Depakote

1 INDICATIONS AND USAGE Depakote is an anti-epileptic drug indicated for: Treatment of manic episodes associated with bipolar disorder ( 1.1 ) Monotherapy and adjunctive therapy of complex partial seizures and simple and complex absence seizures; adjunctive therapy in patients with multiple seizure types that include absence seizures ( 1.2 ) Prophylaxis of migraine headaches ( 1.3 ) 1.1 Mania Depakote (divalproex sodium) is a valproate and is indicated for the treatment of the manic episodes associated with bipolar disorder. A manic episode is a distinct period of abnormally and persistently elevated, expansive, or irritable mood. Typical symptoms of mania include pressure of speech, motor hyperactivity, reduced need for sleep, flight of ideas, grandiosity, poor judgment, aggressiveness, and possible hostility. The efficacy of Depakote was established in 3-week trials with patients meeting DSM-III-R criteria for bipolar disorder who were hospitalized for acute mania [see Clinical Studies ( 14.1 ) ] . The safety and effectiveness of Depakote for long-term use in mania, i.e., more than 3 weeks, has not been demonstrated in controlled clinical trials. Therefore, healthcare providers who elect to use Depakote for extended periods should continually reevaluate the long-term usefulness of the drug for the individual patient. 1.2 Epilepsy Depakote is indicated as monotherapy and adjunctive therapy in the treatment of patients with complex partial seizures that occur either in isolation or in association with other types of seizures. Depakote is also indicated for use as sole and adjunctive therapy in the treatment of simple and complex absence seizures, and adjunctively in patients with multiple seizure types that include absence seizures. Simple absence is defined as very brief clouding of the sensorium or loss of consciousness accompanied by certain generalized epileptic discharges without other detectable clinical signs. Complex absence is the term used when other signs are also present. 1.3 Migraine Depakote is indicated for prophylaxis of migraine headaches. There is no evidence that Depakote is useful in the acute treatment of migraine headaches. 1.4 Important Limitations Because of the risk to the fetus of decreased IQ, neurodevelopmental disorders, neural tube defects, and other major congenital malformations, which may occur very early in pregnancy, valproate should not be used to treat women with epilepsy or bipolar disorder who are pregnant or who plan to become pregnant unless other medications have failed to provide adequate symptom control or are otherwise unacceptable. Valproate should not be administered to a woman of childbearing potential unless other medications have failed to provide adequate symptom control or are otherwise unacceptable [see Warnings and Precautions ( 5.2 , 5.3 , 5.4 ) , Use in Specific Populations ( 8.1 ) , and Patient Counseling Information ( 17 ) ] . For prophylaxis of migraine headaches, Depakote is contraindicated in women who are pregnant and in women of childbearing potential who are not using effective contraception [see Contraindications ( 4 ) ] .

2 DOSAGE AND ADMINISTRATION Depakote tablets are intended for oral administration. Depakote tablets should be swallowed whole and should not be crushed or chewed. Patients should be informed to take Depakote every day as prescribed. If a dose is missed it should be taken as soon as possible, unless it is almost time for the next dose. If a dose is skipped, the patient should not double the next dose. Depakote is administered orally in divided doses. Depakote should be swallowed whole and should not be crushed or chewed ( 2.1 , 2.2 ). Mania: Initial dose is 750 mg daily, increasing as rapidly as possible to achieve therapeutic response or desired plasma level ( 2.1 ). The maximum recommended dosage is 60 mg/kg/day ( 2.1 , 2.2 ). Complex Partial Seizures: Start at 10 to 15 mg/kg/day, increasing at 1 week intervals by 5 to 10 mg/kg/day to achieve optimal clinical response; if response is not satisfactory, check valproate plasma level; see full prescribing information for conversion to monotherapy ( 2.2 ). The maximum recommended dosage is 60 mg/kg/day ( 2.1 , 2.2 ). Absence Seizures: Start at 15 mg/kg/day, increasing at 1 week intervals by 5 to 10 mg/kg/day until seizure control or limiting side effects ( 2.2 ). The maximum recommended dosage is 60 mg/kg/day ( 2.1 , 2.2 ). Migraine: The recommended starting dose is 250 mg twice daily, thereafter increasing to a maximum of 1,000 mg/day as needed ( 2.3 ). 2.1 Mania Depakote tablets are administered orally. The recommended initial dose is 750 mg daily in divided doses. The dose should be increased as rapidly as possible to achieve the lowest therapeutic dose which produces the desired clinical effect or the desired range of plasma concentrations. In placebo-controlled clinical trials of acute mania, patients were dosed to a clinical response with a trough plasma concentration between 50 and 125 mcg/mL. Maximum concentrations were generally achieved within 14 days. The maximum recommended dosage is 60 mg/kg/day. There is no body of evidence available from controlled trials to guide a clinician in the longer term management of a patient who improves during Depakote treatment of an acute manic episode. While it is generally agreed that pharmacological treatment beyond an acute response in mania is desirable, both for maintenance of the initial response and for prevention of new manic episodes, there are no data to support the benefits of Depakote in such longer-term treatment. Although there are no efficacy data that specifically address longer-term antimanic treatment with Depakote, the safety of Depakote in long-term use is supported by data from record reviews involving approximately 360 patients treated with Depakote for greater than 3 months. 2.2 Epilepsy Depakote tablets are administered orally. Depakote is indicated as monotherapy and adjunctive therapy in complex partial seizures in adults and pediatric patients down to the age of 10 years, and in simple and complex absence seizures. As the Depakote dosage is titrated upward, concentrations of clonazepam, diazepam, ethosuximide, lamotrigine, tolbutamide, phenobarbital, carbamazepine, and/or phenytoin may be affected [see Drug Interactions ( 7.2 ) ] . Complex Partial Seizures For adults and children 10 years of age or older. Monotherapy (Initial Therapy) Depakote has not been systematically studied as initial therapy. Patients should initiate therapy at 10 to 15 mg/kg/day. The dosage should be increased by 5 to 10 mg/kg/week to achieve optimal clinical response. Ordinarily, optimal clinical response is achieved at daily doses below 60 mg/kg/day. If satisfactory clinical response has not been achieved, plasma levels should be measured to determine whether or not they are in the usually accepted therapeutic range (50 to 100 mcg/mL). No recommendation regarding the safety of valproate for use at doses above 60 mg/kg/day can be made. The probability of thrombocytopenia increases significantly at total trough valproate plasma concentrations above 110 mcg/mL in females and 135 mcg/mL in males. The benefit of improved seizure control with higher doses should be weighed against the possibility of a greater incidence of adverse reactions. Conversion to Monotherapy Patients should initiate therapy at 10 to 15 mg/kg/day. The dosage should be increased by 5 to 10 mg/kg/week to achieve optimal clinical response. Ordinarily, optimal clinical response is achieved at daily doses below 60 mg/kg/day. If satisfactory clinical response has not been achieved, plasma levels should be measured to determine whether or not they are in the usually accepted therapeutic range (50-100 mcg/mL). No recommendation regarding the safety of valproate for use at doses above 60 mg/kg/day can be made. Concomitant antiepilepsy drug (AED) dosage can ordinarily be reduced by approximately 25% every 2 weeks. This reduction may be started at initiation of Depakote therapy, or delayed by 1 to 2 weeks if there is a concern that seizures are likely to occur with a reduction. The speed and duration of withdrawal of the concomitant AED can be highly variable, and patients should be monitored closely during this period for increased seizure frequency. Adjunctive Therapy Depakote may be added to the patient's regimen at a dosage of 10 to 15 mg/kg/day. The dosage may be increased by 5 to 10 mg/kg/week to achieve optimal clinical response. Ordinarily, optimal clinical response is achieved at daily doses below 60 mg/kg/day. If satisfactory clinical response has not been achieved, plasma levels should be measured to determine whether or not they are in the usually accepted therapeutic range (50 to 100 mcg/mL). No recommendation regarding the safety of valproate for use at doses above 60 mg/kg/day can be made. If the total daily dose exceeds 250 mg, it should be given in divided doses. In a study of adjunctive therapy for complex partial seizures in which patients were receiving either carbamazepine or phenytoin in addition to valproate, no adjustment of carbamazepine or phenytoin dosage was needed [see Clinical Studies ( 14.2 ) ] . However, since valproate may interact with these or other concurrently administered AEDs as well as other drugs, periodic plasma concentration determinations of concomitant AEDs are recommended during the early course of therapy [see Drug Interactions ( 7 ) ] . Simple and Complex Absence Seizures The recommended initial dose is 15 mg/kg/day, increasing at one week intervals by 5 to 10 mg/kg/day until seizures are controlled or side effects preclude further increases. The maximum recommended dosage is 60 mg/kg/day. If the total daily dose exceeds 250 mg, it should be given in divided doses. A good correlation has not been established between daily dose, serum concentrations, and therapeutic effect. However, therapeutic valproate serum concentrations for most patients with absence seizures is considered to range from 50 to 100 mcg/mL. Some patients may be controlled with lower or higher serum concentrations [see Clinical Pharmacology ( 12.3 ) ] . As the Depakote dosage is titrated upward, blood concentrations of phenobarbital and/or phenytoin may be affected [see Drug Interactions ( 7.2 ) ] . Antiepilepsy drugs should not be abruptly discontinued in patients in whom the drug is administered to prevent major seizures because of the strong possibility of precipitating status epilepticus with attendant hypoxia and threat to life. In epileptic patients previously receiving valproic acid therapy, Depakote tablets should be initiated at the same daily dose and dosing schedule. After the patient is stabilized on Depakote tablets, a dosing schedule of two or three times a day may be elected in selected patients. 2.3 Migraine Depakote is indicated for prophylaxis of migraine headaches in adults. Depakote tablets are administered orally. The recommended starting dose is 250 mg twice daily. Some patients may benefit from doses up to 1,000 mg/day. In the clinical trials, there was no evidence that higher doses led to greater efficacy. 2.4 General Dosing Advice Dosing in Elderly Patients Due to a decrease in unbound clearance of valproate and possibly a greater sensitivity to somnolence in the elderly, the starting dose should be reduced in these patients. Dosage should be increased more slowly and with regular monitoring for fluid and nutritional intake, dehydration, somnolence, and other adverse reactions. Dose reductions or discontinuation of valproate should be considered in patients with decreased food or fluid intake and in patients with excessive somnolence. The ultimate therapeutic dose should be achieved on the basis of both tolerability and clinical response [see Warnings and Precautions ( 5.16 ) , Use in Specific Populations ( 8.5 ) , and Clinical Pharmacology ( 12.3 ) ] . Dose-Related Adverse Reactions The frequency of adverse effects (particularly elevated liver enzymes and thrombocytopenia) may be dose-related. The probability of thrombocytopenia appears to increase significantly at total valproate concentrations of ≥ 110 mcg/mL (females) or ≥ 135 mcg/mL (males) [see Warnings and Precautions ( 5.8 ) ] . The benefit of improved therapeutic effect with higher doses should be weighed against the possibility of a greater incidence of adverse reactions. G.I. Irritation Patients who experience G.I. irritation may benefit from administration of the drug with food or by slowly building up the dose from an initial low level. 2.5 Dosing in Patients Taking Rufinamide Patients stabilized on rufinamide before being prescribed valproate should begin valproate therapy at a low dose, and titrate to a clinically effective dose [see Drug Interactions ( 7.2 )] .

6 ADVERSE REACTIONS The following serious adverse reactions are described below and elsewhere in the labeling: Hepatic Failure [see Warnings and Precautions ( 5.1 ) ] Birth Defects [see Warnings and Precautions ( 5.2 ) ] Decreased IQ and Neurodevelopmental Disorders Following in utero Exposure [see Warnings and Precautions ( 5.3 ) ] Pancreatitis [see Warnings and Precautions ( 5.5 ) ] Hyperammonemic Encephalopathy [see Warnings and Precautions ( 5.6 , 5.9 , 5.10 ) ] Suicidal Behavior and Ideation [see Warnings and Precautions ( 5.7 ) ] Bleeding and Other Hematopoietic Disorders [see Warnings and Precautions ( 5.8 ) ] Hypothermia [see Warnings and Precautions ( 5.11 ) ] Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity Reactions [see Warnings and Precautions ( 5.12 ) ] Serious Dermatologic Reactions [see Warnings and Precautions ( 5.13 ) ] Angioedema [see Warnings and Precautions ( 5.14 ) ] Somnolence in the Elderly [see Warnings and Precautions ( 5.16 ) ] Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice. Most common adverse reactions (reported ≥15% for any indication) are abdominal pain, alopecia, asthenia, diarrhea, diplopia, dizziness, headache, infection, insomnia, nausea, somnolence, thrombocytopenia, tremor, vomiting ( 6.1 , 6.2 , 6.3 ). The safety and tolerability of valproate in pediatric patients were shown to be comparable to those in adults ( 8.4 ). To report SUSPECTED ADVERSE REACTIONS, contact AbbVie Inc. at 1-800-633-9110 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Mania The incidence of treatment-emergent events has been ascertained based on combined data from two three week placebo-controlled clinical trials of Depakote in the treatment of manic episodes associated with bipolar disorder. The adverse reactions were usually mild or moderate in intensity, but sometimes were serious enough to interrupt treatment. In clinical trials, the rates of premature termination due to intolerance were not statistically different between placebo, Depakote, and lithium carbonate. A total of 4%, 8% and 11% of patients discontinued therapy due to intolerance in the placebo, Depakote, and lithium carbonate groups, respectively. Table 2 summarizes those adverse reactions reported for patients in these trials where the incidence rate in the Depakote-treated group was greater than 5% and greater than the placebo incidence, or where the incidence in the Depakote-treated group was statistically significantly greater than the placebo group. Vomiting was the only reaction that was reported by significantly (p ≤ 0.05) more patients receiving Depakote compared to placebo. Table 2. Adverse Reactions Reported by > 5% of Depakote-Treated Patients During Placebo-Controlled Trials of Acute Mania 1 Adverse Reaction Depakote (n = 89) % Placebo (n = 97) % Nausea 22 15 Somnolence 19 12 Dizziness 12 4 Vomiting 12 3 Accidental Injury 11 5 Asthenia 10 7 Abdominal Pain 9 8 Dyspepsia 9 8 Rash 6 3 1 The following adverse reactions occurred at an equal or greater incidence for placebo than for Depakote: back pain, headache, constipation, diarrhea, tremor, and pharyngitis. The following additional adverse reactions were reported by greater than 1% but not more than 5% of the 89 Depakote-treated patients in controlled clinical trials: Body as a Whole: Chest pain, chills, chills and fever, fever, neck pain, neck rigidity. Cardiovascular System: Hypertension, hypotension, palpitations, postural hypotension, tachycardia, vasodilation. Digestive System: Anorexia, fecal incontinence, flatulence, gastroenteritis, glossitis, periodontal abscess. Hemic and Lymphatic System: Ecchymosis. Metabolic and Nutritional Disorders: Edema, peripheral edema. Musculoskeletal System: Arthralgia, arthrosis, leg cramps, twitching. Nervous System: Abnormal dreams, abnormal gait, agitation, ataxia, catatonic reaction, confusion, depression, diplopia, dysarthria, hallucinations, hypertonia, hypokinesia, insomnia, paresthesia, reflexes increased, tardive dyskinesia, thinking abnormalities, vertigo. Respiratory System: Dyspnea, rhinitis. Skin and Appendages: Alopecia, discoid lupus erythematosus, dry skin, furunculosis, maculopapular rash, seborrhea. Special Senses: Amblyopia, conjunctivitis, deafness, dry eyes, ear pain, eye pain, tinnitus. Urogenital System: Dysmenorrhea, dysuria, urinary incontinence. 6.2 Epilepsy Based on a placebo-controlled trial of adjunctive therapy for treatment of complex partial seizures, Depakote was generally well tolerated with most adverse reactions rated as mild to moderate in severity. Intolerance was the primary reason for discontinuation in the Depakote-treated patients (6%), compared to 1% of placebo-treated patients. Table 3 lists treatment-emergent adverse reactions which were reported by ≥ 5% of Depakote-treated patients and for which the incidence was greater than in the placebo group, in the placebo-controlled trial of adjunctive therapy for treatment of complex partial seizures. Since patients were also treated with other antiepilepsy drugs, it is not possible, in most cases, to determine whether the following adverse reactions can be ascribed to Depakote alone, or the combination of Depakote and other antiepilepsy drugs. Table 3. Adverse Reactions Reported by ≥ 5% of Patients Treated with Depakote During Placebo-Controlled Trial of Adjunctive Therapy for Complex Partial Seizures Body System/Reaction Depakote (n = 77) % Placebo (n = 70) % Body as a Whole Headache 31 21 Asthenia 27 7 Fever 6 4 Gastrointestinal System Nausea 48 14 Vomiting 27 7 Abdominal Pain 23 6 Diarrhea 13 6 Anorexia 12 0 Dyspepsia 8 4 Constipation 5 1 Nervous System Somnolence 27 11 Tremor 25 6 Dizziness 25 13 Diplopia 16 9 Amblyopia/Blurred Vision 12 9 Ataxia 8 1 Nystagmus 8 1 Emotional Lability 6 4 Thinking Abnormal 6 0 Amnesia 5 1 Respiratory System Flu Syndrome 12 9 Infection 12 6 Bronchitis 5 1 Rhinitis 5 4 Other Alopecia 6 1 Weight Loss 6 0 Table 4 lists treatment-emergent adverse reactions which were reported by ≥ 5% of patients in the high dose valproate group, and for which the incidence was greater than in the low dose group, in a controlled trial of Depakote monotherapy treatment of complex partial seizures. Since patients were being titrated off another antiepilepsy drug during the first portion of the trial, it is not possible, in many cases, to determine whether the following adverse reactions can be ascribed to Depakote alone, or the combination of valproate and other antiepilepsy drugs. Table 4. Adverse Reactions Reported by ≥ 5% of Patients in the High Dose Group in the Controlled Trial of Valproate Monotherapy for Complex Partial Seizures 1 Body System/Reaction High Dose (n = 131) % Low Dose (n = 134) % Body as a Whole Asthenia 21 10 Digestive System Nausea 34 26 Diarrhea 23 19 Vomiting 23 15 Abdominal Pain 12 9 Anorexia 11 4 Dyspepsia 11 10 Hemic/Lymphatic System Thrombocytopenia 24 1 Ecchymosis 5 4 Metabolic/Nutritional Weight Gain 9 4 Peripheral Edema 8 3 Nervous System Tremor 57 19 Somnolence 30 18 Dizziness 18 13 Insomnia 15 9 Nervousness 11 7 Amnesia 7 4 Nystagmus 7 1 Depression 5 4 Respiratory System Infection 20 13 Pharyngitis 8 2 Dyspnea 5 1 Skin and Appendages Alopecia 24 13 Special Senses Amblyopia/Blurred Vision 8 4 Tinnitus 7 1 1 Headache was the only adverse reaction that occurred in ≥ 5% of patients in the high dose group and at an equal or greater incidence in the low dose group. The following additional adverse reactions were reported by greater than 1% but less than 5% of the 358 patients treated with valproate in the controlled trials of complex partial seizures: Body as a Whole: Back pain, chest pain, malaise. Cardiovascular System: Tachycardia, hypertension, palpitation. Digestive System: Increased appetite, flatulence, hematemesis, eructation, pancreatitis, periodontal abscess. Hemic and Lymphatic System: Petechia. Metabolic and Nutritional Disorders: SGOT increased, SGPT increased. Musculoskeletal System: Myalgia, twitching, arthralgia, leg cramps, myasthenia. Nervous System: Anxiety, confusion, abnormal gait, paresthesia, hypertonia, incoordination, abnormal dreams, personality disorder. Respiratory System: Sinusitis, cough increased, pneumonia, epistaxis. Skin and Appendages: Rash, pruritus, dry skin. Special Senses: Taste perversion, abnormal vision, deafness, otitis media. Urogenital System: Urinary incontinence, vaginitis, dysmenorrhea, amenorrhea, urinary frequency. 6.3 Migraine Based on two placebo-controlled clinical trials and their long term extension, valproate was generally well tolerated with most adverse reactions rated as mild to moderate in severity. Of the 202 patients exposed to valproate in the placebo-controlled trials, 17% discontinued for intolerance. This is compared to a rate of 5% for the 81 placebo patients. Including the long term extension study, the adverse reactions reported as the primary reason for discontinuation by ≥ 1% of 248 valproate-treated patients were alopecia (6%), nausea and/or vomiting (5%), weight gain (2%), tremor (2%), somnolence (1%), elevated SGOT and/or SGPT (1%), and depression (1%). Table 5 includes those adverse reactions reported for patients in the placebo-controlled trials where the incidence rate in the Depakote-treated group was greater than 5% and was greater than that for placebo patients. Table 5. Adverse Reactions Reported by > 5% of Depakote-Treated Patients During Migraine Placebo-Controlled Trials with a Greater Incidence Than Patients Taking Placebo 1 Body System Reaction Depakote (N = 202) % Placebo (N = 81) % Gastrointestinal System Nausea 31 10 Dyspepsia 13 9 Diarrhea 12 7 Vomiting 11 1 Abdominal Pain 9 4 Increased Appetite 6 4 Nervous System Asthenia 20 9 Somnolence 17 5 Dizziness 12 6 Tremor 9 0 Other Weight Gain 8 2 Back Pain 8 6 Alopecia 7 1 1 The following adverse reactions occurred in at least 5% of Depakote-treated patients and at an equal or greater incidence for placebo than for Depakote: flu syndrome and pharyngitis. The following additional adverse reactions were reported by greater than 1% but not more than 5% of the 202 Depakote-treated patients in the controlled clinical trials: Body as a Whole: Chest pain, chills, face edema, fever and malaise. Cardiovascular System: Vasodilatation. Digestive System: Anorexia, constipation, dry mouth, flatulence, gastrointestinal disorder (unspecified), and stomatitis. Hemic and Lymphatic System: Ecchymosis. Metabolic and Nutritional Disorders: Peripheral edema, SGOT increase, and SGPT increase. Musculoskeletal System: Leg cramps and myalgia. Nervous System : Abnormal dreams, amnesia, confusion, depression, emotional lability, insomnia, nervousness, paresthesia, speech disorder, thinking abnormalities, and vertigo. Respiratory System: Cough increased, dyspnea, rhinitis, and sinusitis. Skin and Appendages: Pruritus and rash. Special Senses: Conjunctivitis, ear disorder, taste perversion, and tinnitus. Urogenital System: Cystitis, metrorrhagia, and vaginal hemorrhage. 6.4 Post m arketing Experience The following adverse reactions have been identified during post approval use of Depakote. 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. Dermatologic: Hair texture changes, hair color changes, photosensitivity, erythema multiforme, toxic epidermal necrolysis, nail and nail bed disorders, Stevens-Johnson syndrome, hyperpigmentation, and acute generalized exanthematous pustulosis [see Warnings and Precautions ( 5.13 ) ]. Psychiatric: Emotional upset, psychosis, aggression, psychomotor hyperactivity, hostility, disturbance in attention, learning disorder, and behavioral deterioration. Neurologic: Paradoxical convulsion, parkinsonism There have been several reports of acute or subacute cognitive decline and behavioral changes (apathy or irritability) with cerebral pseudoatrophy on imaging associated with valproate therapy; both the cognitive/behavioral changes and cerebral pseudoatrophy reversed partially or fully after valproate discontinuation. There have been reports of acute or subacute encephalopathy in the absence of elevated ammonia levels, elevated valproate levels, or neuroimaging changes. The encephalopathy reversed partially or fully after valproate discontinuation. Musculoskeletal: Fractures, decreased bone mineral density, osteopenia, osteoporosis, and weakness. Hematologic: Relative lymphocytosis, macrocytosis, leukopenia, acquired Pelger-Huet anomaly, anemia including macrocytic with or without folate deficiency, bone marrow suppression, pancytopenia, aplastic anemia, agranulocytosis, and acute intermittent porphyria. Endocrine: Irregular menses, secondary amenorrhea, hyperandrogenism, hirsutism, elevated testosterone level, breast enlargement, galactorrhea, parotid gland swelling, polycystic ovary disease, decreased carnitine concentrations, hyponatremia, hyperglycinemia, and inappropriate ADH secretion. There have been rare reports of Fanconi's syndrome occurring chiefly in children. Metabolism and nutrition: Weight gain. Reproductive: Aspermia, azoospermia, decreased sperm count, decreased spermatozoa motility, male infertility, and abnormal spermatozoa morphology. Genitourinary: Enuresis, urinary tract infection, and tubulointerstitial nephritis. Special Senses: Hearing loss. Other: Allergic reaction, anaphylaxis, developmental delay, bone pain, bradycardia, cutaneous vasculitis, and angioedema [see Warnings and Precautions ( 5.14 ) ] .

7 DRUG INTERACTIONS Hepatic enzyme-inducing drugs (e.g., phenytoin, carbamazepine, phenobarbital, primidone, rifampin) can increase valproate clearance, while enzyme inhibitors (e.g., felbamate) can decrease valproate clearance. Therefore increased monitoring of valproate and concomitant drug concentrations and dosage adjustment are indicated whenever enzyme-inducing or inhibiting drugs are introduced or withdrawn ( 7.1 ) Aspirin, carbapenem antibiotics, estrogen-containing hormonal contraceptives, methotrexate: Monitoring of valproate concentrations is recommended ( 7.1 ) Co-administration of valproate can affect the pharmacokinetics of other drugs (e.g., diazepam, ethosuximide, lamotrigine, phenytoin) by inhibiting their metabolism or protein binding displacement ( 7.2 ) Patients stabilized on rufinamide should begin valproate therapy at a low dose, and titrate to clinically effective dose ( 7.2 ) Dosage adjustment of amitriptyline/nortriptyline, propofol, warfarin, and zidovudine may be necessary if used concomitantly with Depakote ( 7.2 ) Topiramate: Hyperammonemia and encephalopathy ( 5.10 , 7.3 ) Cannabidiol: ALT and/or AST elevation ( 7.4 ) 7.1 Effects of Co-Administered Drugs on Valproate Clearance Drugs that affect the level of expression of hepatic enzymes, particularly those that elevate levels of glucuronosyltransferases (such as ritonavir), may increase the clearance of valproate. For example, phenytoin, carbamazepine, and phenobarbital (or primidone) can double the clearance of valproate. Thus, patients on monotherapy will generally have longer half-lives and higher concentrations than patients receiving polytherapy with antiepilepsy drugs. In contrast, drugs that are inhibitors of cytochrome P450 isozymes, e.g., antidepressants, may be expected to have little effect on valproate clearance because cytochrome P450 microsomal mediated oxidation is a relatively minor secondary metabolic pathway compared to glucuronidation and beta-oxidation. Because of these changes in valproate clearance, monitoring of valproate and concomitant drug concentrations should be increased whenever enzyme inducing drugs are introduced or withdrawn. The following list provides information about the potential for an influence of several commonly prescribed medications on valproate pharmacokinetics. The list is not exhaustive nor could it be, since new interactions are continuously being reported. Drugs for which a potentially important interaction has been observed Aspirin A study involving the co-administration of aspirin at antipyretic doses (11 to 16 mg/kg) with valproate to pediatric patients (n=6) revealed a decrease in protein binding and an inhibition of metabolism of valproate. Valproate free fraction was increased 4-fold in the presence of aspirin compared to valproate alone. The β-oxidation pathway consisting of 2-E-valproic acid, 3-OH-valproic acid, and 3-keto valproic acid was decreased from 25% of total metabolites excreted on valproate alone to 8.3% in the presence of aspirin. Caution should be observed if valproate and aspirin are to be co-administered. Carbapenem Antibiotics A clinically significant reduction in serum valproic acid concentration has been reported in patients receiving carbapenem antibiotics (for example, ertapenem, imipenem, meropenem; this is not a complete list) and may result in loss of seizure control. The mechanism of this interaction is not well understood. Serum valproic acid concentrations should be monitored frequently after initiating carbapenem therapy. Alternative antibacterial or anticonvulsant therapy should be considered if serum valproic acid concentrations drop significantly or seizure control deteriorates [see Warnings and Precautions ( 5.15 ) ] . Estrogen-Containing Hormonal Contraceptives Estrogen-containing hormonal contraceptives may increase the clearance of valproate, which may result in decreased concentration of valproate and potentially increased seizure frequency. Prescribers should monitor serum valproate concentrations and clinical response when adding or discontinuing estrogen containing products. Felbamate A study involving the co-administration of 1,200 mg/day of felbamate with valproate to patients with epilepsy (n=10) revealed an increase in mean valproate peak concentration by 35% (from 86 to 115 mcg/mL) compared to valproate alone. Increasing the felbamate dose to 2,400 mg/day increased the mean valproate peak concentration to 133 mcg/mL (another 16% increase). A decrease in valproate dosage may be necessary when felbamate therapy is initiated. Methotrexate Methotrexate may decrease serum valproate levels and potentially result in increased frequency of seizures or bipolar symptoms. Prescribers should monitor serum valproate concentrations and clinical response when adding or discontinuing methotrexate and adjust valproate dosage, if necessary. Rifampin A study involving the administration of a single dose of valproate (7 mg/kg) 36 hours after 5 nights of daily dosing with rifampin (600 mg) revealed a 40% increase in the oral clearance of valproate. Valproate dosage adjustment may be necessary when it is co-administered with rifampin. 7.2 Effects of Valproate on Other Drugs Valproate has been found to be a weak inhibitor of some P450 isozymes, epoxide hydrase, and glucuronosyltransferases. The following list provides information about the potential for an influence of valproate co-administration on the pharmacokinetics or pharmacodynamics of several commonly prescribed medications. The list is not exhaustive, since new interactions are continuously being reported. Drugs for which a potentially important valproate interaction has been observed Amitriptyline/Nortriptyline Administration of a single oral 50 mg dose of amitriptyline to 15 normal volunteers (10 males and 5 females) who received valproate (500 mg BID) resulted in a 21% decrease in plasma clearance of amitriptyline and a 34% decrease in the net clearance of nortriptyline. Rare postmarketing reports of concurrent use of valproate and amitriptyline resulting in an increased amitriptyline level have been received. Concurrent use of valproate and amitriptyline has rarely been associated with toxicity. Monitoring of amitriptyline levels should be considered for patients taking valproate concomitantly with amitriptyline. Consideration should be given to lowering the dose of amitriptyline/nortriptyline in the presence of valproate. Carbamazepine/carbamazepine-10,11-Epoxide Serum levels of carbamazepine (CBZ) decreased 17% while that of carbamazepine-10,11-epoxide (CBZ-E) increased by 45% upon co-administration of valproate and CBZ to epileptic patients. Clonazepam The concomitant use of valproate and clonazepam may induce absence status in patients with a history of absence type seizures. Diazepam Valproate displaces diazepam from its plasma albumin binding sites and inhibits its metabolism. Co-administration of valproate (1,500 mg daily) increased the free fraction of diazepam (10 mg) by 90% in healthy volunteers (n=6). Plasma clearance and volume of distribution for free diazepam were reduced by 25% and 20%, respectively, in the presence of valproate. The elimination half-life of diazepam remained unchanged upon addition of valproate. Ethosuximide Valproate inhibits the metabolism of ethosuximide. Administration of a single ethosuximide dose of 500 mg with valproate (800 to 1,600 mg/day) to healthy volunteers (n=6) was accompanied by a 25% increase in elimination half-life of ethosuximide and a 15% decrease in its total clearance as compared to ethosuximide alone. Patients receiving valproate and ethosuximide, especially along with other anticonvulsants, should be monitored for alterations in serum concentrations of both drugs. Lamotrigine In a steady-state study involving 10 healthy volunteers, the elimination half-life of lamotrigine increased from 26 to 70 hours with valproate co-administration (a 165% increase). The dose of lamotrigine should be reduced when co-administered with valproate. Serious skin reactions (such as Stevens-Johnson syndrome and toxic epidermal necrolysis) have been reported with concomitant lamotrigine and valproate administration. See lamotrigine package insert for details on lamotrigine dosing with concomitant valproate administration. Phenobarbital Valproate was found to inhibit the metabolism of phenobarbital. Co-administration of valproate (250 mg BID for 14 days) with phenobarbital to normal subjects (n=6) resulted in a 50% increase in half-life and a 30% decrease in plasma clearance of phenobarbital (60 mg single-dose). The fraction of phenobarbital dose excreted unchanged increased by 50% in presence of valproate. There is evidence for severe CNS depression, with or without significant elevations of barbiturate or valproate serum concentrations. All patients receiving concomitant barbiturate therapy should be closely monitored for neurological toxicity. Serum barbiturate concentrations should be obtained, if possible, and the barbiturate dosage decreased, if appropriate. Primidone, which is metabolized to a barbiturate, may be involved in a similar interaction with valproate. Phenytoin Valproate displaces phenytoin from its plasma albumin binding sites and inhibits its hepatic metabolism. Co-administration of valproate (400 mg TID) with phenytoin (250 mg) in normal volunteers (n=7) was associated with a 60% increase in the free fraction of phenytoin. Total plasma clearance and apparent volume of distribution of phenytoin increased 30% in the presence of valproate. Both the clearance and apparent volume of distribution of free phenytoin were reduced by 25%. In patients with epilepsy, there have been reports of breakthrough seizures occurring with the combination of valproate and phenytoin. The dosage of phenytoin should be adjusted as required by the clinical situation. Propofol The concomitant use of valproate and propofol may lead to increased blood levels of propofol. Reduce the dose of propofol when co-administering with valproate. Monitor patients closely for signs of increased sedation or cardiorespiratory depression. Rufinamide Based on a population pharmacokinetic analysis, rufinamide clearance was decreased by valproate. Rufinamide concentrations were increased by <16% to 70%, dependent on concentration of valproate (with the larger increases being seen in pediatric patients at high doses or concentrations of valproate). Patients stabilized on rufinamide before being prescribed valproate should begin valproate therapy at a low dose, and titrate to a clinically effective dose [see Dosage and Administration ( 2.5 ) ] . Similarly, patients on valproate should begin at a rufinamide dose lower than 10 mg/kg per day (pediatric patients) or 400 mg per day (adults). Tolbutamide From in vitro experiments, the unbound fraction of tolbutamide was increased from 20% to 50% when added to plasma samples taken from patients treated with valproate. The clinical relevance of this displacement is unknown. Warfarin In an in vitro study, valproate increased the unbound fraction of warfarin by up to 32.6%. The therapeutic relevance of this is unknown; however, coagulation tests should be monitored if valproate therapy is instituted in patients taking anticoagulants. Zidovudine In six patients who were seropositive for HIV, the clearance of zidovudine (100 mg q8h) was decreased by 38% after administration of valproate (250 or 500 mg q8h); the half-life of zidovudine was unaffected. 7.3 Topiramate Concomitant administration of valproate and topiramate has been associated with hyperammonemia with and without encephalopathy [see Contraindications ( 4 ) and Warnings and Precautions ( 5.6 , 5.9 , 5.10 ) ] . Concomitant administration of topiramate with valproate has also been associated with hypothermia in patients who have tolerated either drug alone. It may be prudent to examine blood ammonia levels in patients in whom the onset of hypothermia has been reported [see Warnings and Precautions ( 5.9 , 5.11 ) ] . 7.4 Cannabidiol Concomitant administration of valproate and cannabidiol has been associated with an increased risk of ALT and/or AST elevation. This has been manageable by dose reduction or, in more severe cases, by discontinuation of one or both drugs. Liver function, including serum transaminase and total bilirubin levels, should be monitored during concomitant treatment [see Warnings and Precautions ( 5.1 ) ] .