Clonazepam

INDICATIONS AND USAGE Seizure Disorders: Clonazepam tablets are useful alone or as an adjunct in the treatment of the Lennox-Gastaut syndrome (petit mal variant), akinetic, and myoclonic seizures. In patients with absence seizures (petit mal) who have failed to respond to succinimides, clonazepam tablets may be useful. Some loss of effect may occur during the course of clonazepam treatment (see PRECAUTIONS : Loss of Effect ). Panic Disorder: Clonazepam tablets are indicated for the treatment of panic disorder, with or without agoraphobia, as defined in DSM-V. Panic disorder is characterized by the occurrence of unexpected panic attacks and associated concern about having additional attacks, worry about the implications or consequences of the attacks, and/or a significant change in behavior related to the attacks. The efficacy of clonazepam tablets was established in two 6- to 9-week trials in panic disorder patients whose diagnoses corresponded to the DSM-IIIR category of panic disorder (see CLINICAL PHARMACOLOGY: Clinical Trials) . Panic disorder (DSM-V) is characterized by recurrent unexpected panic attacks, i.e., a discrete period of intense fear or discomfort in which four (or more) of the following symptoms develop abruptly and reach a peak within 10 minutes: (1) palpitations, pounding heart or accelerated heart rate; (2) sweating; (3) trembling or shaking; (4) sensations of shortness of breath or smothering; (5) feeling of choking; (6) chest pain or discomfort; (7) nausea or abdominal distress; (8) feeling dizzy, unsteady, lightheaded or faint; (9) derealization (feelings of unreality) or depersonalization (being detached from oneself); (10) fear of losing control; (11) fear of dying; (12) paresthesias (numbness or tingling sensations); (13) chills or hot flushes. The effectiveness of clonazepam tablets in long-term use, that is, for more than 9 weeks, has not been systematically studied in controlled clinical trials. The physician who elects to use clonazepam tablets for extended periods should periodically reevaluate the long-term usefulness of the drug for the individual patient (see DOSAGE AND ADMINISTRATION ).

DOSAGE AND ADMINISTRATION Clonazepam is available as a tablet. The tablets should be administered with water by swallowing the tablet whole. Seizure Disorders: The use of multiple anticonvulsants may result in an increase of CNS depressant adverse effects. This should be considered before adding clonazepam tablets to an existing anticonvulsant regimen. Adults: The initial dose for adults with seizure disorders should not exceed 1.5 mg/day divided into three doses. Dosage may be increased in increments of 0.5 mg to 1 mg every 3 days until seizures are adequately controlled or until side effects preclude any further increase. Maintenance dosage must be individualized for each patient depending upon response. Maximum recommended daily dose is 20 mg. Pediatric Patients: Clonazepam tablets are administered orally. In order to minimize drowsiness, the initial dose for infants and children (up to 10 years of age or 30 kg of body weight) should be between 0.01 and 0.03 mg/kg/day but not to exceed 0.05 mg/kg/day given in two or three divided doses. Dosage should be increased by no more than 0.25 mg to 0.5 mg every third day until a daily maintenance dose of 0.1 to 0.2 mg/kg of body weight has been reached, unless seizures are controlled or side effects preclude further increase. Whenever possible, the daily dose should be divided into three equal doses. If doses are not equally divided, the largest dose should be given before retiring. Geriatric Patients: There is no clinical trial experience with clonazepam tablets in seizure disorder patients 65 years of age and older. In general, elderly patients should be started on low doses of clonazepam tablets and observed closely (see PRECAUTIONS: Geriatric Use ). Panic Disorder: Adults: The initial dose for adults with panic disorder is 0.25 mg twice daily. An increase to the target dose for most patients of 1 mg/day may be made after 3 days. The recommended dose of 1 mg/day is based on the results from a fixed dose study in which the optimal effect was seen at 1 mg/day. Higher doses of 2, 3 and 4 mg/day in that study were less effective than the 1 mg/day dose and were associated with more adverse effects. Nevertheless, it is possible that some individual patients may benefit from doses of up to a maximum dose of 4 mg/day, and in those instances, the dose may be increased in increments of 0.125 mg to 0.25 mg twice daily every 3 days until panic disorder is controlled or until side effects make further increases undesired. To reduce the inconvenience of somnolence, administration of one dose at bedtime may be desirable. Treatment should be discontinued gradually, with a decrease of 0.125 mg twice daily every 3 days, until the drug is completely withdrawn. There is no body of evidence available to answer the question of how long the patient treated with clonazepam should remain on it. Therefore, the physician who elects to use clonazepam tablets for extended periods should periodically reevaluate the long-term usefulness of the drug for the individual patient. Pediatric Patients: There is no clinical trial experience with clonazepam tablets in panic disorder patients under 18 years of age. Geriatric Patients: There is no clinical trial experience with clonazepam tablets in panic disorder patients 65 years of age and older. In general, elderly patients should be started on low doses of clonazepam tablets and observed closely (see PRECAUTIONS: Geriatric Use ). Discontinuation or Dosage Reduction of Clonazepam Tablets: To reduce the risk of withdrawal reactions, increased seizure frequency, and status epilepticus, use a gradual taper to discontinue clonazepam tablets or reduce the dosage. If a patient develops withdrawal reactions, consider pausing the taper or increasing the dosage to the previous tapered dosage level. Subsequently decrease the dosage more slowly (see WARNINGS: Dependence and Withdrawal Reactions and DRUG ABUSE AND DEPENDENCE: Dependence ).

ADVERSE REACTIONS The adverse experiences for clonazepam tablets are provided separately for patients with seizure disorders and with panic disorder. Seizure Disorders: The most frequently occurring side effects of clonazepam tablets are referable to CNS depression. Experience in treatment of seizures has shown that drowsiness has occurred in approximately 50% of patients and ataxia in approximately 30%. In some cases, these may diminish with time; behavior problems have been noted in approximately 25% of patients. Others, listed by system, including those identified during postapproval use of clonazepam tablets are: Cardiovascular: Palpitations Dermatologic: Hair loss, hirsutism, skin rash, ankle and facial edema Gastrointestinal: Anorexia, coated tongue, constipation, diarrhea, dry mouth, encopresis, gastritis, increased appetite, nausea, sore gums Genitourinary: Dysuria, enuresis, nocturia, urinary retention Hematopoietic: Anemia, leukopenia, thrombocytopenia, eosinophilia Hepatic: Hepatomegaly, transient elevations of serum transaminases and alkaline phosphatase Musculoskeletal: Muscle weakness, pains Miscellaneous: Dehydration, general deterioration, fever, lymphadenopathy, weight loss or gain Neurologic: Abnormal eye movements, aphonia, choreiform movements, coma, diplopia, dysarthria, dysdiadochokinesis, ‘‘glassy-eyed’’ appearance, headache, hemiparesis, hypotonia, nystagmus, respiratory depression, slurred speech, tremor, vertigo Psychiatric: Confusion, depression, amnesia, hysteria, increased libido, insomnia, psychosis (the behavior effects are more likely to occur in patients with a history of psychiatric disturbances). The following paradoxical reactions have been observed: irritability, aggression, agitation, nervousness, hostility, anxiety, sleep disturbances, nightmares, abnormal dreams, hallucinations. Respiratory: Chest congestion, rhinorrhea, shortness of breath, hypersecretion in upper respiratory passages Panic Disorder: Adverse events during exposure to clonazepam tablets were obtained by spontaneous report and recorded by clinical investigators using terminology of their own choosing. Consequently, it is not possible to provide a meaningful estimate of the proportion of individuals experiencing adverse events without first grouping similar types of events into a smaller number of standardized event categories. In the tables and tabulations that follow, CIGY dictionary terminology has been used to classify reported adverse events, except in certain cases in which redundant terms were collapsed into more meaningful terms, as noted below. The stated frequencies of adverse events represent the proportion of individuals who experienced, at least once, a treatment-emergent adverse event of the type listed. An event was considered treatment-emergent if it occurred for the first time or worsened while receiving therapy following baseline evaluation. Adverse Findings Observed in Short-Term, Placebo-Controlled Trials: Adverse Events Associated with Discontinuation of Treatment: Overall, the incidence of discontinuation due to adverse events was 17% in clonazepam tablets compared to 9% for placebo in the combined data of two 6- to 9-week trials. The most common events (≥ 1%) associated with discontinuation and a dropout rate twice or greater for clonazepam tablets than that of placebo included the following: Table 2 Most Common Adverse Events (≥ 1%) Associated with Discontinuation of Treatment Adverse Event Clonazepam Tablets (N = 574) Placebo (N = 294) Somnolence 7% 1% Depression 4% 1% Dizziness 1% < 1% Nervousness 1% 0% Ataxia 1% 0% Intellectual Ability Reduced 1% 0% Adverse Events Occurring at an Incidence of 1% or More among Clonazepam Tablets-Treated Patients: Table 3 enumerates the incidence, rounded to the nearest percent, of treatment-emergent adverse events that occurred during acute therapy of panic disorder from a pool of two 6- to 9-week trials. Events reported in 1% or more of patients treated with clonazepam tablets (doses ranging from 0.5 to 4 mg/day) and for which the incidence was greater than that in placebo-treated patients are included. The prescriber should be aware that the figures in Table 3 cannot be used to predict the incidence of side effects in the course of usual medical practice where patient characteristics and other factors differ from those that prevailed in the clinical trials. Similarly, the cited frequencies cannot be compared with figures obtained from other clinical investigations involving different treatments, uses and investigators. The cited figures, however, do provide the prescribing physician with some basis for estimating the relative contribution of drug and nondrug factors to the side effect incidence in the population studied. Table 3. Treatment-Emergent Adverse Event Incidence in 6- to 9- Week Placebo-Controlled Clinical Trials Events reported by at least 1% of patients treated with clonazepam tablets and for which the incidence was greater than that for placebo. Clonazepam Maximum Daily Dose Adverse Event by Body System < 1 mg n = 96 % 1- < 2 mg n = 129 % 2- < 3 mg n = 113 % ≥ 3 mg n = 235 % All Clonazepam Tablets Groups N = 574 % Placebo N = 294 % Central & Peripheral Nervous System Somnolence Indicates that the p-value for the dose-trend test (Cochran-Mantel-Haenszel) for adverse event incidence was ≤ 0.10. 26 35 50 36 37 10 Dizziness 5 5 12 8 8 4 Coordination Abnormal † 1 2 7 9 6 0 Ataxia † 2 1 8 8 5 0 Dysarthria † 0 0 4 3 2 0 Psychiatric Depression 7 6 8 8 7 1 Memory Disturbance 2 5 2 5 4 2 Nervousness 1 4 3 4 3 2 Intellectual Ability Reduced 0 2 4 3 2 0 Emotional Lability 0 1 2 2 1 1 Libido Decreased 0 1 3 1 1 0 Confusion 0 2 2 1 1 0 Respiratory System Upper Respiratory Tract Infection † 10 10 7 6 8 4 Sinusitis 4 2 8 4 4 3 Rhinitis 3 2 4 2 2 1 Coughing 2 2 4 0 2 0 Pharyngitis 1 1 3 2 2 1 Bronchitis 1 0 2 2 1 1 Gastrointestinal System Constipation † 0 1 5 3 2 2 Appetite Decreased 1 1 0 3 1 1 Abdominal Pain † 2 2 2 0 1 1 Body as a Whole Fatigue 9 6 7 7 7 4 Allergic Reaction 3 1 4 2 2 1 Musculoskeletal Myalgia 2 1 4 0 1 1 Resistance Mechanism Disorders Influenza 3 2 5 5 4 3 Urinary System Micturition Frequency 1 2 2 1 1 0 Urinary Tract Infection † 0 0 2 2 1 0 Vision Disorders Blurred Vision 1 2 3 0 1 1 Reproductive Disorders Denominators for events in gender-specific systems are: n = 240 (clonazepam), 102 (placebo) for male, and 334 (clonazepam), 192 (placebo) for female. Female Dysmenorrhea 0 6 5 2 3 2 Colpitis 4 0 2 1 1 1 Male Ejaculation Delayed 0 0 2 2 1 0 Impotence 3 0 2 1 1 0 Commonly Observed Adverse Events: Table 4. Incidence of Most Commonly Observed Adverse Events Treatment-emergent events for which the incidence in the clonazepam patients was ≥ 5% and at least twice that in the placebo patients. in Acute Therapy in Pool of 6- to 9- Week Trials Adverse Event Clonazepam (N = 574) Placebo (n = 294) Somnolence 37% 10% Depression 7% 1% Coordination Abnormal 6% 0% Ataxia 5% 0% Treatment-Emergent Depressive Symptoms: In the pool of two short-term placebo-controlled trials, adverse events classified under the preferred term “depression” were reported in 7% of clonazepam tablets-treated patients compared to 1% of placebo-treated patients, without any clear pattern of dose relatedness. In these same trials, adverse events classified under the preferred term “depression” were reported as leading to discontinuation in 4% of clonazepam tablets-treated patients compared to 1% of placebo-treated patients. While these findings are noteworthy, Hamilton Depression Rating Scale (HAM-D) data collected in these trials revealed a larger decline in HAM-D scores in the clonazepam group than the placebo group suggesting that clonazepam tablets-treated patients were not experiencing a worsening or emergence of clinical depression. Other Adverse Events Observed During the Premarketing Evaluation of Clonazepam Tablets in Panic Disorder: Following is a list of modified CIGY terms that reflect treatment-emergent adverse events reported by patients treated with clonazepam tablets at multiple doses during clinical trials. All reported events are included except those already listed in Table 3 or elsewhere in labeling, those events for which a drug cause was remote, those event terms which were so general as to be uninformative, and events reported only once and which did not have a substantial probability of being acutely life-threatening. It is important to emphasize that, although the events occurred during treatment with clonazepam tablets, they were not necessarily caused by it. Events are further categorized by body system and listed in order of decreasing frequency. These adverse events were reported infrequently, which is defined as occurring in 1/100 to 1/1000 patients. Body as a Whole: weight increase, accident, weight decrease, wound, edema, fever, shivering, abrasions, ankle edema, edema foot, edema periorbital, injury, malaise, pain, cellulitis, inflammation localized Cardiovascular Disorders: chest pain, hypotension postural Central and Peripheral Nervous System Disorders: migraine, paresthesia, drunkenness, feeling of enuresis, paresis, tremor, burning skin, falling, head fullness, hoarseness, hyperactivity, hypoesthesia, tongue thick, twitching Gastrointestinal System Disorders: abdominal discomfort, gastrointestinal inflammation, stomach upset, toothache, flatulence, pyrosis, saliva increased, tooth disorder, bowel movements frequent, pain pelvic, dyspepsia, hemorrhoids Hearing and Vestibular Disorders: vertigo, otitis, earache, motion sickness Heart Rate and Rhythm Disorders: palpitation Metabolic and Nutritional Disorders: thirst, gout Musculoskeletal System Disorders: back pain, fracture traumatic, sprains and strains, pain leg, pain nape, cramps muscle, cramps leg, pain ankle, pain shoulder, tendinitis, arthralgia, hypertonia, lumbago, pain feet, pain jaw, pain knee, swelling knee Platelet, Bleeding and Clotting Disorders: bleeding dermal Psychiatric Disorders: insomnia, organic disinhibition, anxiety, depersonalization, dreaming excessive, libido loss, appetite increased, libido increased, reactions decreased, aggression, apathy, disturbance in attention, excitement, anger, hunger abnormal, illusion, nightmares, sleep disorder, suicide ideation, yawning Reproductive Disorders, Female: breast pain, menstrual irregularity Reproductive Disorders, Male: ejaculation decreased Resistance Mechanism Disorders: infection mycotic, infection viral, infection streptococcal, herpes simplex infection, infectious mononucleosis, moniliasis Respiratory System Disorders: sneezing excessive, asthmatic attack, dyspnea, nosebleed, pneumonia, pleurisy Skin and Appendages Disorders: acne flare, alopecia, xeroderma, dermatitis contact, flushing, pruritus, pustular reaction, skin burns, skin disorder Special Senses Other, Disorders: taste loss Urinary System Disorders: dysuria, cystitis, polyuria, urinary incontinence, bladder dysfunction, urinary retention, urinary tract bleeding, urine discoloration Vascular (Extracardiac) Disorders: thrombophlebitis leg Vision Disorders: eye irritation, visual disturbance, diplopia, eye twitching, styes, visual field defect, xerophthalmia

Pharmacokinetics: Clonazepam is rapidly and completely absorbed after oral administration. The absolute bioavailability of clonazepam is about 90%. Maximum plasma concentrations of clonazepam are reached within 1 to 4 hours after oral administration. Clonazepam is approximately 85% bound to plasma proteins. Clonazepam is highly metabolized, with less than 2% unchanged clonazepam being excreted in the urine. Biotransformation occurs mainly by reduction of the 7-nitro group to the 4-amino derivative. This derivative can be acetylated, hydroxylated and glucuronidated. Cytochrome P-450 including CYP3A, may play an important role in clonazepam reduction and oxidation. The elimination half-life of clonazepam is typically 30 to 40 hours. Clonazepam pharmacokinetics are dose-independent throughout the dosing range. There is no evidence that clonazepam induces its own metabolism or that of other drugs in humans. Pharmacokinetics in Demographic Subpopulations and in Disease States: Controlled studies examining the influence of gender and age on clonazepam pharmacokinetics have not been conducted, nor have the effects of renal or liver disease on clonazepam pharmacokinetics been studied. Because clonazepam undergoes hepatic metabolism, it is possible that liver disease will impair clonazepam elimination. Thus, caution should be exercised when administering clonazepam to these patients (see CONTRAINDICATIONS ). In children, clearance values of 0.42 ± 0.32 mL/min/kg (ages 2 to 18 years) and 0.88 ± 0.4 mL/min/kg (ages 7 to 12 years) were reported; these values decreased with increasing body weight. Ketogenic diet in children does not affect clonazepam concentrations.