Drug-drug interaction between methotrexate and levetiracetam resulting in delayed methotrexate elimination

Real-world safety of Levetiracetam: Mining and analysis of its adverse drug reactions based on FAERS database

INTRODUCTION

Levetiracetam is a relatively new and widely utilized anti-seizure medication; however, limited information is available regarding its adverse effects. This study aims to thoroughly investigate, evaluate, and present evidence on the safety profile of Levetiracetam, relying on data from the FDA Adverse Event Reporting System (FAERS) database to facilitate informed clinical decision-making.

METHODS

We employed various statistical measures, including Reporting Odds Ratio (ROR), Proportionate Reporting Ratio (PRR), and analysis by the Medicines and Healthcare Products Regulatory Agency (MHRA), to identify signals of adverse reactions associated with Levetiracetam. Positive signals consistent with Designated Medical Event (DME) were singled out for focused comparison and discussion.

RESULTS

The analysis of 26,182 adverse events linked to Levetiracetam as the primary suspected drug revealed 692 positive signals spanning 22 System Organ Classes (SOCs). Nervous system disorders were the most frequently reported, followed by psychiatric disorders, and general disorders and administration site conditions. 11 positive signals consistent with Preferred Terms (PTs) in DME were identified, predominantly concentrated in 6 SOCs. Among these, rhabdomyolysis, Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS) exhibited relatively large values of A, ROR, and Chi-squared. Additionally, PTs related to spontaneous abortion, drug interaction, urethral atresia, ventricular septal defect, and atrial septal defect showed significant strength.

CONCLUSIONS

The study indicates that Levetiracetam carries a potential risk of causing rhabdomyolysis, SJS, TEN, DRESS as well as spontaneous abortion. Signals related to drug interaction, urethral atresia, ventricular septal defect, and atrial septal defect warrant heightened attention in clinical use.

A critical review of methotrexate clinical interactions: role of transporters

INTRODUCTION

Methotrexate (MTX) is an anti-folate and immunosuppressive drug prescribed for various malignancies and immune diseases. However, delayed elimination of MTX associated with concomitant use of some medications can lead to severe and life-threatening adverse effects.

AREAS COVERED

This paper investigated drug-MTX interactions that lead to elevated MTX levels and related adverse effects due to the role of transporters. Methotrexate toxicity occurs at both low and high doses administrations. According to the studies we reviewed in this paper, most interaction records with methotrexate occurred with co-administration of indomethacin, ketoprofen, omeprazole, piperacillin/tazobactam, ciprofloxacin, co-trimoxazole, probenecid, and imatinib, mainly due to the role of transporters. However, most studies were performed as case reports or series, and confirming the exact drug-methotrexate interaction still needs further clinical investigations.

EXPERT OPINION

Our findings showed no firm evidence of interactions of proton pump inhibitors (PPIs), levetiracetam, and NSAIDS with MTX. Moreover, patients' risk factors, hypoalbuminemia, renal failure, third space fluid retention, the elderly, polypharmacy, and transport inhibition are the most critical factors for MTX toxicity. If substitution or temporary discontinuation is not possible, healthcare providers should be aware of interactions, especially in patients with risk factors for MTX toxicity.

Pharmacokinetic considerations surrounding the use of levetiracetam for seizure prophylaxis in neurocritical care - an overview

INTRODUCTION

Levetiracetam (LEV) is one of the most widely used anti-seizure medications (ASMs) in clinical practice. This is due both to a different mechanism of action when compared to other ASMs and its easy handling. Indeed, because of its interesting pharmacokinetic properties, it is often used outside of the labelled indications, notably in the neurocritical setting as prophylaxis of epileptic seizures.

AREAS COVERED

A literature search was conducted and the most relevant studies on the pharmacokinetic properties of LEV were selected by two independent investigators. Current evidence on the use of ASM prophylaxis in the neurocritical setting was also reviewed, highlighting and discussing the strengths and limits of LEV as drug of choice for anti-epileptic prophylaxis in this scenario.

EXPERT OPINION

LEV has a "near-ideal" pharmacokinetic profile, which makes it an attractive drug for ASM prophylaxis in neurocritical care. However, current recommendations restrict ASMs prophylaxis to very selected circumstances and the role of LEV is marginal. Moreover, studies are generally designed to compare LEV versus phenytoin, whereas studies comparing LEV versus placebo are lacking. Further randomized trials will be needed to better elucidate LEV utility and its neuroprotective role in the neurocritical setting.

Urine volume to hydration volume ratio is associated with pharmacokinetics of high-dose methotrexate in patients with primary central nervous system lymphoma

High-dose methotrexate (HD-MTX)-based chemotherapy is the first-line treatment for primary central nervous system lymphoma (PCNSL), but is associated with severe adverse effects, including myelosuppression and renal impairment. MTX is primarily excreted by the kidneys. Renal function calculated using serum creatinine (Scr) derived from muscle may be overestimated in elderly PCNSL patients. Therefore, we aimed to construct a population pharmacokinetic model in PCNSL patients and explore the factors associated with MTX clearance. Sixteen PCNSL patients (median age, 66 years) treated with HD-MTX were included, and serum MTX concentrations were measured at 193 points in 49 courses. A population pharmacokinetic analysis was performed using NONMEM. A Monte Carlo simulation was conducted, in which serum MTX concentrations were stratified into three groups of creatine clearance (Ccr) (50, 75, and 100 ml/min) with three groups of the urine volume to hydration volume (UV/HV) ratio (<1, 1-2, and >2). The final model was constructed as follows: MTX clearance = 4.90·(Ccr/94.5)0.456 ·(UV/HV)0.458 . In the Monte Carlo simulation, serum MTX concentrations were below the standard values (10, 1, and 0.1 µM at 24, 48, and 72 h, respectively, after the start of the MTX administration) in most patients with UV/HV >2, even with Ccr of 50 ml/min. Conversely, half of the patients with UV/HV <1 and Ccr of 50 ml/min failed to achieve the standard values. The present results demonstrated that the UV/HV ratio was useful for describing the pharmacokinetics of MTX in PCNSL patients.

Effects of piperacillin/tazobactam or cefepime on folinate dose in patients receiving high-dose methotrexate: A retrospective cohort study using Japanese administrative claims data

INTRODUCTION

Delayed methotrexate (MTX) clearance with the co-administration of piperacillin/tazobactam (PIPC/TAZ) has been reported. Penicillins have been associated with reduced MTX clearance but the evidence is limited. There are no cases described with cefepime but penicillins are listed as interacting with MTX. We aimed to reveal whether the co-administration of PIPC/TAZ or CFPM affects MTX clearance using data from an administrative database.

METHODS

We used data from the JMDC database, a large insurance claims database constructed in Japan. We included patients who were prescribed PIPC/TAZ or CFPM between days 1 and 3 in high-dose MTX (HD-MTX). We compared one co-administration episode (with PIPC/TAZ or CFPM) to one control episode (without), as a match-control study of two different episodes in the same patient. The primary outcomes were the duration and cumulative dose of leucovorin (LV) as a surrogate indicator of delayed MTX clearance.

RESULTS

Three patients who were co-administered PIPC/TAZ and 16 patients who were co-administered CFPM with HD-MTX were included. In the PIPC/TAZ group, the duration and the cumulative doses of LV were similar in co-administration and control episode (median 3.0 vs. 3.0 days and 288.0 vs. 219.0 mg). In the CFPM group, the duration and the cumulative doses of LV were not significantly different in co-administration and control episode (3.0 vs. 4.0 days and 169.5 vs. 258.0 mg).

CONCLUSIONS

Our findings revealed that PIPC/TAZ did not necessarily cause a delay in MTX clearance during HD-MTX therapy. Moreover, the co-administration of CFPM with HD-MTX did not affect MTX clearance.

Delayed methotrexate elimination in a patient with primary central nervous system lymphoma: A case report

WHAT IS KNOWN AND OBJECTIVE

Methotrexate (MTX) is an important agent for the treatment of primary central nervous system lymphomas (PCNSL) but needs to be given in big doses by intravenous infusions to achieve therapeutic concentrations in the cerebrospinal fluid. However, co-administration with many drugs may delay the excretion of MTX which may cause serious adverse effects if the serum concentration exceeds 0.1 µmol/L 72 h after an intravenous infusion.

CASE SUMMARY

A 67-year-old Japanese female with PCNSL was treated with high-dose MTX-based chemotherapy. The serum MTX concentration 72 h post-infusion was 0.153 µmol/L when she was taking levofloxacin (LVFX) but <0.1 µmol/L 72 h after 4 subsequent infusions when she was not taking LVFX. She was given many other drugs but the timing of the short course of LVFX and the fact that ciprofloxacin also delays MTX excretion suggests that LVFX was the cause.

WHAT IS NEW AND CONCLUSION

Co-administration of LVFX may delay the excretion of MTX. Therefore, serum concentrations of MTX should be monitored to help prevent and improve the management of potentially serious MTX drug-drug interaction.

Lack of drug interaction between levetiracetam and high-dose methotrexate in patients with lymphoma

STUDY OBJECTIVE

To determine whether there is a drug-drug interaction precluding the concomitant use of levetiracetam and high-dose methotrexate (HDMTX).

DESIGN

Retrospective analysis.

SETTING

Large academic tertiary care medical center.

PATIENTS

Adult lymphoma patients who received HDMTX as a 4-h infusion with or without concomitant levetiracetam.

MEASUREMENTS AND MAIN RESULTS

Generalized estimating equations clustered on patient were used to assess each outcome. The primary outcome was the incidence of delayed MTX elimination (MTX level >1 µmol/L at 48 h). Secondary outcomes included incidence of acute kidney injury (AKI) and hospital length of stay (LOS). The 430 included patients receiving 1993 doses of HDMTX had a median (IQR) age of 66 (57.5, 72.6) years, 88 (20.5%) received concomitant levetiracetam with at least one dose of MTX, 267 (62.1%) were male, and 397 (92.3%) were Caucasian. HDMTX doses ranged from 1 to 8 g/m² . The most common lymphoma diagnoses were systemic diffuse large B-cell lymphoma (DLBCL; 58.5%) and systemic DLBCL with central nervous system (CNS) involvement (32.8%). Rates of delayed elimination with and without levetiracetam were 13.4% and 16.3%, respectively (OR = 0.80, 95% CI 0.47-1.34, p = 0.39). AKI occurred in 15.6% and 17.0% of patients with and without concomitant levetiracetam, respectively (OR = 0.83, 95% CI 0.52-1.33, p = 0.28). The median LOS with and without levetiracetam was 4.2 and 4.1 days, respectively (p = 0.039). On multivariable analyses, only age, body surface area, diagnosis of systemic DLBCL with CNS involvement, serum creatinine, hemoglobin, total bilirubin, and dose of HDMTX were associated with delayed elimination.

CONCLUSIONS

High-dose methotrexate administered with concomitant levetiracetam was not associated with increased risk for delayed MTX elimination or AKI. These results support that levetiracetam and HDMTX are safe for coadministration.

Population pharmacokinetics of high-dose methotrexate in Chinese pediatric patients with medulloblastoma

Methotrexate (MTX) pharmacokinetics has substantial inter-individual variability and toxicity. In children with medulloblastoma treated with high-dose methotrexate (HD-MTX), the pharmacokinetic properties of methotrexate have not been established. A total of 660 serum samples from 105 pediatric patients with medulloblastoma were included in a population pharmacokinetic (PPK) analysis of methotrexate by using the nonlinear mixed-effects modeling method. The basic one-compartment population pharmacokinetic model was established by NONMEM software and the first-order conditional estimation (FOCE) method, and the final covariate model was obtained by the stepwise regression method. Weight (WT), creatinine clearance (CrCL), and whether the treatment was combined with dexamethasone (DEX) were covariates that had significant effects on the clearance rate (CL) of the model. The pharmacokinetic equation of CL in the final covariate model was as follows: CL_i = 9.23× (1 + 0.0005× (θ_CrCL -105.78)) × (1 + 0.0017× (θ_WT -16)) × e^ηcl,i (L/h), IF (θ_DEX ) CL_i = 1.19× CL_i (L/h). The estimation accuracy of all pharmacokinetic parameters were acceptable (relative standard error < 14.74%). The goodness-of-fit diagram and bootstrap tests indicated that the final PPK model was stable with acceptable predictive ability. The PPK model may be useful for determining personalized medication levels in pediatric medulloblastoma patients undergoing HD-MTX therapy.

Managing the patient with epilepsy and renal impairment

PURPOSE

Epilepsy affects more than 50 million people worldwide and its management can be complicated by comorbidities such as impaired renal function. To optimize epilepsy control in patients with kidney disease, clinicians need to be aware of how antiepileptic drugs (AEDs) are affected by impaired renal function and how the kidneys are affected by epilepsy management strategies. Herein we present a narrative review with systematic literature search to discuss the use of AEDs in patients with renal impairment, including those undergoing dialysis, as well as the nephrotoxic effects of some AEDs. We finally conclude the article by providing practical tips about our approach to using AEDs in the setting of renal disease.

METHODS

A literature search targeting epilepsy management in patients with kidney disease was performed in MEDLINE database (1946 to 7th Jan 2019).

RESULTS

A total of 1193 articles were found. After duplicate removal, title and abstract screening followed by full text screening, a total of 110 references were included in this review. Additional information was included from drug product monographs.

CONCLUSION

The disposition of AEDs can be altered in patients with impaired renal function, leading to a higher risk of AED toxicity or therapy failure. Renal dosage adjustment and close monitoring is recommended. Although AED-induced nephrotoxicity is rare, it is unpredictable and clinicians need to vigilant about this possibility. In addition, AEDs renal adverse reactions and renal drug interactions should be considered when selecting an AED.

Effect of Levetiracetam on Time to High-Dose Methotrexate Clearance in Patients With Hematologic Malignancies

High-dose methotrexate (HDMTX) is a commonly used treatment for hematologic malignancies involving the central nervous system. Two case reports described possible delayed methotrexate clearance in patients receiving concurrent levetiracetam, while a retrospective cohort study did not find this association. The objective of this single-center, retrospective case-control study of 121 patients who received their first cycle of HDMTX was to investigate the association between HDMTX clearance time and concomitant levetiracetam use. The most common diagnosis was primary central nervous system lymphoma (47.9%). The mean HDMTX dose was 4601 mg/m² (standard deviation [SD], 2052.6 mg/m² ). Concurrent levetiracetam was administered in 30 of 121 patients (24.8%), with a mean total daily levetiracetam dose of 1434.4 mg (SD, 622.9 mg; range, 900-3000 mg). Baseline characteristics were similar between patients who received concomitant levetiracetam and those who did not. The mean time to methotrexate clearance was 82.5 hours (SD, 51.2; 95% confidence interval, 69.4-95.7) in the concomitant levetiracetam group and 72.4 hours (SD, 31.2; 95% confidence interval, 61.7-83.0) in the nonlevetiracetam group, which was not significantly different (P > .05), even in the subgroup receiving methotrexate doses >3500 mg/m² . Grade 3 or higher toxicity occurred in 33.3% of the concomitant levetiracetam group and in 34.1% of nonconcomitant levetiracetam patients. This study, which, to our knowledge, is the first examining levetiracetam effect on only the first dose of HDMTX, supports the larger retrospective study finding no significant effect of levetiracetam on HDMTX clearance time, and suggests that administering concomitant levetiracetam does not affect HDMTX toxicity.

Safety and efficacy of a urine alkalinization protocol developed for high-dose methotrexate patients during intravenous bicarbonate shortage

PURPOSE

Urinary alkalinization with intravenous sodium bicarbonate is standard during high-dose methotrexate administration. Due to a national intravenous sodium bicarbonate shortage, a urinary alkalinization protocol involving hyperhydration with intravenous fluids, oral bicarbonate, and intravenous or oral acetazolamide was utilized from 10 April to 30 May 2017 ("shortage protocol"). This study compared outcomes between protocols.

METHODS

A single-center, retrospective chart review was conducted for adults who received methotrexate ≥500 mg/m² on ≥ two occasions, at least once during each protocol, between 19 February and 19 July 2017.

RESULTS

Eighteen patients (50% male), median age 65 years, received 76 total high-dose methotrexate cycles. Shortage protocol was used in 37 cycles (48.7%). Mean time to methotrexate clearance did not differ between groups (p = ns). Mean time to urinary alkalinization and duration of hospitalization were not statistically different (p = 0.49 and 0.23, respectively). Average total bicarbonate administered per 24 hours was higher in standard protocol (p < 0.05), but hydration rates were similar (p = 0.73). Creatinine clearance and urine output on days 1 and 2 post-high-dose methotrexate did not significantly differ (creatinine clearance day 1, p = 0.27; creatinine clearance day 2, p = 0.55; urine output day 1, p = 0.62; urine output day 2, p = 0.60). Interruptions in alkalinization were significantly higher during shortage (0.41 ± 0.75 instances of urine pH < 7 during standard vs. 1.3 ± 1.7 under shortage, p < 0.05).

Population-Based Study of Risk of AKI with Levetiracetam

BACKGROUND AND OBJECTIVES

Regulatory agencies warn about the risk of AKI with levetiracetam use on the basis of information from case reports. We conducted this study to determine whether new levetiracetam use versus nonuse is associated with a higher risk of AKI.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a population-based retrospective cohort study of adults with epilepsy in Ontario, Canada. Patients who received a new outpatient prescription for levetiracetam between January 1, 2004 and March 1, 2017 were matched to two nonusers on stage of CKD, recorded seizure in the prior 90 days, and logit of a propensity score for levetiracetam use. The primary outcome was a hospital encounter (emergency department visit or hospitalization) with AKI within 30 days of cohort entry. Secondary outcomes were AKI within 180 days and change in the concentration of serum creatinine. We assessed the primary outcome using health care diagnosis codes. We evaluated the change in the concentration of serum creatinine in a subpopulation with laboratory measurements.

RESULTS

We matched 3980 levetiracetam users to 7960 nonusers (mean age 55 years, 51% women). Levetiracetam use was not significantly associated with a higher risk of AKI within 30 days (13 [0.33%] events in levetiracetam users and 21 [0.26%] events in nonusers [odds ratio, 1.24; 95% confidence interval, 0.62 to 2.47]). Similarly, there was no significant association with AKI within 180 days (odds ratio, 0.70; 95% confidence interval, 0.43 to 1.13). The change in the concentration of serum creatinine did not significantly differ between levetiracetam users and nonusers.

CONCLUSIONS

In this population-based study levetiracetam use was not associated with a higher risk of AKI.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2018_12_11_Yau_Podcast.mp3.

Population Pharmacokinetics of High-Dose Methotrexate in Patients With Primary Central Nervous System Lymphoma

The intra- and inter-individual variances of methotrexate (MTX) pharmacokinetics are extremely large, and the pharmacokinetic property of MTX in patients with primary central nervous system lymphoma (PCNSL) is unestablished. A total of 701 MTX plasma concentrations from 98 patients with PCNSL under high-dose MTX therapy were used to develop the population pharmacokinetic (popPK) model of MTX by using the nonlinear mixed-effects modeling method. A 2-compartment model was employed to describe the pharmacokinetic property of MTX. In the final popPK model, inclusion of serum creatinine and body surface area significantly reduced objective function value for clearance over the base model (p <0.001), and inclusion of age significantly reduced objective function value for distribution volume of central compartment (V_c) over the base model (p <0.001). In the final popPK model, the inter-individual clearance = 6.67 × (SCR/68.1)^-0.48 × (BSA/1.75)^1.17; V_c = 24.46 × (age/57.16)^0.81. The precision of all parameters was acceptable (relative standard error <28.61%). Bootstrap and visual predictive check results indicated that the final popPK model was stable with acceptable predictive ability. The popPK model may be useful for personalized medication in PCNSL patients under high-dose MTX therapy. Further studies are warranted to confirm the results.

Preventing and Managing Toxicities of High-Dose Methotrexate

: High-dose methotrexate (HDMTX), defined as a dose higher than 500 mg/m2, is used to treat a range of adult and childhood cancers. Although HDMTX is safely administered to most patients, it can cause significant toxicity, including acute kidney injury (AKI) in 2%-12% of patients. Nephrotoxicity results from crystallization of methotrexate in the renal tubular lumen, leading to tubular toxicity. AKI and other toxicities of high-dose methotrexate can lead to significant morbidity, treatment delays, and diminished renal function. Risk factors for methotrexate-associated toxicity include a history of renal dysfunction, volume depletion, acidic urine, and drug interactions. Renal toxicity leads to impaired methotrexate clearance and prolonged exposure to toxic concentrations, which further worsen renal function and exacerbate nonrenal adverse events, including myelosuppression, mucositis, dermatologic toxicity, and hepatotoxicity. Serum creatinine, urine output, and serum methotrexate concentration are monitored to assess renal clearance, with concurrent hydration, urinary alkalinization, and leucovorin rescue to prevent and mitigate AKI and subsequent toxicity. When delayed methotrexate excretion or AKI occurs despite preventive strategies, increased hydration, high-dose leucovorin, and glucarpidase are usually sufficient to allow renal recovery without the need for dialysis. Prompt recognition and effective treatment of AKI and associated toxicities mitigate further toxicity, facilitate renal recovery, and permit patients to receive other chemotherapy or resume HDMTX therapy when additional courses are indicated.

IMPLICATIONS FOR PRACTICE

High-dose methotrexate (HDMTX), defined as a dose higher than 500 mg/m2, is used for a range of cancers. Although HDMTX is safely administered to most patients, it can cause significant toxicity, including acute kidney injury (AKI), attributable to crystallization of methotrexate in the renal tubular lumen, leading to tubular toxicity. When AKI occurs despite preventive strategies, increased hydration, high-dose leucovorin, and glucarpidase allow renal recovery without the need for dialysis. This article, based on a review of the current associated literature, provides comprehensive recommendations for prevention of toxicity and, when necessary, detailed treatment guidance to mitigate AKI and subsequent toxicity.

Methotrexate Elimination When Coadministered With Levetiracetam

Background: Delayed elimination of methotrexate was previously reported in 2 patients receiving concomitant levetiracetam. Objective: To explore the potential interaction between methotrexate and levetiracetam in patients receiving high-dose methotrexate. Methods: This retrospective study reviewed the records of 81 adults receiving 280 cycles of methotrexate to determine the effects of levetiracetam on methotrexate elimination. Institutional review board approval was obtained. Results: Levetiracetam was administered in 33 (12%) cycles of methotrexate. Patients receiving levetiracetam had significantly lower 24-hour methotrexate concentrations compared with those not receiving levetiracetam (2.91 vs 7.37 µmol/L, P = 0.005). Despite this difference, concentrations at 48 and 72 hours were similar between groups. Times to nontoxic methotrexate concentration (<0.1 µmol/L) were the same regardless of the presence of levetiracetam. The frequency of delayed elimination at 24, 48, and 72 hours was similar in both groups as was the frequency of delayed elimination at any time point. Cox regression demonstrated that levetiracetam was not a significant predictor of time to nontoxic methotrexate concentration ( P = 0.796; HR = 1.058; 95% CI = 0.692-1.617), and logistic regression demonstrated that levetiracetam was not a significant predictor of delayed elimination at any time point. Levetiracetam use was similar between groups when comparing patients experiencing delayed elimination at any time point with those without delayed elimination (13% vs 10%, respectively, P = 0.527). Conclusion: This study does not support the previous reports of a significant interaction between levetiracetam and methotrexate. A clinically significant interaction is unlikely in those without additional risk factors for delayed elimination.

Anticonvulsant therapy in brain-tumor related epilepsy

Background. The lifetime risk of patients with brain tumors to have focal epileptic seizures is 10-100%; the risk depends on different histology. Specific guidelines for drug treatment of brain tumor-related seizures have not yet been established.

Aim. This review addresses the special aspects of antiepileptic drug (AED) therapy in brain tumor-related epilepsy.

Methods. We analyzed the literature up to December 2015.

Results. Based on current evidence the management of tumor-related seizures does not differ substantially from that applied to epilepsies from other etiologies. Therefore, the choice of an AED is based, above all, on tolerability and pharmacokinetic interactions with chemotherapeutic drugs. Levetiracetam is recommended by many authors as first-line therapy in brain tumor-related epilepsy. Due to the possibility of interactions, the combination of enzyme-inducing AEDs and chemotherapeutic drugs, is usually not recommended as a first choice. Currently there is no evidence that prophylactic prescription of long-term AEDs in brain tumor-patients who did not present with seizures is justified. Because of the high risk of recurrence, however, AED treatment should be strongly considered after a single brain tumor-related seizure. The decision to withdraw AEDs must carefully consider the risk of seizure recurrence.

Conclusion. At present levetiracetam is the preferred drug in brain tumor-related epilepsy, especially when drug interactions need to be avoided. In the future we hope to acquire more targeted drugs against this disorder by uncovering its pathogenesis.

Seizures and cancer: drug interactions of anticonvulsants with chemotherapeutic agents, tyrosine kinase inhibitors and glucocorticoids

Patients with cancer commonly experience seizures. Combined therapy with anticonvulsant drugs (AEDs) and chemotherapeutic drugs or tyrosine kinase inhibitors carries inherent risks on drug-drug interactions (DDIs). In this review, pharmacokinetic studies of AEDs with chemotherapeutic drugs, tyrosine kinase inhibitors, and glucocorticoids are discussed, including data on maximum tolerated dose, drug clearance, elimination half-life, and organ exposure. Enzyme-inducing AEDs (EIAEDs) cause about a 2-fold to 3-fold faster clearance of concurrent chemotherapeutic drugs metabolized along the same pathway, including cyclophosphamide, irinotecan, paclitaxel, and teniposide, and up to 4-fold faster clearance with the tyrosine kinase inhibitors crizotinib, dasatinib, imatinib, and lapatinib. The use of tyrosine kinase inhibitors, particularly imatinib and crizotinib, may lead to enzyme inhibition of concurrent therapy. Many of the newer generation AEDs do not induce or inhibit drug metabolism, but they can alter enzyme activity by other drugs including AEDs, chemotherapeutics and tyrosine kinase inhibitors. Glucocorticoids can both induce and undergo metabolic change. Quantitative data on changes in drug metabolism help to apply the appropriate dose regimens. Because the large individual variability in metabolic activity increases the risks for undertreatment and/or toxicity, we advocate routine plasma drug monitoring. There are insufficient data available on the effects of tyrosine kinase inhibitors on AED metabolism.