The FDA has approved Lyrica CR (pregabalin, Pfizer) for the management of neuropathic pain associated with diabetic peripheral neuropathy (DPN) or postherpetic neuralgia (PHN). It is not approved for managing fibromyalgia or as an adjunctive therapy for adults with partial onset seizures. Lyrica CR is available as a once-daily extended-release tablet. The medication is a Schedule V controlled substance.1

PHARMACOLOGY AND PHARMACOKINETICS
Although the exact mechanism of action of Lyrica CR has not been established, it binds with high affinity to the alpha2-delta site in the central nervous system tissue, which may be responsible for its pain relief effects. Lyrica CR does not bind directly to GABAA or GABAB, but prolonged application of the medication has been found to increase the density of the GABA transporter protein and increase the rate of functional GABA transport.

Steady-state concentration is achieved after 48 to 72 hours of treatment. Taking Lyrica CR on an empty stomach reduces its bioavailability.1

DOSAGE AND ADMINISTRATION
Lyrica CR should be taken once daily after an evening meal. It should be swallowed whole and never split, crushed, or chewed. For patients with DPN, the initial dose is 165 mg once daily. Within 1 week, the dose should be increased to the target and maximum daily dose of 330 mg once daily. For patients with PHN, treatment should begin with 165 mg once daily and increase to 330 mg once daily within 1 week. If significant pain relief is not achieved by 2 to 4 weeks of treatment and the medication is tolerated, the dose may be increased to the maximum of 660 mg once daily. Switching treatment from Lyrica capsules or oral solution to Lyrica CR requires a dose conversion because the products are not interchangeable. The dose should be modified for patients with renal impairment. Patients with creatinine clearance less than 30 mL/min or who are undergoing hemodialysis should not use Lyrica CR.1

CLINICAL TRIALS
Lyrica CR was evaluated for safety and efficacy in a 19-week, randomized, placebo-controlled trial of patients with PHN. The study began with a 6-week, single-blind, dose-optimization phase and was followed by a 13-week double-blind phase. The patients using Lyrica CR displayed a statistically significant improvement in their change in mean pain score from baseline compared with placebo, with 73.6% of patients in the Lyrica CR group achieving at least 50% improvement in pain intensity compared with 54.6% of patients in the placebo group. These PHN data were supportive of the DPN and PHN indications for Lyrica CR, as both are peripheral neuropathic pain conditions.1,2

CONTRAINDICATIONS, WARNINGS, AND PRECAUTIONS
The use of Lyrica CR is contraindicated in patients with a known hypersensitivity to the medication or any of its components. Lyrica CR should be discontinued immediately if angioedema or hypersensitivity reactions occur. Antiepileptic drugs, including Lyrica CR, may increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication. Patients using any antiepileptic drug should be monitored for the onset or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior. Lyrica CR may cause peripheral edema, dizziness, or somnolence. In patients with a seizure disorder, rapid discontinuation of the medication may increase seizure frequency. Lyrica CR may cause fetal harm when used during pregnancy. It should not be used during breastfeeding. The most common adverse reactions are blurred vision, dizziness, dry mouth, fatigue, headaches, nau- sea, peripheral edema, somnolence, and weight gain.1 
 
Monica Holmberg, PharmD, BCPS, earned her PharmD at the University of Connecticut in Storrs and completed an ambulatory care residency at the Phoenix VA Healthcare System in Arizona. Her practice has also included pediatrics and inpatient mental health. She lives in Phoenix.

References
  1. Lyrica CR [prescribing information]. New York, NY: Parke-Davis Division of Pfizer Inc; 2017. labeling.pfizer.com/ShowLabeling. aspx?id=9678. Accessed January 30, 2018.
  2. U.S. FDA approves Lyrica CR (pregabalin) extended-release tablets CV [news release]. New York, NY: Pfizer Inc; October 12, 2017. pfizer.com/news/press-release/press-release-detail/u_s_ fda_approves_lyrica_cr_pregabalin_extended_release_tablets_cv. Accessed January 30, 2018.