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mrsD · 11-29-2007, 01:25 PM

Here is a handy website converter.
I put in fentanyl .025 (for daily) since .075 would be for 3 days
(you have to use milligrams not micrograms)
I used 0% cross tolerance reduction just because I don't know your situation.

http://www.globalrph.com/narcotic.cgi
and got:

Quote:

Based on your selections above, here is the result:
Equivalent dose for opiate selected in Step 3 above: 5.00 mg
Reduction for incomplete cross tolerance: 0 %

This is for IV fentanyl-- they don't have a patch listed.

Another converter:
http://www.mywhatever.com/cifwriter/...y/70/4932.html

Quote:

Fentanyl. Fentanyl comes in patches from 25 to 100 ug/h. Patches are changed every 72 hours. A 25 ug/h patch is approximately equal to 50 to 75 mg of oral morphine over 24 h. Levy suggests a simple rule of thumb: that the Fentanyl patch strength (in mcg/h e.g., 25, 50, 100, etc.) is equal to the SR morphine dose given BID.34 Thus, by this rule a 150 mcg/h patch is equivalent to 150 mg SR morphine q12h. Jannsen, the manufacturer of fentanyl patches, suggests a more conservative dosing schedule in converting to fentanyl patches. Jannsen's dosing table does not allow for a simple conversion value. They suggest a relatively higher patch strength at low oral morphine equivalents (25 mcg patch for 45-134 mg morphine/24h - consistent with Levy's rule) and a relatively lower patch strengths at higher morphine doses (200 mcg patch at 675-764 mg morphine/24h - not consistent with Levy's rule). (See manufacturer's product information for details). Their product information stresses that conservative conversion values used for converting to fentanyl patches may result in drug overdosage if used to convert from patches to other opioids, highlighting the danger of a simplistic use of conversion tables.

You have to know the generic names. You can find them by using Rxlist.com
Percocet=oxycodone

Because the patches work differently for everyone, it is harder to calculate your response. The body also metabolizes differently when a patch is used compared to oral.

The global site is more accurate for oral- to oral meds IMO.

The ratio of oxy to morphine is 20:30 for a 24 hr period. Typically most calculator charts use morphine as the standard.

This site explains more about patches:
http://www.medicineau.net.au/clinica...2.html#anchor1

Quote:

Conversions
The patch comes in four sizes - 25mcg/hr, 50, 75 and 100. When transferring a patient from morphine to Fentanyl there is a conversion table of equivalent doses shown below.

A quick approximate method of conversion is to divide the total 24 hour dose of morphine by 3.6, e.g 360mg oral morphine divided by 3.6 equals 100mcg/hr patch. It should be noted that there is wide variation in morphine to Fentanyl conversion, therefore it is safer to underestimate the size of patch required.

Benefits The benefits of Fentanyl patches over slow-release morphine tablets are:

1. Less constipation (statistically significant)
2. Less nausea (anecdotal evidence)
3. Less sedation (anecdotal evidence)
4. Patient preference.

Useful tips

1. In opiod-naive patients it is good practice to adjust the dose of analgesics required with four hourly morphine first to find the 24 hour morphine requirement and then convert to the equivalent Fentanyl patch.
2. If patients require less than 40mg oral morphine per day then even a 25mcg/hr patch may be 'too strong' and cause side effects.
3. Fentanyl patches are very unhelpful with unstable pain. Again it is good practice to use four hourly morphine in this situation until analgesic requirements are steady and then convert morphine to the equivalent patch.
4. When changing from morphine to Fentanyl the patients can experience opioid withdrawal, eg. abdominal cramps, sweats and flu-like symptoms. This is abated with a dose of four hourly morphine and should only last a few days.
5. A small number of patients find the patches last 48 hours and not 72 hours. In these instances it is appropriate to replace the patch every 48 hours rather than increasing the patch size.
6. Due to the heat in summer the patches can slide off. Do not use Opsite over the patch to keep it in place, this will cause a faster delivery of Fentanyl and possible overdose. Instead stick micropore tape around the outside of the patch and not directly over the drug reservoir. Incidentally, direct heat, such as a hot water bottle can also increase absorption.
7. When changing from morphine, put a patch on at night with the usual dose of bedtime morphine then use oral morphine as needed for breakthrough pain.
8. Cut hair rather than shave the skin before applying a patch as shaving will disrupt the top fatty layer of skin and therefore increase the rate of absorption.
9. It is possible to increase the dose above 100mcg/hr by using more than one patch at a time.

This above site then goes on to detail fentanyl:
http://www.medicineau.net.au/clinica...lliative1.html

Fentanyl is very strong. So coming down to oral oxycodone would require pretty high doses.

It can be very dicey switching opiates. So while you can give your doctor these links, I do think a specialist would help you better. The most complex switch is with methadone. People can die during this switch, from long QT syndrome. So if you ever decide to try methadone, have an EKG done before and see a specialist to do it. I have a post in Useful Websites on Chronic Pain forum about methadone in particular.

Based on the conversions I'd say your dose of 40mg of oxy/day is low compared to fentanyl.
I cannot TELL you what to use...since this board is not for that purpose.
But you can read up on what I gave you to get an idea of what you need.
And you can give your doctor these links to use. It would be a help for him/her.