TOPIRAMATE (topiramate 100 mg) Dailymed

Description

Topiramate is a sulfamate-substituted monosaccharide. Topiramate tablets are available as 25 mg, 50 mg, 100 mg, and 200 mg circular tablets for oral administration.

Topiramate is a white crystalline powder with a bitter taste. Topiramate USP is most soluble in alkaline solutions containing sodium hydroxide or sodium phosphate and having a pH of 9 to 10. It is freely soluble in acetone, chloroform, dimethylsulfoxide, and ethanol. The solubility in water is 9.8 mg/mL. Its saturated solution has a pH of 6.3. Topiramate has the molecular formula C ₁₂H ₂₁NO ₈S and a molecular weight of 339.37. Topiramate is designated chemically as 2,3:4,5-Di- O-isopropylidene-β-D-fructopyranose sulfamate and has the following structural formula:

Topiramate tablets contain the following inactive ingredients: anhydrous lactose, microcrystalline cellulose, pregelatinized starch, sodium starch glycolate, magnesium stearate, purified water, polyvinyl alcohol, titanium dioxide, polyethylene glycol and talc.

In addition, individual tablets contain:

50 mg tablets: iron oxide yellow 100 mg tablets: iron oxide yellow, and D&C Yellow # 10 Aluminum Lake 200 mg tablets: iron oxide red, lecithin (soya), and iron oxide black

Clinical Pharmacology

Mechanism of Action:

The precise mechanisms by which topiramate exerts its anticonvulsant effects are unknown; however, preclinical studies have revealed four properties that may contribute to topiramate's efficacy for epilepsy. Electrophysiological and biochemical evidence suggests that topiramate, at pharmacologically relevant concentrations, blocks voltage-dependent sodium channels, augments the activity of the neurotransmitter gamma-aminobutyrate at some subtypes of the GABA-A receptor, antagonizes the AMPA/kainate subtype of the glutamate receptor, and inhibits the carbonic anhydrase enzyme, particularly isozymes II and IV.

Pharmacodynamics:

Topiramate has anticonvulsant activity in rat and mouse maximal electroshock seizure (MES) tests. Topiramate is only weakly effective in blocking clonic seizures induced by the GABAA receptor antagonist, pentylenetetrazole. Topiramate is also effective in rodent models of epilepsy, which include tonic and absence-like seizures in the spontaneous epileptic rat (SER) and tonic and clonic seizures induced in rats by kindling of the amygdala or by global ischemia.

Pharmacokinetics:

The sprinkle formulation is bioequivalent to the immediate release tablet formulation and, therefore, may be substituted as a therapeutic equivalent.

Absorption of topiramate is rapid, with peak plasma concentrations occurring at approximately 2 hours following a 400 mg oral dose. The relative bioavailability of topiramate from the tablet formulation is about 80% compared to a solution. The bioavailability of topiramate is not affected by food.

The pharmacokinetics of topiramate are linear with dose proportional increases in plasma concentration over the dose range studied (200 to 800 mg/day). The mean plasma elimination half-life is 21 hours after single or multiple doses. Steady state is thus reached in about 4 days in patients with normal renal function. Topiramate is 15 to 41% bound to human plasma proteins over the blood concentration range of 0.5 to 250 mcg/mL. The fraction bound decreased as blood concentration increased.

Carbamazepine and phenytoin do not alter the binding of topiramate. Sodium valproate, at 500 mcg/mL (a concentration 5 to 10 times higher than considered therapeutic for valproate) decreased the protein binding of topiramate from 23% to 13%. Topiramate does not influence the binding of sodium valproate.

Metabolism and Excretion:

Topiramate is not extensively metabolized and is primarily eliminated unchanged in the urine (approximately 70% of an administered dose). Six metabolites have been identified in humans, none of which constitutes more than 5% of an administered dose. The metabolites are formed via hydroxylation, hydrolysis, and glucuronidation. There is evidence of renal tubular reabsorption of topiramate. In rats, given probenecid to inhibit tubular reabsorption, along with topiramate, a significant increase in renal clearance of topiramate was observed. This interaction has not been evaluated in humans. Overall, oral plasma clearance (CL/F) is approximately 20 to 30 mL/min in humans following oral administration.

Pharmacokinetic Interactions

(see also Drug Interactions):

Antiepileptic Drugs

Potential interactions between topiramate and standard AEDs were assessed in controlled clinical pharmacokinetic studies in patients with epilepsy. The effect of these interactions on mean plasma AUCs are summarized under PRECAUTIONS (Table 4) .

Special Populations:

Renal Impairment:

The clearance of topiramate was reduced by 42% in moderately renally impaired (creatinine clearance 30 to 69 mL/min/1.73m ²) and by 54% in severely renally impaired subjects (creatinine clearance <30 mL/min/1.73m ²) compared to normal renal function subjects (creatinine clearance >70 mL/min/1.73m ²). Since topiramate is presumed to undergo significant tubular reabsorption, it is uncertain whether this experience can be generalized to all situations of renal impairment. It is conceivable that some forms of renal disease could differentially affect glomerular filtration rate and tubular reabsorption resulting in a clearance of topiramate not predicted by creatinine clearance. In general, however, use of one-half the usual starting and maintenance dose is recommended in patients with moderate or severe renal impairment (see PRECAUTIONS: Adjustment of Dose in Renal Failure and DOSAGE AND ADMINISTRATION ) .

Hemodialysis:

Topiramate is cleared by hemodialysis. Using a high efficiency, counterflow, single pass-dialysate hemodialysis procedure, topiramate dialysis clearance was 120 mL/min with blood flow through the dialyzer at 400 mL/min. This high clearance (compared to 20 to 30 mL/min total oral clearance in healthy adults) will remove a clinically significant amount of topiramate from the patient over the hemodialysis treatment period. Therefore, a supplemental dose may be required (see DOSAGE AND ADMINISTRATION ) .

Hepatic Impairment:

In hepatically impaired subjects, the clearance of topiramate may be decreased; the mechanism underlying the decrease is not well understood.

Age, Gender, and Race:

The pharmacokinetics of topiramate in elderly subjects (65 to 85 years of age, N=16) were evaluated in a controlled clinical study. The elderly subject population had reduced renal function [creatinine clearance (-20%)] compared to young adults. Following a single oral 100 mg dose, maximum plasma concentration for elderly and young adults was achieved at approximately 1 to 2 hours. Reflecting the primary renal elimination of topiramate, topiramate plasma and renal clearance were reduced 21% and 19%, respectively, in elderly subjects, compared to young adults. Similarly, topiramate half-life was longer (13%) in the elderly. Reduced topiramate clearance resulted in slightly higher maximum plasma concentration (23%) and AUC (25%) in elderly subjects than observed in young adults. Topiramate clearance is decreased in the elderly only to the extent that renal function is reduced. As recommended for all patients, dosage adjustment may be indicated in the elderly patient when impaired renal function (creatinine clearance rate ≤70 mL/min/1.73 m ²) is evident. It may be useful to monitor renal function in the elderly patient (see Special Populations: Renal Impairment , PRECAUTIONS: Adjustment of Dose in Renal Failure and DOSAGE AND ADMINISTRATION ).

Clearance of topiramate in adults was not affected by gender or race.

Pediatric Pharmacokinetics:

Pharmacokinetics of topiramate were evaluated in patients ages 4 to 17 years receiving one or two other antiepileptic drugs. Pharmacokinetic profiles were obtained after one week at doses of 1, 3, and 9 mg/kg/day. Clearance was independent of dose.

Pediatric patients have a 50% higher clearance and consequently shorter elimination half-life than adults. Consequently, the plasma concentration for the same mg/kg dose may be lower in pediatric patients compared to adults. As in adults, hepatic enzyme-inducing antiepileptic drugs decrease the steady state plasma concentrations of topiramate.

The data described in the following section were obtained using topiramate tablets.

Monotherapy Epilepsy

The adverse events in the controlled trial that occurred most commonly in adults in the 400 mg/day group and at a rate higher than the 50 mg/day group were: paresthesia, weight decrease, somnolence, anorexia, dizziness, and difficulty with memory NOS [see Table 5].

The adverse events in the controlled trial that occurred most commonly in children (10 years up to 16 years of age) in the 400 mg/day group and at a rate higher than the 50 mg/day group were: weight decrease, upper respiratory tract infection, paresthesia, anorexia, diarrhea, and mood problems [see Table 6].

Approximately 21% of the 159 adult patients in the 400 mg/day group who received topiramate as monotherapy in the controlled clinical trial discontinued therapy due to adverse events. Adverse events associated with discontinuing therapy (≥2%) included depression, insomnia, difficulty with memory (NOS), somnolence, paresthesia, psychomotor slowing, dizziness, and nausea.

Approximately 12% of the 57 pediatric patients in the 400 mg/day group who received topiramate as monotherapy in the controlled clinical trial discontinued therapy due to adverse events. Adverse events associated with discontinuing therapy (≥5%) included difficulty with concentration/attention.

The prescriber should be aware that these data 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 the clinical study. Similarly, the cited frequencies cannot be directly compared with data obtained from other clinical investigations involving different treatments, uses, or investigators. Inspection of these frequencies, however, does provide the prescribing physician with a basis to estimate the relative contribution of drug and non-drug factors to the adverse event incidences in the population studied.

Table 5: Incidence of Treatment-Emergent Adverse Events in the Monotherapy Epilepsy Trial in Adults ^a Where Rate Was at Least 2% in the 400 mg/day Topiramate Group and Greater Than the Rate in the 50 mg/day Topiramate Group

	Topiramate Dosage (mg/day)
Body System/ Adverse Event	50 (N= 160)	400 (N=159)
a Values represent the percentage of patients reporting a given adverse event. Patients may have reported more than one adverse event during the study and can be included in more than one adverse event category.
Body as a Whole-General Disorders
Asthenia	4	6
Leg Pain	2	3
Chest Pain	1	2
Central & Peripheral Nervous System Disorders
Paresthesia	21	40
Dizziness	13	14
Hypoaesthesia	4	5
Ataxia	3	4
Hypertonia	0	3
Gastro-Intestinal System Disorders
Diarrhea	5	6
Constipation	1	4
Gastritis	0	3
Dry Mouth	1	3
Gastroesophageal Reflux	1	2
Liver and Biliary System Disorders
Gamma-GT Increased	1	3
Metabolic and Nutritional Disorders
Weight Decrease	6	16
Psychiatric Disorders
Somnolence	9	15
Anorexia	4	14
Difficulty with Memory NOS	5	10
Insomnia	8	9
Depression	7	9
Difficulty with Concentration/Attention	7	8
Anxiety	4	6
Psychomotor Slowing	3	5
Mood Problems	2	5
Confusion	3	4
Cognitive Problem NOS	1	4
Libido Decreased	0	3
Reproductive Disorders, Female
Vaginal Hemorrhage	0	3
Red Blood Cell Disorders
Anemia	1	2
Resistance Mechanism Disorders
Infection Viral	6	8
Infection	2	3
Respiratory System Disorders
Bronchitis	3	4
Rhinitis	2	4
Dyspnea	1	2
Skin and Appendages Disorders
Rash	1	4
Pruritus	1	4
Acne	2	3
Special Senses Other, Disorders
Taste Perversion	3	5
Urinary System Disorders
Cystitis	1	3
Renal Calculus	0	3
Urinary Tract Infection	1	2
Dysuria	0	2
Micturition Frequency	0	2

Table 6: Incidence of Treatment-Emergent Adverse Events in the Monotherapy Epilepsy Trial in Children Ages 10 up to 16 Years ^a Where Rate Was at Least 5% in the 400 mg/day Topiramate Group and Greater Than the Rate in the 50 mg/day Topiramate Group

	Topiramate Dosage (mg/day)
Body System/ Adverse Event	50 (N=57)	400 (N=57)
a Values represent the percentage of patients reporting a given adverse event. Patients may have reported more than one adverse event during the study and can be included in more than one adverse event category.
Body as a Whole-General Disorders
Fever	0	9
Central & Peripheral Nervous System Disorders
Paresthesia	2	16
Gastro-Intestinal System Disorders
Diarrhea	5	11
Metabolic and Nutritional Disorders
Weight Decrease	7	21
Psychiatric Disorders
Anorexia	11	14
Mood Problems	2	11
Difficulty with Concentration/Attention	4	9
Cognitive Problems NOS	0	7
Nervousness	4	5
Resistance Mechanism Disorders
Infection Viral	4	9
Infection	2	7
Respiratory System Disorders
Upper Respiratory Tract Infection	16	18
Rhinitis	2	7
Bronchitis	2	7
Sinusitis	2	5
Skin and Appendages Disorders
Alopecia	2	5

Adjunctive Therapy Epilepsy

The most commonly observed adverse events associated with the use of topiramate at dosages of 200 to 400 mg/day in controlled trials in adults with partial onset seizures, primary generalized tonic-clonic seizures, or Lennox-Gastaut syndrome, that were seen at greater frequency in topiramate-treated patients and did not appear to be dose-related were: somnolence, dizziness, ataxia, speech disorders and related speech problems, psychomotor slowing, abnormal vision, difficulty with memory, paresthesia and diplopia [see Table 7]. The most common dose-related adverse events at dosages of 200 to 1,000 mg/day were: fatigue, nervousness, difficulty with concentration or attention, confusion, depression, anorexia, language problems, anxiety, mood problems, and weight decrease [see Table 9].

Adverse events associated with the use of topiramate at dosages of 5 to 9 mg/kg/day in controlled trials in pediatric patients with partial onset seizures, primary generalized tonic-clonic seizures, or Lennox-Gastaut syndrome, that were seen at greater frequency in topiramate-treated patients were: fatigue, somnolence, anorexia, nervousness, difficulty with concentration/attention, difficulty with memory, aggressive reaction, and weight decrease [see Table 10].

In controlled clinical trials in adults, 11% of patients receiving topiramate 200 to 400 mg/day as adjunctive therapy discontinued due to adverse events. This rate appeared to increase at dosages above 400 mg/day. Adverse events associated with discontinuing therapy included somnolence, dizziness, anxiety, difficulty with concentration or attention, fatigue, and paresthesia and increased at dosages above 400 mg/day. None of the pediatric patients who received topiramate adjunctive therapy at 5 to 9 mg/kg/day in controlled clinical trials discontinued due to adverse events.

Approximately 28% of the 1,757 adults with epilepsy who received topiramate at dosages of 200 to 1,600 mg/day in clinical studies discontinued treatment because of adverse events; an individual patient could have reported more than one adverse event. These adverse events were: psychomotor slowing (4%), difficulty with memory (3.2%), fatigue (3.2%), confusion (3.1%), somnolence (3.2%), difficulty with concentration/attention (2.9%), anorexia (2.7%), depression (2.6%), dizziness (2.5%), weight decrease (2.5%), nervousness (2.3%), ataxia (2.1%), and paresthesia (2%). Approximately 11% of the 310 pediatric patients who received topiramate at dosages up to 30 mg/kg/day discontinued due to adverse events. Adverse events associated with discontinuing therapy included aggravated convulsions (2.3%), difficulty with concentration/attention (1.6%), language problems (1.3%), personality disorder (1.3%), and somnolence (1.3%).

Incidence in Epilepsy Controlled Clinical Trials - Adjunctive Therapy Partial Onset Seizures, Primary Generalized Tonic-Clonic Seizures, and Lennox-Gastaut Syndrome

Table 7 uls treatment-emergent adverse events that occurred in at least 1% of adults treated with 200 to 400 mg/day topiramate in controlled trials that were numerically more common at this dose than in the patients treated with placebo. In general, most patients who experienced adverse events during the first eight weeks of these trials no longer experienced them by their last visit. Table 10 uls treatment-emergent adverse events that occurred in at least 1% of pediatric patients treated with 5 to 9 mg/kg topiramate in controlled trials that were numerically more common than in patients treated with placebo.

The prescriber should be aware that these data were obtained when topiramate was added to concurrent antiepileptic drug therapy and 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 data obtained from other clinical investigations involving different treatments, uses, or investigators. Inspection of these frequencies, however, does provide the prescribing physician with a basis to estimate the relative contribution of drug and non-drug factors to the adverse event incidences in the population studied.

Other Adverse Events Observed During Double-Blind Epilepsy Adjunctive Therapy Trials

Other events that occurred in more than 1% of adults treated with 200 to 400 mg of topiramate in placebo-controlled epilepsy trials but with equal or greater frequency in the placebo group were: headache, injury, anxiety, rash, pain, convulsions aggravated, coughing, fever, diarrhea, vomiting, muscle weakness, insomnia, personality disorder, dysmenorrhea, upper respiratory tract infection, and eye pain.

Table 7: Incidence of Treatment-Emergent Adverse Events in Placebo-Controlled, Add-On Epilepsy Trials in Adults ^a,b Where Rate Was > 1% in Any Topiramate Group and Greater Than the Rate in Placebo-Treated Patients

		Topiramate Dosage (mg/day)
Body System/ Adverse Event c	Placebo (N=291)		200 to 400 (N=183)		600 to 1,000 (N=414)
a Patients in these add-on trials were receiving 1 to 2 concomitant antiepileptic drugs in addition to topiramate or placebo.
b Values represent the percentage of patients reporting a given adverse event. Patients may have reported more than one adverse event during the study and can be included in more than one adverse event category.
c Adverse events reported by at least 1% of patients in the topiramate 200 to 400 mg/day group and more common than in the placebo group are uled in this table.
Body as a Whole-General Disorders
Fatigue	13		15		30
Asthenia	1		6		3
Back Pain	4		5		3
Chest Pain	3		4		2
Influenza-Like Symptoms	2		3		4
Leg Pain	2		2		4
Hot Flushes	1		2		1
Allergy	1		2		3
Edema	1		2		1
Body Odor	0		1		0
Rigors	0		1		<1
Central & Peripheral Nervous System Disorders
Dizziness	15		25		32
Ataxia	7		16		14
Speech Disorders/Related Speech Problems	2		13		11
Paresthesia	4		11		19
Nystagmus	7		10		11
Tremor	6		9		9
Language Problems	1		6		10
Coordination Abnormal	2		4		4
Hypoaesthesia	1		2		1
Gait Abnormal	1		3		2
Muscle Contractions Involuntary	1		2		2
Stupor	0		2		1
Vertigo	1		1		2
Gastro-Intestinal System Disorders
Nausea	8		10		12
Dyspepsia	6		7		6
Abdominal Pain	4		6		7
Constipation	2		4		3
Gastroenteritis	1		2		1
Dry Mouth	1		2		4
Gingivitis	<1		1		1
GI Disorder	<1		1		0
Hearing and Vestibular Disorders
Hearing Decreased	1		2		1
Metabolic and Nutritional Disorders
Weight Decrease	3		9		13
Muscle-Skeletal System Disorders
Myalgia	1		2		2
Skeletal Pain	0		1		0
Platelet, Bleeding, & Clotting Disorders
Epistaxis	1		2		1
Psychiatric Disorders
Somnolence	12		29		28
Nervousness	6		16		19
Psychomotor Slowing	2		13		21
Difficulty with Memory	3		12		14
Anorexia	4		10		12
Confusion	5		11		14
Depression	5		5		13
Difficulty with Concentration/Attention	2		6		14
Mood Problems	2		4		9
Agitation	2		3		3
Aggressive Reaction	2		3		3
Emotional Lability	1		3		3
Cognitive Problems	1		3		3
Libido Decreased	1		2		<1
Apathy	1		1		3
Depersonalization	1		1		2
Reproductive Disorders, Female
Breast Pain	2		4		0
Amenorrhea	1		2		2
Menorrhagia	0		2		1
Menstrual Disorder	1		2		1
Reproductive Disorders, Male
Prostatic Disorder	<1		2		0
Resistance Mechanism Disorders
Infection	1		2		1
Infection Viral	1		2		<1
Moniliasis	<1		1		0
Respiratory System Disorders
Pharyngitis	2		6		3
Rhinitis	6		7		6
Sinusitis	4		5		6
Dyspnea	1		1		2
Skin and Appendages Disorders
Skin Disorder	<1		2		1
Sweating Increased	<1		1		<1
Rash Erythematous	<1		1		<1
Special Sense Other, Disorders
Taste Perversion	0		2		4
Urinary System Disorders
Hematuria	1		2		<1
Urinary Tract Infection	1		2		3
Micturition Frequency	1		1		2
Urinary Incontinence	<1		2		1
Urine Abnormal	0		1		<1
Vision Disorders
Vision Abnormal	2		13		10
Diplopia	5		10		10
White Cell and RES Disorders
Leukopenia	1		2		1

Incidence in Study 119 Add-On Therapy Adults with Partial Onset Seizures

Study 119 was a randomized, double-blind, placebo-controlled, parallel group study with 3 treatment arms: 1) placebo; 2) topiramate 200 mg/day with a 25 mg/day starting dose, increased by 25 mg/day each week for 8 weeks until the 200 mg/day maintenance dose was reached; and 3) topiramate 200 mg/day with a 50 mg/day starting dose, increased by 50 mg/day each week for 4 weeks until the 200 mg/day maintenance dose was reached. All patients were maintained on concomitant carbamazepine with or without another concomitant antiepileptic drug.

The incidence of adverse events ( Table 8) did not differ significantly between the 2 topiramate regimens. Because the frequencies of adverse events reported in this study were markedly lower than those reported in the previous epilepsy studies, they cannot be directly compared with data obtained in other studies.

Table 8: Incidence of Treatment-Emergent Adverse Events in Study 119 ^a,b Where Rate Was ≥ 2% in the Topiramate Group and Greater Than the Rate in Placebo-Treated Patients

		Topiramate Dosage (mg/day)
Body System/ Adverse Event c	Placebo (N=92)	200 (N=171)
a Patients in these add-on trials were receiving 1 to 2 concomitant antiepileptic drugs in addition to topiramate or placebo.
b Values represent the percentage of patients reporting a given adverse event. Patients may have reported more than one adverse event during the study and can be included in more than one adverse event category.
c Adverse events reported by at least 2% of patients in the topiramate 200 mg/day group and more common than in the placebo group are uled in this table.
Body as a Whole-General Disorders
Fatigue	4	9
Chest Pain	1	2
Cardiovascular Disorders, General
Hypertension	0	2
Central & Peripheral Nervous System Disorders
Paresthesia	2	9
Dizziness	4	7
Tremor	2	3
Hypoasthesia	0	2
Leg Cramps	0	2
Language Problems	0	2
Gastro-Intestinal System Disorders
Abdominal Pain	3	5
Constipation	0	4
Diarrhea	1	2
Dyspepsia	0	2
Dry Mouth	0	2
Hearing and Vestibular Disorders
Tinnitus	0	2
Metabolic and Nutritional Disorders
Weight Decrease	4	8
Psychiatric Disorders
Somnolence	9	15
Anorexia	7	9
Nervousness	2	9
Difficulty with Concentration/Attention	0	5
Insomnia	3	4
Difficulty with Memory	1	2
Aggressive Reaction	0	2
Respiratory System Disorders
Rhinitis	0	4
Urinary System Disorders
Cystitis	0	2
Vision Disorders
Diplopia	0	2
Vision Abnormal	0	2

Table 9: Incidence (%) of Dose-Related Adverse Events From Placebo-Controlled, Add-On Trials in Adults with Partial Onset Seizures ^a

		Topiramate Dosage (mg/day)
Adverse Event	Placebo (N = 216)	200 (N = 45)	400 (N = 68)	600 to 1,000 (N = 414)
a Dose-response studies were not conducted for other adult indications or for pediatric indications.
Fatigue	13	11	12	30
Nervousness	7	13	18	19
Difficulty with Concentration/Attention	1	7	9	14
Confusion	4	9	10	14
Depression	6	9	7	13
Anorexia	4	4	6	12
Language problems	<1	2	9	10
Anxiety	6	2	3	10
Mood problems	2	0	6	9
Weight decrease	3	4	9	13

Table 10: Incidence (%) of Treatment-Emergent Adverse Events in Placebo-Controlled, Add-On Epilepsy Trials in Pediatric Patients Ages 2 to 16 Years ^a,b (Events that Occurred in at Least 1% of Topiramate-Treated Patients and Occurred More Frequently in Topiramate-Treated Than Placebo-Treated Patients)

Body System/ Adverse Event	Placebo (N=101)	Topiramate (N=98)
a Patients in these add-on trials were receiving 1 to 2 concomitant antiepileptic drugs in addition to topiramate or placebo.
b Values represent the percentage of patients reporting a given adverse event. Patients may have reported more than one adverse event during the study and can be included in more than one adverse event category.
Body as a Whole - General Disorders
Fatigue	5	16
Injury	13	14
Allergic Reaction	1	2
Back Pain	0	1
Pallor	0	1
Cardiovascular Disorders, General
Hypertension	0	1
Central & Peripheral Nervous System Disorders
Gait Abnormal	5	8
Ataxia	2	6
Hyperkinesia	4	5
Dizziness	2	4
Speech Disorders/Related Speech Problems	2	4
Hyporeflexia	0	2
Convulsions Grand Mal	0	1
Fecal Incontinence	0	1
Paresthesia	0	1
Gastro-Intestinal System Disorders
Nausea	5	6
Saliva Increased	4	6
Constipation	4	5
Gastroenteritis	2	3
Dysphagia	0	1
Flatulence	0	1
Gastroesophageal Reflux	0	1
Glossitis	0	1
Gum Hyperplasia	0	1
Heart Rate and Rhythm Disorders
Bradycardia	0	1
Metabolic and Nutritional Disorders
Weight Decrease	1	9
Thirst	1	2
Hypoglycemia	0	1
Weight Increase	0	1
Platelet, Bleeding, & Clotting Disorders
Purpura	4	8
Epistaxis	1	4
Hematoma	0	1
Prothrombin Increased	0	1
Thrombocytopenia	0	1
Psychiatric Disorders
Somnolence	16	26
Anorexia	15	24
Nervousness	7	14
Personality Disorder (Behavior Problems)	9	11
Difficulty with Concentration/Attention	2	10
Aggressive Reaction	4	9
Insomnia	7	8
Difficulty with Memory NOS	0	5
Confusion	3	4
Psychomotor Slowing	2	3
Appetite Increased	0	1
Neurosis	0	1
Reproductive Disorders, Female
Leukorrhoea	0	2
Resistance Mechanism Disorders
Infection Viral	3	7
Respiratory System Disorders
Pneumonia	1	5
Respiratory Disorder	0	1
Skin and Appendages Disorders
Skin Disorder	2	3
Alopecia	1	2
Dermatitis	0	2
Hypertrichosis	1	2
Rash Erythematous	0	2
Eczema	0	1
Seborrhoea	0	1
Skin Discoloration	0	1
Urinary System Disorders
Urinary Incontinence	2	4
Nocturia	0	1
Vision Disorders
Eye Abnormality	1	2
Vision Abnormal	1	2
Diplopia	0	1
Lacrimation Abnormal	0	1
Myopia	0	1
White Cell and RES Disorders
Leukopenia	0	2

Other Adverse Events Observed During All Epilepsy Clinical Trials

Topiramate has been administered to 2,246 adults and 427 pediatric patients with epilepsy during all clinical studies, only some of which were placebo controlled. During these studies, 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 WHOART dictionary terminology. The frequencies presented represent the proportion of patients who experienced an event of the type cited on at least one occasion while receiving topiramate. Reported events are included except those already uled in the previous tables or text, those too general to be informative, and those not reasonably associated with the use of the drug.

Events are classified within body system categories and enumerated in order of decreasing frequency using the following definitions: frequent occurring in at least 1/100 patients; infrequent occurring in 1/100 to 1/1000 patients; rare occurring in fewer than 1/1000 patients.

Autonomic Nervous System Disorders: Infrequent: vasodilation.

Body as a Whole: Frequent: syncope. Infrequent: abdomen enlarged. Rare: alcohol intolerance.

Cardiovascular Disorders, General: Infrequent: hypotension, postural hypotension, angina pectoris.

Central & Peripheral Nervous System Disorders: Infrequent : neuropathy, apraxia, hyperaesthesia, dyskinesia, dysphonia, scotoma, ptosis, dystonia, visual field defect, encephalopathy, EEG abnormal. Rare: upper motor neuron lesion, cerebellar syndrome, tongue paralysis.

Gastrointestinal System Disorders: Infrequent: hemorrhoids, stomatitis, melena, gastritis, esophagitis. Rare: tongue edema.

Heart Rate and Rhythm Disorders: Infrequent: AV block.

Liver and Biliary System Disorders: Infrequent: SGPT increased, SGOT increased.

Metabolic and Nutritional Disorders: Infrequent: dehydration, hypokalemia, alkaline phosphatase increased, hypocalcemia, hyperlipemia, hyperglycemia, xerophthalmia, diabetes mellitus. Rare: hyperchloremia, hypernatremia, hyponatremia, hypocholesterolemia, hypophosphatemia, creatinine increased.

Musculoskeletal System Disorders: Frequent: arthralgia. Infrequent: arthrosis.

Neoplasms: Infrequent: thrombocythemia. Rare: polycythemia.

Platelet, Bleeding, and Clotting Disorders: Infrequent: gingival bleeding, pulmonary embolism.

Psychiatric Disorders: Frequent: impotence, hallucination, psychosis, suicide attempt. Infrequent: euphoria, paranoid reaction, delusion, paranoia, delirium, abnormal dreaming. Rare: libido increased, manic reaction.

Red Blood Cell Disorders: Frequent: anemia. Rare: marrow depression, pancytopenia.

Reproductive Disorders, Male: Infrequent: ejaculation disorder, breast discharge.

Skin and Appendages Disorders: Infrequent: urticaria, photosensitivity reaction, abnormal hair texture. Rare: chloasma.

Special Senses Other, Disorders: Infrequent: taste loss, parosmia.

Urinary System Disorders: Infrequent: urinary retention, face edema, renal pain, albuminuria, polyuria, oliguria.

Vascular (Extracardiac) Disorders: Infrequent: flushing, deep vein thrombosis, phlebitis. Rare: vasospasm.

Vision Disorders: Frequent: conjunctivitis. Infrequent: abnormal accommodation, photophobia, strabismus. Rare: mydriasis, iritis.

White Cell and Reticuloendothelial System Disorders: Infrequent: lymphadenopathy, eosinophilia, lymphopenia, granulocytopenia. Rare: lymphocytosis.

Postmarketing and Other Experience

In addition to the adverse experiences reported during clinical testing of topiramate, the following adverse experiences have been reported worldwide in patients receiving topiramate post-approval.

These adverse experiences have not been uled above and data are insufficient to support an estimate of their incidence or to establish causation. The uling is alphabetized: bullous skin reactions (including erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis), hepatic failure (including fatalities), hepatitis, maculopathy, pancreatitis, pemphigus, and renal tubular acidosis.