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Letters to the Editor August 2014

Opioid calculator, fibromyalgia, and fibromyalgia and hormones.
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Opioid Calculator

I have a question regarding the calculations from a fentanyl transdermal patch (TDF) and fentanyl intravenous (IV) to oral morphine (PO).

The 1:100 ratio of morphine to fentanyl typically applies to an IV bolus of fentanyl in opioid-naïve patients with acute resolving pain. Also, TDF can be converted to IV fentanyl at the same hourly rate using a conversion of 1:1 (transdermal:IV).

Since IV fentanyl and TDF are considered 1:1 (ie, fentanyl 25 mcg/h IV = fentanyl 25 mcg/h patch), the 25 mcg/h TDF = 45 mg/d oral morphine conversion has also been extrapolated to IV fentanyl. For example, 50 mcg/h TDF or IV fentanyl would be approximately 90 mg/d PO morphine.

With the PPM Opioid Calculator, 50 mcg/h TDF, or 1,200 mcg/d, does equal 90 mg/d PO morphine. However, 50 mcg/h fentanyl IV, or 1,200 mcg/d, equals 360 mg/d PO morphine. Yikes!

My question is, do you use or recommend the TDF calculator for a patient on a continuous infusion of IV fentanyl (at steady state) with stable pain?

Thanks for your help.

Jeanne Miller, PharmD, BSPC

Dear Dr. Miller,

The PPM Opioid Calculator is intended for patients receiving chronic opioid therapy when converting from one opioid to another. An opioid-naïve patient receiving IV fentanyl for an acute surgical intervention does not fit into that category.

You are correct that the conversions to/from fentanyl transdermal patches are out of sync when compared with IV fentanyl.

This is because two separate equations have been used to keep the TDF conversions very conservative when going to/from a transdermal patch. In part this was done because of the tremendous absorption variability with transdermal products, as published within the package insert.

The 1:100 ratio of morphine to fentanyl is the only available conversion that we can reference, as accepted by the American Pain Society.

In general, we do not recommend using the calculator for acute-care opioid conversions.

Jeffrey Fudin, BS, PharmD, FCCP

Fibromyalgia: Secondary Diagnosis

In regards to the etiopathologenesis of fibromyalgia, I take note with an article and subsequent editorial in Practical Pain Management.1,2 Like many clinicians, the author seeks a “pain generator” for fibromyalgia due to past or presumed diseases and anatomical changes misattributed to trauma and other variations of normal anatomy that are age-related.

The cost to our society for spinal surgeries and interventional procedures followed by indiscriminate long-term opioid therapy is enormous! The centralization of peripheral pain is, in reality, a retraining of an individual’s nervous system in response to iatrogenic and biopsychosocial factors that reinforce illness behavior and self-defeating thoughts and behaviors in patients with predisposing factors, such as post-traumatic stress disorder, anxiety and depression, who catastrophize and continue pain avoidance behavior that reinforces deconditioning and learned helplessness.

In 35 years of rheumatology practice, I have yet to see anybody with fibromyalgia syndrome who has “lived happily ever after.” Like the rest of the population, the patients have major psychosocial stressors and behavioral considerations. A deficiency of self-empowering coping skills, resulting in pain behavior (learned helplessness, hypervigilence, and catastrophizing) appears to be a more likely cause of the putative retraining of the central nervous system function (centralization), rather than anatomical changes of a non-specific nature.

David S. Knapp, MD, FACR

Fibromyalgia and Hormones

Back in 2012, I developed fibromyalgia and could not walk across the room. After ruling out multiple sclerosis, systemic lupus erythematous and other diseases that mimic fibromyalgia, my doctor diagnosed fibromyalgia. He prescribed pregabalin (Lyrica), but I didn’t want to take medication.

I decided to pour myself into researching fibromyalgia and everything pertinent that I could get my hands on. Years earlier, I had been on a diet containing the hormone human chorionic gonadotropin (hCG) for weight loss, which I now realize had helped to improve the beginning symptoms of fibromyalgia. To me, it made sense. Middle-aged women have the highest incidence of fibromyalgia, and what happens at middle age? The thyroid stops producing hormones.

I went on an hCG diet (using the typical dose for weight loss) for a month and found that after only 2 weeks my pain was 80% gone. After a month, I went off the diet and my pain came back in 3 weeks—
interestingly, this is the same amount of time that the maintenance part of the diet lasts. I then went back on the diet for 2 months and then when I went off hCG, my pain came back after 3 weeks. I went back on hCG for 3 months, then went off it and the pain remained absent for 3 months. I went back on again when the pain started to return.

Here is my dilemma. I have been back on sublingual hCG for 5 months and I noticed the pain has increased in the last 2 months, though not at the level it was. My question is: would increasing the sublingual dose help? I have also read about a GABA/glutamine imbalance in the brain where the glutamine levels are very low in fibromyalgia patients. Should I also be taking GABA along with glutamine, taurine, and other amino acids? My doctor tested my thyroid and I do not have hypothyroidism.

Lastly, what exercises would you recommend? I know when I push myself while running, it causes a pain flare-up. Are elliptical machines better?

Carrie McBirney

Dear Carrie,

Your letter and experiences not only make sense, but also match the information I have. First, I recommend that every chronic pain patient take pure g-aminobutyric acid (GABA), glutamine, or taurine supplements, which are available at health food stores. Manufacturers market GABA “as a remedy for relieving anxiety and improving mood and attention, as well as promoting lean muscle growth, burning fat, stabilizing blood pressure, and relieving pain.” GABA is a neurotransmitter in the central nervous system, and patients with fibromyalgia may need to supplement GABA levels. Many of my fibromyalgia patients take 10 to 20 mg of GABA at night.

I am also am a fan of low-dose naltrexone (0.5-1 mg/d). Naltrexone is an opioid antagonist and is often used to treat opioid overdose. By blocking the opioid receptors in the brain, naltrexone boosts pain-killing endorphin production in the brain.

Your experiences with sublingual hCG are typical. For fibromyalgia patients, I recommend a dose that is higher than normally used for weight control. We begin patients on 125 units per day, taken once or twice daily—dosages range from 250 units to 750 units. Most patients take it 3 days a week. 

Have you had a hormone profile taken? HCG may not work optimally unless the major hormone levels are normal. You should be tested for cortisol, pregnenolone, dehydroepiandrosterone (DHEA), and progesterone.

Last updated on: May 19, 2015
First published on: August 1, 2014