A new review of past research found that venlafaxine (brand name Effexor) — which is usually prescribed for anxiety symptoms — may also help with fibromyalgia symptoms. Medications called serotonin and norepinephrine reuptake inhibitors (SNRIs) have been used successfully to treat fibromyalgia symptoms. Venlafaxine — which is an SNRI — has also been used, but there is little research on how well it works.
"Studies assessing the efficacy of venlafaxine in the treatment of fibromyalgia to date have been limited by small sample size, inconsistent venlafaxine dosing, lack of placebo [fake treatment] control ..." wrote the authors of this study, led by Luke A. VanderWeide, PharmD, of the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences in Aurora. "In the context of these limitations, venlafaxine appears to be at least modestly effective in treating fibromyalgia."
Steve Leuck, PharmD, a pharmacist and founder of AudibleRx, told dailyRx News that it is important for patients to receive counseling before starting a medication like venlafaxine.
"When a patient picks up an antidepressant medication for the first time, it is important to spend some time with him or her to describe how the medication works, especially if they are using it for an off label indication such as fibromyalgia," said Dr. Leuck.
"Patients need to realize that during the first week of therapy, they may feel a little anxious, agitated, tired, or irritable. It may take 7 to 14 days for the neurotransmitters to become balanced, and a good 5 weeks before the patient sees how well this particular dose is going to work for them," he said. "At that point, the patient will be following up with their physician to see if the dose needs to be adjusted."
For their research review, Dr. VanderWeide and colleagues looked at five studies on the use of venlafaxine for fibromyalgia symptoms. These studies were small, with 11 to 102 patients, and ranged in length from six weeks to six months.
Dr. VanderWeide and team noted that SNRIs often take up to 12 weeks to show benefits. Shorter trials may not provide a clear picture of the medication’s effectiveness.
Four of the five trials showed that patients’ symptoms improved when they took venlafaxine. Depending on the study and the assessment tool, patients reported different improvements. However, patients noted decreases in pain, fatigue or depression in some of the studies.
The cause of fibromyalgia is unknown and there is no cure. It affects around 5 million Americans, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMSD). Most fibromyalgia patients are women — 80 to 90 percent, the NIAMSD reports.
Fibromyalgia patients typically have fatigue and pain in their muscles and joints. They may also have trouble thinking, sleep disturbances, and sensitivity to bright lights or loud noises.
Some of the symptoms of fibromyalgia are similar to those of arthritis, but the two diseases are not the same. Although the symptoms of fibromyalgia can appear much earlier, most people are diagnosed in middle age.
Dr. VanderWeide and team called for bigger and higher quality studies on venlafaxine's effect on fibromyalgia.
Since venlafaxine is less expensive than some other SNRIs and is well-tolerated overall, it may be a better choice for many patients. Large, high-quality studies could help doctors and patients make better decisions when choosing an SNRI.
This study will be published in the February issue of the Journal of Clinical Pharmacy and Therapeutics.
The authors disclosed no funding sources or conflicts of interest.