methadone in the chronic pain setting is with the tablet version of methadone and I have never had a reason to convert it to oral morphine.

    Conversions to methadone is a complicated process and there is little data on the conversion FROM methadone to morphine. In a quick guide I found written by Quill and Kuderer for the Palliative Care Program for the University of Rochester Medical Centre (1), they recommended starting with an oral dose conversion of methadone:morphine at a ratio of 1:1 to 1:3 and to “be prepared to increase the dose rapidly”.

    As such, the suggestion by your regular physician seems reasonable.

    References
    (1) Quill T., Kuderer N. Methadone dose conversion guidelines. Palliative Care Program, University of Rochester Medical Center. [Link]

  12. Robert K said,

    Thank you I have only found a study for this conversion done in Austrailia but the persons involved were using methadone as treatment for non perscribed opiate & heroin drug addiction listed below

    http://www.blackwell-synergy.com/loi/ADD?open=1980#year1980

    thank you much
    Robert K

  13. kk said,

    A patient is taking 60mg of Oxycontin every 12 hours for pain; what is an appropriate breakthrough dose of Oxynorm liquid for this patient?

    thank you

  14. Michael Tam said,

    A not-unreasonable starting breakthrough dose would be 50% of the maintenance opiate.

    That is: oxycodone 60 mg / 24 hours.

    Or, oxycodone elixir 10 mg up to every 4 hours PRN.

  15. Angela said,

    Dear Micheal , I would like to do a quick taper from Oxycontin 20mg .

    I know this is not the best and pleasant way to do it,but cant get enough pills for a slow taper.

    I am on around 160-200-mg per day . I have been on them for five years,and also know I will need clonidine . What do you think is best .

    Regards Angela

  16. Michael Tam said,

    Dear Angela,

    You are on a large dose of Oxycontin and it would be inappropriate for me to recommend any specific therapeutic regimen. I strongly suggest that you discuss this with your regular General Practitioner, or seek the services of a drug and alcohol clinic.

  17. Guilherme said,

    Hi Tam, currently on 50mg oral methadone daily but wants to taper & come off alogether. Withdrawal from methadone is notoriously difficult. Am considering transfering him from oral methadone to tramadol tablets for this purpose as withdrawal from Tramadol is easier. Can you recommend a conversion rate from methadone to tramadol?

  18. Michael Tam said,

    Dear Guilherme.

    The maximum safe dose of tramadol (400 mg total daily dose) has an effect much lower than your stated dose of methadone. There is no recommended conversion rate..

    I strongly suggest that you discuss this with your General Practitioner, or seek the services of a drug and alcohol clinic.

  19. kelly said,

    my husband takes oxycontin 80mg 2 four times a day which is no longer helping his pain what do you suggest for breakthrough pain?

  20. Michael Tam said,

    Dear Kelly,

    I strongly recommend that your husband seeks advice from his regular pain physician or general practitioner.

  21. Loren Kott said,

    I’m presently taking 190mg Methadone per day, for a few years. If I convert to oral morphine what is the conversion ratio or total dosage I should take?

    I know that dealing with Methadone leaves a lot of unconsidered factors like Methadone populating many more types of opioid receptors and populating any one receptor, like Mu, to a higher degree. The length of time I’ve been taking Methadone. All these many factors and more, notwithstanding, there must be a generally accepted ratio or dosage per unit factor?? If there is one that does consider factors as those above, that would be even greater.

    Thanks for your consideration and going out on a limb, so to speak.

  22. hassan said,

    conversion from oral morphine to subcutenous infusion

    g. The pain sister asks for your advice. A patient on the ward has been receiving morphine sulphate 60 mg tablets every four hours. She would like to change over to morphine sulphate subcutaneous infusion every 24 hours.
    What daily dose of morphine sulphate subcutaneous infusion would be equivalent to the patient’s oral daily dose?
    A 30 mg
    B 60 mg
    C 90 mg
    D 120 mg

  23. Michael Tam said,

    120 mg

  24. Graham said,

    Dear Michael Tam,

    I have suffered from increasingly severe lumbar arachnoiditis for the last 2 years following in the introduction of infection to my spinal chord after surgery. My pain level and perceptions have increased significantly over that time also. My new GP currently has me on 40mg (morning) and 30mg (nightly) oxycontin per day, with provision for 5mg doses of endone when required for breakthrough pain. However, I fear this new doctor (who has only taken over my case in the last 3 weeks since my regular doctor moved interstate) will show disapproval if my endone use seems excessive. Frequently in the past 2 weeks I have required such breakthrough endone doses 3 to 4 times a day. I would greatly appreciate any advice.
    Best regards,
    Graham

    • Michael Tam said,

      I strongly recommend discussing these issues with your new general practitioner.

  25. Scott Craver said,

    Dear sir, I am 51 yrs. male and have been on 190mg of methadone per day for 10 yrs. I have epilepisy and suffer from severe chronic pain. Due to the expence of the clinic I go to $300.00 per mo. I have to withdraw from it. Can you plz give me advice on the easiest way to come off this medication. My overall health is poor & I’m very afraid of complications. Can you tell me if just tapering off would be the best way to do it? Trouble is I can’t afford to keep going to this clinic. What would be a good alternate to withdraw for this nasty Methadone? Thank you for taking your time to help me with my problem. Godbless, Scott Craver

    • Michael Tam said,

      Withdraw from large doses of methadone is best done under close supervision. I would recommend discussing this with your regular prescriber or regular pain physician.


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