Felbatol Side Effects

Generic Name: felbamate

Please note - some side effects for Felbatol may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Side Effects of Felbatol - for the Consumer

Felbatol

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Felbatol:

Constipation; diarrhea; dizziness; drowsiness; fatigue; headache; indigestion; loss of appetite; mild stomach pain; nausea; trouble sleeping; vomiting; weight changes.

Seek medical attention right away if any of these SEVERE side effects occur when using Felbatol:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); agitation; chest pain; dark urine; fast or irregular heartbeat; fever, chills, or persistent sore throat; loss of coordination; mouth sores; muscle pain; nervousness; new or worsening mental or mood changes (eg, anxiety, depression, restlessness, irritability, panic attacks, behavior changes); new or worsening seizures; red, swollen, blistered, or peeling skin; severe or persistent stomach pain; suicidal thoughts or actions; unusual bruising or bleeding; vision changes; weakness; yellowing of the eyes or skin.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

Felbatol Suspension

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Felbatol Suspension:

Constipation; diarrhea; dizziness; drowsiness; fatigue; headache; indigestion; loss of appetite; mild stomach pain; nausea; trouble sleeping; vomiting; weight changes.

Seek medical attention right away if any of these SEVERE side effects occur when using Felbatol Suspension:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); agitation; chest pain; dark urine; fast or irregular heartbeat; fever, chills, or persistent sore throat; loss of coordination; mouth sores; muscle pain; nervousness; new or worsening mental or mood changes (eg, anxiety, depression, restlessness, irritability, panic attacks, behavior changes); new or worsening seizures; red, swollen, blistered, or peeling skin; severe or persistent stomach pain; suicidal thoughts or actions; unusual bruising or bleeding; vision changes; weakness; yellowing of the eyes or skin.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

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Felbatol Side Effects - for the Professional

Felbatol

To report SUSPECTED ADVERSE REACTIONS, contact Meda Pharmaceuticals Inc. at 1-800-526-3840 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .

The most common adverse reactions seen in association with Felbatol® (felbamate) in adults during monotherapy are anorexia, vomiting, insomnia, nausea, and headache. The most common adverse reactions seen in association with Felbatol® in adults during adjunctive therapy are anorexia, vomiting, insomnia, nausea, dizziness, somnolence, and headache.

The most common adverse reactions seen in association with Felbatol® in children during adjunctive therapy are anorexia, vomiting, insomnia, headache, and somnolence.

The dropout rate because of adverse experiences or intercurrent illnesses among adult felbamate patients was 12 percent (120/977). The dropout rate because of adverse experiences or intercurrent illnesses among pediatric felbamate patients was six percent (22/357). In adults, the body systems associated with causing these withdrawals in order of frequency were: digestive (4.3%), psychological (2.2%), whole body (1.7%), neurological (1.5%), and dermatological (1.5%). In children, the body systems associated with causing these withdrawals in order of frequency were: digestive (1.7%), neurological (1.4%), dermatological (1.4%), psychological (1.1%), and whole body (1.0%). In adults, specific events with an incidence of 1% or greater associated with causing these withdrawals, in order of frequency were: anorexia (1.6%), nausea (1.4%), rash (1.2%), and weight decrease (1.1%). In children, specific events with an incidence of 1% or greater associated with causing these withdrawals, in order of frequency was rash (1.1%).

Incidence in Clinical Trials:
The prescriber should be aware that the figures cited in the following table cannot be used to predict the incidence of side effects in the course of usual medical practice where patient characteristics and other factors differ from those which prevailed in the clinical trials. Similarly, the cited frequencies cannot be compared with figures obtained from other clinical investigations involving different investigators, treatments, and uses including the use of Felbatol® (felbamate) as adjunctive therapy where the incidence of adverse events may be higher due to drug interactions. The cited figures, however, do provide the prescribing physician with some basis for estimating the relative contribution of drug and nondrug factors to the side effect incidence rate in the population studied.

Adults
Incidence in Controlled Clinical Trials--Monotherapy Studies in Adults:
The table that follows enumerates adverse events that occurred at an incidence of 2% or more among 58 adult patients who received Felbatol® monotherapy at dosages of 3600 mg/day in double-blind controlled trials. Table 3 presents reported adverse events that were classified using standard WHO-based dictionary terminology.

Table 3 Adults Treatment-Emergent Adverse Event Incidence in Controlled Monotherapy Trials

*3600 mg/day;** 15 mg/kg/day
	Felbatol®* (N=58)	Low Dose Valproate** (N=50)
Body System Event	%	%
Body as a Whole   Fatigue   Weight Decrease   Face Edema	6.9 3.4 3.4	4.0 0 0
Central Nervous System   Insomnia   Headache   Anxiety	8.6 6.9 5.2	4.0 18.0 2.0
Dermatological   Acne   Rash	3.4 3.4	0 0
Digestive   Dyspepsia   Vomiting   Constipation   Diarrhea   SGPT Increased	8.6 8.6 6.9 5.2 5.2	2.0 2.0 2.0 0 2.0
Metabolic/Nutritional   Hypophosphatemia	3.4	0
Respiratory   Upper Respiratory Tract Infection   Rhinitis	8.6 6.9	4.0 0
Special Senses   Diplopia   Otitis Media	3.4 3.4	4.0 0
Urogenital   Intramenstrual Bleeding   Urinary Tract Infection	3.4 3.4	0 2.0

Incidence in Controlled Add-On Clinical Studies in Adults:
Table 4 enumerates adverse events that occurred at an incidence of 2% or more among 114 adult patients who received Felbatol® adjunctive therapy in add-on controlled trials at dosages up to 3600 mg/day. Reported adverse events were classified using standard WHO-based dictionary terminology.

Many adverse experiences that occurred during adjunctive therapy may be a result of drug interactions. Adverse experiences during adjunctive therapy typically resolved with conversion to monotherapy, or with adjustment of the dosage of other antiepileptic drugs.

Table 4 Adults Treatment-Emergent Adverse Event Incidence in Controlled Add-On Trials

	Felbatol®	Placebo
	(N=114)	(N=43)
Body System/Event	%	%
Body as a Whole   Fatigue   Fever   Chest Pain	16.8 2.6 2.6	7.0 4.7 0
Central Nervous System   Headache   Somnolence   Dizziness   Insomnia   Nervousness   Tremor   Anxiety   Gait Abnormal   Depression   Paraesthesia   Ataxia   Mouth Dry   Stupor	36.8 19.3 18.4 17.5 7.0 6.1 5.3 5.3 5.3 3.5 3.5 2.6 2.6	9.3 7.0 14.0 7.0 2.3 2.3 4.7 0 0 2.3 0 0 0
Dermatological   Rash	3.5	4.7
Digestive   Nausea   Anorexia   Vomiting   Dyspepsia   Constipation   Diarrhea   Abdominal Pain   SGPT Increased	34.2 19.3 16.7 12.3 11.4 5.3 5.3 3.5	2.3 2.3 4.7 7.0 2.3 2.3 0 0
Musculoskeletal   Myalgia	2.6	0
Respiratory   Upper Respiratory Tract Infection   Sinusitis   Pharyngitis	5.3 3.5 2.6	7.0 0 0
Special Senses   Diplopia   Taste Perversion   Vision Abnormal	6.1 6.1 5.3	0 0 2.3

Children
Incidence in a Controlled Add-On Trial in Children with Lennox-Gastaut Syndrome:
Table 5 enumerates adverse events that occurred more than once among 31 pediatric patients who received Felbatol® up to 45 mg/kg/day or a maximum of 3600 mg/day. Reported adverse events were classified using standard WHO-based dictionary terminology.

Table 5 Children Treatment-Emergent Adverse Event Incidence in Controlled Add-On Lennox-Gastaut Trials

	Felbatol®	Placebo
	(N=31)	(N=27)
Body System/Event	%	%
Body as a Whole   Fever   Fatigue   Weight Decrease   Pain	22.6 9.7 6.5 6.5	11.1 3.7 0 0
Central Nervous System   Somnolence   Insomnia   Nervousness   Gait Abnormal   Headache   Thinking Abnormal   Ataxia   Urinary Incontinence   Emotional Lability   Miosis	48.4 16.1 16.1 9.7 6.5 6.5 6.5 6.5 6.5 6.5	11.1 14.8 18.5 0 18.5 3.7 3.7 7.4 0 0
Dermatological   Rash	9.7	7.4
Digestive   Anorexia   Vomiting   Constipation   Hiccup   Nausea   Dyspepsia	54.8 38.7 12.9 9.7 6.5 6.5	14.8 14.8 0 3.7 0 3.7
Hematologic   Purpura   Leukopenia	12.9 6.5	7.4 0
Respiratory   Upper Respiratory Tract Infection   Pharyngitis   Coughing	45.2 9.7 6.5	25.9 3.7 0
Special Senses   Otitis Media	9.7	0

Other Events Observed in Association with the Administration of Felbatol® (felbamate):
In the paragraphs that follow, the adverse clinical events, other than those in the preceding tables, that occurred in a total of 977 adults and 357 children exposed to Felbatol® (felbamate) and that are reasonably associated with its use are presented. They are listed in order of decreasing frequency. Because the reports cite events observed in open-label and uncontrolled studies, the role of Felbatol® in their causation cannot be reliably determined.

Events are classified within body system categories and enumerated in order of decreasing frequency using the following definitions: frequent adverse events are defined as those occurring on one or more occasions in at least 1/100 patients; infrequent adverse events are those occurring in 1/100-1/1000 patients; and rare events are those occurring in fewer than 1/1000 patients.

Event frequencies are calculated as the number of patients reporting an event divided by the total number of patients (N=1334) exposed to Felbatol®.

Body as a Whole:Frequent: Weight increase, asthenia, malaise, influenza-like symptoms; Rare: anaphylactoid reaction, chest pain substernal.
Cardiovascular:Frequent: Palpitation, tachycardia; Rare: supraventricular tachycardia.
Central Nervous System:Frequent: Agitation, psychological disturbance, aggressive reaction: Infrequent: hallucination, euphoria, suicide attempt, migraine.
Digestive:Frequent: SGOT increased; Infrequent: esophagitis, appetite increased; Rare: GGT elevated.
Hematologic:Infrequent: Lymphadenopathy, leukopenia, leukocytosis, thrombocytopenia, granulocytopenia; Rare: antinuclear factor test positive, qualitative platelet disorder, agranulocytosis.
Metabolic/Nutritional:Infrequent: Hypokalemia, hyponatremia, LDH increased, alkaline phosphatase increased, hypophosphatemia; Rare: creatinine phosphokinase increased.
Musculoskeletal:Infrequent: Dystonia.
Dermatological:Frequent: Pruritus; Infrequent: urticaria, bullous eruption; Rare: buccal mucous membrane swelling, Stevens-Johnson Syndrome.
Special Senses:Rare: Photosensitivity allergic reaction.

Postmarketing Adverse Event Reports:
Voluntary reports of adverse events in patients taking Felbatol® (usually in conjunction with other drugs) have been received since market introduction and may have no causal relationship with the drug(s). These include the following by body system:
Body as a Whole: neoplasm, sepsis, L.E. syndrome, SIDS, sudden death, edema, hypothermia, rigors, hyperpyrexia.
Cardiovascular: atrial fibrillation, atrial arrhythmia, cardiac arrest, torsade de pointes, cardiac failure, hypotension, hypertension, flushing, thrombophlebitis, ischemic necrosis, gangrene, peripheral ischemia, bradycardia, Henoch-Schönlein purpura (vasculitis).
Central & Peripheral Nervous System: delusion, paralysis, mononeuritis, cerebrovascular disorder, cerebral edema, coma, manic reaction, encephalopathy, paranoid reaction, nystagmus, choreoathetosis, extrapyramidal disorder, confusion, psychosis, status epilepticus, dyskinesia, dysarthria, respiratory depression, apathy, concentration impaired.
Dermatological: abnormal body odor, sweating, lichen planus, livedo reticularis, alopecia, toxic epidermal necrolysis.
Digestive: (Refer to WARNINGS ) hepatitis, hepatic failure, G.I. hemorrhage, hyperammonemia, pancreatitis, hematemesis, gastritis, rectal hemorrhage, flatulence, gingival bleeding, acquired megacolon, ileus, intestinal obstruction, enteritis, ulcerative stomatitis, glossitis, dysphagia, jaundice, gastric ulcer, gastric dilatation, gastroesophageal reflux.
Fetal Disorders: fetal death, microcephaly, genital malformation, anencephaly, encephalocele.
Hematologic: (Refer to WARNINGS ) increased and decreased prothrombin time, anemia, hypochromic anemia, aplastic anemia, pancytopenia, hemolytic uremic syndrome, increased mean corpuscular volume (mcv) with and without anemia, coagulation disorder, embolism-limb, disseminated intravascular coagulation, eosinophilia, hemolytic anemia, leukemia, including myelogenous leukemia, and lymphoma, including T-cell and B-cell lymphoproliferative disorders.
Metabolic/Nutritional: hypernatremia, hypoglycemia, SIADH, hypomagnesemia, dehydration, hyperglycemia, hypocalcemia.
Musculoskeletal: arthralgia, muscle weakness, involuntary muscle contraction, rhabdomyolysis.
Respiratory: dyspnea, pneumonia, pneumonitis, hypoxia, epistaxis, pleural effusion, respiratory insufficiency, pulmonary hemorrhage, asthma.
Special Senses: hemianopsia, decreased hearing, conjunctivitis.
Urogenital: menstrual disorder, acute renal failure, hepatorenal syndrome, hematuria, urinary retention, nephrosis, vaginal hemorrhage, abnormal renal function, dysuria, placental disorder.

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Side Effects by Body System - for Healthcare Professionals

Nervous system

In controlled trials with felbamate as monotherapy, no nervous system effect occurred with a frequency greater than 7%. However, the frequency of nervous system effects (particularly sedative effects) was much greater in controlled studies of felbamate as adjuvant therapy with other antiepileptic agents. Ataxia, tremor, involuntary movements, psychosis, and blurred vision have also been reported rarely.

One prospective investigation found 20 of 60 (33%) epileptic patients to have reported a headache. The headache was pounding in 11 patients, steady in 9 patients, and moderate or severe in 19 patients. Patients who had the headaches reported that they occurred at least once a week.

Nervous system side effects are common and include insomnia, headache, anxiety, dizziness, somnolence, fatigue, and lethargy.

Gastrointestinal

Gastrointestinal side effects are common and include nausea, vomiting, dyspepsia, constipation, diarrhea, and bad taste in mouth. Some clinicians have reported that anorexia and weight loss occur commonly.

Dyspepsia and vomiting occur in as many as 9% of treated patients.

Hepatic

Hepatic side effects include mild elevations of liver function tests which occur in as many as 5% of treated patients. The manufacturer reports that several cases of acute liver failure have also occurred in patients taking felbamate. A case of massive acute hepatic necrosis and death within 40 days of initiation of felbamate therapy has also been reported.

Dermatologic

Dermatologic side effects including rashes and acne occur in approximately 3% of treated patients. The Stevens-Johnson syndrome has been reported rarely. A case of toxic epidermal necrolysis has also been reported.

Metabolic

Metabolic side effects including hypophosphatemia have been reported in approximately 3% of treated patients.

Hematologic

Hematologic side effects include leukopenia, thrombocytopenia, and agranulocytosis rarely. Nine cases of aplastic anemia have been reported in the United States from the time of commercial release of felbamate to August 1, 1994.

Genitourinary

Genitourinary side effects including a case of urolithiasis have been reported.

Hypersensitivity

Hypersensitivity side effects including a case of felbamate induced delayed anaphylaxis have been reported.

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