In the pivotal trial for PHN, HORIZANT significantly reduced 24-hour average pain score during the Week 1 up-titration.
Adjusted mean change from baseline, Week 1
At Week 13, HORIZANT reduced mean 24‑hour average pain intensity score by 2.47 points (vs 1.66 points for placebo; P=0.013).
Improvement in 24-hour average pain intensity score by weeka
aThe value of each week is the mean of the daily scores for that week.
54% of PHN patients taking HORIZANT 600 mg BID had a reduction in pain intensity score of 30% or greater.
A 30% reduction in pain intensity score represents a clinically important result.
Improvement in pain intensity score from baseline to end of maintenance treatment
IMPORTANT SAFETY INFORMATION
WARNINGS AND PRECAUTIONS
Tumorigenic Potential In an oral carcinogenicity study, gabapentin enacarbil increased the incidence of pancreatic acinar cell adenoma and carcinoma in male and female rats. The clinical significance of this finding is unknown.
HORIZANT® (gabapentin enacarbil) Extended-Release Tablets are indicated for the treatment of moderate-to-severe primary Restless Legs Syndrome (RLS) in adults. HORIZANT is not recommended for patients who are required to sleep during the daytime and remain awake at night.
HORIZANT® (gabapentin enacarbil) Extended-Release Tablets are indicated for the management of postherpetic neuralgia (PHN) in adults.
IMPORTANT SAFETY INFORMATION
WARNINGS AND PRECAUTIONS
Effects on Driving
HORIZANT may cause significant driving impairment. The duration of driving impairment after starting therapy is unknown. Patients should not drive until they have enough experience on HORIZANT to know if it impairs their driving. Patients’ ability to assess their driving competence and degree of somnolence caused by HORIZANT can be imperfect.
Somnolence/Sedation and Dizziness
HORIZANT causes somnolence/sedation and dizziness. Patients should not drive or operate other complex machinery until they have enough experience on HORIZANT to know if it impairs their ability to perform these tasks.
Lack of Interchangeability With Gabapentin
HORIZANT is not interchangeable with other gabapentin products because of differing pharmacokinetic profiles. The same dose of HORIZANT results in different plasma concentrations of gabapentin relative to other gabapentin products. The safety and effectiveness of HORIZANT in patients with epilepsy have not been studied.
Suicidal Behavior and Ideation
HORIZANT is a prodrug of gabapentin, an antiepileptic drug (AED). AEDs increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication. As a prodrug of gabapentin, HORIZANT also increases this risk. Patients treated with any AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior. Anyone considering prescribing HORIZANT must balance the risk of suicidal thoughts or behavior with the risk of untreated illness.
Patients, caregivers, and families should be informed that HORIZANT increases the risk of suicidal thoughts and behavior and should be advised of the need to be alert for the emergence or worsening of the signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts of self-harm. Behaviors of concern should be reported immediately to healthcare providers.
Drug Reaction With Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity
Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), also known as multiorgan hypersensitivity, has been reported in patients taking antiepileptic drugs, including gabapentin. HORIZANT is a prodrug of gabapentin. Some of these events have been fatal or life-threatening. DRESS typically, although not exclusively, presents with fever, rash, and/or lymphadenopathy, in association with other organ system involvement, such as hepatitis, nephritis, hematological abnormalities, myocarditis, or myositis sometimes resembling an acute viral infection. Eosinophilia is often present. Because this disorder is variable in its expression, other organ systems not noted here may be involved.
It is important to note that early manifestations of hypersensitivity, such as fever or lymphadenopathy, may be present even though rash is not evident. If such signs or symptoms are present, the patient should be evaluated immediately. HORIZANT should be discontinued if an alternative etiology for the signs or symptoms cannot be established.
Discontinuation of HORIZANT
When discontinuing HORIZANT, patients with RLS receiving 600 mg or less once daily can discontinue the drug without tapering. If the recommended dose is exceeded, the dose should be reduced to 600 mg daily for 1 week prior to discontinuation to minimize the potential of withdrawal seizure.
In patients with PHN receiving HORIZANT twice daily, the dose should be reduced to once daily for 1 week prior to discontinuation to minimize the potential of withdrawal seizure.
In an oral carcinogenicity study, gabapentin enacarbil increased the incidence of pancreatic acinar cell adenoma and carcinoma in male and female rats. The clinical significance of this finding is unknown.
The most common adverse reactions for patients with RLS (incidence >10% and at least 2 times the rate of placebo) were somnolence/sedation and dizziness.
The most common adverse reactions for patients with PHN (incidence >10% and greater than placebo) were dizziness, somnolence, and headache.
Gabapentin enacarbil is released faster from HORIZANT Extended-Release tablets in the presence of alcohol. Consumption of alcohol is not recommended when taking HORIZANT.
HORIZANT taken in conjunction with morphine causes increased somnolence/sedation, dizziness, and nausea.
USE IN SPECIAL POPULATIONS
Pregnancy and Lactation
Pregnancy Category C. There are no adequate and well-controlled studies with HORIZANT in pregnant women. In nonclinical studies in rat and rabbits, administration of gabapentin enacarbil was developmentally toxic when administered to pregnant animals at doses and gabapentin exposures greater than those used clinically. HORIZANT should be used during pregnancy only if potential benefit justifies potential risk to fetus.
It is not known whether gabapentin derived from HORIZANT is secreted in human milk; however, gabapentin is secreted into human milk following oral administration of gabapentin products. Because of the potential for adverse reactions in nursing infants from HORIZANT, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Safety and effectiveness of HORIZANT in pediatric patients have not been studied.
Gabapentin is known to be almost exclusively excreted by the kidney, and the risk of adverse reactions to this drug may be greater in patients with impaired renal function. The dose of HORIZANT should be adjusted in patients with renal impairment based upon creatinine clearance. HORIZANT is not recommended for treatment of RLS in patients receiving hemodialysis.
For additional safety information, consult the HORIZANT full Prescribing Information here.
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch, or call 1-800-FDA-1088.
Horizant [prescribing information]. Atlanta, GA: Arbor Pharmaceuticals, LLC.
Cundy KC, Sastry S, Luo W, Zou J, Moors TL, Canafax DM. Clinical pharmacokinetics of XP13512, a novel transported prodrug of gabapentin. J Clin Pharmacol. 2008;48(12):1378-1388.
Neurontin® [prescribing information]. New York, NY. Pfizer® Inc.
Data on file. Arbor Pharmaceuticals, LLC.
Zhang L, Rainka M, Freeman R, et al. A randomized, double-blind, placebo-controlled trial to assess the efficacy and safety of gabapentin enacarbil in subjects with neuropathic pain associated with postherpetic neuralgia (PXN110748). J Pain. 2013;14(6):590-603.
Farrar JT, Young JP Jr, LaMoreaux L, Werth JL, Poole RM. Clinical importance of changes in chronic pain intensity measured on an 11-point numerical pain rating scale. Pain. 2001;94(2):149-158.