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Topiramate is a brand name for Topiramate. The medicine, its uses, side effects and dosage are the same regardless of brand.
Used for: 1 INDICATIONS AND USAGE Topiramate is indicated for: Epilepsy: initial monotherapy for the treatment of partial-onset or primary generalized tonic-clonic seizures in patients 2 years of age and older (1.1); adjunctive therapy for the treatment of partial-onset seizures, primary generalized tonic-clonic seizures, or…
Verbatim from this product's FDA label. Tap a section to expand.
2 DOSAGE AND ADMINISTRATION Topiramate initial dose, titration, and recommended maintenance dose varies by indication and age group. 1 Dosing in Monotherapy Epilepsy Adults and Pediatric Patients 10 Years of Age and Older The recommended dose for topiramate monotherapy in adults and pediatric patients 10 years of age and older is 400 mg/day in two divided doses.
The dose should be achieved by titration according to the following schedule (Table 1): Table 1: Monotherapy Titration Schedule for Adults and Pediatric Patients 10 years and older Morning Dose Evening Dose Week 1 25 mg 25 mg Week 2 50 mg 50 mg Week 3 75 mg 75 mg Week 4 100 mg 100 mg Week 5 150 mg 150 mg Week 6 200 mg 200 mg Pediatric Patients 2 to 9 Years of Age Dosing in patients 2 to 9 years of age is based on weight.
During the titration period, the initial dose of topiramate is 25 mg/day nightly for the first week. Based upon tolerability, the dosage can be increased to 50 mg/day (25 mg twice daily) in the second week. Dosage can be increased by 25 to 50 mg/day each subsequent week as tolerated.
Titration to the minimum maintenance dose should be attempted over 5 to 7 weeks of the total titration period. Based upon tolerability and clinical response, additional titration to a higher dose (up to the maximum maintenance dose) can be attempted at 25 to 50 mg/day weekly increments.
The total daily dose should not exceed the maximum maintenance dose for each range of body weight (Table 2). 2 Dosing in Adjunctive Therapy Epilepsy Adults (17 Years of Age and Older) The recommended total daily dose of topiramate as adjunctive therapy in adults with partial onset seizures or Lennox-Gastaut Syndrome is 200 to 400 mg/day in two divided doses, and 400 mg/day in two divided doses as adjunctive treatment in adults with primary generalized tonic-clonic seizures.
Topiramate should be initiated at 25 to 50 mg/day, followed by titration to an effective dose in increments of 25 to 50 mg/day every week. Titrating in increments of 25 mg/day every week may delay the time to reach an effective dose.
Doses above 400 mg/day have not been shown to improve responses in adults with partial-onset seizures. Pediatric Patients 2 to 16 Years of Age The recommended total daily dose of topiramate tablets as adjunctive therapy for pediatric patients 2 to 16 years of age with partial-onset seizures, primary generalized tonic-clonic seizures, or seizures associated with Lennox-Gastaut syndrome is approximately 5 to 9 mg/kg/day in two divided doses.
14)] The data described in the following sections were obtained using topiramate tablets. 1) To report SUSPECTED ADVERSE REACTIONS, contact Sun Pharmaceutical Industries, Inc. gov/medwatch . 1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, the incidence of adverse reactions observed in the clinical trials of a drug cannot be directly compared to the incidence of adverse reactions in the clinical trials of another drug, and may not reflect the incidence of adverse reactions observed in practice.
Monotherapy Epilepsy Adults 16 Years of Age and Older The most common adverse reactions in the controlled clinical trial (Study 1) that occurred in adults in the 400 mg/day topiramate group and at an incidence higher (≥ 10 %) than in the 50 mg/day group were: paresthesia, weight loss and anorexia (see Table 5).
Approximately 21% of the 159 adult patients in the 400 mg/day group who received topiramate as monotherapy in Study 1 discontinued therapy due to adverse reactions. The most common (≥ 2% more frequent than low-dose 50 mg/day topiramate) adverse reactions causing discontinuation were difficulty with memory, fatigue, asthenia, insomnia, somnolence, and paresthesia.
Pediatric Patients 6 to 15 Years of Age The most common adverse reactions in the controlled clinical trial (Study 1) that occurred in pediatric patients in the 400 mg/day topiramate group and at an incidence higher (≥10%) than in the 50 mg/day group were fever and weight loss (see Table 5).
Approximately 14% of the 77 pediatric patients in the 400 mg/day group who received topiramate as monotherapy in the controlled clinical trial discontinued therapy due to adverse reactions. The most common (≥2% more frequent than low-dose 50 mg/day topiramate) adverse reactions resulting in discontinuation were difficulty with concentration/attention, fever, flushing, and confusion.
1 Acute Myopia and Secondary Angle Closure Glaucoma Syndrome A s y nd rome consisting of acute myopia associated with secondary angle closure glaucoma has been reported in patients receiving topiramate. Symptoms include acute onset of decreased visual acuity and/or ocular pain.
Ophthalmologic findings can include some or all of the following: myopia, mydriasis, anterior chamber shallowing, ocular hyperemia (redness), choroidal detachments, retinal pigment epithelial detachments, macular striae, and increased intraocular pressure.
This syndrome may be associated with supraciliary effusion resulting in anterior displacement of the lens and iris, with secondary angle closure glaucoma. Symptoms typically occur within 1 month of initiating topiramate therapy. In contrast to primary narrow angle glaucoma, which is rare under 40 years of age, secondary angle closure glaucoma associated with topiramate has been reported in pediatric patients as well as adults.
The primary treatment to reverse symptoms is discontinuation of topiramate as rapidly as possible, according to the judgment of the treating physician. Other measures, in conjunction with discontinuation of topiramate, may be helpful.
Elevated intraocular pressure of any etiology, if left untreated, can lead to serious sequelae including permanent vision loss. 2 Visual Field Defects Visual field defects (independent of elevated intraocular pressure) have been reported in clinical trials and in postmarketing experience in patients receiving topiramate.
In clinical trials, most of these events were reversible after topiramate discontinuation. If visual problems occur at any time during topiramate treatment, consideration should be given to discontinuing the drug. 3 Oligohidrosis and Hyperthermia Oligohidrosis (decreased sweating), infrequently resulting in hospitalization, has been reported in association with topiramate use.
4 CONTRAINDICATIONS None. None (4)
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Titration should begin at 25 mg/day (or less, based on a range of 1 to 3 mg/kg/day) nightly for the first week. The dosage should then be increased at 1- or 2-week intervals by increments of 1 to 3 mg/kg/day (administered in two divided doses), to achieve optimal clinical response.
Dose titration should be guided by clinical outcome. The total daily dose should not exceed 400 mg/day. 3 Dosing for the Preventive Treatment of Migraine The recommended total daily dose of topiramate as treatment for patients 12 years of age and older for the preventive treatment of migraine is 100 mg/day administered in two divided doses (Table 3).
The recommended titration rate for topiramate for the preventive treatment of migraine is as follows: Table 3: Preventive Treatment of Migraine Titration Schedule for Patients 12 Years of Age and Older Morning Dose Evening Dose Week 1 None 25 mg Week 2 25 mg 25 mg Week 3 25 mg 50 mg Week 4 50 mg 50 mg Dose and titration rate should be guided by clinical outcome.
If required, longer intervals between dose adjustments can be used. 4 Administration Information Topiramate tablets can be taken without regard to meals. Because of the bitter taste, tablets should not be broken. 3) ]. 6 Dosing in Patients Undergoing Hemodialysis To avoid rapid drops in topiramate plasma concentration during hemodialysis, a supplemental dose of topiramate may be required.
3) ].
Table 5 presents the incidence of adverse reactions occurring in at least 3% of adult and pediatric patients treated with 400 mg/day topiramate and occurring with greater incidence than 50 mg/day topiramate.
Table 5:
Adverse Reactions in the High Dose Group As Compared to the Low Dose Group, in Monotherapy Epilepsy Trial (Study 1) in Adult and Pediatric Patients Body System Adverse Reaction Age Group Pediatric (6 to 15 Years) Adult (Age ≥16 Years) Topiramate Daily Dosage Group (mg/day) 50 400 50 400 (N=74) % (N=77) % (N=160) % (N=159) % Body as a Whole - General Disorders Asthenia 0 3 4 6 Fever 1 12 Leg pain 2 3 Central & Peripheral Nervous System Disorders Paresthesia 3 12 21 40 Dizziness 13 14 Ataxia 3 4 Hypoesthesia 4 5 Hypertonia 0 3 Involuntary muscle contractions 0 3 Vertigo 0 3 Gastro-Intestinal System Disorders Constipation 1 4 Diarrhea 8 9 Gastritis 0 3 Dry mouth 1 3 Liver and Biliary System Disorders Increase in Gamma-GT 1 3 Metabolic and Nutritional Disorders Weight loss 7 17 6 17 Platelet, Bleeding & Clotting Disorders Epistaxis 0 4 Psychiatric Disorders Anorexia 4 14 Anxiety 4 6 Cognitive problems 1 6 1 4 Confusion 0 3 Depression 0 3 7 9 Difficulty with concentration or attention 7 10 7 8 Difficulty with memory 1 3 6 11 Insomnia 8 9 Decrease in libido 0 3 Mood problems 1 8 2 5 Personality disorder (behavior problems) 0 3 Psychomotor slowing 3 5 Somnolence 10 15 Red Blood Cell Disorders Anemia 1 3 Reproductive Disorders, Female Intermenstrual bleeding 0 3 Vaginal hemorrhage 0 3 Resistance Mechanism Disorders Infection 3 8 2 3 Viral infection 3 6 6 8 Respiratory System Disorders Bronchitis 1 5 3 4 Upper respiratory tract infection 16 18 Rhinitis 5 6 2 4 Sinusitis 1 4 Skin and Appendages Disorders Alopecia 1 4 3 4 Pruritus 1 4 Rash 3 4 1 4 Acne 2 3 Special Senses Other, Disorders Taste perversion 3 5 Urinary System Disorders Cystitis 1 3 Micturition frequency 0 3 Renal calculus 0 3 Urinary incontinence 1 3 Vascular (Extracardiac) Disorders Flushing 0 5 Adjunctive Therapy Epilepsy Adults 16 Years of Age and Older In pooled controlled clinical trials in adults with partial-onset seizures, primary generalized tonic- clonic seizures, or Lennox-Gastaut syndrome, 183 patients received adjunctive therapy with topiramate at dosages of 200 to 400 mg/day (recommended dosage range) and 291 patients received placebo.
Patients in these trials were receiving 1 to 2 concomitant antiepileptic drugs in addition to topiramate or placebo. The most common adverse reactions in the controlled clinical trial that occurred in adult patients in the 200 to 400 mg/day topiramate group with an incidence higher (≥ 10 %) than in the placebo group were: dizziness, speech disorders/related speech problems, somnolence, nervousness, psychomotor slowing, and vision abnormal (Table 6).
Table 6 presents the incidence of adverse reactions occurring in at least 3% of adult patients treated with 200 to 400 mg/day topiramate and was greater than placebo incidence. , 600 mg to 1000 mg daily) compared to the incidence of these adverse reactions at the recommended dosing (200 mg to 400 mg daily) range.
Table 6:
Most Common Adverse Reactions in Pooled Placebo-Controlled, Adjunctive Epilepsy Trials in Adults a Body System Adverse Reaction Placebo (N=291) Topiramate Dosage (mg/day) 200 to 400 (N=183) Body as a Whole-General Disorders Fatigue 13 15 Asthenia 1 6 Back pain 4 5 Chest pain 3 4 Influenza-like symptoms 2 3 Central & Peripheral Nervous System Disorders Dizziness 15 25 Ataxia 7 16 Speech disorders/Related speech problems 2 13 Paresthesia 4 11 Nystagmus 7 10 Tremor 6 9 Language problems 1 6 Coordination abnormal 2 4 Gait abnormal 1 3 Gastro-Intestinal System Disorders Nausea 8 10 Dyspepsia 6 7 Abdominal pain 4 6 Constipation 2 4 Metabolic and Nutritional Disorders Weight loss 3 9 Psychiatric Disorders Somnolence 12 29 Nervousness 6 16 Psychomotor slowing 2 13 Difficulty with memory 3 12 Confusion 5 11 Anorexia 4 10 Difficulty with concentration/attention 2 6 Mood problems 2 4 Agitation 2 3 Aggressive reaction 2 3 Emotional lability 1 3 Cognitive problems 1 3 Reproductive Disorders Breast pain 2 4 Respiratory System Disorders Rhinitis 6 7 Pharyngitis 2 6 Sinusitis 4 5 Vision Disorders Vision abnormal 2 13 Diplopia 5 10 a Patients in these adjunctive trials were receiving 1 to 2 concomitant antiepileptic drugs in addition to topiramate or placebo.
In controlled clinical trials in adults, 11% of patients receiving topiramate 200 to 400 mg/day as adjunctive therapy discontinued due to adverse reactions. This rate appeared to increase at dosages above 400 mg/day. Adverse reactions associated with discontinuing topiramate included somnolence, dizziness, anxiety, difficulty with concentration or attention, fatigue and paresthesia.
Pediatric Patients 2 to 15 Years of Age In pooled, controlled clinical trials in pediatric patients (2 to 15 years of age) with partial-onset seizures, primary generalized tonic-clonic seizures, or Lennox-Gastaut syndrome, 98 patients received adjunctive therapy with topiramate at dosages of 5 to 9 mg/kg/day (recommended dose range) and 101 patients received placebo.
The most common adverse reactions in the controlled clinical trial that occurred in pediatric patients in the 5 mg to 9 mg/kg/day topiramate group with an incidence higher (≥ 10 %) than in the placebo group were: fatigue and somnolence (Table 7).
Table 7 presents the incidence of adverse reactions that occurred in at least 3% of pediatric patients 2 to 15 years of age receiving 5 mg to 9 mg/kg/day (recommended dose range) of topiramate and was greater than placebo incidence.
Table 7:
Adverse Reactions in Pooled Placebo-Controlled, Adjunctive Epilepsy Trials in Pediatric Patients 2 to 15 Years of Age a,b Body System/ Adverse Reaction Placebo (N=101) % Topiramate (N=98) % Body as a Whole - General Disorders Fatigue 5 16 Injury 13 14 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 Gastro-Intestinal System Disorders Nausea 5 6 Saliva increased 4 6 Constipation 4 5 Gastroenteritis 2 3 Metabolic and Nutritional Disorders Weight loss 1 9 Platelet, Bleeding, & Clotting Disorders Purpura 4 8 Epistaxis 1 4 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 0 5 Confusion 3 4 Psychomotor slowing 2 3 Resistance Mechanism Disorders Infection viral 3 7 Respiratory System Disorders Pneumonia 1 5 Skin and Appendages Disorders Skin disorder 2 3 Urinary System Disorders Urinary incontinence 2 4 a Patients in these adjunctive 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 reaction. Patients may have reported more than one adverse reaction during the study and can be included in more than one adverse reaction category. 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 reactions.
Migraine Adults In the four multicenter, randomized, double-blind, placebo-controlled, parallel group migraine clinical trials for the preventive treatment of migraine (which included 35 pediatric patients 12 to 15 years of age), most adverse reactions occurred more frequently during the titration period than during the maintenance period.
The most common adverse reactions with topiramate 100 mg in the clinical trials for the preventive treatment of migraine of predominantly adults that were seen at an incidence higher (≥ 5 %) than in the placebo group were: paresthesia, anorexia, weight loss, taste perversion, diarrhea, difficulty with memory, hypoesthesia, and nausea (see Table 8).
Table 8 includes those adverse reactions that occurred in the placebo-controlled trials where the incidence in any topiramate treatment group was at least 3% and was greater than that for placebo patients. , fatigue, dizziness, somnolence, difficulty with memory, difficulty with concentration/attention) was dose-related and greater at higher than recommended topiramate dosing (200 mg daily) compared to the incidence of these adverse reactions at the recommended dosing (100 mg daily).
Table 8:
Adverse Reactions in Pooled, Placebo-Controlled, Migraine Trials in Adults a,b Body System / Adverse Reaction Placebo (N=445)% Topiramate Dosage (mg/day) 50 (N=235) % 100 (N=386) % Body as a Whole-General Disorders Fatigue 11 14 15 Injury 7 9 6 Central & Peripheral Nervous System Disorders Paresthesia 6 35 51 Dizziness 10 8 9 Hypoesthesia 2 6 7 Language problems 2 7 6 Gastro-Intestinal System Disorders Nausea 8 9 13 Diarrhea 4 9 11 Abdominal pain 5 6 6 Dyspepsia 3 4 5 Dry mouth 2 2 3 Gastroenteritis 1 3 3 Metabolic and Nutritional Disorders Weight loss 1 6 9 Musculoskeletal System Disorders Arthralgia 2 7 3 Psychiatric Disorders Anorexia 6 9 15 Somnolence 5 8 7 Difficulty with memory 2 7 7 Insomnia 5 6 7 Difficulty with concentration/attention 2 3 6 Mood problems 2 3 6 Anxiety 3 4 5 Depression 4 3 4 Nervousness 2 4 4 Confusion 2 2 3 Psychomotor slowing 1 3 2 Reproductive Disorders, Female Menstrual disorder 2 3 2 Reproductive Disorders, Male Ejaculation premature 0 3 0 Resistance Mechanism Disorders Viral infection 3 4 4 Respiratory System Disorders Upper respiratory tract infection 12 13 14 Sinusitis 6 10 6 Pharyngitis 4 5 6 Coughing 2 2 4 Bronchitis 2 3 3 Dyspnea 2 1 3 Skin and Appendages Disorders Pruritis 2 4 2 Special Sense Other, Disorders Taste perversion 1 15 8 Urinary System Disorders Urinary tract infection 2 4 2 Vision Disorders Blurred vision c 2 4 2 a Includes 35 adolescent patients age 12 to 15 years.
b Values represent the percentage of patients reporting a given adverse reaction. Patients may have reported more than one adverse reaction during the study and can be included in more than one adverse reaction category. c Blurred vision was the most common term considered as vision abnormal.
Blurred vision was an included term that accounted for >50% of reactions coded as vision abnormal, a preferred term. Of the 1,135 patients exposed to topiramate in the adult placebo-controlled studies, 25% of topiramate-treated patients discontinued due to adverse reactions, compared to 10% of the 445 placebo-treated patients.
The adverse reactions associated with discontinuing therapy in the topiramate-treated patients included paresthesia (7%), fatigue (4%), nausea (4%), difficulty with concentration/attention (3%), insomnia (3%), anorexia (2%), and dizziness (2%).
Patients treated with topiramate experienced mean percent reductions in body weight that were dose-dependent. This change was not seen in the placebo group. Mean changes of 0%, -2%, -3%, and -4% were seen for the placebo group, topiramate 50, 100, and 200 mg groups, respectively.
Pediatric Patients 12 to 17 Years of Age In five, randomized, double-blind, placebo-controlled, parallel group clinical trials for the preventive treatment of migraine, most adverse reactions occurred more frequently during the titration period than during the maintenance period.
Among adverse reactions with onset during titration, approximately half persisted into the maintenance period. In four, fixed-dose, double-blind clinical trials for the preventive treatment of migraine in topiramate-treated pediatric patients 12 to 17 years of age, the most common adverse reactions with topiramate 100 mg that were seen at an incidence higher (≥5%) than in the placebo group were: paresthesia, upper respiratory tract infection, anorexia, and abdominal pain (see Table 9).
3)] ) in which 103 pediatric patients were treated with placebo or 50 mg or 100 mg of topiramate, and three predominantly adult trials in which 49 pediatric patients (12 to 17 years of age) were treated with placebo or 50 mg, 100 mg or 200 mg of topiramate.
Table 9 also shows adverse reactions in pediatric patients in the controlled migraine trials when the incidence in a topiramate dose group was at least 5 % or higher and greater than the incidence of placebo. Many adverse reactions shown in Table 9 indicate a dose-dependent relationship.
, allergy, fatigue, headache, anorexia, insomnia, somnolence, and viral infection) was dose-related and greater at higher than recommended topiramate dosing (200 mg daily) compared to the incidence of these adverse reactions at the recommended dosing (100 mg daily).
Table 9:
Adverse Reactions in Pooled Double-Blind Studies for the Preventive Treatment of Migraine in Pediatric Patients 12 to 17 Years of Age a,b,c Body System/ Adverse Reaction Placebo (N=45)% Topiramate Dosage 50 mg/day (N=46) % 100 mg/day (N=48) % Body as a Whole-General Disorders Fatigue 7 7 8 Fever 2 4 6 Central & Peripheral Nervous System Disorders Paresthesia 7 20 19 Dizziness 4 4 6 Gastrointestinal System Disorders Abdominal pain 9 7 15 Nausea 4 4 8 Metabolic and Nutritional Disorders Weight loss 2 7 4 Psychiatric Disorders Anorexia 4 9 10 Somnolence 2 2 6 Insomnia 2 9 2 Resistance Mechanism Disorders Infection viral 4 4 8 Respiratory System Disorders Upper respiratory tract infection 11 26 23 Rhinitis 2 7 6 Sinusitis 2 9 4 Coughing 0 7 2 Special Senses Other, Disorders Taste perversion 2 2 6 Vision Disorders Conjunctivitis 4 7 4 a 35 adolescent patients aged 12 to <16 years were also included in adverse reaction assessment for adults (Tables 11 and 12) b Incidence is based on the number of subjects experiencing at least 1 adverse event, not the number of events.
c Included studies MIG-3006, MIGR-001, MIGR-002 and MIGR-003 In the double-blind placebo-controlled studies, adverse reactions led to discontinuation of treatment in 8% of placebo patients compared with 6% of topiramate-treated patients.
Adverse reactions associated with discontinuing therapy that occurred in more than one topiramate-treated patient were fatigue (1%), headache (1%), and somnolence (1%). Increased Risk for Bleeding Topiramate is associated with an increased risk for bleeding.
3% in pediatric patients). 4% versus 0% for pediatric patients. Adverse bleeding reactions reported with topiramate ranged from mild epistaxis, ecchymosis, and increased menstrual bleeding to life-threatening hemorrhages. , aspirin, nonsteroidal anti-inflammatory drugs, selective serotonin reuptake inhibitors, or warfarin or other anticoagulants).
Other Adverse Reactions Observed During Clinical Trials Other adverse reactions seen during clinical trials were: abnormal coordination, eosinophilia, gingival bleeding, hematuria, hypotension, myalgia, myopia, postural hypotension, scotoma, suicide attempt, syncope, and visual field defect.
12)] . 1 % placebo). 4)] . Topiramate is not indicated for partial-onset seizures in pediatric patients less than 2 years of age. 4)] . Topiramate is not indicated for the preventive treatment of migraine in pediatric patients less than 12 years of age.
2 Postmarketing Experience The following adverse reactions have been identified during post approval use of topiramate. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
1) ], maculopathy Hematological Disorders: decrease of the International Normalized Ratio (INR) or prothrombin time when given concomitantly with vitamin K antagonist anticoagulant medications such as warfarin.
Decreased sweating and an elevation in body temperature above normal characterized these cases. Some of the cases were reported after exposure to elevated environmental temperatures. The majority of the reports have been in pediatric patients.
Patients (especially pediatric patients) treated with topiramate should be monitored closely for evidence of decreased sweating and increased body temperature, especially in hot weather. Caution should be used when topiramate is given with other drugs that predispose patients to heat-related disorders; these drugs include, but are not limited to, other carbonic anhydrase inhibitors and drugs with anticholinergic activity.
, decreased serum bicarbonate below the normal reference range in the absence of chronic respiratory alkalosis). This metabolic acidosis is caused by renal bicarbonate loss due to carbonic anhydrase inhibition by topiramate. Topiramate-induced metabolic acidosis can occur at any time during treatment.
Bicarbonate decrements are usually mild-moderate (average decrease of 4 mEq/L at daily doses of 400 mg in adults and at approximately 6 mg/kg/day in pediatric patients); rarely, patients can experience severe decrements to values below 10 mEq/L.
Conditions or therapies that predispose patients to acidosis (such as renal disease, severe respiratory disorders, status epilepticus, diarrhea, ketogenic diet, or specific drugs) may be additive to the bicarbonate lowering effects of topiramate.
Metabolic acidosis was commonly observed in adult and pediatric patients treated with topiramate in clinical trials. The incidence of decreased serum bicarbonate in pediatric trials, for adjunctive treatment of Lennox-Gastaut syndrome or refractory partial-onset seizures was as high as 67% for topiramate (at approximately 6 mg/kg/day), and 10% for placebo.
, absolute value < 17 mEq/L and >5 mEq/L decrease from pretreatment) in these trials was up to 11%, compared to < 2% for placebo. Manifestations of acute or chronic metabolic acidosis may include hyperventilation, nonspecific symptoms such as fatigue and anorexia, or more severe sequelae including cardiac arrhythmias or stupor.
13)] . 4)] . Chronic metabolic acidosis in pediatric patients may also reduce growth rates, which may decrease the maximal height achieved. Long-term, open-label treatment of pediatric patients 1 to 24 months old with intractable partial epilepsy, for up to 1 year, showed reductions from baseline in length, weight, and head circumference compared to age and sex-matched normative data, although these patients with epilepsy are likely to have different growth rates than normal 1 to 24 month old pediatrics.
4)] . 1)] . Measurement of Serum Bicarbonate in Epilepsy and Migraine Patients Measurement of baseline and periodic serum bicarbonate during topiramate treatment is recommended. If metabolic acidosis develops and persists, consideration should be given to reducing the dose or discontinuing topiramate (using dose tapering).
If the decision is made to continue patients on topiramate in the face of persistent acidosis, alkali treatment should be considered. 5 Suicidal Behavior and Ideation Antiepileptic drugs (AEDs), including topiramate, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication.
Patients treated with any AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior. 7) of suicidal thinking or behavior compared to patients randomized to placebo.
24% among 16,029 placebo-treated patients, representing an increase of approximately one case of suicidal thinking or behavior for every 530 patients treated. There were four suicides in drug-treated patients in the trials and none in placebo-treated patients, but the number is too small to allow any conclusion about drug effect on suicide.
The increased risk of suicidal thoughts or behavior with AEDs was observed as early as one week after starting drug treatment with AEDs and persisted for the duration of treatment assessed. Because most trials included in the analysis did not extend beyond 24 weeks, the risk of suicidal thoughts or behavior beyond 24 weeks could not be assessed.
The risk of suicidal thoughts or behavior was generally consistent among drugs in the data analyzed. The finding of increased risk with AEDs of varying mechanisms of action and across a range of indications suggests that the risk applies to all AEDs used for any indication.
The risk did not vary substantially by age (5 to 100 years) in the clinical trials analyzed. Table 4 shows absolute and relative risk by indication for all evaluated AEDs. 9 The relative risk for suicidal thoughts or behavior was higher in clinical trials for epilepsy than in clinical trials for psychiatric or other conditions, but the absolute risk differences were similar for the epilepsy and psychiatric indications.
Anyone considering prescribing topiramate or any other AED must balance the risk of suicidal thoughts or behavior with the risk of untreated illness. Epilepsy and many other illnesses for which AEDs are prescribed are themselves associated with morbidity and mortality and an increased risk of suicidal thoughts and behavior.
Should suicidal thoughts and behavior emerge during treatment, the prescriber needs to consider whether the emergence of these symptoms in any given patient may be related to the illness being treated. 6 Cognitive/Neuropsychiatric Adverse Reactions Topiramate can cause cognitive/neuropsychiatric adverse reactions.
, depression or mood problems); and 3) Somnolence or fatigue. Adult Patients Cognitive-Related Dysfunction Rapid titration rate and higher initial dose were associated with higher incidences of cognitive- related dysfunction. In adult epilepsy adjunctive controlled trials, which used rapid titration (100 to 200 mg/day weekly increments), and target topiramate doses of 200 mg to 1000 mg/day, 56% of patients in the 800 mg/day and 1000 mg/day dose groups experienced cognitive-related dysfunction compared to approximately 42% of patients in the 200 to 400 mg/day groups and 14% for placebo.
In this rapid titration regimen, these dose-related adverse reactions began in the titration or in the maintenance phase, and in some patients these events began during titration and persisted into the maintenance phase. In the monotherapy epilepsy controlled trial, the proportion of patients who experienced one or more cognitive-related adverse reactions was 19% for topiramate 50 mg/day and 26% for 400 mg/day.
In the 6-month controlled trials for the preventive treatment of migraine, which used a slower titration regimen (25 mg/day weekly increments), the proportion of patients who experienced one or more cognitive-related adverse reactions was 19% for topiramate 50 mg/day, 22% for 100 mg/day (the recommended dose), 28% for 200 mg/day, and 10% for placebo.
Cognitive adverse reactions most commonly developed during titration and sometimes persisted after completion of titration. 5) ]. Somnolence/Fatigue Somnolence and fatigue were the adverse reactions most frequently reported during clinical trials of topiramate for adjunctive epilepsy.
For the adjunctive epilepsy population, the incidence of fatigue, appeared dose related. For the monotherapy epilepsy population, the incidence of somnolence was dose-related. For the migraine population, the incidences of both fatigue and somnolence were dose-related and more common in the titration phase.
Pediatric Patients In pediatric epilepsy trials (adjunctive and monotherapy), the incidence of cognitive/neuropsychiatric adverse reactions was generally lower than that observed in adults. These reactions included psychomotor slowing, difficulty with concentration/attention, speech disorders/related speech problems, and language problems.
The most frequently reported cognitive/neuropsychiatric reactions in pediatric epilepsy patients during adjunctive therapy double-blind studies were somnolence and fatigue. The most frequently reported cognitive/neuropsychiatric reactions in pediatric epilepsy patients in the 50 mg/day and 400 mg/day groups during the monotherapy double-blind study were headache, dizziness, anorexia, and somnolence.
In pediatric migraine patients, the incidence of cognitive/neuropsychiatric adverse reactions was increased in topiramate-treated patients compared to placebo. The risk for cognitive/neuropsychiatric adverse reactions was dose-dependent, and was greatest at the highest dose (200 mg).
This risk for cognitive/neuropsychiatric adverse reactions was also greater in younger patients (6 to 11 years of age) than in older patients (12 to 17 years of age). The most common cognitive/neuropsychiatric adverse reaction in these trials was difficulty with concentration/attention.
Cognitive adverse reactions most commonly developed during titration and sometimes persisted for various durations after completion of titration. 3) ]. Mean change from baseline in certain CANTAB tests suggests that topiramate treatment may result in psychomotor slowing and decreased verbal fluency.
7 Fetal Toxicity Topiramate can cause fetal harm when administered to a pregnant woman. Data from pregnancy registries indicate that infants exposed to topiramate in utero have an increased risk of major congenital malformations, including but not limited to cleft lip and/or cleft palate (oral clefts), and of being small for gestational age (SGA).
1) ]. 1), Patient Counseling Information (17) ]. Topiramate should be used during pregnancy only if the potential benefit outweighs the potential risk. 1) ]. 8 Withdrawal of Antiepileptic Drugs In patients with or without a history of seizures or epilepsy, antiepileptic drugs, including topiramate, should be gradually withdrawn to minimize the potential for seizures or increased seizure frequency [see Clinical Studies (14) ].
In situations where rapid withdrawal of topiramate is medically required, appropriate monitoring is recommended. 4)] . 5 or greater) compared to 0 patients in the control group. Although decreases in BMD occurred across all pediatric age subgroups, patients 6 to 9 years of age were most commonly affected.
The sample size and study duration were too small to determine if fracture risk is increased. 4)] . , serum alkaline phosphatase, calcium, phosphorus, and 1,25-dihydroxyvitamin D) occurred in topiramate-treated patients, more significant decreases in serum parathyroid hormone and 25-hydroxyvitamin D, hormones involved in bone metabolism, were observed, along with an increased excretion of urinary calcium.
4)] . Although continued growth was observed in both treatment groups, the topiramate group showed statistically significant reductions in mean annual change from baseline in body weight compared to the control group. A similar trend of attenuation in height velocity and height change from baseline was also observed in the topiramate group compared to the control group.
Negative effects on weight and height were seen across all topiramate age subgroups. Growth (height and weight) of children receiving prolonged topiramate therapy should be carefully monitored. 11 Serious Skin Reactions Serious skin reactions (Stevens-Johnson Syndrome [SJS] and Toxic Epidermal Necrolysis [TEN]) have been reported in patients receiving topiramate.
Topiramate should be discontinued at the first sign of a rash, unless the rash is clearly not drug-related. If signs or symptoms suggest SJS/TEN, use of this drug should not be resumed and alternative therapy should be considered. Inform patients about the signs of serious skin reactions.
2) ]. The risk for hyperammonemia with topiramate appears dose-related. Hyperammonemia has been reported more frequently when topiramate is used concomitantly with valproic acid. 1)]. Clinical symptoms of hyperammonemic encephalopathy often include acute alterations in level of consciousness and/or cognitive function with lethargy and/or vomiting.
In most cases, hyperammonemic encephalopathy abated with discontinuation of treatment. The incidence of hyperammonemia in pediatric patients 12 to 17 years of age in the preventive treatment of migraine trials was 26% in patients taking topiramate monotherapy at 100 mg/day, and 14% in patients taking topiramate at 50 mg/day, compared to 9% in patients taking placebo.
There was also an increased incidence of markedly increased hyperammonemia at the 100 mg dose. Dose-related hyperammonemia was also seen in pediatric patients 1 to 24 months of age treated with topiramate and concomitant valproic acid for partial-onset epilepsy and this was not due to a pharmacokinetic interaction.
In some patients, hyperammonemia can be asymptomatic. Monitoring for Hyperammonemia Patients with inborn errors of metabolism or reduced hepatic mitochondrial activity may be at an increased risk for hyperammonemia with or without encephalopathy.
Although not studied, topiramate treatment or an interaction of concomitant topiramate and valproic acid treatment may exacerbate existing defects or unmask deficiencies in susceptible persons. In patients who develop unexplained lethargy, vomiting or changes in mental status associated with any topiramate treatment, hyperammonemic encephalopathy should be considered and an ammonia level should be measured.
13 Kidney Stones Topiramate increases the risk of kidney stones. 5%, an incidence about 2 to 4 times greater than expected in a similar, untreated population. As in the general population, the incidence of stone formation among topiramate-treated patients was higher in men.
Kidney stones have also been reported in pediatric patients taking topiramate for epilepsy or migraine. During long-term (up to 1 year) topiramate treatment in an open-label extension study of 284 pediatric patients 1 to 24 months old with epilepsy, 7% developed kidney or bladder stones.
4) ]. Topiramate is a carbonic anhydrase inhibitor. 4) ]. The concomitant use of topiramate with any other drug producing metabolic acidosis, or potentially in patients on a ketogenic diet, may create a physiological environment that increases the risk of kidney stone formation, and should therefore be avoided.
Increased fluid intake increases the urinary output, lowering the concentration of substances involved in stone formation. Hydration is recommended to reduce new stone formation. 4)]. This increased ratio of urinary calcium/citrate increases the risk of kidney stones and/or nephrocalcinosis.
14 Hypothermia with Concomitant Valproic Acid Use Hypothermia, defined as a drop in body core temperature to <35°C (95°F), has been reported in association with topiramate use with concomitant valproic acid both in conjunction with hyperammonemia and in the absence of hyperammonemia.
1) ]. Consideration should be given to stopping topiramate or valproate in patients who develop hypothermia, which may be manifested by a variety of clinical abnormalities including lethargy, confusion, coma, and significant alterations in other major organ systems such as the cardiovascular and respiratory systems.
Clinical management and assessment should include examination of blood ammonia levels.