Cymbalta for Back Pain

Cymbalta: Newly Approved Drug for Chronic Pain

Cymbalta Dangers

Is Cymbalta Dangerous?

Duloxetine Hydrochloride (Cymbalta) has been used since 2004 as a treatment for major depressive disorder and diabetic neuropathy.  In 2007 it also became available for treatment of general anxiety disorder, and then for fibromyalgia in 2008.  On the 4th November the FDA approved Cymbalta for use in chronic debilitating conditions such as musculoskeletal pain, including chronic back pain, and osteoarthritis.  Spinal stenosis sufferers in the US may now be prescribed Cymbalta, with the usual dose being set at one 60mg capsule a day.  The director of the FDA’s Center for Drug Evaluation and Research, Janet Woodcock, MD, said that this provides “another treatment option… [as] Up to three-quarters of the population experience chronic pain at some time in their lives.”  But, should spinal stenosis sufferers be heralding this approval as the answer to all their pain problems, or are there more factors to consider before adding Cymbalta to your treatment plan?

Cymbalta Clinical Trials

The evidence from clinical trials shows that Cymbalta significantly reduced chronic pain in comparison to placebo, with more than 29,000 patients with osteoarthritis, or chronic low back pain involved in these clinical trials.  The four major trials involved in the analysis of the drug’s efficacy and safety were double-blind, placebo-controlled, randomized clinical trials (RCTs), providing the highest class of rigorous scientific investigation into new drug therapies.  These RCTs were, however, short-term, and the FDA expressed concerns over approving a pain-relief medication that had some serious side-effects associated with it including potential liver damage.

Cymbalta Side Effects

The most serious side-effects occurred in less than 1% of those studied in the trial and, aside from liver damage, include facial swelling, urticaria (hives), rashes, depression, suicidal thoughts and behaviour, and possible pneumonia.  Perahia (2006) found an incidence of 34.7% of nausea in patients being treated with Cymbalta for depression, 22.7% of patients experienced dry mouth, 20% headaches, and 18.7% dizziness, other studies found insomnia, drowsiness, and fatigue to also be fairly common complications.  All of these symptoms were higher in the Cymbalta users than the placebo group with the exception of headaches.  These side-effects associated with Cymbalta, may make some spinal stenosis sufferers think twice about altering their treatment and either maintain their current regimen or decide to use alternative spinal stenosis treatments such as fish oil or glucosamine to relieve their chronic back pain.

Cymbalta’s Other Ingredients

Another consideration for those exploring the possible use of Cymbalta are the various non-medicinal ingredients in the tablet, which may not be mentioned by your doctor at the time of prescription.  These include FD&C Blue No. 2, gelatin, hypromellose, hydroxypropyl methylcellulose acetate succinate, sodium lauryl sulfate (SLS), sucrose, sugar spheres, talc, titanium dioxide, and triethyl citrate; A plethora of substances that may in themselves be responsible for some of the side-effects and will have ethical and allergy considerations for others (such as the gelatin, and SLS).  The 20 and 60 mg capsules also contain iron oxide yellow.

Cymbalta Long Term Concerns

Duloxetine Hydrochloride works as a serotonin and norepinephrine reuptake inhibitor, with a higher affinity for both of these neurotransmitters’ receptors than a number of other antidepressants.  Patients usually observe significant pain relief within a week of taking the drug, and the half-life is thought to be around eight to twelve hours, with most of the metabolites excreted through the urine or faeces.  As the clinical trials have all been short-term, and the collection of data from patients who have been using Cymbalta since 2004 has either not been collected or collated in a systematic way amenable to analysis, there remains significant concern over the drug’s long-term effects on both natural neurotransmitter levels and the health of the liver.  Serious withdrawal symptoms have been noted amongst users weaning themselves off Cymbalta, as with other SSRIs, leading to campaigns against the drug, and a mushrooming of websites and blogs detailing individuals’ personal experiences with this medication.

Cymbalta in the Liver

As the drug is metabolized by two specific liver enzymes – P450 isozymes, CYP1A2 and CYP2D6, and every individual has some variation in the efficiency of these enzymes, there should be concern over each patient’s capacity for utilizing and clearing the drug from their system.  It is thought that 5-10% of caucasians are ‘poor-metabolizers’ of xenobiotics using the CYP2D6 enzyme pathway, which increases their risk of side-effects from the drug as they struggle to detoxify and excrete it; significant polymorphisms in the activity and expression of CYP1A2 also exist.  Cymbalta’s clearance rate will also be affected by dietary and lifestyle factors as a diet low in protein will decrease phase II enzyme activity and compromise liver function, whereas a diet rich in cytochrome P450 Phase II enzyme-activating foods, such as curcumin (from turmeric), brazil nuts, broccoli, onions, and legumes can help reduce the toxic burden on the liver, but may compromise the intial phase I enzymes.  If you take Cymbalta and experience significant side-effects then it may be that dietary changes are appropriate, or different medication may be required in order to optimise liver health.  Functional medicine tests are available to assess genetic polymorphisms in these detoxification enzymes.

Cymbalta for Chronic Pain

The approval of Cymbalta for chronic pain from musculoskeletal issues, and osteoarthritis could be fantastic news for some who have found other treatments ineffective, but as with most prescription medications there are a number of factors to consider before deciding on this treatment.  Eli Lilly, the manufacturer of Cymbalta already make around $3.5billion a year from the drug, but are set to lose their patent rights mid 2013, which should lower the cost of the medication.  There are already trials investigating Cymbalta’s use for Parkinsonism-associated-pain and for use in chronic headaches.  In the long-term, however, other pain-management therapies may be the better option for spinal stenosis treatment as the drug does nothing to halt the progression of the disease, or alleviate underlying factors.  Its pain-masking effect, like any analgesic, could increase the risk of potentially compromising activity and exercise that may in the long-run exacerbate spinal stenosis; patients should approach its use with caution and explore all of their treatment options with their physician.

3 replies
  1. Ann
    Ann says:

    I would just like to point out that all patients in the trials concerning cymbalta and chronic pain no sujects had evidence of spinal stenosis.


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