Evaluation of the mechanisms of antiepileptic drug-related chronic leukopenia

Evaluation of systemic inflammation in seizure phenotypes following meningioma resection

PURPOSE

To investigate the association between perioperative peripheral blood inflammatory markers and seizures in patients who have undergone meningioma resection.

MATERIALS AND METHODS

A single neurosurgery tertiary centre blood bank database was screened to extract pre-operative and post-operative white cell count (WCC), neutrophils, lymphocytes, monocytes, platelets and neutrophil-lymphocyte ratio (NLR) and derived NLR (dNLR). All patients who underwent resection of meningioma from 2012 to 2020 were eligible. Patients were excluded if they had an inflammatory condition, peri-operative infection, medical illness or operative complication.

RESULTS

30 patients suffered pre-operative seizures only, 16 experienced de novo post-operative seizures within 1 year and 42 patients did not experience seizures throughout their treatment timeline. Patients with post-operative de novo seizures had a significantly higher WCC when compared those who never had a seizure (7.1 vs. 4.8x109/L, p =.048, 95 % 1.96 to 5.60). However, this difference of WCC was poorly predictive of de novo seizures at one year (AUC 0.61). dNLR was significantly higher in patients with continued post-operative seizures than in patients in which seizures were terminated with tumour resection (1.2 vs. 0.1, p =.035, 95 % 1.47 to 2.29). dNLR was predictive of seizures at one year with an 87.5 % sensitivity and 82.1 % specificity.

CONCLUSIONS

There is a significantly higher post-operative systemic white cell count response in patients who suffered de novo seizures after meningioma resection. Peripheral blood markers have the potential to predict seizures in patients with meningioma.

Pearls for the diagnosis and possible pathophysiological mechanisms of valproic acid-induced lupus erythematosus: A literature review

Background: Drug-induced lupus erythematosus (DILE) accounts for 10-15% of systemic lupus erythematosus (SLE) cases, with more than 100 pharmaceutical agents implicated in its development. Depending on the offending drug, clinical and serological manifestations present great variability and, thus, DILE may be overlooked in clinical practice. Valproic acid (VPA) - induced lupus erythematosus has not been analytically reported in the literature, rendering the recognition of such cases even more difficult.Objective: The aim of this study was to analyze VPA - induced lupus features and to discuss possible pathophysiological mechanisms.Materials and Methods: This literature review was conducted in PubMed and Embase databases in June 2021, in search of DILE cases induced by VPA. We found 164 manuscripts, out of which 140 articles regarding other adverse effects or drugs were discarded. Finally, 15 cases fulfilled the eligibility criteria to be included in this review.Results: Although SLE is more common in females, VPA-induced lupus presented a male predilection. Patients developed DILE within the first three months of treatment with VPA at a percentage of 50%, whereas four patients from one to five years after VPA initiation. DILE frequently presented with mild symptoms. In most patients, serositis manifested with polyarthritis, pleural effusion or pericarditis. Notably, one patient presented with Rowell's syndrome, a rare subtype of lupus erythematosus with erythema multiforme and speckled pattern of antinuclear antibodies (ANAs). Central nervous system, renal and skin involvement was scarcely observed. Cytopenia was noted in 7 patients. Immunological findings included positive ANAs in the vast majority of the patients (86.7%), positive anti-histone antibodies in five, positive anti-dsDNA antibodies in three and hypocomplementemia in two patients. Despite the prompt resolution of clinical symptoms after VPA discontinuation, serological abnormalities persisted up to 18 months. Apart from the discontinuation of VPA administration for the resolution of DILE, treatment included corticosteroids in 8 cases.Conclusion: Valproic acid has been implicated in several cases of DILE. Clinicians should be aware of this entity and recognize it promptly to ensure a favorable outcome. Possible pathophysiologic associations may be extrapolated, but a clearer understanding of this syndrome is to be gained by further studies.

Case Report: Predicting the Range of Lamotrigine Concentration Using Pharmacokinetic Models Based on Monte Carlo Simulation: A Case Study of Antiepileptic Drug-Related Leukopenia

Lamotrigine (LTG), a wide-spectrum antiepileptic drug, is frequently associated with cutaneous side-effects, whereas hematological side-effects such as leukopenia have rarely been reported for it. We report the case of a 15-year-old Chinese female epileptic patient weighing 60 kg who developed combined asymptomatic leukopenia after receiving concomitant therapy with LTG and valproate acid (VPA). In this case report, antiepileptic drug-related leukopenia may have occurred in definite relation to an increase in LTG concentration and reversed with the discontinuation of VPA. Monte Carlo (MC) simulations were performed to estimate the steady-state serum concentrations (C_ss) of LTG for different dosing regimens in adolescent Chinese epileptic patients weighing the same as the patient considered in the case study, based on pharmacokinetic (PK) models published in past research. Adjustments to the dosage of LTG for the patient were analyzed to illustrate the application of MC simulations and verify the results. The predicted LTG concentrations within a prediction interval between the 10th and 90th percentiles that represented 80% of the simulated populations, could adequately capture the measured LTG concentrations of the patient, indicating that MC simulations are a useful tool for estimating drug concentrations. Clinicians may benefit from the timely probabilistic predictions of the range of drug concentration based on an MC simulation that considers a large sample of virtual patients. The case considered here highlights the importance of therapeutic drug monitoring (TDM) and implementing model-informed precision dosing in the course of a patient’s individualized treatment to minimize adverse reactions.

Phenobarbital/Lamotrigine coadministration-induced blood dyscrasia in a patient with epilepsy

OBJECTIVE

To report on a patient with epilepsy who developed leukopenia and thrombocytopenia during phenobarbital/lamotrigine treatment.

CASE REPORT

A 45-year-old woman with a 10-year history of complex partial seizures being treated with phenobarbital 100 mg/day presented due to the development of complex partial seizure episodes (8 episodes/month in the last 6 months). Results of laboratory tests on admission showed normal platelets (250 x 10³/μL) and white blood cells (8.2 x 10³/μL). After clinical evaluation, lamotrigine titrated to a final dose of 100 mg twice daily was added to the phenobarbital. About 2 months later no epileptic manifestations were reported, but hematologic tests revealed a decrease in both platelets (36 x 10³/μL) and white blood cells (2.0 x 10³/μL). One day later, phenobarbital was discontinued and the patient developed 2 episodes of complex partial seizure. Levetiracetam titrated to 1500 mg/day was added to lamotrigine, with a normalization of platelets (260 x 10³/μL) and white blood cell (7.9 x 10³/μL) counts about 20 days later. After a few days, levetiracetam was discontinued and phenobarbital rechallenge during lamotrigine treatment induced a new blood dyscrasia in about 2 weeks (platelets 80 x 10³/μL; white blood cells 3.2 x 10³/μL). Phenobarbital was discontinued and levetiracetam was restarted, with a recovery of normal hematopoiesis in 25 days. The patient is presently receiving treatment with both lamotrigine 200 mg/day and levetiracetam 1500 mg/day and shows no seizure symptoms, blood abnormalities, or other adverse effects.

DISCUSSION

Using the Horn Drug Interaction Probability Scale, we estimated a probable relationship between the drug-drug interaction and blood dyscrasia. The underlying mechanism of this interaction has not been well characterized. Cytochrome P450 enzyme induction by phenobarbital could be responsible for the production of reactive metabolites of lamotrigine that might be causative for the observed hematologic effects. A pharmacodynamic interaction between the 2 drugs is also a possible mechanism of this interaction.

CONCLUSIONS

Our patient with epilepsy developed blood dyscrasia during lamotrigine/phenobarbital treatment. Clinicians should carefully monitor hematologic parameters during lamotrigine/phenobarbital treatment.

Delayed-onset neutropenia with divalproex sodium

OBJECTIVE

To report the development of neutropenia in a patient after almost 8 years of being stabilized on delayed-release divalproex sodium (DVPX).

CASE SUMMARY

A 45-year-old man had been maintained on DVPX for nearly 8 years, with serum valproic acid concentrations of 85-128 mg/L and normal white blood cell (WBC) counts and absolute neutrophil counts (ANCs). Five months prior to the development of neutropenia (defined as ANC <1800 cells/microL), the patient's DVPX dosage was decreased by 250 mg to 1250 mg every morning and 1500 mg every evening. After 2 months of that regimen, the DVPX dosage was increased back to 1500 mg twice daily. Three months after that increase, the patient's WBC count dropped to 3.7 x 10(3)/microL and ANC was 1199 cells/microL. Although the ANC was below 1800 cells/microL, he showed no physical manifestations consistent with neutropenia. DVPX was discontinued, and 2 weeks later the patient's WBC count was 7.2 x 10(3)/microL and ANC was 2290 cells/microL.

DISCUSSION

Although a complete blood cell count with differential is a commonly accepted form of therapeutic drug monitoring with DVPX, the monitoring is considered most necessary to identify dose-related thrombocytopenia. However, neutropenia has been rarely associated with the use of DVPX and could contribute to the development of different types of infection, including those of a bacterial, viral, or fungal origin. Although neutropenia is generally mild in severity, potentially severe DVPX-associated neutropenia can occur any time during the course of therapy, although it is most common within the first few months of treatment. In this case, DVPX was the probable cause of the neutropenia, according to the Naranjo probability scale. However, this case of neutropenia is atypical with respect to the timeframe in which it developed and was identified. Although the documented laboratory findings suggest neutropenia, the patient did not experience any clinical complications as a result. The late onset of the patient's neutropenia is unlike other cases that have been documented in the literature.

CONCLUSIONS

Hematologic therapeutic drug monitoring continues to be clinically important regardless of whether the patient is early in therapy or even years later in the course. In this patient, continued regular therapeutic drug monitoring identified a suspected drug-related complication and the medication was able to be discontinued without the development of clinical complications.

Practical considerations for carbamazepine use in bipolar disorder

Carbamazepine (CBZ) has a long history of successful use in epilepsy and, therefore, has a safety profile that is well characterised. Additionally, an extended-release formulation of CBZ (CBZ-ERC; Equetro, Shire US) has recently been approved for use in bipolar disorder. The most frequent adverse events associated with CBZ are somnolence, fatigue, dizziness and headache. Rash and leukopoenia may occur in approximately 10% of patients, but are benign and transient in most cases. Rare serious adverse effects include agranulocytosis, aplastic anaemia, Stevens-Johnson syndrome and toxic epidermal necrolysis. Although changes in lipid profiles have been noted, hyperglycaemia does not occur with CBZ, and clinically significant weight gain is uncommon. Proper monitoring and careful titration of the extended-release formulation should allow for successful use of CBZ in psychiatric patients.

A Complex Interaction between Clozapine and Phenytoin

Objective:

As of July 9, 2004, to report the first case of potential pharmacodynamic and pharmacokinetic interactions between clozapine and phenytoin occurring simultaneously in a patient.

Case Summary:

A 60-year-old African American female treated with clozapine and phenytoin developed neutropenia after the clozapine dose was increased from 650 to 900 mg/day. The neutropenia resolved after phenytoin was discontinued, and the clozapine dose was decreased from 900 to 300 mg/day without any significant change in clozapine levels.

Discussion:

Neutropenia can be explained on the basis of a potential pharmacodynamic interaction between clozapine and phenytoin. However, neutropenia did not occur until the clozapine dose was increased from 650 to 900 mg/day, corresponding to an increase in clozapine levels from 90 to 114 ng/mL. Neutropenia resolved after phenytoin was discontinued, even though the clozapine concentrations achieved after phenytoin discontinuation (137 ng/mL) were almost the same as those when phenytoin was coadministered (114 ng/mL). This finding suggests that neutropenia was precipitated not only by an increase in the clozapine dose, but also by the concomitant use of phenytoin. On the other hand, the decrease in clozapine concentrations can be explained on the basis of a pharmacokinetic interaction between clozapine and phenytoin. Phenytoin has the potential to decrease clozapine concentrations by inducing the activity of CYP1A2, which provides a primary metabolic pathway for clozapine.

Conclusions:

Concomitant use of phenytoin may not only decrease clozapine concentrations and compromise its efficacy, but can also precipitate neutropenia. Although based on a single case report, these findings warrant caution when coadministering clozapine and phenytoin.

Nitroso-urea-cisplatin-based chemotherapy associated with valproate: increase of haematologic toxicity

BACKGROUND

The incidence of haematologic toxicity of valproate (VPA) ranges from 1% to 32% and consists mainly of asymptomatic, dose-dependent thrombopenia. We describe a potentiation of haematologic side-effects of nitroso-urea (NU) when prescribed in association with VPA.

PATIENTS AND METHODS

We followed a cohort of 70 patients (58 men, 22 women, mean age: 56 years, range 20-75 years). Patients with high-grade gliomas were treated with up-front chemotherapy regimen consisting of fotemustine (d3: 100 mg/m2), cisplatin (d1-3: 33 mg/m2) and etoposide (d1-3: 75 mg/m2) followed by whole brain radiotherapy at progression. Sixty patients required anti-epileptic drugs (AED) for either a single, well-documented epileptic seizure, or immediatly initiated after neurosurgical procedures. AED included VPA (35 of 60), phenobarbital (PB) (17 of 60), carbamazepine (CBZ) (2 of 60) and phenytoin (PHT) (3 of 60). Two patients had both PB and CBZ and one PB and PHT.

RESULTS

Haematologic toxicity (grade 3-4 thrombopenia, neutropenia or both) was observed in 37 of 70 (52.85%) patients. Among them 24 (65%) had VPA. Group C were patients treated with fotemustine alone with or without VPA (23 patients).

CONCLUSION

When prescribed in association with a fotemustine-cisplatin regimen, VPA treatment results in a three-fold higher incidence of reversible thrombopenia, neutropenia or both. Haematologic side-effects decrease after AED modification during the continued chemotherapy. This adverse event should be managed with caution.

[Severe agranulocytosis induced by carbamazepine (Tegretol)]

We describe a case of severe drug-induced agranulocytosis, with the risk of a lethal outcome in a patient with a posttraumatic tetraplegia. Intercurrent complications required numerous medicaments. One month after admission, the neutrophil count decreased for ten days until a nadir of 70.mm-3, associated with an infectious syndrome. The bone marrow biopsy showed a severe granulocyte hypoplasia with absence of final differentiation. Administration of ienograstime (granulocyte stimulating factor) was efficient. In this patient, carbamazepine was the most probable causal factor for agranulocytosis. However, other medicaments, mainly antibiotics, could have been contributing factors.

Referral patterns of family physicians may allow population-based incidence studies of childhood epilepsy

PURPOSE

To evaluate the burden of illness of childhood epilepsy on patient, care giver, and society, representative incidence cohorts must be followed longitudinally. Case ascertainment through pediatricians and neurologists would be a valid method if family physicians refered all new cases of childhood epilepsy. The study objective was to determine whether family physicians' referral patterns in Southwestern Ontario make it possible to conduct a population-based incidence study of childhood epilepsy by sampling only from specialists' practices.

METHODS

Of the 1,718 family physicians practicing in Southwestern Ontario, a systematic sample participated in a mailed survey. Case simulations describing seven types of childhood seizures were presented to physicians with instructions to respond as to whether they would investigate/manage without referral; refer to a specialist only if problems occurred; or refer to a specialist always.

RESULTS

Of 214 family physicians, 185 (86.4%) returned completed surveys; 86% would not refer a child with a febrile seizure. Referral to a specialist would be made always by 93% of family physicians for patients with status epilepticus, 95% for worsening partial epilepsy, 82% for a first, brief, generalized clonic seizure, 80% for absence epilepsy, and 99% for neonatal seizures. Only 50% of family physicians would always refer a neurodevelopmentally abnormal child with generalized clonic epilepsy, but a further 37% would refer if problems occurred.

CONCLUSIONS

It is feasible to recruit a representative population-based cohort of recently diagnosed patients for epidemiologic studies of childhood epilepsy by surveying pediatricians and neurologists. These survey results could be used to adjust estimates of incidence obtained through specialists' practices for the bias in case ascertainment that may result from this practical method.

EEG background as predictor of electrographic seizures in high-risk neonates

PURPOSE

Experience with continuous EEG monitoring in 29 consecutive infants at risk of neonatal seizures demonstrated that background abnormalities on the initial EEG were strongly associated with electrographic seizures in the subsequent 18-24 h. To test this association prospectively, we examined the relationship between EEG background and the presence of electrographic seizures in the next 22 at-risk infants monitored for seizures.

METHODS

A standard EEG was recorded for each infant at risk for seizures. Based on specific criteria, the background was graded as normal; immature for age; or mildly, moderately, or severely abnormal. The EEG was then monitored continuously until no electrographic seizures were recorded for 18-24 h.

RESULTS

Findings in the retrospective group of 29 infants and the prospective group of 22 infants did not differ. For the combined 51 infants, a normal or immature initial EEG background predicted the absence of seizures in the subsequent 18-24 h with a sensitivity of 96% [confidence interval (CI) 0.88, 1.0] and specificity of 81% (CI 0.67, 0.96). Administration of antiepileptic drugs (AEDs) before the start of the EEG recording did not affect this association.

CONCLUSIONS

In 51 consecutively monitored infants at risk for neonatal seizures, a normal or immature EEG background strongly predicted the absence of electrographic seizures in the subsequent 18-24 h; background abnormalities strongly predicted the occurrence of electrographic seizures concomitantly or in the subsequent 18-24 h of recording. Screening infants at risk for neonatal seizures with a routine EEG allows identification of infants at highest risk for seizures, thus conserving resources required for continuous EEG monitoring and facilitating early intervention for seizures.

Carbamazepine affects neutrophil function through an action on peripheral benzodiazepine receptors

The aims of this study were to assess the possible role of peripheral benzodiazepine receptors (pBZrs)1 in mediating the in vitro effects of carbamazepine (CBZ) on some neutrophil functions in healthy volunteers and to investigate neutrophil function and pBZr expression in patients with epilepsia on CBZ monotherapy for at least 1 year. In vitro CBZ (42-168 microM) concentration-dependently inhibited chemotaxis induced by N-formyl-methionyl-leucyl-phenylalanine (FMLP) or lipopolysaccharide (LPS)-activated human serum. CBZ did not affect random migration, phagocytosis index, phagocytosis frequency, NBT reduction frequency, C. albicans lethality index and resting superoxide production. The pBZr antagonist PK 11195 (1 microM, per se ineffective) reversed the inhibitory effect of CBZ on chemotaxis induced by endotoxin-activated serum or FMLP. The pBZr agonist Ro 5-4864 (10-100 microM) mimicked the effect of CBZ on chemotaxis induced by endotoxin-activated serum or FMLP and had no effect on the other parameters. Neutrophils from epileptic patients on chronic CBZ monotherapy had impaired FMLP- and serum-induced chemotaxis and enhanced expression of pBZrs on neutrophils. These data strongly suggest an involvement of pBZrs in mediating the in vitro effects of CBZ on chemotaxis; furthermore, impairment of the same neutrophil function parameters and overexpression of pBZrs in patients are consistent with the hypothesis of an in vivo interaction of CBZ with pBZrs.

Allergy to carbamazepine: parallel in vivo and in vitro detection

PURPOSE

Five to 20% of patients discontinue antiepileptic drug (AED) therapy because of adverse reactions. Careful reintroduction, however, may be considered if true drug allergy can be ruled out. Definitive assessment of such immunologically mediated reactions requires demonstration of either specific antibodies or sensitized lymphocytes.

METHODS

We investigated whether skin patch tests (PTs) and in vitro lymphocyte proliferation assays (LPAs) were suitable for detection of allergy to carbamazepine (CBZ) and the possibly cross-reactive oxcarbazepine (OCBZ). Data of 65 patients displaying a wide range of possibly allergic side effects to CBZ were available for analysis. Data of CBZ users without any side effects and healthy volunteers served as controls. Both PTs and LPAs were done with CBZ, OCBZ and three metabolites [CBZ-10,11-epoxide (CBZ-E), 10-monohydroxy-CBZ (MHD), and 10,11-dihydroxy-CBZ (DIOL)].

RESULTS

Positive PTs with CBZ were seen in 20% and with OCBZ in 14% of the patients. Positive LPA results with CBZ and OCBZ, respectively, were found in 40 and 19%. Both tests were positive in 14 and 7% of the patients. Cross-reactivity to OCBZ was seen in -40% of CBZ-reactive patients in both PTs and LPAs.

CONCLUSION

These data illustrate the additional value of LPAs in the detection of CBZ allergy while showing that a major part of side effects to CBZ and OCBZ is not immunologically mediated, according to PTs and LPAs.

Incidence of epilepsy in rural Iceland: a population-based study

PURPOSE

We wished to determine the incidence of epilepsy in the population of rural Iceland.

METHODS

Cases were identified through review of records of primary care facilities for the study population, supplemented by review of referrals to EEG facilities and neurologic specialists.

RESULTS

The incidence of epilepsy (recurrent unprovoked seizures) was 47 in 100,000. Age-specific incidence was bimodal, highest in the youngest and oldest age groups. About one third of the patients had an identifiable etiology, and one third had partial seizures. Integration of imaging and neurophysiologic data did little to modify the distribution of etiology or seizure type.

CONCLUSIONS

The present study confirms findings of other recent studies of incidence in Western Countries.

Exfoliative dermatitis due to immunologically confirmed carbamazepine hypersensitivity

A 6-year-old Caucasian girl experienced a generalized erythematous skin rash during carbamazepine therapy. Over the next four days the eruption worsened into erythroderma with fever and generalized lymphadenopathy. Routine laboratory studies revealed increased serum levels of liver enzymes and eosinophilia. Immunologic reactivity to the anticonvulsant carbamazepine and its analogs was investigated both in vivo and in vitro by patch tests and lymphocyte proliferation assays, respectively.