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Dr. Holmberg is a pharmacy resident at the Carl T. Hayden Veterans Affairs Medical Center in Phoenix, Ariz.
After an expedited review, the FDA has approved Pfizer's Lyrica (pregabalin) for the treatment of fibromyalgia. Before Lyrica's approval, there were no FDA-approved products for the treatment of fibromyalgia.1 Lyrica is a Schedule V controlled substance.2
Fibromyalgia is a chronic pain condition affecting more than 6 million Americans.1 Its characteristic symptoms include pain, fatigue, and sleep problems.3 Other symptoms may vary over time and include headaches, irritable bowel syndrome, irritable bladder, cognitive and memory problems, temporomandibular joint disorder, pelvic pain, restless legs syndrome, sensitivity to noise and temperature, anxiety, and depression.4 While its exact cause is unknown, fibromyalgia is believed to be associated with abnormal levels of spinal substance P, thus causing patients to have an increased response to stimuli that do not usually cause painful reactions.4 Fibromyalgia tends to affect women more than men and usually occurs in adulthood.3
Lyrica's exact mechanism of action is unknown; however, it has been shown to bind to the alpha2-delta site in the tissue of the central nervous system, which may be responsible for its pain-relief effects. Additionally, prolonged application of Lyrica has been found to increase the density of the GABA transporter protein and to increase the rate of GABA transport.2
Lyrica's efficacy for the treatment of fibromyalgia was assessed in 2 studies, both of which selected patients with fibromyalgia diagnosed via the American College of Rheumatology criteria.
In Study F1, patients in the Lyrica group were found to have a significant decrease in pain, with some patients experiencing pain relief as early as 1 week after starting treatment.
In Study F2, patients responding to treatment (defined as having both a 50% reduction in pain and rating their pain as "much improved" or "very much improved") were randomized and double-blinded to receive either their treatment dose or placebo and followed for up to 6 months. Patients using Lyrica had a longer duration until loss of therapeutic response: 53% of Lyrica patients compared with 33% of placebo patients continued the drug and maintained their therapeutic response until Week 26. Lyrica patients also experienced a longer time to loss of overall assessment of patient status.2
The treatment dose for Lyrica is 300 to 450 mg daily. Dose titration is as follows:
In patients with renal dysfunction, the dose should be decreased.
Lyrica can be taken with or without food.2
Lyrica is contraindicated in patients with a hypersensitivity to any of its ingredients.
Angioedema has been reported in some patients using Lyrica; should angioedemia occur, emergency treatment should be sought immediately, and Lyrica should be discontinued. Treatment with Lyrica should be stopped and emergency care should be obtained if hypersensitivity reactions, such as hives, dyspnea, and wheezing occur. Patients with seizure disorder may experience increased seizure frequency if Lyrica is suddenly stopped. Lyrica has been associated with peripheral edema and should be used with caution in patients using concomitant thiazolidinedione antidiabetic agents. Weight gain, increased creatine kinase levels, decreased platelets, and P-R interval prolongation have been noted. Patients using Lyrica may experience dizziness or somnolence that may impair their ability to drive or operate machinery.
Lyrica is a Pregnancy Category C drug. Patients who are breast-feeding should discontinue either treatment with Lyrica or breast-feeding.2
In clinical trials, 7% of patients using Lyrica experienced blurred vision. Other side effects associated with Lyrica included dizziness, somnolence, dry mouth, edema, weight gain, constipation, euphoric mood, balance disorder, increased appetite, and abnormal thinking.1