Medication

INDICATIONS & USAGE Gabapentin Tablets, USP Read the Medication Guide before you start taking gabapentin and each time you get a refill. There may be new information. This information does not take the place of talking to your healthcare provider about your medical condition or treatment. What is the most important information I should know about gabapentin? Do not stop taking gabapentin without first talking to your healthcare provider. Stopping gabapentin suddenly can cause serious problems. Gabapentin can cause serious side effects including: 1. Like other antiepileptic drugs, gabapentin may cause suicidal thoughts or actions in a very small number of people, about 1 in 500. Call a healthcare provider right away if you have any of these symptoms, especially if they are new, worse, or worry you: thoughts about suicide or dying attempts to commit suicide new or worse depression new or worse anxiety feeling agitated or restless panic attacks trouble sleeping (insomnia) new or worse irritability acting aggressive, being angry, or violent acting on dangerous impulses an extreme increase in activity and talking (mania) other unusual changes in behavior or mood How can I watch for early symptoms of suicidal thoughts and actions? Pay attention to any changes, especially sudden changes, in mood, behaviors, thoughts, or feelings. Keep all follow-up visits with your healthcare provider as scheduled. Call your healthcare provider between visits as needed, especially if you are worried about symptoms. Do not stop taking gabapentin without first talking to a healthcare provider. Stopping gabapentin suddenly can cause serious problems. Stopping a seizure medicine suddenly in a patient who has epilepsy can cause seizures that will not stop (status epilepticus). Suicidal thoughts or actions can be caused by things other than medicines. If you have suicidal thoughts or actions, your healthcare provider may check for other causes. 2. Changes in behavior and thinking - Using gabapentin in children 3 to 12 years of age can cause emotional changes, aggressive behavior, problems with concentration, restlessness, changes in school performance, and hyperactivity. What is gabapentin? Gabapentin is a prescription medicine used to treat: Pain from damaged nerves (postherpetic pain) that follows healing of shingles (a painful rash that comes after a herpes zoster infection) in adults. Partial seizures when taken together with other medicines in adults and children 3 years of age and older. Who should not take gabapentin? Do not take gabapentin if you are allergic to gabapentin or any of the other ingredients in gabapentin. See the end of this Medication Guide for a complete list of ingredients in gabapentin. What should I tell my healthcare provider before taking gabapentin? Before taking gabapentin, 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 are pregnant or plan to become pregnant. It is not known if gabapentin can harm your unborn baby. Tell your healthcare provider right away if you become pregnant while taking gabapentin. You and your healthcare provider will decide if you should take gabapentin while you are pregnant. If you become pregnant while taking gabapentin, talk to your healthcare provider about registering with the North American Antiepileptic Drug (NAAED) Pregnancy Registry. The purpose of this registry is to collect information about the safety of antiepileptic drugs during pregnancy. You can enroll in this registry by calling 1-888-233-2334. are breastfeeding or plan to breastfeed. Gabapentin can pass into breast milk. You and your healthcare provider should decide how you will feed your baby while you take gabapentin. Tell your healthcare provider about all the medicines you take , including prescription and non-prescription medicines, vitamins, and herbal supplements. Taking gabapentin with certain other medicines can cause side effects or affect how well they work. Do not start or stop other medicines without talking to your healthcare provider. 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. How should I take gabapentin? Take gabapentin exactly as prescribed. Your healthcare provider will tell you how much gabapentin to take. Do not change your dose of gabapentin without talking to your healthcare provider. If you break a tablet in half the unused half of the tablet should be taken at your next scheduled dose. Half tablets not used within several days of breaking should be thrown away. Gabapentin can be taken with or without food. If you take an antacid containing aluminum and magnesium, such as Maalox®, Mylanta®, Gelusil®, Gaviscon®, or Di-Gel®, you should wait at least 2 hours before taking your next dose of gabapentin. If you take too much gabapentin, call your healthcare provider or your local Poison Control Center right away. What should I avoid while taking gabapentin? Do not drink alcohol or take other medicines that make you sleepy or dizzy while taking gabapentin without first talking with your healthcare provider. Taking gabapentin with alcohol or drugs that cause sleepiness or dizziness may make your sleepiness or dizziness worse. Do not drive, operate heavy machinery, or do other dangerous activities until you know how gabapentin affects you. Gabapentin can slow your thinking and motor skills. What are the possible side effects of gabapentin? See "What is the most important information I should know about gabapentin?" The most common side effects of gabapentin include: dizziness lack of coordination viral infection feeling drowsy feeling tired fever jerky movements difficulty with speaking temporary loss of memory (amnesia) tremor difficulty with coordination double vision unusual eye movement Tell your healthcare provider if you have any side effect that bothers you or that does not go away. These are not all the possible side effects of gabapentin. For more information, ask your healthcare provider or pharmacist. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. How should I store gabapentin? Store gabapentin tablets at 20° to 25°C (68° to 77°F). [See USP controlled room temperature]. Keep gabapentin and all medicines out of the reach of children. General information about the safe and effective use of gabapentin Medicines are sometimes prescribed for purposes other than those listed in a Medication Guide. Do not use gabapentin for a condition for which it was not prescribed. Do not give gabapentin to other people, even if they have the same symptoms that you have. It may harm them. This Medication Guide summarizes the most important information about gabapentin. If you would like more information, talk with your healthcare provider. You can ask your healthcare provider or pharmacist for information about gabapentin that was written for healthcare professionals. For more information about gabapentin tablets, or to report side effects regarding gabapentin tablets, please call Exelan Pharmaceuticals Inc. at 1-855-295-7455. What are the ingredients in gabapentin Tablets? Active ingredient: Gabapentin, USP Inactive ingredients: Mannitol, Hydroxypropyl Cellulose, Crospovidone, Talc, Magnesium Stearate and Aquarius® BP18114 Cool Vanilla. Postherpetic Neuralgia Gabapentin tablets USP are indicated for the management of postherpetic neuralgia in adults. Epilepsy Gabapentin tablets USP are indicated as adjunctive therapy in the treatment of partial seizures with and without secondary generalization in patients over 12 years of age with epilepsy. Gabapentin tablets USP are also indicated as adjunctive therapy in the treatment of partial seizures in pediatric patients age 3 to 12 years.

DOSAGE & ADMINISTRATION Gabapentin tablets USP are given orally with or without food. Patients should be informed that, should they break the scored 600 or 800 mg tablet in order to administer a half-tablet, they should take the unused half-tablet as the next dose. Half-tablets not used within several days of breaking the scored tablet should be discarded. If gabapentin tablets USP dose is reduced, discontinued or substituted with an alternative medication, this should be done gradually over a minimum of 1 week (a longer time period may be needed at the discretion of the prescriber). Postherpetic Neuralgia In adults with postherpetic neuralgia, gabapentin therapy may be initiated as a single 300 mg dose on Day 1, 600 mg/day on Day 2 (divided BID), and 900 mg/day on Day 3 (divided TID). The dose can subsequently be titrated up as needed for pain relief to a daily dose of 1800 mg (divided TID). In clinical studies, efficacy was demonstrated over a range of doses from 1800 mg/day to 3600 mg/day with comparable effects across the dose range. Additional benefit of using doses greater than 1800 mg/day was not demonstrated. Epilepsy Gabapentin tablets USP, are recommended for add-on therapy in patients 3 years of age and older. Effectiveness in pediatric patients below the age of 3 years has not been established. Patients >12 years of age: The effective dose of gabapentin is 900 to 1800 mg/day and given in divided doses (three times a day) using 300 or 400 mg capsules, 600 or 800 mg tablets. The starting dose is 300 mg three times a day. If necessary, the dose may be increased using 300 or 400 mg capsules, 600 or 800 mg tablets three times a day up to 1800 mg/day. Dosages up to 2400 mg/day have been well tolerated in long-term clinical studies. Doses of 3600 mg/day have also been administered to a small number of patients for a relatively short duration, and have been well tolerated. The maximum time between doses in the TID schedule should not exceed 12 hours. Pediatric Patients Age 3 to 12 years: The starting dose should range from 10 to 15 mg/kg/day in 3 divided doses, and the effective dose reached by upward titration over a period of approximately 3 days. The effective dose of gabapentin in patients 5 years of age and older is 25 to 35 mg/kg/day and given in divided doses (three times a day). The effective dose in pediatric patients ages 3 and 4 years is 40 mg/kg/day and given in divided doses (three times a day) (see CLINICAL PHARMACOLOGY, Pediatrics ). Gabapentin may be administered as the oral solution, capsule, or tablet, or using combinations of these formulations. Dosages up to 50 mg/kg/day have been well tolerated in a long-term clinical study. The maximum time interval between doses should not exceed 12 hours. It is not necessary to monitor gabapentin plasma concentrations to optimize gabapentin therapy. Further, because there are no significant pharmacokinetic interactions among gabapentin and other commonly used antiepileptic drugs, the addition of gabapentin does not alter the plasma levels of these drugs appreciably. If gabapentin tablets are discontinued and/or an alternate anticonvulsant medication is added to the therapy, this should be done gradually over a minimum of 1 week. Dosage in Renal Impairment Creatinine clearance is difficult to measure in outpatients. In patients with stable renal function, creatinine clearance (C Cr ) can be reasonably well estimated using the equation of Cockcroft and Gault: for females C Cr =(0.85)(140-age)(weight)/[(72)(S Cr )] for males C Cr =(140-age)(weight)/[(72)(S Cr )] where age is in years, weight is in kilograms and S Cr is serum creatinine in mg/dL. Dosage adjustment in patients ≥12 years of age with compromised renal function or undergoing hemodialysis is recommended as follows (see dosing recommendations above for effective doses in each indication). TABLE 6. Gabapentin Dosage Based on Renal Function Renal Function Creatinine Clearance (mL/min) Total Daily Dose Range (mg/day) Dose Regimen (mg) ≥60 900 to 3600 300 TID 400 TID 600 TID 800 TID 1200 TID >30 to 59 400 to 1400 200 BID 300 BID 400 BID 500 BID 700 BID >15 to 29 200 to 700 200 QD 300 QD 400 QD 500 QD 700 QD 15 For patients with creatinine clearance <15 mL/min, reduce daily dose in proportion to creatinine clearance (e.g., patients with a creatinine clearance of 7.5 mL/min should receive one-half the daily dose that patients with a creatinine clearance of 15 mL/min receive). 100 to 300 100 QD 125 QD 150 QD 200 QD 300 QD Post-Hemodialysis Supplemental Dose (mg) Patients on hemodialysis should receive maintenance doses based on estimates of creatinine clearance as indicated in the upper portion of the table and a supplemental post-hemodialysis dose administered after each 4 hours of hemodialysis as indicated in the lower portion of the table. Hemodialysis 125 150 200 250 350 The use of gabapentin tablets USP in patients <12 years of age with compromised renal function has not been studied. Dosage in Elderly Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and dose should be adjusted based on creatinine clearance values in these patients.

ADVERSE REACTIONS Postherpetic Neuralgia The most commonly observed adverse events associated with the use of gabapentin in adults, not seen at an equivalent frequency among placebo-treated patients, were dizziness, somnolence, and peripheral edema. In the 2 controlled studies in postherpetic neuralgia, 16% of the 336 patients who received gabapentin and 9% of the 227 patients who received placebo discontinued treatment because of an adverse event. The adverse events that most frequently led to withdrawal in gabapentin-treated patients were dizziness, somnolence, and nausea. Incidence in Controlled Clinical Trials Table 3 lists treatment-emergent signs and symptoms that occurred in at least 1% of gabapentin-treated patients with postherpetic neuralgia participating in placebo-controlled trials and that were numerically more frequent in the gabapentin group than in the placebo group. Adverse events were usually mild to moderate in intensity. TABLE 3. Treatment-Emergent Adverse Event Incidence in Controlled Trials in Postherpetic Neuralgia (Events in at least 1% of Gabapentin-Treated Patients and Numerically More Frequent Than in the Placebo Group) Body System/ Preferred Term Gabapentin N=336 % Placebo N=227 % Body as a Whole Asthenia 5.7 4.8 Infection 5.1 3.5 Headache 3.3 3.1 Accidental injury 3.3 1.3 Abdominal pain 2.7 2.6 Digestive System Diarrhea 5.7 3.1 Dry mouth 4.8 1.3 Constipation 3.9 1.8 Nausea 3.9 3.1 Vomiting 3.3 1.8 Flatulence 2.1 1.8 Metabolic and Nutritional Disorders Peripheral edema 8.3 2.2 Weight gain 1.8 0.0 Hyperglycemia 1.2 0.4 Nervous System Dizziness 28.0 7.5 Somnolence 21.4 5.3 Ataxia 3.3 0.0 Thinking abnormal 2.7 0.0 Abnormal gait 1.5 0.0 Incoordination 1.5 0.0 Amnesia 1.2 0.9 Hypesthesia 1.2 0.9 Respiratory System Pharyngitis 1.2 0.4 Skin and Appendages Rash 1.2 0.9 Special Senses Amblyopia Reported as blurred vision 2.7 0.9 Conjunctivitis 1.2 0.0 Diplopia 1.2 0.0 Otitis media 1.2 0.0 Other events in more than 1% of patients but equally or more frequent in the placebo group included pain, tremor, neuralgia, back pain, dyspepsia, dyspnea, and flu syndrome. There were no clinically important differences between men and women in the types and incidence of adverse events. Because there were few patients whose race was reported as other than white, there are insufficient data to support a statement regarding the distribution of adverse events by race. Epilepsy The most commonly observed adverse events associated with the use of gabapentin in combination with other antiepileptic drugs in patients > 12 years of age, not seen at an equivalent frequency among placebo-treated patients, were somnolence, dizziness, ataxia, fatigue, and nystagmus. The most commonly observed adverse events reported with the use of gabapentin in combination with other antiepileptic drugs in pediatric patients 3 to 12 years of age, not seen at an equal frequency among placebo-treated patients, were viral infection, fever, nausea and/or vomiting, somnolence, and hostility (see WARNINGS , Neuropsychiatric Adverse Events ). Approximately 7% of the 2074 patients > 12 years of age and approximately 7% of the 449 pediatric patients 3 to 12 years of age who received gabapentin in premarketing clinical trials discontinued treatment because of an adverse event. The adverse events most commonly associated with withdrawal in patients > 12 years of age were somnolence (1.2%), ataxia (0.8%), fatigue (0.6%), nausea and/or vomiting (0.6%), and dizziness (0.6%). The adverse events most commonly associated with withdrawal in pediatric patients were emotional lability (1.6%), hostility (1.3%), and hyperkinesia (1.1%). Incidence in Controlled Clinical Trials Table 4 lists treatment-emergent signs and symptoms that occurred in at least 1% of gabapentin -treated patients > 12 years of age with epilepsy participating in placebo-controlled trials and were numerically more common in the gabapentin group. In these studies, either gabapentin or placebo was added to the patient's current antiepileptic drug therapy. Adverse events were usually mild to moderate in intensity. The prescriber should be aware that these figures, obtained when gabapentin was added to concurrent antiepileptic drug therapy, cannot be used to predict the frequency of adverse events in the course of usual medical practice where patient characteristics and other factors may differ from those prevailing during clinical studies. Similarly, the cited frequencies cannot be directly compared with figures obtained from other clinical investigations involving different treatments, uses, or investigators. An inspection of these frequencies, however, does provide the prescribing physician with one basis to estimate the relative contribution of drug and nondrug factors to the adverse event incidences in the population studied. TABLE 4. Treatment-Emergent Adverse Event Incidence in Controlled Add-On Trials In Patients >12 years of age (Events in at least 1% of gabapentin patients and numerically more frequent than in the placebo group) Body System/ Adverse Event Gabapentin Plus background antiepileptic drug therapy N=543 % Placebo N=378 % Body As A Whole Fatigue 11.0 5.0 Weight Increase 2.9 1.6 Back Pain 1.8 0.5 Peripheral Edema 1.7 0.5 Cardiovascular Vasodilatation 1.1 0.3 Digestive System Dyspepsia 2.2 0.5 Mouth or Throat Dry 1.7 0.5 Constipation 1.5 0.8 Dental Abnormalities 1.5 0.3 Increased Appetite 1.1 0.8 Hematologic and Lymphatic Systems Leukopenia 1.1 0.5 Musculoskeletal System Myalgia 2.0 1.9 Fracture 1.1 0.8 Nervous System Somnolence 19.3 8.7 Dizziness 17.1 6.9 Ataxia 12.5 5.6 Nystagmus 8.3 4.0 Tremor 6.8 3.2 Nervousness 2.4 1.9 Dysarthria 2.4 0.5 Amnesia 2.2 0.0 Depression 1.8 1.1 Thinking Abnormal 1.7 1.3 Twitching 1.3 0.5 Coordination Abnormal 1.1 0.3 Respiratory System Rhinitis 4.1 3.7 Pharyngitis 2.8 1.6 Coughing 1.8 1.3 Skin and Appendages Abrasion 1.3 0.0 Pruritus 1.3 0.5 Urogenital System Impotence 1.5 1.1 Special Senses Diplopia 5.9 1.9 Amblyopia Amblyopia was often described as blurred vision. 4.2 1.1 Laboratory Deviations WBC Decreased 1.1 0.5 Other events in more than 1% of patients >12 years of age but equally or more frequent in the placebo group included: headache, viral infection, fever, nausea and/or vomiting, abdominal pain, diarrhea, convulsions, confusion, insomnia, emotional lability, rash, acne. Among the treatment-emergent adverse events occurring at an incidence of at least 10% of gabapentin-treated patients, somnolence and ataxia appeared to exhibit a positive dose-response relationship. The overall incidence of adverse events and the types of adverse events seen were similar among men and women treated with gabapentin. The incidence of adverse events increased slightly with increasing age in patients treated with either gabapentin or placebo. Because only 3% of patients (28/921) in placebo-controlled studies were identified as nonwhite (black or other), there are insufficient data to support a statement regarding the distribution of adverse events by race. Table 5 lists treatment-emergent signs and symptoms that occurred in at least 2% of gabapentin -treated patients age 3 to 12 years of age with epilepsy participating in placebo-controlled trials and were numerically more common in the gabapentin group. Adverse events were usually mild to moderate in intensity. TABLE 5. Treatment-Emergent Adverse Event Incidence in Pediatric Patients Age 3 to 12 Years in a Controlled Add-On Trial (Events in at least 2% of gabapentin patients and numerically more frequent than in the placebo group) Body System/ Adverse Event Gabapentin Plus background antiepileptic drug therapy N=119 % Placebo N=128 % Body As A Whole Viral Infection 10.9 3.1 Fever 10.1 3.1 Weight Increase 3.4 0.8 Fatigue 3.4 1.6 Digestive System Nausea and/or Vomiting 8.4 7 Nervous System Somnolence 8.4 4.7 Hostility 7.6 2.3 Emotional Lability 4.2 1.6 Dizziness 2.5 1.6 Hyperkinesia 2.5 0.8 Respiratory System Bronchitis 3.4 0.8 Respiratory Infection 2.5 0.8 Other events in more than 2% of pediatric patients 3 to 12 years of age but equally or more frequent in the placebo group included: pharyngitis, upper respiratory infection, headache, rhinitis, convulsions, diarrhea, anorexia, coughing, and otitis media. Other Adverse Events Observed During All Clinical Trials Clinical Trials in Adults and Adolescents (Except Clinical Trials in Neuropathic Pain) Gabapentin has been administered to 4717 patients > 12 years of age during all adjunctive therapy clinical trials (except clinical trials in patients with neuropathic pain), only some of which were placebo-controlled. During these trials, all adverse events were recorded by the clinical investigators using terminology of their own choosing. To provide a meaningful estimate of the proportion of individuals having adverse events, similar types of events were grouped into a smaller number of standardized categories using modified COSTART dictionary terminology. These categories are used in the listing below. The frequencies presented represent the proportion of the 4717 patients > 12 years of age exposed to gabapentin who experienced an event of the type cited on at least one occasion while receiving gabapentin. All reported events are included except those already listed in Table 4 , those too general to be informative, and those not reasonably associated with the use of the drug. Events are further classified within body system categories and enumerated in order of decreasing frequency using the following definitions: frequent adverse events are defined as those occurring in at least 1/100 patients; infrequent adverse events are those occurring in 1/100 to 1/1000 patients; rare events are those occurring in fewer than 1/1000 patients. Body As A Whole: Frequent: asthenia, malaise, face edema. Infrequent: allergy, generalized edema, weight decrease, chill. Rare: strange feelings, lassitude, alcohol intolerance, hangover effect. Cardiovascular System: Frequent: hypertension. Infrequent: hypotension, angina pectoris, peripheral vascular disorder, palpitation, tachycardia, migraine, murmur. Rare: atrial fibrillation, heart failure, thrombophlebitis, deep thrombophlebitis, myocardial infarction, cerebrovascular accident, pulmonary thrombosis, ventricular extrasystoles, bradycardia, premature atrial contraction, pericardial rub, heart block, pulmonary embolus, hyperlipidemia, hypercholesterolemia, pericardial effusion, pericarditis. Digestive System: Frequent: anorexia, flatulence, gingivitis. Infrequent: glossitis, gum hemorrhage, thirst, stomatitis, increased salivation, gastroenteritis, hemorrhoids, bloody stools, fecal incontinence, hepatomegaly. Rare: dysphagia, eructation, pancreatitis, peptic ulcer, colitis, blisters in mouth, tooth discolor, perlèche, salivary gland enlarged, lip hemorrhage, esophagitis, hiatal hernia, hematemesis, proctitis, irritable bowel syndrome, rectal hemorrhage, esophageal spasm. Endocrine System: Rare: hyperthyroid, hypothyroid, goiter, hypoestrogen, ovarian failure, epididymitis, swollen testicle, cushingoid appearance. Hematologic and Lymphatic System: Frequent: purpura most often described as bruises resulting from physical trauma. Infrequent: anemia, thrombocytopenia, lymphadenopathy. Rare: WBC count increased, lymphocytosis, non-Hodgkin’s lymphoma, bleeding time increased. Musculoskeletal System: Frequent: arthralgia. Infrequent: tendinitis, arthritis, joint stiffness, joint swelling, positive Romberg test. Rare: costochondritis, osteoporosis, bursitis, contracture. Nervous System: Frequent: vertigo, hyperkinesia, paresthesia, decreased or absent reflexes, increased reflexes, anxiety, hostility. Infrequent: CNS tumors, syncope, dreaming abnormal, aphasia, hypesthesia, intracranial hemorrhage, hypotonia, dysesthesia, paresis, dystonia, hemiplegia, facial paralysis, stupor, cerebellar dysfunction, positive Babinski sign, decreased position sense, subdural hematoma, apathy, hallucination, decrease or loss of libido, agitation, paranoia, depersonalization, euphoria, feeling high, doped-up sensation, psychosis. Rare: choreoathetosis, orofacial dyskinesia, encephalopathy, nerve palsy, personality disorder, increased libido, subdued temperament, apraxia, fine motor control disorder, meningismus, local myoclonus, hyperesthesia, hypokinesia, mania, neurosis, hysteria, antisocial reaction. Respiratory System: Frequent: pneumonia. Infrequent: epistaxis, dyspnea, apnea. Rare: mucositis, aspiration pneumonia, hyperventilation, hiccup, laryngitis, nasal obstruction, snoring, bronchospasm, hypoventilation, lung edema. Dermatological: Infrequent: alopecia, eczema, dry skin, increased sweating, urticaria, hirsutism, seborrhea, cyst, herpes simplex. Rare: herpes zoster, skin discolor, skin papules, photosensitive reaction, leg ulcer, scalp seborrhea, psoriasis, desquamation, maceration, skin nodules, subcutaneous nodule, melanosis, skin necrosis, local swelling. Urogenital System: Infrequent: hematuria, dysuria, urination frequency, cystitis, urinary retention, urinary incontinence, vaginal hemorrhage, amenorrhea, dysmenorrhea, menorrhagia, breast cancer, unable to climax, ejaculation abnormal. Rare: kidney pain, leukorrhea, pruritus genital, renal stone, acute renal failure, anuria, glycosuria, nephrosis, nocturia, pyuria, urination urgency, vaginal pain, breast pain, testicle pain. Special Senses: Frequent: abnormal vision. Infrequent: cataract, conjunctivitis, eyes dry, eye pain, visual field defect, photophobia, bilateral or unilateral ptosis, eye hemorrhage, hordeolum, hearing loss, earache, tinnitus, inner ear infection, otitis, taste loss, unusual taste, eye twitching, ear fullness. Rare: eye itching, abnormal accommodation, perforated ear drum, sensitivity to noise, eye focusing problem, watery eyes, retinopathy, glaucoma, iritis, corneal disorders, lacrimal dysfunction, degenerative eye changes, blindness, retinal degeneration, miosis, chorioretinitis, strabismus, eustachian tube dysfunction, labyrinthitis, otitis externa, odd smell. Clinical trials in Pediatric Patients With Epilepsy Adverse events occurring during epilepsy clinical trials in 449 pediatric patients 3 to 12 years of age treated with gabapentin that were not reported in adjunctive trials in adults are: Body as a Whole: dehydration, infectious mononucleosis Digestive System: hepatitis Hemic and Lymphatic System: coagulation defect Nervous System: aura disappeared, occipital neuralgia Psychobiologic Function: sleepwalking Respiratory System: pseudocroup, hoarseness Clinical Trials in Adults With Neuropathic Pain of Various Etiologies Safety information was obtained in 1173 patients during double-blind and open-label clinical trials including neuropathic pain conditions for which efficacy has not been demonstrated. Adverse events reported by investigators were grouped into standardized categories using modified COSTART IV terminology. Listed below are all reported events except those already listed in Table 3 and those not reasonably associated with the use of the drug. Events are further classified within body system categories and enumerated in order of decreasing frequency using the following definitions: frequent adverse events are defined as those occurring in at least 1/100 patients; infrequent adverse events are those occurring in 1/100 to 1/1000 patients; rare events are those occurring in fewer than 1/1000 patients. Body as a Whole: Infrequent: chest pain, cellulitis, malaise, neck pain, face edema, allergic reaction, abscess, chills, chills and fever, mucous membrane disorder Rare: body odor, cyst, fever, hernia, abnormal BUN value, lump in neck, pelvic pain, sepsis, viral infection Cardiovascular System: Infrequent: hypertension, syncope, palpitation, migraine, hypotension, peripheral vascular disorder, cardiovascular disorder, cerebrovascular accident, congestive heart failure, myocardial infarction, vasodilatation Rare: angina pectoris, heart failure, increased capillary fragility, phlebitis, thrombophlebitis, varicose vein Digestive System: Infrequent: gastroenteritis, increased appetite, gastrointestinal disorder, oral moniliasis, gastritis, tongue disorder, thirst, tooth disorder, abnormal stools, anorexia, liver function tests abnormal, periodontal abscess Rare: cholecystitis, cholelithiasis, duodenal ulcer, fecal incontinence, gamma glutamyl transpeptidase increased, gingivitis, intestinal obstruction, intestinal ulcer, melena, mouth ulceration, rectal disorder, rectal hemorrhage, stomatitis Endocrine System: Infrequent: diabetes mellitus Hemic and Lymphatic System: Infrequent: ecchymosis, anemia Rare: lymphadenopathy, lymphoma-like reaction, prothrombin decreased Metabolic and Nutritional: Infrequent: edema, gout, hypoglycemia, weight loss Rare: alkaline phosphatase increased, diabetic ketoacidosis, lactic dehydrogenase increased Musculoskeletal: Infrequent: arthritis, arthralgia, myalgia, arthrosis, leg cramps, myasthenia Rare: shin bone pain, joint disorder, tendon disorder Nervous System: Frequent: confusion, depression Infrequent: vertigo, nervousness, paresthesia, insomnia, neuropathy, libido decreased, anxiety, depersonalization, reflexes decreased, speech disorder, abnormal dreams, dysarthria, emotional lability, nystagmus, stupor, circumoral paresthesia, euphoria, hyperesthesia, hypokinesia Rare: agitation, hypertonia, libido increased, movement disorder, myoclonus, vestibular disorder Respiratory System: Infrequent: cough increased, bronchitis, rhinitis, sinusitis, pneumonia, asthma, lung disorder, epistaxis Rare: hemoptysis, voice alteration Skin and Appendages: Infrequent: pruritus, skin ulcer, dry skin, herpes zoster, skin disorder, fungal dermatitis, furunculosis, herpes simplex, psoriasis, sweating, urticaria, vesiculobullous rash Rare: acne, hair disorder, maculopapular rash, nail disorder, skin carcinoma, skin discoloration, skin hypertrophy Special Senses: Infrequent: abnormal vision, ear pain, eye disorder, taste perversion, deafness Rare: conjunctival hyperemia, diabetic retinopathy, eye pain, fundi with microhemorrhage, retinal vein thrombosis, taste loss Urogenital System: Infrequent: urinary tract infection, dysuria, impotence, urinary incontinence, vaginal moniliasis, breast pain, menstrual disorder, polyuria, urinary retention Rare: cystitis, ejaculation abnormal, swollen penis, gynecomastia, nocturia, pyelonephritis, swollen scrotum, urinary frequency, urinary urgency, urine abnormality Postmarketing and Other Experience In addition to the adverse experiences reported during clinical testing of gabapentin, the following adverse experiences have been reported in patients receiving marketed gabapentin. These adverse experiences have not been listed above and data are insufficient to support an estimate of their incidence or to establish causation. The listing is alphabetized: angioedema, blood glucose fluctuation, breast hypertrophy, erythema multiforme, elevated liver function tests, fever, hyponatremia, jaundice, movement disorder, Stevens-Johnson syndrome. Adverse events following the abrupt discontinuation of gabapentin have also been reported. The most frequently reported events were anxiety, insomnia, nausea, pain and sweating.

Drug Interactions In vitro studies were conducted to investigate the potential of gabapentin to inhibit the major cytochrome P450 enzymes (CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4) that mediate drug and xenobiotic metabolism using isoform selective marker substrates and human liver microsomal preparations. Only at the highest concentration tested (171 mcg/mL; 1 mM) was a slight degree of inhibition (14% to 30%) of isoform CYP2A6 observed. No inhibition of any of the other isoforms tested was observed at gabapentin concentrations up to 171 mcg/mL (approximately 15 times the C max at 3600 mg/day). Gabapentin is not appreciably metabolized nor does it interfere with the metabolism of commonly coadministered antiepileptic drugs. The drug interaction data described in this section were obtained from studies involving healthy adults and adult patients with epilepsy.