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Clinically significant hyponatremia (sodium < 125 mmol/L) may develop during Oxtellar XR™ use. Serum sodium levels less than 125 mmol/L have occurred in immediate-release oxcarbazepine-treated patients generally in the first three months of treatment. However, clinically significant hyponatremia may develop more than a year after initiating therapy.
Most immediate-release oxcarbazepine-treated patients who developed hyponatremia were asymptomatic in clinical trials. However, some of these patients had their dose reduced, discontinued, or had their fluid intake restricted for hyponatremia. Serum sodium levels returned toward normal when the dosage was reduced or discontinued, or when the patient was treated conservatively (e.g., fluid restriction). Post-marketing cases of symptomatic hyponatremia have been reported during post-marketing use of immediate-release oxcarbazepine.
Among treated patients in a controlled trial of adjunctive therapy with Oxtellar XR™ in 366 adults with complex partial seizures, 1 patient receiving 2400 mg experienced a severe reduction in serum sodium (117 mEq/L) requiring discontinuation from treatment, while 2 other patients receiving 1200 mg experienced serum sodium concentrations low enough (125 and 126 mEq/L) to require discontinuation from treatment. The overall incidence of clinically significant hyponatremia in patients treated with Oxtellar XR™ was 1.2%, although slight shifts in serum sodium concentrations from Normal to Low ( < 135 mEq/L) were observed for the 2400 mg (6.5%) and 1200 mg (9.8%) groups compared to placebo (1.7%).Measure serum sodium concentrations if patients develop symptoms of hyponatremia (e.g., nausea, malaise, headache, lethargy, confusion, obtunded consciousness, or increase in seizure frequency or severity). Consider measurement of serum sodium concentrations during treatment with Oxtellar XR™, particularly if the patient receives concomitant medications known to decrease serum sodium levels (for example, drugs associated with inappropriate ADH secretion).
Anaphylactic Reactions and Angioedema
Rare cases of anaphylaxis and angioedema involving the larynx, glottis, lips and eyelids have been reported in patients after taking the first or subsequent doses of immediate-release oxcarbazepine. Angioedema associated with laryngeal edema can be fatal. If a patient develops any of these reactions after treatment with Oxtellar XR™, discontinue the drug and initiate an alternative treatment. Do not rechallenge these patients with Oxtellar XR™.
Hypersensitivity Reactions in Patients with Hypersensitivity to Carbamazepine
Inform patients who have had hypersensitivity reactions to carbamazepine that approximately 25%-30% of them will experience hypersensitivity reactions with Oxtellar XR™. Question patients about any prior adverse reactions with carbamazepine. Patients with a history of hypersensitivity reactions to carbamazepine should ordinarily be treated with Oxtellar XR™ only if the potential benefit justifies the potential risk. Discontinue Oxtellar XR™ immediately if signs or symptoms of hypersensitivity develop.
Serious Dermatological Reactions
Serious dermatological reactions, including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), have occurred in both children and adults in treated with immediate-release oxcarbazepine use. The median time of onset for reported cases was 19 days. Such serious skin reactions may be life threatening, and some patients have required hospitalization with very rare reports of fatal outcome. Recurrence of the serious skin reactions following rechallenge with immediate-release oxcarbazepine has also been reported.
The reporting rate of TEN and SJS associated with immediate-release oxcarbazepine use, which is generally accepted to be an underestimate due to underreporting, exceeds the background incidence rate estimates by a factor of 3- to 10-fold. Estimates of the background incidence rate for these serious skin reactions in the general population range between 0.5 to 6 cases per million-person years. Therefore, if a patient develops a skin reaction while taking Oxtellar XR™, consider discontinuing Oxtellar XR™ use and prescribing another AED.
Suicidal Behavior and Ideation
Antiepileptic drugs (AEDs), including Oxtellar XR™, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication. Monitor patients treated with any AED for any indication for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior.
Pooled analyses of 199 placebo-controlled clinical trials (mono- and adjunctive therapy) of 11 different AEDs showed that patients randomized to one of the AEDs had approximately twice the risk (adjusted Relative Risk 1.8, 95% CI:1.2, 2.7) of suicidal thinking or behavior compared to patients randomized to placebo. In these trials, which had a median treatment duration of 12 weeks, the estimated incidence rate of suicidal behavior or ideation among 27,863 AED-treated patients was 0.43%, compared to 0.24% among 16,029 placebo-treated patients, representing an increase of approximately one case of suicidal thinking or behavior for every 530 patients treated. There were four suicides in drug-treated patients in the trials and none in placebo-treated patients, but the number is too small to allow any conclusion about drug effect on suicide.
The increased risk of suicidal thoughts or behavior with AEDs was observed as early as one week after starting drug treatment with AEDs and persisted for the duration of treatment assessed. Because most trials included in the analysis did not extend beyond 24 weeks, the risk of suicidal thoughts or behavior beyond 24 weeks could not be assessed.
The risk of suicidal thoughts or behavior was generally consistent among drugs in the data analyzed. The finding of increased risk with AEDs of varying mechanisms of action and across a range of indications suggests that the risk applies to all AEDs used for any indication. The risk did not vary substantially by age (5-100 years) in the clinical trials analyzed. Table 2 shows absolute and relative risk by indication for all evaluated AEDs.
Table 2: Risk by Indication for Antiepileptic Drugs in the Pooled
|Indication||Placebo Patients with Events per 1,000 Patients||Drug Patients with Events per 1,000 Patients||Relative Risk: Incidence of Events in Drug Patients/Incidence in Placebo Patients||Risk Difference: Additional Drug Patients with Events per 1,000 Patients|
The relative risk for suicidal thoughts or behavior was higher in clinical trials for epilepsy than in clinical trials for psychiatric or other conditions, but the absolute risk differences were similar for the epilepsy and psychiatric indications.
Anyone considering prescribing Oxtellar XR™ or any other AED must balance the risk of suicidal thoughts or behavior with the risk of untreated illness. Epilepsy and many other illnesses for which AEDs are prescribed are themselves associated with morbidity and mortality and an increased risk of suicidal thoughts and behavior. Should suicidal thoughts and behavior emerge during Oxtellar XR™ treatment, the prescriber needs to consider whether the emergence of these symptoms in any given patient may be related to the illness being treated.
Patients, their caregivers, and families should be informed that AEDs increase the risk of suicidal thoughts and behavior and should be advised of the need to be alert for the emergence or worsening of the signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm. Behaviors of concern should be reported immediately to healthcare providers.
Withdrawal of AEDs
As with all AEDs, Oxtellar XR™ should be withdrawn gradually to minimize the potential of increased seizure frequency.
Multi-organ hypersensitivity reactions have occurred in close temporal association (median time to detection 13 days: range 4-60) to the initiation of immediate-release oxcarbazepine therapy in adult and pediatric patients. Although there have been a limited number of reports, many of these cases resulted in hospitalization and some were life-threatening. Signs and symptoms of this disorder were diverse; however, patients typically, although not exclusively, presented with fever and rash associated with other organ system involvement. These included the following: hematologic and lymphatic (e.g., eosinophilia, thrombocytopenia, lymphadenopathy, leukopenia, neutropenia, splenomegaly), hepatobiliary (e.g., hepatitis, liver function test abnormalities), renal (e.g., proteinuria, nephritis, oliguria, renal failure), muscles and joints (e.g., joint swelling, myalgia, arthralgia, asthenia), nervous system (e.g., hepatic encephalopathy), respiratory (e.g., dyspnea, pulmonary edema, asthma, bronchospasm, interstitial lung disease), hepatorenal syndrome, pruritus, and angioedema. Because the disorder is variable in its expression, other organ system symptoms and signs, not noted here, may occur. If this reaction is suspected, discontinue Oxtellar XR™ and initiate an alternative treatment.
Rare reports of pancytopenia, agranulocytosis, and leukopenia have been seen in patients treated with immediate-release oxcarbazepine during post-marketing experience. Discontinuation of Oxtellar XR™ should be considered if any evidence of these hematologic reactions develops.
Risk of Seizures in the Pregnant Patient
Due to physiological changes during pregnancy, plasma concentrations of the active metabolite of oxcarbazepine, the 10-monohydroxy derivative (MHD), may gradually decrease throughout pregnancy. Monitor patients carefully during pregnancy and through the postpartum period because MHD concentrations may increase after delivery.
Laboratory data from clinical trials suggest that immediate-release oxcarbazepine may be associated with decreases in T4, without changes in T3 or TSH.
Patient Counseling Information
See FDA-Approved patient labeling (Medication Guide).
Inform patients and caregivers of the availability of a Medication Guide. Instruct patients and caregivers to read the Medication Guide prior to taking Oxtellar XR™.
- Advise patients to take the tablet whole with water or other liquid, and not to cut, chew or crush the tablet. Cutting, chewing or crushing Oxtellar XR™ tablet could affect its performance.
- Advise patients to take Oxtellar XR™ on an empty stomach. This means they should take Oxtellar XR™ at least one hour before food or at least two hours after food [see CLINICAL PHARMACOLOGY].
- Advise patients that Oxtellar XR™ may reduce serum sodium concentrations especially if they are taking other medications that can lower sodium. Advise patients to report symptoms of low sodium like nausea, tiredness, lack of energy, confusion, and more frequent or more severe seizures [see WARNINGS AND PRECAUTIONS].
- Anaphylactic reactions and angioedema may occur during treatment with Oxtellar XR™. Advise patients to immediately report signs and symptoms suggesting angioedema (swelling of the face, eyes, lips, tongue or difficulty in swallowing or breathing) and to stop taking the drug until they have consulted with their physician [see WARNINGS AND PRECAUTIONS].
- Inform patients who have exhibited hypersensitivity reactions to carbamazepine that approximately 25%-30% of these patients may also experience hypersensitivity reactions with Oxtellar XR™. If patients experience a hypersensitivity reaction while taking Oxtellar XR™, advise them to consult with their physician immediately [see WARNINGS AND PRECAUTIONS].
- Advise patients that serious skin reactions have been reported in association with immediate-release oxcarbazepine. If patients experience a skin reaction while taking Oxtellar XR™, advise patients to consult with their physician immediately [see WARNINGS AND PRECAUTIONS].
- Instruct patients that a fever associated with other organ system involvement (rash, lymphadenopathy, etc.) occurring during treatment with Oxtellar XR™ may be drug-related and advise them to consult their physician immediately [see WARNINGS AND PRECAUTIONS].
- Advise patients that there have been rare reports of blood disorders reported in patients treated with immediate-release oxcarbazepine. Instruct patients to immediately consult with their physician if they experience symptoms suggestive of blood disorders during treatment with Oxtellar XR™ [see WARNINGS AND PRECAUTIONS].
- Warn female patients of childbearing age that the concurrent use of Oxtellar XR™ with hormonal contraceptives may render this method of contraception less effective [see DRUG INTERACTIONS]. Additional non-hormonal forms of contraception are recommended when using Oxtellar XR™.
- Counsel patients, their caregivers, and families that AEDs, including Oxtellar XR™, may increase the risk of suicidal thoughts and behavior and that they need to be alert for the emergence or worsening of symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm. Advise them to immediately report behaviors of concern to healthcare providers.
- Advise patients to exercise caution if alcohol is taken in combination with Oxtellar XR™ therapy, due to a possible additive sedative effect.
- Advise patients that Oxtellar XR™ may cause dizziness and somnolence. Accordingly, advise patients not to drive or operate machinery until they have gained sufficient experience on Oxtellar XR™ to gauge whether it adversely affects their ability to drive or operate machinery.
- Encourage patients to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry if they become pregnant. This registry is collecting information about the safety of antiepileptic drugs during pregnancy. To enroll, patients can call the toll free number 1-888-233-2334 [see Use in Specific Populations].
- Advise patients that they should call their healthcare provider or poison control center (phone number 1-800-222-1222) if they take too much Oxtellar XR™.
- Discuss with your patient what they should do if they miss a dose.
Carcinogenesis, Mutagenesis, Impairment of Fertility
In two-year carcinogenicity studies, oxcarbazepine was administered in the diet at doses of up to 100 mg/kg/day to mice and by gavage at doses of up to 250 mg/kg/day to rats, and the pharmacologically active 10-hydroxy metabolite (MHD) was administered orally at doses of up to 600 mg/kg/day to rats.
In mice, a dose-related increase in the incidence of hepatocellular adenomas was observed at oxcarbazepine doses ≥ 70 mg/kg/day or approximately 0.1 times the maximum recommended human dose (MRHD) on a mg/m² basis.
In rats, the incidence of hepatocellular carcinomas was increased in females treated with oxcarbazepine at doses ≥ 25 mg/kg/day (0.1 times the MRHD on a mg/m² basis), and incidences of hepatocellular adenomas and/or carcinomas were increased in males and females treated with MHD at doses of 600 mg/kg/day (2.4 times the MRHD on a mg/m² basis) and ≥ 250 mg/kg/day (equivalent to the MRHD on a mg/m² basis), respectively.
There was an increase in the incidence of benign testicular interstitial cell tumors in rats at 250 mg oxcarbazepine/kg/day and at ≥ 250 mg MHD/kg/day, and an increase in the incidence of granular cell tumors in the cervix and vagina in rats at 600 mg MHD/kg/day.
Oxcarbazepine increased mutation frequencies in the Ames test in vitro in the absence of metabolic activation in one of five bacterial strains. Both oxcarbazepine and MHD produced increases in chromosomal aberrations and 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.
Impairment of Fertility
In a fertility study in which rats were administered MHD (50, 150, or 450 mg/kg) orally prior to and during mating and early gestation, estrous cyclicity was disrupted and numbers of corpora lutea, implantations, and live embryos were reduced in females receiving the highest dose (approximately two times the MRHD on a mg/m² basis).
Use In Specific Populations
Oxtellar XR™ plasma concentrations may decrease during pregnancy [see WARNINGS AND PRECAUTIONS]
Pregnancy Category C
There are no adequate and well-controlled clinical studies of Oxtellar XR™ in pregnant women; however, Oxtellar XR™ is closely related structurally to carbamazepine, which is considered to be teratogenic in humans. Given this fact, and the results of the animal studies described, it is likely that Oxtellar XR™ is a human teratogen. Oxtellar XR™ should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Increased incidences of fetal structural abnormalities and other manifestations of developmental toxicity (embryolethality, growth retardation) were observed in the offspring of animals treated with either oxcarbazepine or its active 10-hydroxy metabolite (MHD) during pregnancy at doses similar to the maximum recommended human dose.
When pregnant rats were given oxcarbazepine (30, 300, or 1000 mg/kg) orally throughout the period of organogenesis, increased incidences of fetal malformations (craniofacial, cardiovascular, and skeletal) and variations were observed at the intermediate and high doses (approximately 1.2 and 4 times, respectively, the maximum recommended human dose [MRHD] on a mg/m² basis). Increased embryofetal death and decreased fetal body weights were seen at the high dose. Doses ≥ 300 mg/kg were also maternally toxic (decreased body weight gain, clinical signs), but there is no evidence to suggest that teratogenicity was secondary to the maternal effects.
In a study in which pregnant rabbits were orally administered MHD (20, 100, or 200 mg/kg) during organogenesis, embryofetal mortality was increased at the highest dose (1.5 times the MRHD on a mg/m² basis). This dose produced only minimal maternal toxicity.
In a study in which female rats were dosed orally with oxcarbazepine (25, 50, or 150 mg/kg) during the latter part of gestation and throughout the lactation period, a persistent reduction in body weights and altered behavior (decreased activity) were observed in offspring exposed to the highest dose (0.6 times the MRHD on a mg/m² basis). Oral administration of MHD (25, 75, or 250 mg/kg) to rats during gestation and lactation resulted in a persistent reduction in offspring weights at the highest dose (equivalent to the MRHD on a mg/m² basis).
To provide information regarding the effects of in utero exposure to Oxtellar XR™, physicians are advised to recommend that pregnant patients taking Oxtellar XR™ enroll in the NAAED Pregnancy Registry. This can be done by calling the toll free number 1888-233-2334, and must be done by patients themselves. Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/.
Oxcarbazepine and its active metabolite (MHD) are excreted in human milk. A milk-toplasma concentration ratio of 0.5 was found for both. Because of the potential for serious adverse reactions to Oxtellar XR™ in nursing infants, a decision should be made about whether to discontinue nursing or to discontinue the drug in nursing women, taking into account the importance of the drug to the mother.
The short term safety and effectiveness of Oxtellar XR™ in pediatric patients ages 6 to 16 years with partial onset seizures is supported by:
- An adequate and well-controlled short term safety and efficacy study of Oxtellar XR™ in adults that included pharmacokinetic sampling [see Clinical Studies],
- A pharmacokinetic study of Oxtellar XR™ in pediatric patients ages 4 to 16 years [see CLINICAL PHARMACOLOGY], and
- Safety and efficacy studies with the immediate-release formulation in adults and pediatric patients [see Clinical Studies and ADVERSE REACTIONS].
Oxtellar XR™ is not approved for pediatric patients less than 6 years of age because the size of the tablets are inappropriate for younger children, and has not been studied in patients younger than 4 years of age.
Following administration of single (300 mg) and multiple (600 mg/day) doses of immediate-release oxcarbazepine to elderly volunteers (60-82 years of age), the maximum plasma concentrations and AUC values of MHD were 30%-60% higher than in younger volunteers (18-32 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. Consider starting at a lower dose and lower titration [see DOSAGE AND ADMINISTRATION].
The pharmacokinetics of Oxtellar XR™ has not been evaluated in patients with renal impairment. In patients with severe renal impairment (creatinine clearance < 30 mL/min) given immediate release oxcarbazepine, the elimination half-life of MHD was prolonged with a corresponding two-fold increase in AUC [see CLINICAL PHARMACOLOGY]. In these patients initiate Oxtellar XR™ at a lower starting dose and increase, if necessary, at a slower than usual rate until the desired clinical response is achieved [see DOSAGE AND ADMINISTRATION].
The pharmacokinetics of oxcarbazepine and MHD has not been evaluated in severe hepatic impairment, and therefore is not recommended in these patients. [see CLINICAL PHARMACOLOGY].
Last reviewed on RxList: 11/9/2012
This monograph has been modified to include the generic and brand name in many instances.
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