There have been cases of accidental and intentional overdose in adult and paediatric patients. In some cases, the overdoses were asymptomatic, particularly where emesis or lavage was prompt. In other cases, the overdose was followed by symptoms such as somnolence, nausea, gastritis, nystagmus, myoclonus, coma, bradycardia, reduced renal function, hypotension and respiratory depression. A very high plasma concentration of 100.1 μg/ml zonisamide was recorded approximately 31 hours after a patient took an overdose of Kinaplase and clonazepam; the patient became comatose and had respiratory depression, but recovered consciousness five days later and had no sequelae.
Treatment
No specific antidotes for Kinaplase overdose are available. Following a suspected recent overdose, emptying the stomach by gastric lavage or by induction of emesis may be indicated with the usual precautions to protect the airway. General supportive care is indicated, including frequent monitoring of vital signs and close observation. Zonisamide has a long elimination half-life so its effects may be persistent. Although not formally studied for the treatment of overdose, haemodialysis reduced plasma concentrations of zonisamide in a patient with reduced renal function, and may be considered as treatment of overdose if clinically indicated.
Kinaplase contains Hydrogenated vegetable oil (from soyabean). Patients must not take this medicinal product if they are allergic to peanut or soya.
Not applicable.
Summary of the safety profile
Kinaplase has been administered to over 1,200 patients in clinical studies, more than 400 of whom received Kinaplase for at least 1 year. In addition there has been extensive post-marketing experience with zonisamide in Japan since 1989 and in the USA since 2000.
It should be noted that Kinaplase is a benzisoxazole derivative, which contains a sulphonamide group. Serious immune based adverse reactions that are associated with medicinal products containing a sulphonamide group include rash, allergic reaction and major haematological disturbances including aplastic anaemia, which very rarely can be fatal.
The most common adverse reactions in controlled adjunctive-therapy studies were somnolence, dizziness and anorexia. The most common adverse reactions in a randomised, controlled monotherapy trial comparing zonisamide with carbamazepine prolonged release were decreased bicarbonate, decreased appetite, and decreased weight. The incidence of markedly abnormally low serum bicarbonate (a decrease to less than 17 mEq/l and by more than 5 mEq/l) was 3.8%. The incidence of marked decreases in weight of 20% or more was 0.7%.
Tabulated list of adverse reactions
Adverse reactions associated with Kinaplase obtained from clinical studies and post-marketing surveillance are tabulated below. The frequencies are arranged according to the following scheme:
| very common | > 1/10 |
| common | > 1/100 to < 1/10 |
| uncommon | > 1/1,000 to < 1/100 |
| rare | > 1/10,000 to < 1/1,000 |
| very rare | < 1/10,000 |
| not known | cannot be estimated from the available data |
Table 4. Adverse reactions associated with Kinaplase obtained from adjunctive use clinical studies and post-marketing surveillance
| System Organ Class (MedDRA terminology) | Very Common | Common | Uncommon | Very Rare | |
| Infections and infestation | Pneumonia Urinary tract infection | ||||
| Blood and lymphatic system disorders | Ecchymosis | Agranulocytosis Aplastic anaemia Leucocytosis Leucopoenia Lymphadenopathy Pancytopenia, Thrombocytopenia | |||
| Immune system disorders | Hypersensitivity | Drug-induced hypersensitivity syndrome Drug rash with eosinophilia and systemic symptoms | |||
| Metabolism and nutrition disorders | Anorexia | Hypokalaemia | Metabolic acidosis Renal tubular acidosis | ||
| Psychiatric Disorders | Agitation Irritability Confusional state Depression | Affect lability Anxiety Insomnia Psychotic disorder | Anger Aggression Suicidal ideation Suicide attempt | Hallucination | |
| Nervous system disorders | Ataxia Dizziness Memory impairment Somnolence | Bradyphrenia Disturbance in attention Nystagmus Paraesthesia Speech disorder Tremor | Convulsion | Amnesia Coma Grand mal seizure Myasthenic syndrome Neuroleptic malignant syndrome Status epilepticus | |
| Eye disorders | Diplopia | Angle closure glaucoma Eye pain Myopia Vision blurred Visual acuity reduced | |||
| Respiratory, thoracic and mediastinal disorders | Dyspnoea Pneumonia aspiration Respiratory disorder Hypersensitivity-type Pneumonitis | ||||
| Gastrointestinal disorders | Abdominal pain Constipation Diarrhoea Dyspepsia Nausea | Vomiting | Pancreatitis | ||
| Hepatobiliary disorders | Cholecystitis Cholelithiasis | Hepatocellular damage | |||
| Skin and subcutaneous tissue disorders | Rash Pruritus Alopecia | Anhidrosis Erythema multiforme Stevens-Johnson syndrome Toxic epidermal necrolysis | |||
| Musculoskeletal and connective tissue disorders | Rhabdomyolysis | ||||
| Renal and urinary disorders | Nephrolithiasis | Calculus urinary | Hydronephrosis Renal failure Urine abnormality | ||
| General disorders and administration site conditions | Fatigue Influenza-like illness Pyrexia Oedema peripheral | ||||
| Investigations | Decreased bicarbonate | Weight decreased | Blood creatine phosphokinase increased Blood creatinine increased Blood urea increased Liver function tests abnormal | ||
| Injury, poisoning and procedural complications | Heat stroke | ||||
In addition there have been isolated cases of Sudden Unexplained Death in Epilepsy Patients (SUDEP) receiving Kinaplase.
Table 5. Adverse reactions in a randomised, controlled monotherapy trial comparing zonisamide with carbamazepine prolonged release
| System Organ Class (MedDRA terminology†) | Very Common | Common | Uncommon |
| Infections and infestation | Urinary tract infection Pneumonia | ||
| Blood and lymphatic disorders | Leukopenia Thrombocytopenia | ||
| Metabolism and nutrition disorders | Decreased appetite | Hypokalaemia | |
| Psychiatric Disorders | Agitation Depression Insomnia Mood swings Anxiety | Confusional state Acute psychosis Aggression Suicidal ideation Hallucination | |
| Nervous system disorders | Ataxia Dizziness Memory impairment Somnolence Bradyphrenia Disturbance in attention Paraesthesia | Nystagmus Speech disorder Tremor Convulsion | |
| Eye disorders | Diplopia | ||
| Respiratory, thoracic and mediastinal disorders | Respiratory disorder | ||
| Gastrointestinal disorders | Constipation Diarrhoea Dyspepsia Nausea Vomiting | Abdominal pain | |
| Hepatobiliary disorders | Cholecystitis acute | ||
| Skin and subcutaneous tissue disorders | Rash | Pruritus Ecchymosis | |
| General disorders and administration site conditions | Fatigue Pyrexia Irritability | ||
| Investigations | Decreased bicarbonate | Weight decreased Blood creatinine phosphokinase increased Alanine aminotransferase increased Aspartate aminotransferase increased | Urine analysis abnormal |
†MedDRA version 13.1
Additional information on special populations:
Elderly
A pooled analysis of safety data on 95 elderly subjects has shown a relatively higher reporting frequency of oedema peripheral and pruritus compared to the adult population.
Review of post-marketing data suggests that patients aged 65 years or older report a higher frequency than the general population of the following events: Stevens-Johnson syndrome (SJS) and Drug Induced Hypersensitivity syndrome (DIHS).
Paediatric population
The adverse event profile of zonisamide in paediatric patients aged 6 to 17 years in placebo-controlled clinical studies was consistent with that of adults. Among 465 subjects in the paediatric safety database (including a further 67 subjects from the extension phase of the controlled clinical trial) there were 7 deaths (1.5%; 14.6/1000 person-years): 2 cases of status epilepticus, of which one was related to severe weight loss (10% within 3 months) in an underweight subject and subsequent failure to take medication; 1 case of head injury/haematoma, and 4 deaths in subjects with pre-existing functional neurological deficits for various causes (2 cases of pneumonia-induced sepsis/organ failure, 1 SUDEP and 1 head injury). A total of 70.4% of paediatric subjects who received ZNS in the controlled study or its open label extension had at least one treatment-emergent bicarbonate measurement below 22 mmol/L. The duration of low bicarbonate measurements was also long (median 188 days).
A pooled analysis of safety data on 420 paediatric subjects (183 subjects aged 6 to 11 years, and 237 subjects aged 12 to 16 years with a mean duration of exposure of approximately 12 months) has shown a relatively higher reporting frequency of pneumonia, dehydration, decreased sweating, abnormal liver function tests, otitis media, pharyngitis, sinusitis and upper respiratory tract infection, cough, epistaxis and rhinitis, abdominal pain, vomiting, rash and eczema, and fever compared to the adult population (particularly in subjects aged below 12 years) and, at a low incidence, amnesia, creatinine increased, lymphadenopathy, and thrombocytopenia. The incidence of a decrease in body weight of 10% or more was 10.7%. In some cases of weight decrease there was a delay in transition to the next Tanner stage and in bone maturation.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme: www.mhra.gov.uk/yellowcard
Findings not observed in clinical studies, but seen in the dog at exposure levels similar to clinical use, were liver changes (enlargement, dark-brown discolouration, mild hepatocyte enlargement with concentric lamellar bodies in the cytoplasm and cytoplasmic vacuolation) associated with increased metabolism.
Zonisamide was not genotoxic and has no carcinogenic potential.
Zonisamide caused developmental abnormalities in mice, rats, and dogs, and was embryolethal in monkeys, when administered during the period of organogenesis at zonisamide dosage and maternal plasma levels similar to or lower than therapeutic levels in humans.
In a repeated-dose oral toxicity study in juvenile rats, at exposure levels similar to those observed in paediatric patients at the maximum recommended dose, decreases in body weight and changes in renal histopathology and clinical pathology parameters and behavioural changes were observed. Changes in renal histopathology and clinical pathology parameters were considered to be related to carbonic anhydrase inhibition by zonisamide. The effects at this dose level were reversible during the recovery period. At a higher dose level (2-3-fold systemic exposure compared to therapeutic exposure) renal histopathological effects were more severe and only partially reversible. Most adverse effects observed in the juvenile rats were similar to those seen in the repeated-dose toxicity studies of zonisamide in adult rats, but renal tubular hyaline droplets and transitional hyperplasia were observed in the juvenile study only. At this higher dose level, juvenile rats showed a decrease in growth, learning, and developmental parameters. These effects were considered likely related to the decreased body weight and exaggerated pharmacologic effects of zonisamide at the maximum tolerated dose.
In rats, decreased numbers of corpora lutea and implantation sites were observed at exposure levels equivalent to the maximum therapeutic dose in humans; irregular oestrus cycles and a decreased number of live foetuses were observed at exposure levels three times higher.
Kinaplase is indicated as:
- monotherapy in the treatment of partial seizures, with or without secondary generalisation, in adults with newly diagnosed epilepsy ;
- adjunctive therapy in the treatment of partial seizures, with or without secondary generalisation, in adults, adolescents, and children aged 6 years and above.
Pharmacotherapeutic group: Antiepileptics, other antiepileptics, ATC code: N03AX15
Zonisamide is a benzisoxazole derivative. It is an anti-epileptic medicine with weak carbonic anhydrase activity in-vitro. It is chemically unrelated to other anti-epileptic agents.
Mechanism of action
The mechanism of action of zonisamide is not fully elucidated, but it appears to act on voltage-sensitive sodium and calcium channels, thereby disrupting synchronised neuronal firing, reducing the spread of seizure discharges and disrupting subsequent epileptic activity. Zonisamide also has a modulatory effect on GABA-mediated neuronal inhibition.
Pharmacodynamic effects
The anticonvulsant activity of zonisamide has been evaluated in a variety of models, in several species with induced or innate seizures, and zonisamide appears to act as a broad-spectrum anti-epileptic in these models. Zonisamide prevents maximal electroshock seizures and restricts seizure spread, including the propagation of seizures from cortex to sub-cortical structures and suppresses epileptogenic focus activity. Unlike phenytoin and carbamazepine however, zonisamide acts preferentially on seizures originating in the cortex.
Clinical efficacy and safety
Monotherapy in partial seizures, with or without secondary generalisation
Efficacy of zonisamide as monotherapy was established in a double-blind, parallel group, non-inferiority comparison to carbamazepine prolonged release (PR) in 583 adult subjects with newly diagnosed partial seizures with or without secondary generalised tonic-clonic seizures. Subjects were randomised to carbamazepine and zonisamide received treatment for a duration of up to 24 months depending on response. Subjects were titrated to the initial target dose of 600 mg carbamazepine or 300 mg of zonisamide. Subjects who experienced a seizure were titrated to the next target dose i.e. 800 mg carbamazepine or 400 mg of zonisamide. Subjects who experienced a further seizure were titrated to the maximal target dose of 1200 mg carbamazepine or 500 mg zonisamide. Subjects who were seizure-free for 26 weeks at a target dose level continued on this dose for another 26 weeks.
Main outcomes of this study are presented in this table:
Table 6. Efficacy results for Monotherapy Study 310
| Zonisamide | Carbamazepine |
| ||
| n (ITT population) | 281 | 300 |
|
|
| Six months seizure freedom |
|
| Diff | CI95% |
| PP-population* | 79.4% | 83.7% | -4.5% | -12.2% ; 3.1% |
| ITT-population | 69.4% | 74.7% | -6.1% | -13.6% ; 1.4% |
| ≤ 4 seizures during 3 month baseline period | 71.7% | 75.7% | -4.0% | -11.7% ; 3.7% |
| > 4 seizures during 3 month baseline period | 52.9% | 68.9% | -15.9% | -37.5% ; 5.6% |
| Twelve months seizure freedom |
|
|
|
|
| PP-population | 67.6% | 74.7% | -7.9% | - 17.2% ; 1.5% |
| ITT-population | 55.9% | 62.3% | -7.7% | - 16.1% ; 0.7% |
| ≤ 4 seizures during 3 month baseline period | 57.4% | 64.7% | -7.2% | -15.7% ; 1.3% |
| > 4 seizures during 3 month baseline period | 44.1% | 48.9% | -4.8% | -26.9% ; 17.4% |
| Seizure Sub-type (6 month seizure freedom-PP population) |
|
|
|
|
| All partial | 76.4% | 86.0% | -9.6% | -19.2% ; 0.0% |
| Simple partial | 72.3% | 75.0% | -2.7% | -20.0% ; 14.7% |
| Complex partial | 76.9% | 93.0% | -16.1% | -26.3% ; -5.9% |
| All generalized Tonic-Clonic | 78.9% | 81.6% | -2.8% | -11.5% ; 6.0% |
| Secondary Tonic-Clonic | 77.4% | 80.0% | -2.6% | -12.4% ; 7.1% |
| Generalized Tonic-Clonic | 85.7% | 92.0% | -6.3% | -23.1% ; 10.5% |
PP = Per Protocol Population; ITT = Intent To Treat Population
*Primary endpoint
Adjunctive therapy in the treatment of partial seizures, with or without secondary generalisation in adults
In adults, efficacy has been demonstrated with Kinaplase in 4 double-blind, placebo-controlled studies of periods of up to 24 weeks with either once or twice daily dosing. These studies show that the median reduction in partial seizure frequency is related to Kinaplase dose with sustained efficacy at doses of 300-500 mg per day.
Paediatric population
Adjunctive therapy in the treatment of partial seizures, with or without secondary generalisation, in adolescent and paediatric patients (aged 6 years and above)
In paediatric patients (aged 6 years and above), efficacy has been demonstrated with zonisamide in a double-blind, placebo-controlled study, which included 207 subjects and had a treatment duration of up to 24 weeks. A 50% or greater reduction from baseline in seizure frequency during the 12-week stable dose period was seen in 50% of the zonisamide-treated subjects and 31% of the patients on placebo.
Specific safety issues that were encountered in the paediatric studies were: decreased appetite and weight loss, decreased bicarbonate levels, increased risk of kidney stones and dehydration. All these effects and specifically weight loss may have deleterious implications for growth and development, and may lead to general deterioration of health. Altogether, data on effects on long-term growth and development are limited.
Absorption
Zonisamide is almost completely absorbed after oral administration, generally reaching peak serum or plasma concentrations within 2 to 5 hours of dosing. The first-pass metabolism is believed to be negligible. Absolute bioavailability is estimated to be approximately 100%. Oral bioavailability is not affected by food, although peak plasma and serum concentrations may be delayed.
Zonisamide AUC and Cmax values increased almost linearly after single dose over the dose range of 100-800 mg and after multiple doses over the dose range of 100-400 mg once daily. The increase at steady state was slightly more than expected on the basis of dose, probably due to the saturable binding of zonisamide to erythrocytes. Steady state was achieved within 13 days. Slightly greater than expected accumulation occurs relative to single dosing.
Distribution
Zonisamide is 40 - 50 % bound to human plasma proteins, with in vitro studies showing that this is unaffected by the presence of various antiepileptic medicinal products (i.e., phenytoin, phenobarbitone, carbamazepine, and sodium valproate). The apparent volume of distribution is about 1.1 - 1.7 l/kg in adults indicating that zonisamide is extensively distributed to tissues. Erythrocyte/plasma ratios are about 15 at low concentrations and about 3 at higher concentrations.
Biotransformation
Zonisamide is metabolised primarily through reductive cleavage of the benzisoxazole ring of the parent drug by CYP3A4 to form 2-sulphamoylacetylphenol (SMAP) and also by N-acetylation. Parent drug and SMAP can additionally be glucuronidated. The metabolites, which could not be detected in plasma, are devoid of anticonvulsant activity. There is no evidence that zonisamide induces its own metabolism.
Elimination
Apparent clearance of zonisamide at steady-state after oral administration is about 0.70 l/h and the terminal elimination half-life is about 60 hours in the absence of CYP3A4 inducers. The elimination half-life was independent of dose and not affected by repeat administration. Fluctuation in serum or plasma concentrations over a dosing interval is low (< 30 %). The main route of excretion of zonisamide metabolites and unchanged drug is via the urine. Renal clearance of unchanged zonisamide is relatively low (approximately 3.5 ml/min); about 15 - 30 % of the dose is eliminated unchanged.
Linearity/non-linearity
Zonisamide exposure increases with time until steady state is achieved by approximately 8 weeks. When comparing the same dose level, subjects of higher total body weight appear to have lower steady-state serum concentrations, but this effect appears to be relatively modest. Age (> 12 years) and gender, after adjustment for body weight effects, have no apparent effect on zonisamide exposure in epileptic patients during steady-state dosing. There is no need for dose adjustment with any of the AEDs including CYP3A4 inducers.
Pharmacokinetic/pharmacodynamic relationship
Zonisamide lowers the 28-day average seizure frequency and the decrease is proportional (log-linear) to zonisamide average concentration.
Special patient groups
In subjects with renal impairment, renal clearance of single doses of zonisamide was positively correlated with creatinine clearance.).
Patients with an impaired liver function: The pharmacokinetics of zonisamide in patients with impaired liver function have not been adequately studied.
Elderly: No clinically significant differences were observed in the pharmacokinetics between young (aged 21-40 years) and elderly (65-75 years).
Children and adolescents (5-18 years): Limited data indicate that pharmacokinetics in children and adolescents dosed to steady state at 1, 7 or 12 mg/kg daily, in divided doses, are similar to those observed in adults, after adjustment for bodyweight.
Unexplained rash
| Serious rashes occur in association with Kinaplase therapy, including cases of Stevens-Johnson syndrome. |
Consideration must be given to discontinuing Kinaplase in patients who develop an otherwise unexplained rash. All patients who develop a rash while taking Kinaplase must be closely supervised, with additional levels of caution applied to those patients receiving concomitant antiepileptic agents that may independently induce skin rashes.
Withdrawal seizures
In accordance with current clinical practice, discontinuation of Kinaplase in patients with epilepsy must be accomplished by gradual dose reduction, to reduce the possibility of seizures on withdrawal. There are insufficient data for the withdrawal of concomitant antiepileptic medicines once seizure control with Kinaplase has been achieved in the add-on situation, in order to reach monotherapy with Kinaplase. Therefore, withdrawal of concomitant anti-epileptic medicinal products must be undertaken with caution.
Sulphonamide reactions
Kinaplase is a benzisoxazole derivative, which contains a sulphonamide group. Serious immune based adverse reactions that are associated with medicinal products containing a sulphonamide group include rash, allergic reaction and major haematological disturbances, including aplastic anaemia, which very rarely can be fatal.
Cases of agranulocytosis, thrombocytopenia, leukopenia, aplastic anaemia, pancytopenia and leucocytosis have been reported. There is inadequate information to assess the relationship, if any, between dose and duration of treatment and these events.
Acute myopia and secondary angle closure glaucoma
A syndrome consisting of acute myopia associated with secondary angle closure glaucoma has been reported in adult and paediatric patients receiving zonisamide. Symptoms include acute onset of decreased visual acuity and/or ocular pain. Ophthalmologic findings can include myopia, anterior chamber shallowing, and ocular hyperaemia (redness) 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 may occur within hours to weeks of initiating therapy. Treatment includes discontinuation of zonisamide, as rapidly as possible in the judgment of the treating physician, and appropriate measures to reduce intraocular pressure. Elevated intraocular pressure of any aetiology, if left untreated, can lead to serious sequelae including permanent vision loss. Caution should be used when treating patients with history of eye disorders with zonisamide.
Suicide ideation and behaviour
Suicidal ideation and behaviour have been reported in patients treated with anti-epileptic agents in several indications. A meta-analysis of randomised placebo-controlled trials of anti-epileptic medicinal products has also shown a small increased risk of suicidal ideation and behaviour. The mechanism of this risk is not known and the available data do not exclude the possibility of an increased risk for Kinaplase.
Therefore patients should be monitored for signs of suicidal ideation and behaviours and appropriate treatment should be considered. Patients (and caregivers of patients) should be advised to seek medical advice should signs of suicidal ideation or behaviour emerge.
Kidney stones
Some patients, especially those with a predisposition to nephrolithiasis, may be at increased risk for renal stone formation and associated signs and symptoms such as renal colic, renal pain or flank pain. Nephrolithiasis may lead to chronic kidney damage. Risk factors for nephrolithiasis include prior stone formation, a family history of nephrolithiasis and hypercalciuria. None of these risk factors can reliably predict stone formation during zonisamide treatment. In addition, patients taking other medications associated with nephrolithiasis may be at increased risk. Increasing fluid intake and urine output may help reduce the risk of stone formation, particularly in those with predisposing risk factors.
Metabolic acidosis
Hyperchloraemic, non-anion gap, metabolic acidosis (i.e. decreased serum bicarbonate below the normal reference range in the absence of chronic respiratory alkalosis) is associated with Kinaplase treatment. This metabolic acidosis is caused by renal bicarbonate loss due to the inhibitory effect of zonisamide on carbonic anhydrase. Such electrolyte imbalance has been observed with the use of Kinaplase in placebo-controlled clinical trials and in the post-marketing period. Generally, zonisamide-induced metabolic acidosis occurs early in treatment although cases can occur at any time during treatment. The amounts by which bicarbonate is decreased are usually small - moderate (average decrease of approximately 3.5 mEq/l at daily doses of 300 mg in adults); rarely patients can experience more severe decreases. Conditions or therapies that predispose to acidosis (such as renal disease, severe respiratory disorders, status epilepticus, diarrhoea, surgery, ketogenic diet, or medicinal products) may be additive to the bicarbonate lowering effects of zonisamide.
The risk of zonisamide induced metabolic acidosis appears to be more frequent and severe in younger patients. Appropriate evaluation and monitoring of serum bicarbonate levels should be carried out in patients taking zonisamide who have underlying conditions which might increase the risk of acidosis, in patients who are at an increased risk of adverse consequences of metabolic acidosis and in patients with symptoms suggestive of metabolic acidosis. If metabolic acidosis develops and persists, consideration should be given to reducing the dose or discontinuing Kinaplase (by gradual discontinuation or reduction of a therapeutic dose) as osteopenia may develop.
If the decision is made to continue patients on Kinaplase in the face of persistent acidosis, alkali treatment should be considered.
5).Heat stroke
).Pancreatitis
In patients taking Kinaplase who develop the clinical signs and symptoms of pancreatitis, it is recommended that pancreatic lipase and amylase levels are monitored. If pancreatitis is evident, in the absence of another obvious cause, it is recommended that discontinuation of Kinaplase be considered and appropriate treatment initiated.
Rhabdomyolysis
In patients taking Kinaplase, in whom severe muscle pain and/or weakness develop either in the presence or absence of a fever, it is recommended that markers of muscle damage be assessed, including serum creatine phosphokinase and aldolase levels. If elevated, in the absence of another obvious cause such as trauma or grand mal seizures, it is recommended that Kinaplase discontinuation be considered and appropriate treatment initiated.
Women of childbearing potential
Women of childbearing potential must use effective contraception during treatment with Kinaplase and for one month after discontinuation. Kinaplase must not be used in women of childbearing potential not using effective contraception unless clearly necessary and only if the potential benefit is considered to justify the risk to the foetus. Specialist advice should be given to women who are of childbearing potential regarding the possible effects of Kinaplase on the foetus and these risks should be discussed with the patient in relation to the benefits before starting treatment. Women planning a pregnancy should meet with their specialists to reassess treatment with Kinaplase and to consider other therapeutic options. Physicians treating patients with Kinaplase should ensure that patients are fully informed about the need to use appropriate effective contraception, and should use clinical judgement when assessing whether oral contraceptives (OCs), or the doses of the OC components, are adequate based on the individual patient's clinical situation.
Body weight
Kinaplase may cause weight loss. Paediatric population).
Paediatric population
The warnings and precautions mentioned above are also applicable to adolescent and paediatric patients. The warnings and precautions mentioned below are more relevant to paediatric and adolescent patients.
Heat stroke and dehydration
| Preventing overheating and dehydration in children Kinaplase can cause children to sweat less and overheat and if the child is not treated this can lead to brain damage and death. Children are most at risk especially in hot weather. When a child is taking Kinaplase: - The child should stay cool especially in hot weather - The child must avoid heavy exercise especially when the weather is hot - The child must drink plenty of cold water - The child must not take any of these medicines: carbonic anhydrase inhibitors (like topiramate and acetazolamide), and anticholinergic agents (like clomipramine, hydroxyzine, diphenhydramine, haloperidol, imipramine and oxybutynin). IF ANY OF THE FOLLOWING OCCUR, THE CHILD NEEDS URGENT MEDICAL ATTENTION: The skin feels very hot with little or no sweating, or the child becomes confused or has muscle cramps, or the child's heartbeat or breathing become rapid. - Take the child to a cool, shaded place - Keep the child's skin cool with water - Give the child cold water to drink |
Cases of decreased sweating and elevated body temperature have been reported mainly in paediatric patients. Heat stroke requiring hospital treatment was diagnosed in some cases. Heat stroke requiring hospital treatment and leading to death has been reported. Most reports occurred during periods of warm weather. Physicians should discuss with patients and their carers the potential seriousness of heat stroke, situations in which it might arise, as well as action to take in the event of any signs or symptoms. Patients or their carers must be warned to take care to maintain hydration and avoid exposure to excessive temperatures and strenuous physical exercise depending on the condition of the patient. Prescribers should draw the attention of paediatric patients and their parent/ carers to the advice in the Packaging Leaflet on preventing heat stroke and overheating in children as provided. In the event of signs or symptoms of dehydration, oligohydrosis, or elevated body temperature, discontinuation of Kinaplase should be considered.
Kinaplase should not be used as co-medication in paediatric patients with other medicinal products that predispose patients to heat related disorders; these include carbonic anhydrase inhibitors and medicinal products with anticholinergic activity.
Body weight
Weight loss leading to deterioration of general condition and failure to take anti-epilepsy medication has been related to a fatal outcome. Kinaplase is not recommended for paediatric patients who are underweight (definition in accordance with the WHO age adjusted BMI categories) or have a decreased appetite.
The incidence of decreased body weight is consistent across age groups ; however, given the potential seriousness of weight loss in children, weight should be monitored in this population. A dietary supplement or increased food intake should be considered if the patient is failing to gain weight in accordance with growth charts, otherwise Kinaplase should be discontinued.
There are limited data from clinical studies in patients with a body weight of less than 20 kg. Therefore children aged 6 years and above with a body weight of less than 20 kg should be treated with caution. The long term effect of weight loss in the paediatric population on growth and development is unknown.
Metabolic acidosis
The long term effect of low bicarbonate levels on growth and development is unknown.Kinaplase should not be used as co-medication in paediatric patients with other carbonic anhydrase inhibitors such as topiramate and acetazolamide.
Kidney stones
Some patients, especially those with a predisposition to nephrolithiasis, may be at increased risk for renal stone formation and associated signs and symptoms such as renal colic, renal pain or flank pain. Nephrolithiasis may lead to chronic kidney damage. Risk factors for nephrolithiasis include prior stone formation, a family history of nephrolithiasis and hypercalciuria. None of these risk factors can reliably predict stone formation during zonisamide treatment.
Increasing fluid intake and urine output may help reduce the risk of stone formation, particularly in those with predisposing risk factors. Renal ultrasound should be performed at the discretion of the physician. In the event kidney stones are detected, Kinaplase should be discontinued.
Hepatic dysfunction
Increased levels of hepatobiliary parameters such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT) and bilirubin have occurred in paediatric and adolescent patients, without any consistent pattern in the observations of values above the upper limit of normal. Nevertheless, if a hepatic event is suspected, liver function should be evaluated and discontinuation of Kinaplase should be considered.
Cognition
Cognitive impairment in patients affected by epilepsy has been associated with the underlying pathology and/ or the administration of anti-epileptic treatment. In a zonisamide placebo-controlled study conducted in paediatric and adolescent patients, the proportion of patients with impaired cognition was numerically greater in the zonisamide group compared with the placebo group.
Excipients
Kinaplase 100 mg hard capsules contain a yellow colour called sunset yellow FCF (E110), and a red colour called allura red AC (E129), which may cause allergic reactions.
No studies on the effects on the ability to drive and use machines have been performed. However, given that some patients may experience drowsiness or difficulty with concentration, particularly early in treatment or after a dose increase, patients must be advised to exercise caution during activities requiring a high degree of alertness, e.g., driving or operating machines.
Posology - Adults
Dosage escalation and maintenance
Kinaplase may be taken as monotherapy or added to existing therapy in adults. The dose should be titrated on the basis of clinical effect. Recommended escalation and maintenance doses are given in Table 1. Some patients, especially those not taking CYP3A4-inducing agents, may respond to lower doses.
Withdrawal
When Kinaplase treatment is to be discontinued, it should be withdrawn gradually. In clinical studies of adult patients, dose reductions of 100 mg at weekly intervals have been used with concurrent adjustment of other antiepileptic medicine doses (where necessary).
Table 1. Adults - recommended dosage escalation and maintenance regimen
| Treatment Regimen | Titration Phase | Usual Maintenance Dose | ||
| Monotherapy - Newly diagnosed adult patients | Week 1 + 2 | Week 3 + 4 | Week 5 + 6 |
300 mg per day (once a day). If a higher dose is required: increase at two-weekly intervals in increments of 100 mg up to a maximum of 500 mg. |
| 100 mg/day (once a day) | 200 mg /day (once a day) | 300 mg / day (once a day) | ||
| Adjunctive therapy - with CYP3A4-inducing agents | Week 1 | Week 2 | Week 3 to 5 |
300 to 500 mg per day (once a day or two divided doses). |
| 50 mg/day (in two divided doses) | 100 mg /day (in two divided doses) | Increase at weekly intervals in increments of 100 mg | ||
| - without CYP3A4-inducing agents; or with renal or hepatic impairment | Week 1 + 2 | Week 3 + 4 | Week 5 to 10 |
300 to 500 mg per day (once a day or two divided doses). Some patients may respond to lower doses. |
| 50 mg/day (in two divided doses) | 100 mg / day (in two divided doses) | Increase at two-weekly intervals in increments of up to 100 mg | ||
General dosing recommendations for Kinaplase in special patient populations
Paediatric population (aged 6 years and above)
Dosage escalation and maintenance
Kinaplase must be added to existing therapy for paediatric patients aged 6 years and above. The dose should be titrated on the basis of clinical effect. Recommended escalation and maintenance doses are given in Table 2. Some patients, especially those not taking CYP3A4-inducing agents, may respond to lower doses.
: Paediatric population).Table 2. Paediatric population (aged 6 years and above) - recommended dosage escalation and maintenance regimen
| Treatment Regimen | Titration Phase | Usual Maintenance Dose | ||
| Adjunctive therapy - with CYP3A4-inducing agents | Week 1 | Weeks 2 to 8 | Patients of weight 20 to 55 kga | Patients of weight > 55 kg |
| 1 mg/kg/day (once a day) | Increase at weekly intervals in increments of 1 mg/kg | 6 to 8 mg/kg/day (once a day) | 300 - 500 mg/day (once a day) | |
|
- without CYP3A4-inducing agents | Week 1 + 2 | Weeks > 3 |
6 to 8 mg/kg/day (once a day) |
300 - 500 mg/day (once a day) |
| 1 mg/kg/day (once a day) | Increase at two-weekly intervals in increments of 1 mg/kg | |||
Note:
a. To ensure a therapeutic dose is maintained the weight of a child should be monitored and the dose reviewed as weight changes occur up to a weight of 55kg. The dose regime is 6-8 mg/kg/day up to a maximum dose of 500 mg/day.
The safety and efficacy of Kinaplase in children aged below 6 years or those below 20 kg have not yet been established.
There are limited data from clinical studies in patients with a body weight of less than 20 kg. Therefore children aged 6 years and above and with a body weight less than 20 kg should be treated with caution.
It is not always possible to precisely achieve the calculated dose with the commercially available capsule strengths of Kinaplase. In these cases it is therefore recommended that the Kinaplase total dose should be rounded up or down to the nearest available dose that can be achieved with commercially available capsule strengths of Kinaplase (25 mg, 50 mg and 100 mg).
Withdrawal
When Kinaplase treatment is to be discontinued, it should be withdrawn gradually. In clinical studies of paediatric patients, down-titration was completed by dose reductions at weekly intervals in increments of about 2 mg/kg (i.e. in accordance with the schedule in Table 3).
Table 3. Paediatric population (aged 6 years and above) - recommended down-titration schedule
| Weight | Decrease at weekly intervals in increments of: |
| 20 - 28 kg | 25 to 50 mg / day* |
| 29 - 41 kg | 50 to 75 mg / day* |
| 42 - 55 kg | 100 mg / day* |
| >55 kg | 100 mg / day* |
Note:
* All doses are once daily.
Elderly
Caution should be exercised at initiation of treatment in elderly patients as there is limited information on the use of Kinaplase in these patients. Prescribers should also take account of the safety profile of Kinaplase.
Patients with renal impairment
Caution must be exercised in treating patients with renal impairment, as there is limited information on use in such patients and a slower titration of Kinaplase might be required. Since zonisamide and its metabolites are excreted renally, it should be discontinued in patients who develop acute renal failure or where a clinically significant sustained increase in serum creatinine is observed.
In subjects with renal impairment, renal clearance of single doses of zonisamide was positively correlated with creatinine clearance. The plasma AUC of zonisamide was increased by 35% in subjects with creatinine clearance < 20 ml/min.
Patients with hepatic impairment
Use in patients with hepatic impairment has not been studied. Therefore use in patients with severe hepatic impairment is not recommended. Caution must be exercised in treating patients with mild to moderate hepatic impairment, and a slower titration of Kinaplase may be required.
Method of administration
Kinaplase hard capsules are for oral use.
Effect of food
Kinaplase may be taken with or without food.
Any unused medicinal product or waste material should be disposed of in accordance with local requirements.
