TRILEPTAL Oxcarbazepine 300mg Tablet 1's
Indications/Uses
As a first-line antiepileptic drug for use as monotherapy or adjunctive therapy.
Replacement treatment of other antiepileptic drugs when current therapy provides insufficient seizure control (see Pharmacology: Pharmacodynamics: Clinical Studies under Actions).
Dosage/Direction for Use
When used as replacement for other antiepileptic drugs, the dose of the concomitant antiepileptic drug(s) should be reduced gradually on initiation of oxcarbazepine therapy. In adjunctive therapy, as the total antiepileptic drug load of the patient is increased, the dose of concomitant antiepileptic drug(s) may need to be reduced and/or the oxcarbazepine dose increased more slowly (see Interactions).
Oxcarbazepine (Trileptal) oral suspension and film-coated tablets are bioequivalent and may be interchanged at equal doses (see Pharmacology under Actions).
Oral suspension: The prescription for oxcarbazepine (Trileptal) oral suspension should be given in milliliters (see conversion table as follows which gives the milligram dose in milliliters). (See Table 1.)
Plasma level monitoring of oxcarbazepine or MHD is not routinely warranted. However, plasma level monitoring of MHD may be considered during therapy in order to rule out noncompliance, or in situations where an alteration in MHD clearance is to be expected, including: changes in renal function (see Renal impairment as follows); pregnancy (see Use in Pregnancy & Lactation and Pharmacology under Actions); concomitant use of liver enzyme-inducing drugs (see Interactions).
If any of these situations apply, the dose may be adjusted (based on plasma levels measured 2-4 hours post dose) to maintain peak MHD plasma levels <35 mg/L.
General Target Population: Adults: Monotherapy and adjunctive therapy: Recommended initial dose: Oxcarbazepine (Trileptal) should be initiated with a dose of 600 mg/day (8-10 mg/kg/day) given in 2 divided doses.
Maintenance dose: Good therapeutic effects are seen at doses between 600 mg/day and 2,400 mg/day. If clinically indicated, the dose may be increased by a maximum of 600 mg/day at approximately weekly intervals from the starting dose to achieve the desired clinical response.
Maximum recommended dose: In a controlled hospital setting, dose increases up to 2,400 mg/day have been achieved over 48 hours.
Daily doses above 2,400 mg/day have not been studied systematically in clinical trials.
There is only limited experience with doses up to 4,200 mg/day.
Special populations: Pediatric patients: Recommended initial dose: In mono- and adjunctive therapy, treatment should be initiated with a dose of 8-10 mg/kg/day given in 2 divided doses.
Maintenance dose: The target maintenance dose for adjunctive therapy is 30-46 mg/kg/day and should be achieved over two weeks.
In an adjunctive therapy trial in paediatric patients (aged 3 to 17 years), in which the intention was to reach a target daily dose of 46 mg/kg/day, the median daily dose was 31 mg/kg/day with a range of 6 to 51 mg/kg/day. In an adjunctive therapy trial in paediatric patients (aged 1 month to less than 4 years), in which the intention was to reach a target daily dose of 60 mg/kg/day, 56% of patients reached a final dose of at least 55 mg/kg/day.
Maximum recommended dose: If clinically indicated, the dose may be increased by a maximum of 10 mg/kg/day at approximately weekly intervals from the starting dose, to a maximum daily dose of 60 mg/kg/day, to achieve the desired clinical response (see Pharmacology under Actions).
Effect of weight adjusted MHD clearance on pediatric dosage: Under adjunctive therapy and monotherapy, when normalized by body weight, apparent clearance (L/hr/kg) of MHD (the active metabolite of oxcarbazepine) decreased with age such that children 1 month to less than 4 years of age may require twice the oxcarbazepine dose per body weight compared to adults; and children 4 to 12 years of age may require a 50% higher oxcarbazepine dose per body weight compared to adults (see Pharmacology under Actions).
Effect of concomitant enzyme-inducing antiepileptic drugs on pediatric dosage: For children 1 month to less than 4 years of age, the influence of enzyme-inducing antiepileptic medicinal products on their weight-normalized apparent clearance appeared higher compared to older children. For children 1 month to less than 4 years of age, about 60% higher oxcarbazepine dose per body weight may be required for adjunctive therapy on enzyme-inducing antiepileptic medicinal products relative to monotherapy or adjunctive therapy with non-enzyme-inducing antiepileptic medicinal products. For older children on enzyme-inducing antiepileptic medicinal products, only a slightly higher dose per body weight may be required than their counterparts on monotherapy.
Oxcarbazepine (Trileptal) has not been studied in controlled clinical trials in children below 1 month of age.
Geriatric patients (65 years old and above): No special dose recommendations are necessary in elderly patients because therapeutic doses are individually adjusted. Dosage adjustments are recommended in elderly patients with renal impairment (creatinine clearance <30 mL/min) (see Renal impairment as follows).
Close monitoring of sodium levels is required in patients at risk of hyponatremia (see Precautions).
Hepatic impairment: No dosage adjustment is required for patients with mild to moderate hepatic impairment. Oxcarbazepine (Trileptal) has not been studied in patients with severe hepatic impairment, therefore, caution should be exercised when dosing such patients (see Pharmacology under Actions and Precautions).
Renal impairment: In patients with impaired renal function (creatinine clearance less than 30 mL/min), therapy should be initiated at half the usual starting dose (300 mg/day) and increased slowly to achieve the desired clinical response (see Pharmacology under Actions and Precautions).
Method of Administration: Oxcarbazepine (Trileptal) can be taken with or without food (see Pharmacology under Actions).
Film-coated tablet: The tablets are scored and can be broken in two halves in order to make it easier for the patient to swallow the tablet. For younger children and other patients who cannot swallow tablets or where the required dose cannot be administered using tablets, an oral suspension form is available.
Oxcarbazepine (Trileptal) oral suspension and film-coated tablets are bioequivalent and may be interchanged at equal doses (see Pharmacology under Actions).
Overdosage
Signs and symptoms: Electrolyte and fluid balance conditions: hyponatremia.
Eye disorders: diplopia, miosis, blurred vision.
Gastrointestinal disorders: nausea, vomiting, hyperkinesia.
General disorders and administration site conditions: fatigue.
Investigations: respiratory rate depression, QTc prolongation.
Nervous system disorders: drowsiness and somnolence, dizziness, ataxia, nystagmus, tremor, disturbances in coordination (coordination abnormal), convulsion, headache, coma, loss of consciousness, dyskinesia.
Psychiatric disorders: aggression, agitation, confusional state.
Vascular disorders: hypotension.
Respiratory, thoracic and mediastinal disorders: dyspnea.
Management: There is no specific antidote. Symptomatic and supportive treatment should be administered as appropriate. Removal of the drug by gastric lavage and/or inactivation by administering activated charcoal should be considered.
Administration
Contraindications
Special Precautions
Patients who have exhibited hypersensitivity reactions to carbamazepine should be informed that approximately 25-30% of these patients may experience hypersensitivity reactions with oxcarbazepines (see Adverse Reactions).
Hypersensitivity reactions, including multi-organ hypersensitivity reactions, may also occur in patients without history of hypersensitivity to carbamazepine. Such reactions can affect the skin, liver, blood and lymphatic system or other organs, either individually or together in the context of a systemic reaction (see Adverse Reactions). In general, if signs and symptoms suggestive of hypersensitivity reactions occur, treatment should be withdrawn immediately.
Dermatological effects: Serious dermatological reactions, including Stevens-Johnson syndrome, toxic epidermal necrolysis (Lyell's syndrome) and erythema multiforme, have been reported very rarely in association with the use of oxcarbazepine (Trileptal). Patients with serious dermatological reactions may require hospitalization, as these conditions may be life-threatening and very rarely be fatal. Oxcarbazepine-associated cases occurred in both children and adults. The median time to onset was 19 days. Several isolated cases of recurrence of the serious skin reaction when re-challenged with oxcarbazepine were reported. Should a patient develop a skin reaction, consideration should be given to discontinuing treatment and prescribing another anti-epileptic drug.
Pharmacogenomics: There is growing evidence that different Human Leukocyte Antigen (HLA) alleles play a role in association with adverse cutaneous reactions in predisposed patients.
Association with HLA-B*1502: Retrospective studies in patients of Han Chinese and Thai origin found a strong correlation between SJS/TEN skin reactions associated with carbamazepine and the presence in these patients of the Human Leukocyte Antigen (HLA)-B*1502 allele. As the chemical structure of oxcarbazepine is similar to that of carbamazepine, there is a possibility that patients carrying the HLA-B*1502 allele also have an increased risk of SJS/TEN skin reactions with oxcarbazepine.
The frequency of HLA-B*1502 allele ranges from 2 to 12% in Han Chinese populations and is about 8% in Thai populations, and above 15% in the Philippines and some Malaysian populations. Allele frequencies up to about 2% and 6% have been reported in Korea and India, respectively. The frequency of the HLA-B*1502 allele is negligible in persons from European descent, several African populations, indigenous peoples of the Americas, Hispanic populations sampled and in Japanese (< 1%).
The allele frequencies listed here represent the percentage of chromosomes in the specified population that carry the allele of interest, meaning that the percentage of patients who carry a copy of the allele on at least one of their two chromosomes (i.e., the "carrier frequency") is nearly twice as high as the allele frequency. Therefore, the percentage of patients who may be at risk is nearly twice the allele frequency.
Testing for the presence of the HLA-B*1502 allele should be considered in patients with ancestry in genetically at-risk populations prior to initiating treatment (see Information for the healthcare professionals as follows). The use of oxcarbazepine (Trileptal) should be avoided in tested patients who are found to be positive for HLA-B*1502 unless the benefits clearly outweigh the risks. HLA-B*1502 may be a risk factor for the development of SJS/TEN in Chinese patients taking other anti-epileptic drugs (AED) associated with SJS/TEN. Consideration should therefore be given to avoid use of other drugs associated with SJS/TEN in HLA-B*1502 positive patients, when alternative therapies are otherwise equally acceptable. Screening is not generally recommended in patients from populations in which the prevalence of HLA-B*1502 is low or in current users, as the risk of SJS/TEN is largely confined to the first few months of therapy, regardless of HLA-B*1502 status.
Association with HLA-A*3101: Human Leukocyte Antigen (HLA)-A*3101 may be a risk factor for the development of cutaneous adverse drug reactions such as SJS, TEN, DRESS, AGEP and maculopapular rash.
The frequency of the HLA-A*3101 allele varies widely between ethnic populations and its frequency is about 2 to 5% in European populations and about 10% in the Japanese population. The frequency of this allele is estimated to be less than 5% in the majority of Australian, Asian, African and North American populations with some exceptions within 5 to 12%. Frequency above 15% has been estimated in some ethnic groups in South America (Argentina and Brazil), North America (US Navajo and Sioux, and Mexico Sonora Seri) and Southern India (Tamil Nadu) and between 10% to 15% in other native ethnicities in these same regions.
The allele frequencies listed here represent the percentage of chromosomes in the specified population that carry the allele of interest, meaning that the percentage of patients who carry a copy of the allele on at least one of their two chromosomes (i.e., the "carrier frequency") is nearly twice as high as the allele frequency. Therefore, the percentage of patients who may be at risk is nearly twice the allele frequency.
There is some data that suggest HLA-A*3101 is associated with an increased risk of carbamazepine-induced cutaneous adverse drug reactions including SJS, TEN, drug rash with eosinophilia (DRESS), or less severe acute generalized exanthematous pustulosis (AGEP) and maculopapular rash.
There are insufficient data to support a recommendation for testing the presence of the HLA-A*3101 allele in patients, prior to initiating treatment with oxcarbazepine. Genetic screening is generally not recommended for any current oxcarbazepine users, as the risk of SJS/TEN, AGEP, DRESS and maculopapular rash is largely confined to the first few months of therapy, regardless of HLA-A*3101 status.
Limitation of genetic screening: Genetic screening results must never substitute for appropriate clinical vigilance and patient management. Many Asian patients positive for HLA-B*1502 and treated with oxcarbazepine (Trileptal) will not develop SJS/TEN and patients negative for HLA-B*1502 of any ethnicity can still develop SJS/TEN. Similarly, many patients positive for HLA-A*3101 and treated with oxcarbazepine (Trileptal) will not develop SJS, TEN, DRESS, AGEP or maculopapular rash, and patients negative for HLA-A*3101 of any ethnicity can still develop these severe cutaneous adverse reactions. The role of other possible factors in the development of, and morbidity from, these severe cutaneous adverse reactions, such as AED dose, compliance, concomitant medications, co-morbidities, and the level of dermatologic monitoring have not been studied.
Information for the healthcare professionals: If testing for the presence of the HLA-B*1502 allele is performed, high-resolution "HLA-B*1502 genotyping" is recommended. The test is positive if either one or two HLA-B*1502 alleles are detected and negative if no HLA-B*1502 alleles are detected. Similarly, if testing for the presence of the HLA-A*3101 allele is performed, high resolution "HLA-A*3101 genotyping" is recommended. The test is positive if either one or two HLA-A*3101 alleles are detected and negative if no HLA-A*3101 alleles are detected.
Risk of seizure aggravation: Risk of seizure aggravation has been reported with oxcarbazapine (Trileptal). The risk of seizure aggravation is seen especially in children but may also occur in adults. In case of seizure aggravation, treatment should be discontinued.
Hyponatraemia: Serum sodium levels below 125 mmol/L, usually asymptomatic and not requiring adjustment of therapy, have been observed in up to 2.7% of treated patients. Experience from clinical trials shows that serum sodium levels returned towards normal when the dosage was reduced, discontinued or the patient was treated conservatively (e.g. restricted fluid intake).
In patients with pre-existing renal conditions associated with low sodium levels (e.g. inappropriate ADH secretion like syndrome) or in patients treated concomitantly with sodium-lowering drugs (e.g. diuretics, drugs associated with inappropriate ADH secretion), serum sodium levels should be measured prior to initiating therapy. Thereafter, serum sodium levels should be measured after approximately two weeks and then at monthly intervals for the first three months during therapy, or according to clinical need. These risk factors may apply especially to elderly patients.
For patients on oxcarbazepine (Trileptal) therapy when starting on sodium-lowering drugs, the same approach for sodium checks should be followed. In general, if clinical symptoms suggestive of hyponatraemia occur on therapy (see Adverse Reactions), serum sodium measurement may be considered. Other patients may have serum sodium assessed as part of their routine laboratory studies.
All patients with cardiac insufficiency and secondary heart failure should have regular weight measurements to determine occurrence of fluid retention. In case of fluid retention or worsening of the cardiac condition, serum sodium levels should be checked. If hyponatraemia is observed, water restriction is an important counter-measure. As oxcarbazepine may, very rarely, lead to impairment of cardiac conduction, patients with pre-existing conduction disturbances (e.g. AV-block, arrhythmia) should be monitored carefully.
Hypothyroidism: Hypothyroidism is a very rare adverse drug reaction of oxcarbazepine. Considering the importance of thyroid hormones in children's development after birth, it is advisable to perform a thyroid function test before the start of therapy in the pediatric age group, especially in children aged two years or below. Thyroid function monitoring is recommended in the pediatric age group while on therapy.
Hepatic function: Very rare cases of hepatitis have been reported, which in most cases resolved favorably. In case of suspected hepatitis, discontinuation of oxcarbazepine (Trileptal) should be considered. Caution should be exercised when treating patients with severe hepatic impairment (see Dosage & Administration and Pharmacology under Actions).
Renal function: In patients with impaired renal function (creatinine clearance less than 30 mL/min), caution should be exercised during treatment especially with regard to the starting dose and up titration of the dose (see Dosage & Administration and Pharmacology under Actions).
Hematological effects: Very rare reports of agranulocytosis, aplastic anemia and pancytopenia have been seen in patients treated with oxcarbazepine (Trileptal) during post-marketing experience (see Adverse Reactions). However, due to the very low incidence of these conditions and confounding factors (e.g. underlying disease, concomitant medication), causality cannot be established.
Discontinuation of the drug should be considered if any evidence of significant bone marrow depression develops.
Suicidal ideation and behavior: Suicidal ideation and behavior have been reported in patients treated with antiepileptic agents in several indications. A meta-analysis of randomized placebo-controlled trials of antiepileptic drugs has shown a small increased risk of suicidal ideation and behavior. The mechanism of this risk is not known.
Therefore patients should be monitored for signs of suicidal ideation and behavior and appropriate treatment should be considered. Patients (and caregivers of patients) should be advised to seek medical advice should signs of suicidal ideation or behavior emerge.
Interactions: Hormonal contraceptives: Female patients of childbearing age should be warned that the concurrent use of oxcarbazepine (Trileptal) with hormonal contraceptives may render this type of contraception ineffective (see Use in Pregnancy & Lactation and Interactions). Additional, non-hormonal forms of contraception are therefore recommended when using oxcarbazepine.
Alcohol: Caution should be exercised if alcohol is taken in combination with oxcarbazepine (Trileptal) therapy, due to a possible additive sedative effect.
Withdrawal effects: As with all antiepileptic drugs, oxcarbazepine (Trileptal) should be withdrawn gradually to minimize the potential of increased seizure frequency.
Driving and using machines: Adverse reactions such as dizziness, somnolence, ataxia, diplopia, blurred vision, visual disturbances, hyponatremia and depressed level of consciousness were reported (for the complete list of ADRs see Adverse Reactions), especially at the start of treatment or in connection with dose adjustments (more frequently during the up titration phase). Patients should therefore exercise due caution when driving a vehicle or operating machinery.
Use In Pregnancy & Lactation
Based on data in a North American pregnancy registry, the rate of major congenital malformations, defined as a structural abnormality with surgical, medical, or cosmetic importance, diagnosed within 12 weeks of birth was 2.0% (95% CI 0.6 to 5.1%) among mothers exposed to oxcarbazepine monotherapy in the first trimester. When compared with pregnant women not exposed to any antiepileptic drugs the relative risk (RR) of congenital abnormality in pregnant women on oxcarbazepine is (RR) 1.6, 95% CI 0.46 to 5.7.
Clinical considerations: Taking these data into consideration: If women receiving oxcarbazepine become pregnant, or plan to become pregnant, or if the need to initiate treatment arises during pregnancy, the drug's potential benefits must be carefully weighed against the potential risk of fetal malformations. This is particularly important during the first three months of pregnancy.
Minimum effective doses should be given.
In women of childbearing age, oxcarbazepine (Trileptal) should be administered as monotherapy, whenever possible.
Patients should be counseled regarding the possibility of an increased risk of malformations and given the opportunity of antenatal screening.
During pregnancy, an effective antiepileptic treatment should not be interrupted, since the aggravation of the illness is detrimental to both the mother and the fetus.
Monitoring and prevention: Antiepileptic drugs may contribute to folic acid deficiency, a possible contributory cause of fetal abnormality. Folic acid supplementation is recommended before and during pregnancy.
Due to physiological changes during pregnancy, plasma levels of the active metabolite of oxcarbazepine, the 10-monohydroxy derivative (MHD), may gradually decrease throughout pregnancy. It is recommended that clinical response should be monitored carefully in women receiving treatment during pregnancy and determination of changes in MHD plasma concentrations should be considered to ensure that adequate seizure control is maintained throughout pregnancy (see Dosage & Administration and Pharmacology under Actions). Postpartum MHD plasma levels may also be considered for monitoring especially in the event that medication was increased during pregnancy.
In the newborn child: Bleeding disorders in the newborn caused by antiepileptic agents have been reported. As a precaution, vitamin K1 should be administered as a preventive measure in the last few weeks of pregnancy and to the newborn.
Oxcarbazepine and its active metabolite (MHD) cross the placenta. Neonatal and maternal plasma MHD concentrations were similar in one case.
Animal data: Standard reproductive toxicity studies in rodents and rabbits revealed effects such as increases in the incidence of embryo-fetal mortality and/or some delay in antenatal and/or postnatal growth of the offspring at maternally toxic dose levels. There was an increase in rat fetal malformations in one of the eight embryo-fetal toxicity studies, which were conducted with either oxcarbazepine or MHD, at doses which also caused maternal toxicity. The overall evidence from all animal studies indicates that oxcarbazepine has minor teratogenic potential at doses relevant to humans. However, the animal studies were insufficient to rule out a teratogenic effect of oxcarbazepine.
Lactation: Risk summary: Oxcarbazepine and its active metabolite (MHD) are excreted in human breast milk. A milk-to-plasma concentration ratio of 0.5 was found for both. The effects on the infant exposed to oxcarbazepine (Trileptal) by this route are unknown. Therefore, oxcarbazepine should not be used during breast-feeding.
Females and males of reproductive potential: Contraception: Women of child bearing potential should be advised to use highly effective contraception (preferably non-hormonal; e.g. intrauterine implants) while on treatment. Oxcarbazepine (Trileptal) may result in a failure of the therapeutic effect of oral contraceptive drugs containing ethinylestradiol (EE) and levonorgestrel (LNG) (see Precautions and Interactions).
Infertility: There are no human data on fertility.
In rats, fertility in both sexes was unaffected by oxcarbazepine or MHD at oral doses up to 150 and 450 mg/kg/day, respectively. However, disruption of estrous cyclicity and reduced numbers of corpora lutea, implantations and live embryos were observed in female animals at the highest dose of MHD.
Adverse Reactions
In clinical trials, adverse events (AEs) were generally mild to moderate in severity, of transient nature and occurred predominantly at the start of treatment.
The analysis of the undesirable effect profile by body system is based on AEs from clinical trials assessed as related to oxcarbazepine (Trileptal). In addition, clinically meaningful reports on adverse experiences from named patient programs and post-marketing experience were taken into account.
Tabulated summary of adverse drug reactions from clinical trials: Adverse drug reactions from clinical trials (Table 2) are listed by MedDRA system organ class. Within each system organ class, the adverse drug reactions are ranked by frequency, with the most frequent reactions first. Within each frequency grouping, adverse drug reactions are presented in order of decreasing seriousness. In addition, the corresponding frequency category for each adverse drug reaction is based on the following convention (CIOMS III): 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).
Film-coated tablet: (See Table 2.)
Adverse drug reactions from spontaneous reports and literature cases (frequency not known): The following adverse drug reactions have been derived from post-marketing experience with oxcarbazepine (Trileptal) via spontaneous case reports and literature cases. Because these reactions are reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency which is therefore categorized as not known. Adverse drug reactions are listed according to system organ classes in MedDRA. Within each system organ class, ADRs are presented in order of decreasing seriousness.
Metabolism and nutrition disorders: Inappropriate ADH secretion like syndrome with signs and symptoms of lethargy, nausea, dizziness, decrease in serum (blood) osmolality, vomiting, headache, confusional state or other neurological signs and symptoms.
Skin and subcutaneous tissue disorders: Drug rash with eosinophilia and systemic symptoms (DRESS), acute generalized exanthematous pustulosis (AGEP).
Injury, poisoning and procedural complications: Fall.
Nervous system disorders: Speech disorders (including dysarthria); more frequent during up titration of oxcarbazepine (Trileptal) dose.
Musculoskeletal, connective tissue and bone disorders: There have been reports of decreased bone mineral density, osteopenia, osteoporosis and fractures in patients on long-term therapy with oxcarbazepine. The mechanism by which oxcarbazepine affects bone metabolism has not been identified.
Drug Interactions
Enzyme induction: Oxcarbazepine and MHD induce, in vitro and in vivo, the cytochromes CYP3A4 and CYP3A5 responsible for the metabolism of dihydropyridine calcium antagonists, oral contraceptives, and antiepileptic drugs (e.g. carbamazepine), resulting in a lower plasma concentration of these drugs (see as follows). A decrease in plasma concentrations may also be observed for other drugs mainly metabolized by CYP3A4 and CYP3A5, for example immunosuppressants (e.g. ciclosporin).
In vitro, oxcarbazepine and MHD are weak inducers of UDP-glucuronyl transferase. Therefore, in vivo they are unlikely to have an effect on drugs which are mainly eliminated by conjugation through the UDP-glucuronyl transferases (e.g. valproic acid, lamotrigine). Even in view of the weak induction potential of oxcarbazepine and MHD, a higher dose of concomitantly used drugs which are metabolized via CYP3A4 or via conjugation (UDPGT) may be necessary. In the case of discontinuation of oxcarbazepine (Trileptal) therapy, a dose reduction of the concomitant medication may be necessary.
Induction studies conducted with human hepatocytes confirmed oxcarbazepine and MHD as weak inducers of isoenzymes of the 2B and 3A4 CYP sub-family. The induction potential of oxcarbazepine/MHD on other CYP isoenzymes is not known.
Antiepileptic drugs and enzyme inducing drugs: Potential interactions between oxcarbazepine and other antiepileptic drugs were assessed in clinical studies. The effect of these interactions on mean AUCs and Cmin are summarized in the following Table 4. (See Table 4.)
Strong inducers of cytochrome P450 enzymes and/or UGT (e.g. rifampicin, carbamazepine, phenytoin and phenobarbital) have been shown to decrease the plasma/serum levels of MHD (29-49%).
No autoinduction has been observed with oxcarbazepine (Trileptal).
Hormonal contraceptives: Oxcarbazepine was shown to have an influence on the two components, ethinylestradiol (EE) and levonorgestrel (LNG), of an oral contraceptive. The mean AUC values of EE and LNG were decreased by 48-52 % and 32-52 %, respectively. Studies with other oral or implant contraceptives have not been conducted. Therefore, concurrent use with hormonal contraceptives may render these contraceptives ineffective (see Precautions and Use in Pregnancy & Lactation).
Calcium antagonists: After repeated co-administration, the AUC values of felodipine were lowered by 28 %. However, the plasma levels remained in the recommended therapeutic range.
On the other hand, verapamil produced a decrease of 20 % in the plasma levels of MHD. This decrease in MHD plasma levels is not considered to be of clinical relevance.
Other drug interactions: Cimetidine, erythromycin and dextropropoxyphene had no effect on the pharmacokinetics of MHD, whereas viloxazine produced minor changes in the MHD plasma levels (about 10 % higher after repeated co-administration). Results with warfarin show no evidence of interaction with either single or repeated doses of oxcarbazepine.
Caution For Usage
Instructions for Use and Handling: Oral suspension: Before taking oxcarbazepine (Trileptal) oral suspension, the bottle should be shaken well and the dose prepared immediately afterwards. The prescribed amount of oral suspension should be withdrawn from the bottle using the oral syringe supplied. The amount should be rounded to the nearest 0.5 mL when using the 10 mL syringe (supplied with the bottle containing 250 mL for older children and adults) and to the nearest 0.1 mL when using the 1 mL syringe (supplied with the bottle containing 100 mL for younger children). Oxcarbazepine (Trileptal) oral suspension may be swallowed directly from the syringe or can be mixed in a small glass of water just prior to administration. After each use, the bottle should be closed and the outside of the syringe wiped with a dry, clean tissue.
Storage
Oral suspension: Use within 7 weeks after first opening the bottle.
Action
Pharmacodynamics: Oxcarbazepine and its active metabolite (MHD), are potent and efficacious anticonvulsants in animals. They protected rodents against generalized tonic-clonic and, to a lesser degree, clonic seizures, and abolished or reduced the frequency of chronically recurring partial seizures in Rhesus monkeys with aluminum implants. No tolerance (i.e. attenuation of anticonvulsive activity) against tonic-clonic seizures was observed when mice and rats were treated daily for 5 days or 4 weeks, respectively, with oxcarbazepine or MHD.
Clinical Studies: A total of 10 double blind, well controlled trials, 2 in adjunctive therapy and 8 in monotherapy were conducted in patients with partial seizures which included the seizure subtypes of simple, complex and partial seizures evolving to secondarily generalized seizures. All comparative trials also included patients with generalized tonic-clonic seizures.
Two dose-control monotherapy substitution trials in which patients received a variety of concomitant antiepileptic drugs which included carbamazepine, gabapentin, lamotrigine, phenytoin, and valproate confirm efficacy when these antiepileptic drugs were substituted by oxcarbazepine (Trileptal). Two trials were conducted in children (aged 3 to 17 years), one in adjunctive therapy versus placebo, the other a monotherapy comparison with phenytoin.
Efficacy was demonstrated with doses ranging from 600 mg/day to 2,400 mg/day in all the primary efficacy parameters which included mean or percentage change in seizure frequency from baseline in the adjunctive trials and time to meeting pre-defined exit criteria or the percentage of patients meeting exit criteria in the monotherapy trials.
An adjunctive therapy, rater-blind, trial in children (aged 1 month to less than 4 years) with inadequately-controlled partial seizures on one to two concomitant antiepileptic drugs was conducted, comparing two doses of oxcarbazepine. The primary measure of effectiveness was a between group comparison of the absolute change in study specific seizure frequency per 24 hours compared to the seizure frequency at baseline. This comparison was statistically significant in favor of oxcarbazepine (Trileptal) 60 mg/kg/day.
A monotherapy, rater-blind, trial in children (aged 1 month to 16 years) with inadequately controlled or new-onset partial seizures was conducted comparing two doses of oxcarbazepine. The primary measure of effectiveness was a between group comparison of the time to meet exit criteria which was not statistically significant. The majority of patients in both treatment groups did not experience any video EEG-confirmed seizures during the study and completed this 5-day study without exiting.
It has been shown that oxcarbazepine has similar efficacy to other first line antiepileptic drugs (i.e. valproic acid, phenytoin and carbamazepine) with a statistically significantly better tolerability profile than phenytoin as judged by withdrawals due to adverse events and, a statistically significant longer retention rate (i.e. proportion of patients who stayed on treatment). Similar proportions of patients with partial and generalized tonic-clonic seizures were seizure free over the 12 month treatment period of these trials.
Pharmacokinetics: Absorption: Following oral administration, oxcarbazepine (Trileptal) is completely absorbed and extensively metabolized to its pharmacologically active metabolite (10-monohydroxy derivative, MHD).
The tablet and suspension formulations of oxcarbazepine are bioequivalent since the geometric mean ratio (90% confidence interval) of single dose and steady state Cmax and AUC of MHD were in the range 0.85 to 1.06.
In a mass balance study in man, only 2% of total radioactivity in plasma was due to unchanged oxcarbazepine, approximately 70% was due to MHD, and the remainder attributable to minor secondary metabolites which were rapidly eliminated.
Food has no effect on the rate and extent of absorption of oxcarbazepine, therefore, it can be taken with or without food (see Dosage & Administration).
Film-coated tablet: After single dose administration of 600 mg tablets to healthy male volunteers under fasted conditions, the mean Cmax value of MHD was 34 micromol/L, with a corresponding median tmax of 4.5 hours.
Oral Suspension: After single dose administration of 600 mg oral suspension to healthy male volunteer under fasted conditions, the mean Cmax value of MHD was 24.9 micromol/L, with a corresponding median Tmax of 6 hours.
Distribution: The apparent volume of distribution of MHD is 49 liters.
Approximately 40% of MHD is bound to serum proteins, predominately to albumin. Binding was independent of the serum concentration within the therapeutically relevant range. Oxcarbazepine and MHD do not bind to alpha-1-acid glycoprotein.
Biotransformation/Metabolism: Oxcarbazepine is rapidly reduced by cytosolic enzymes in the liver to MHD, which is primarily responsible for the pharmacological effect. MHD is metabolized further by conjugation with glucuronic acid. Minor amounts (4% of the dose) are oxidized to the pharmacologically inactive metabolite (10, 11-dihydroxy derivative, DHD).
Elimination: Oxcarbazepine is cleared from the body mostly in the form of metabolites, which are predominantly excreted by the kidneys. More than 95% of the dose appears in the urine, with less than 1% as unchanged oxcarbazepine. Fecal excretion accounts for less than 4% of the administered dose. Approximately 80% of the dose is excreted in the urine either as glucuronides of MHD (49%) or as unchanged MHD (27%), whereas the inactive DHD accounts for approximately 3% and conjugates of oxcarbazepine account for 13% of the dose.
Oxcarbazepine is rapidly eliminated from the plasma with apparent half-life values between 1.3 and 2.3 hours. In contrast, the apparent plasma half-life of MHD averaged 9.3 ± 1.8 h.
Linearity/non-linearity: Steady-state plasma concentrations of MHD are reached within 2 to 3 days in patients when oxcarbazepine (Trileptal) is given twice a day. At steady-state, the pharmacokinetics of MHD are linear and show dose proportionality across the dose range of 300 to 2,400 mg/day.
Special populations: Hepatic impairment: The pharmacokinetics and metabolism of oxcarbazepine and MHD were evaluated in healthy volunteers and hepatically impaired subjects after a single 900 mg oral dose. Mild to moderate hepatic impairment did not affect the pharmacokinetics of oxcarbazepine and MHD. Oxcarbazepine (Trileptal) has not been studied in patients with severe hepatic impairment.
Renal impairment: There is a linear correlation between creatinine clearance and the renal clearance of MHD. When oxcarbazepine is administered as a single 300 mg dose in renally impaired patients (creatinine clearance <30 mL/min), the elimination half-life of MHD is prolonged by up to 19 hours, with a two fold increase in AUC.
Pediatric patients (below 18 years): Weight-adjusted MHD clearance decreases as age and weight increases approaching that of adults. The mean weight-adjusted clearance in children 1 month to less than 4 years of age is 93% higher than that of adults. Therefore, MHD exposure in these children is expected to be about one-half that of adults when treated with a similar weight-adjusted dose. The mean weight-adjusted clearance in children 4 to 12 years of age is 43% higher than that of adults. Therefore, MHD exposure in these children is expected to be about two-thirds that of adults when treated with a similar weight-adjusted dose. As weight increases, for patients 13 years of age and above, the weight-adjusted MHD clearance is expected to reach that of adults.
Pregnancy: Due to physiological changes during pregnancy, MHD plasma levels may gradually decrease throughout pregnancy (see Dosage & Administration and Use in Pregnancy & Lactation).
Geriatric patients (65 years or above): Following administration of single (300 mg) and multiple doses (600 mg/day) in elderly volunteers (60 to 82 years of age), the maximum plasma concentrations and AUC values of MHD were 30 to 60% higher than in younger volunteers (18 to 32 years of age). Comparisons of creatinine clearance in young and elderly volunteers indicate that the difference was due to age-related reductions in creatinine clearance. No special dose recommendations are necessary because therapeutic doses are individually adjusted.
Gender: No gender related pharmacokinetic differences have been observed in children, adults, or the elderly.
Toxicology: Non-Clinical Safety Data: Preclinical data indicated no special hazard for humans based on repeated dose toxicity, safety pharmacology and genotoxicity studies with oxcarbazepine and the pharmacologically active metabolite, monohydroxy derivative (MHD).
Immunotoxicity: Immunostimulatory tests in mice showed that MHD (and to a lesser extent oxcarbazepine) can induce delayed hypersensitivity.
Mutagenicity: Oxcarbazepine increased mutation frequencies in one Ames test in vitro in the absence of metabolic activation in one of five bacterial strains. Oxcarbazepine and MHD produced increases in chromosomal aberrations and/or polyploidy in the Chinese hamster ovary assay in vitro in the absence of metabolic activation. MHD was negative in the Ames test, and no mutagenic or clastogenic activity was found with either oxcarbazepine or MHD in V79 Chinese hamster cells in vitro. Oxcarbazepine and MHD were both negative for clastogenic or aneugenic effects (micronucleus formation) in an in vivo rat bone marrow assay.
Carcinogenicity: In the carcinogenicity studies, liver (rats and mice), testicular and female genital tract granular cell (rats) tumors were induced in treated animals. The occurrence of liver tumors was most likely a consequence of the induction of hepatic microsomal enzymes; an inductive effect which, although it cannot be excluded, is weak or absent in patients treated with oxcarbazepine (Trileptal). Testicular tumors may have been induced by elevated luteinizing hormone concentrations. Due to the absence of such an increase in humans, these tumors are considered to be of no clinical relevance. A dose-related increase in the incidence of granular cell tumors of the female genital tract (cervix and vagina) was noted in the rat carcinogenicity study with MHD. These effects occurred at exposure levels comparable with the anticipated clinical exposure. The mechanism for the development of these tumors has not been fully elucidated but could be related to increased estradiol levels specific to the rat. The clinical relevance of these tumors is unclear.
Reproductive toxicity: For reproductive toxicity, see Use in Pregnancy & Lactation.
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- Oxcarbazepine