Horizant

Medicines can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of Horizant there are no specific foods that you must exclude from your diet when receiving Horizant.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

• Bloating or swelling of the face, arms, hands, lower legs, or feet
• discouragement
• feeling sad or empty
• irritability
• lack of appetite
• loss of interest or pleasure
• rapid weight gain
• tingling of the hands or feet
• tiredness
• trouble concentrating

• Black, tarry stools
• bloody or cloudy urine
• changes in behavior
• chest pain or discomfort
• chills or fever
• confusion
• difficulty with breathing
• dizziness or lightheadedness
• fainting
• fast heartbeat
• nausea or vomiting
• painful or difficult urination
• rapid, shallow breathing
• rash
• sore throat
• sores, ulcers, or white spots on the lips or in the mouth
• swelling of the face, feet, or lower legs
• swollen, painful, or tender lymph glands in the neck, armpit, or groin
• thoughts of killing oneself
• unusual bleeding or bruising
• upper right abdominal or stomach pain
• yellow eyes and skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Lack or loss of strength
• sleepiness or unusual drowsiness

• Blurred vision
• decreased interest in sexual intercourse
• dry mouth
• excess air or gas in the stomach or intestines
• inability to have or keep an erection
• sensation of spinning
• weight gain

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
• Signs of kidney problems like unable to pass urine, change in how much urine is passed, blood in the urine, or a big weight gain.
• Feeling confused.
• Feeling very tired or weak.
• Muscle pain or weakness.
• Blurred eyesight.
• Chest pain or pressure.
• Shortness of breath, a big weight gain, or swelling in the arms or legs.
• Any unexplained bruising or bleeding.
• Fever or chills.
• Sore throat.
• Swollen gland.
• Patients who take this medicine may be at a greater risk of having thoughts or actions of suicide. The risk may be greater in people who have had these thoughts or actions in the past. Call the doctor right away if signs like low mood (depression), nervousness, restlessness, grouchiness, panic attacks, or changes in mood or actions are new or worse. Call the doctor right away if any thoughts or actions of suicide occur.

• Store at room temperature.
• Store in the original container. Do not take out the antimoisture cube or packet.
• Store in a dry place. Do not store in a bathroom.
• Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
• Check with your pharmacist about how to throw out unused drugs.

None.

Gabapentin enacarbil is released faster from Horizant Extended-Release tablets in the presence of alcohol. Consumption of alcohol is not recommended when taking Horizant [see Clinical Pharmacology (12.3)].

Morphine: Horizant taken in conjunction with morphine causes increased somnolence/sedation, dizziness, and nausea when compared with either drug alone [see Clinical Pharmacology (12.3)].

Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenesis: Oral (gavage) carcinogenicity studies were conducted in mice and rats. In mice, gabapentin enacarbil was tested at doses of 500, 2,000, or 5,000 mg/kg/day for up to 104 weeks. There was no evidence of drug-related carcinogenicity. The highest dose tested is 16 times the MRHD of 1,200 mg/day, on a plasma AUC basis.

In rats, gabapentin enacarbil was tested at doses of 500, 2,000, or 5,000 mg/kg/day for up to 97 weeks in mid-dose males, 90 weeks in high-dose males, and 104 weeks in females. The plasma exposures (AUC) for gabapentin at these doses are approximately 4, 17, and 37 times, respectively, that in humans at the MRHD. Increases in the incidence of pancreatic acinar adenoma and carcinoma were found in mid-dose males and high-dose males and females.

In 2-year dietary carcinogenicity studies of gabapentin, no evidence of drug-related carcinogenicity was observed in mice treated at doses up to 2,000 mg/kg/day. In rats, increases in the incidence of pancreatic acinar cell adenoma and carcinoma were found in male rats receiving the highest dose (2,000 mg/kg), but not at doses of 250 or 1,000 mg/kg/day. At 1,000 mg/kg/day, the plasma AUC for gabapentin is estimated to be approximately 13 times that in humans at the MRHD.

Studies designed to investigate the mechanism of gabapentin-induced pancreatic carcinogenesis in rats indicate that gabapentin stimulates DNA synthesis in rat pancreatic acinar cells in vitro and thus may be acting as a tumor promoter by enhancing mitogenic activity. It is not known whether gabapentin has the ability to increase cell proliferation in other cell types or in other species, including human.

Mutagenesis: Gabapentin enacarbil was negative in in vitro bacterial reverse mutation (Ames) and in vivo rat micronucleus assays. In an in vitro human lymphocyte assay, there was an increase in the number of chromosomal aberrations with gabapentin enacarbil. This in vitro response was attributed to acetaldehyde released by hydrolysis of gabapentin enacarbil during the incubation period. Acetaldehyde is known to cause chromosome aberrations in vitro, but is readily metabolized in vivo. The small quantity of acetaldehyde formed from gabapentin enacarbil in vivo is rapidly cleared by normal metabolic activity.

Impairment of Fertility: Oral administration of gabapentin enacarbil (doses of 0, 200, 1,000, or 5,000 mg/kg/day) to male and female rats prior to and throughout mating and continuing in females up to day 7 of gestation resulted in no adverse effects on fertility. The highest dose tested is approximately 39 times the MRHD on an AUC basis.

The U.S. Food and Drug Administration (FDA) has approved Horizant (gabapentin enacarbil) Extended-Release Tablets for the treatment of moderate-to-severe primary Restless Legs Syndrome in adults. Horizant is not recommended for patients who are required to sleep during the daytime and remain awake at night. The efficacy of Horizant in the treatment of patients with moderate-to-severe primary Restless Legs Syndrome was demonstrated in two 12-week clinical trials in adults. It is the first medication in its class to be approved for the treatment of moderate-to-severe primary Restless Legs Syndrome. Horizant is also approved for the management of postherpetic neuralgia (PHN) in adults.

Before taking Horizant, tell your healthcare provider if you:

• have or have had kidney problems or are on hemodialysis.
• have or have had depression, mood problems, or suicidal thoughts or behavior.
• if you are pregnant or plan to become pregnant. It is not known if Horizant will harm your unborn baby. Talk to your healthcare provider if you are pregnant or plan to become pregnant while taking Horizant. You and your healthcare provider will decide if you should take Horizant while you are pregnant.
• are breastfeeding or plan to breastfeed. Your body turns Horizant into another drug (gabapentin) that passes into your milk. It is not known if this can harm your baby. You and your healthcare provider should decide if you will take Horizant or breastfeed.

Tell your healthcare provider about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.

Know the medicines you take. Keep a list of them and show it to your healthcare provider and pharmacist when you get a new medicine.

Applies to gabapentin enacarbil: compounding powder, oral capsule, oral solution, oral tablet, oral tablet extended release

Cardiovascular

Common (1% to 10%): Peripheral edema, vasodilation, hypertension
Rare (less than 0.1%): Atrial fibrillation, heart failure, myocardial infarction, cerebrovascular accident, ventricular extrasystoles, bradycardia, premature atrial contraction, pericardial rub, heart block, pericardial effusion, pericarditis
Postmarketing reports: Cardiac arrest, chest pain, palpitation, tachycardia[Ref]

Dermatologic

Common (1% to 10%): Abrasion, facial edema, purpura, rash, pruritus, acne
Uncommon (0.1% to 1%): Alopecia, eczema, dry skin, increased sweating, urticaria, hirsutism, seborrhea, cyst, herpes simplex
Rare (less than 0.1%): Stevens-Johnson syndrome, angioedema, erythema multiforme, drug rash (with eosinophilia and systemic symptoms), herpes zoster, skin discolor, skin papules, photosensitive reaction, psoriasis, desquamation, maceration, skin nodules, subcutaneous nodule, melanosis, skin necrosis, local swelling
Frequency not reported: DRESS/multiorgan hypersensitivity[Ref]

Endocrine

Rare (less than 0.1%): Hyperthyroid, hypothyroid, goiter, hypoestrogenism, ovarian failure, epididymitis, cushingoid appearance[Ref]

Gastrointestinal

Common (1% to 10%): Diarrhea, dry mouth or throat, constipation, nausea, vomiting, dyspepsia, dental abnormalities, gingivitis, abdominal pain, flatulence
Uncommon (0.1% to 1%): Glossitis, gum hemorrhage, thirst, stomatitis, increased salivation, gastroenteritis, hemorrhoids, bloody stools, fecal incontinence
Rare (less than 0.1%): Pancreatitis, dysphagia, eructation, pancreatitis, peptic ulcer, colitis, blisters in mouth, tooth discoloration, perlèche, salivary gland enlarged, lip hemorrhage, esophagitis, hiatal hernia, hematemesis, proctitis, irritable bowel syndrome, rectal hemorrhage, esophageal spasm
Frequency not reported: Dehydration[Ref]

General

The most common adverse reactions associated with the use of this drug were dizziness, somnolence, and peripheral edema.[Ref]

Genitourinary

Common (1% to 10%): Incontinence, impotence
Uncommon (0.1% to 1%): Hematuria, dysuria, urinary frequency, cystitis, urinary retention, vaginal hemorrhage, amenorrhea, dysmenorrhea, menorrhagia
Frequency not reported: Breast hypertrophy, gynecomastia, sexual dysfunction (including changes in libido, ejaculation disorders, and anorgasmia)[Ref]

Hematologic

Common (1% to 10%): Leucopenia, purpura
Uncommon (0.1% to 1%): Anemia, lymphadenopathy
Rare (less than 0.1%): Thrombocytopenia, thrombophlebitis, leukocytosis, lymphocytosis, increased bleeding time
Frequency not reported: Blood creatine phosphokinase increased, coagulation defect[Ref]

Hepatic

Rare (less than 0.1%): Hepatitis, jaundice, elevated liver function tests SGOT (AST), SGPT (ALT), and bilirubin, hepatomegaly, hepatotoxicity[Ref]

Hypersensitivity

Very rare (less than 0.01%): Hypersensitivity syndrome, a systemic reaction with a variable presentation that can include fever, rash, hepatitis, lymphadenopathy, eosinophilia, and sometimes other signs and symptoms[Ref]

Metabolic

Common (1% to 10%): Weight gain, hyperglycemia
Postmarketing reports: Hyponatremia[Ref]

Musculoskeletal

Common (1% to 10%): Back pain, arthralgia, myalgia, twitching
Uncommon (0.1% to 1%): Tendonitis, arthritis, joint stiffness, joint swelling
Frequency not reported: Rhabdomyolysis, myoclonus
Postmarketing reports: Elevated creatine kinase, rhabdomyolysis[Ref]

Nervous system

Very common (10% or more): Somnolence (21%), dizziness (17%), ataxia (13%)
Common (1% to 10%): Abnormal gait, incoordination, neuralgia, tremor, dysarthria, hyperkinesia, seizures, dysarthria, paresthesia, hypesthesia, coordination abnormal, increased/decreased/absent reflexes, vertigo
Uncommon (less than 1%): Hypokinesia
Rare (less than 0.1%): Movement disorders (e.g., choreoathetosis, dyskinesia, dystonia), loss of consciousness
Frequency not reported: Withdrawal precipitated seizure/status epilepticus
Postmarketing reports: Movement disorder[Ref]

Ocular

Common (1% to 10%): Amblyopia, conjunctivitis, diplopia, nystagmus
Uncommon (0.1% to 1%): Cataract, dry eyes, eye pain, visual field defect, photophobia, bilateral or unilateral ptosis, eye hemorrhage, hordeolum, eye twitching
Rare (less than 0.1%): Eye itching, abnormal accommodation, eye focusing problem, watery eyes, retinopathy, glaucoma, iritis, corneal disorders, lacrimal dysfunction, degenerative eye changes, blindness, retinal degeneration, miosis, chorioretinitis, strabismus[Ref]

Oncologic

Uncommon (0.1% to 1%): Breast cancer
Rare (less than 0.1%): Non-Hodgkin's lymphoma[Ref]

Other

Very common (10% or more): Fatigue (11%), fever (11%)
Common (1% to 10%): Asthenia, accidental injury, otitis media, tremor, pain
Rare (0.01% to 0.1%): Tinnitus
Very rare (less than 0.01%): Sudden unexplained death in patients with epilepsy
Frequency not reported: Sleepwalking, withdrawal symptoms, hearing loss, earache, tinnitus, inner ear infection, otitis, taste loss, unusual taste, ear fullness, perforated ear drum, sensitivity to noise, eustachian tube dysfunction, otitis externa, odd smell, labyrinthitis[Ref]

Psychiatric

Common (1% to 10%): Abnormal thinking, amnesia, depression, hostility, confusion, emotional liability, anxiety, nervousness, amnesia, insomnia
Uncommon (0.1% to 1%): Mental impairment
Rare (less than 0.1%): Hallucinations
Frequency not reported: Suicidal behavior and ideation, hypomania[Ref]

Renal

Rare (less than 0.1%): Acute renal failure[Ref]

Respiratory

Common (1% to 10%): Pharyngitis, dyspnea, cough, bronchitis, respiratory infection, rhinitis
Rare (less than 0.1%): Pulmonary thrombosis, pulmonary embolism
Frequency not reported: Pseudo-croup, hoarseness[Ref]

Some side effects of Horizant may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.