Neuroprotective and anti-inflammatory activity of DAT inhibitor R-phenylpiracetam in experimental models of inflammation in male mice.

R-phenylpiracetam (R-PhP, (4R)-2-(4-phenyl-2-oxopyrrolidin-1-yl)acetamide) is an optical isomer of phenotropil, a clinically-used nootropic drug that improves physical condition and cognition. Recently, R-PhP was shown to bind to the dopamine transporter (DAT). Since growing evidence suggests that dysfunction of the dopaminergic system is associated with persistent neuroinflammation, the aim of this study was to determine whether R-PhP, an inhibitor of DAT, has neuroprotective and anti-inflammatory effects in male mice. The pharmacokinetic profiles of R-PhP in mouse plasma and its bioavailability in brain tissue were assessed. To study possible molecular mechanisms involved in the anti-inflammatory activity of R-PhP, target profiling was performed using radioligand binding and enzymatic activity assays. To clarify the neuroprotective and anti-inflammatory effects of R-PhP, we used a lipopolysaccharide (LPS)-induced endotoxaemia model characterized by reduced body temperature and overexpression of inflammatory genes in the brain. In addition, the antinociceptive and anti-inflammatory effects of R-PhP were tested using carrageenan-induced paw oedema and formalin-induced paw-licking tests. R-PhP (50 mg/kg) reached the brain tissue 15 min after intraperitoneal (ip) and peroral (po) injections. The maximal concentration of R-PhP in the brain tissues was 28 µg/g and 18 µg/g tissue after ip and po administration, respectively. In radioligand binding assays, DAT was the only significant molecular target found for R-PhP. A single ip injection of R-PhP significantly attenuated the LPS-induced body temperature reduction and the overexpression of inflammatory genes, such as tumour necrosis factor-α (TNF-α), interleukin 1 beta (IL-1ß) and inducible nitric oxide synthase (iNOS). Seven-day po pretreatment with R-PhP dose-dependently reduced paw oedema and the antinociceptive response, as shown by the carrageenan-induced paw oedema test. In addition, R-PhP decreased the nociceptive response during the inflammatory phase in the formalin-induced paw-licking test. Our study showed that R-PhP possesses neuroprotective and anti-inflammatory effects, demonstrating the potential of DAT inhibitors as effective therapeutics.

Population pharmacokinetic model of levetiracetam in Korean neonates with seizures
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OBJECTIVE: This study was conducted to develop a population pharmacokinetic (PK) model of levetiracetam in Korean neonates with seizures. MATERIALS AND METHODS: Data were obtained from a retrospective study of 18 neonates with seizures admitted to the Neonatal Intensive Care Unit (NICU) of Severance Children's Hospital for the period of from 2013 to 2015. Sampling and dosing times were recorded by clinical research coordinators on case report forms. Demographic factors and laboratory results were tested as potential covariates for PK parameters. Model development was performed within a mixed-effect modeling framework using NONMEM. RESULTS: With a one-compartment model with first-order elimination chosen as a basic PK model based on theory-based allometric relationships, postmenstrual age and serum creatinine were found to have significant influences on clearance (CL). Typical parameter estimates of the final PK model obtained, evaluated at covariate medians, were 1.08 L/kg for volume of distribution (V) and 0.073 L/h/kg (= 1.23 mL/min/kg) for CL, illustrating that V in Korean neonates is a little larger than in Western population while CL is similar. CONCLUSION: A population PK model of levetiracetam for Korean neonates with seizures was developed in this study. The result of this study can be used as a basis to develop an optimal dosage regimen in Korean neonates with seizures.
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Disposition of levetiracetam in healthy adult horses.

Nine horses received 20 mg/kg of intravenous (LEVIV ); 30 mg/kg of intragastric, crushed immediate release (LEVCIR ); and 30 mg/kg of intragastric, crushed extended release (LEVCER ) levetiracetam, in a three-way randomized crossover design. Crushed tablets were dissolved in water and administered by nasogastric tube. Serum samples were collected over 48 hr, and levetiracetam concentrations were determined by immunoassay. Mean ± SD peak concentrations for LEVCIR and LEVCER were 50.72 ± 10.60 and 53.58 ± 15.94 µg/ml, respectively. The y-intercept for IV administration was 64.54 ± 24.99 µg/ml. The terminal half-life was 6.38 ± 1.97, 7.07 ± 1.93 and 6.22 ± 1.35 hr for LEVCIR , LEVCER, and LEVIV , respectively. Volume of distribution at steady-state was 630 ± 73.4 ml/kg. Total body clearance after IV administration was 74.40 ± 19.20 ml kg-1  hr-1 . Bioavailability was 96 ± 10, and 98 ± 13% for LEVCIR and LEVCER , respectively. A single dose of Levetiracetam (LEV) was well tolerated. Based on this study, a recommended dosing regimen of intravenous or oral LEV of 32 mg/kg every 12 hr is likely to achieve and maintain plasma concentrations within the therapeutic range suggested for humans, with optimal kinetics throughout the dosing interval in healthy adult horses. Repeated dosing and pharmacodynamic studies are warranted.

A Review on Pharmacokinetics of Levetiracetam in Neonates.

BACKGROUND: Neonatal seizures are the most common clinical manifestation of Central Nervous System (CNS) dysfunction and are associated with various neurological sequelae. There are currently no evidence-based guidelines for the management of neonatal seizures and currently used drugs such as phenobarbital, and phenytoin have limited efficacy and potential toxicities. Newer second line anticonvulsant, levetiracetam, has been used in refractory neonatal seizures despite limited data and off-label use. OBJECTIVE: In this review, we will discuss various pharmacological properties of levetiracetam when used in neonatal population. METHODS: A PubMed search for MEDLINE was undertaken to look for studies using the terms "Levetiracetam", AND "Neonates" as key words from year 1995 to January 2017. Relevant articles were selected and information was extracted about pharmacokinetics, pharmacodynamics and clinical uses of levetiracetam in neonates. RESULTS: Levetiracetam is an active, water-soluble S-enantiomer of racemic pyrrolidine acetamide which exerts its antiepileptic action by binding to the synaptic vesicle protein within the brain. Metabolism of levetiracetam does not include the CYP P450 system and it is mainly eliminated through kidneys after rapid absorption. Also, no significant interactions with other drugs have been identified. Unlike other commonly used antiepileptic drugs, levetiracetam is not bound to plasma proteins, thereby, reducing the chances of toxicity and severe, life threatening side effects have not been reported. In fact, it has been shown to prevent neuro-degeneration after hypoxia/ischemia in rodent models of epilepsy. CONCLUSION: Levetiracetam has been emerging as a potential therapeutic option for refractory neonatal convulsions owing to its non-hepatic elimination, linear pharmacokinetics, low protein binding and better safety profile.

Antiepileptic drugs in patients with malignant brain tumor: beyond seizures and pharmacokinetics.

In neurological malignancies, antiepileptic drugs (AEDs) are frequently used to control the seizure activity that accompanies the disorder. There is a growing body of evidence on the importance of AED selection for reasons other than pharmacokinetics (PK) properties. Epigenetic modifications may occur in glioblastomas, such as changes in gene methylation and histone acetylation states. Secondary mechanisms of AED drug action which impact these epigenetic modifications could play a significant role in patient survival outcomes. Both valproic acid (VPA) and carbamazepine have histone deacetylase (HDAC) inhibitory activities, and levetiracetam and VPA reduce the activity of O6-methylguanine-DNA methyltransferase (MGMT), a DNA-repair molecule implicated in resistance to alkylating agents used for chemotherapy. The use of AEDs for purposes other than seizure prophylaxis and their selection based on non-PK properties present a potential paradigm shift in the field of neuro-oncology.

Levetiracetam Pharmacokinetics in a Patient Receiving Continuous Venovenous Hemofiltration and Venoarterial Extracorporeal Membrane Oxygenation.

Levetiracetam is a first-line therapy for seizures in critically ill patients because of its clinical efficacy, minimal drug interactions, and wide therapeutic window. The primary mechanism of levetiracetam clearance is renal, and the drug has a low molecular weight. It is hydrophilic and exhibits minimal protein binding. Thus it is expected that levetiracetam will be removed by continuous venovenous hemofiltration (CVVH), with limited clearance by venoarterial extracorporeal membrane oxygenation (ECMO). We describe the case of a 67-year-old man who was admitted to the cardiovascular surgery intensive care unit after cardiac arrest and initiation of venoarterial ECMO. His course was complicated by multiorgan dysfunction including acute renal failure requiring CVVH. On hospital day 6, intravenous levetiracetam, at a loading dose of 2000 mg followed by a maintenance dose of 1000 mg every 12 hours, was initiated for new-onset seizures. The volume of distribution was 0.65 L/kg, and clearance was measured with peak (ranging from 26.5-39.8 µg/ml) and trough (ranging from 13.9-18.2 µg/ml) concentrations. Elimination half-life ranged from 8.7-10.1 hours. Renal dysfunction reduces levetiracetam clearance, and dosage reductions are recommended to prevent accumulation. Current CVVH dosing recommendations are based on predicted removal without clinical data. The volume of distribution and clearance in this case were similar to those of a normal healthy patient. Based on these results, we recommend considering an initial levetiracetam dose of 1000 mg every 12 hours for patients receiving CVVH, with dosage adjustments based on therapeutic drug monitoring.

Effect of chronic administration of phenobarbital, or bromide, on pharmacokinetics of levetiracetam in dogs with epilepsy.

BACKGROUND: Levetiracetam (LEV) is a common add-on antiepileptic drug (AED) in dogs with refractory seizures. Concurrent phenobarbital administration alters the disposition of LEV in healthy dogs. HYPOTHESIS/OBJECTIVES: To evaluate the pharmacokinetics of LEV in dogs with epilepsy when administered concurrently with conventional AEDs. ANIMALS: Eighteen client-owned dogs on maintenance treatment with LEV and phenobarbital (PB group, n = 6), LEV and bromide (BR group, n = 6) or LEV, phenobarbital and bromide (PB-BR group, n = 6). METHODS: Prospective pharmacokinetic study. Blood samples were collected at 0, 1, 2, 4, and 6 hours after LEV administration. Plasma LEV concentrations were determined by high-pressure liquid chromatography. To account for dose differences among dogs, LEV concentrations were normalized to the mean study dose (26.4 mg/kg). Pharmacokinetic analysis was performed on adjusted concentrations, using a noncompartmental method, and area-under-the-curve (AUC) calculated to the last measured time point. RESULTS: Compared to the PB and PB-BR groups, the BR group had significantly higher peak concentration (Cmax ) (73.4 ± 24.0 versus 37.5 ± 13.7 and 26.5 ± 8.96 µg/mL, respectively, P < .001) and AUC (329 ± 114 versus 140 ± 64.7 and 98.7 ± 42.2 h*µg/mL, respectively, P < .001), and significantly lower clearance (CL/F) (71.8 ± 22.1 versus 187 ± 81.9 and 269 ± 127 mL/h/kg, respectively, P = .028). CONCLUSIONS AND CLINICAL IMPORTANCE: Concurrent administration of PB alone or in combination with bromide increases LEV clearance in epileptic dogs compared to concurrent administration of bromide alone. Dosage increases might be indicated when utilizing LEV as add-on treatment with phenobarbital in dogs.

Levetiracetam pharmacokinetics in Japanese subjects with renal impairment.

BACKGROUND AND OBJECTIVE: The anti-epileptic drug levetiracetam is excreted renally. The objective of this trial was to evaluate the pharmacokinetics of levetiracetam in Japanese patients with renal impairment including end-stage renal disease (ESRD) to confirm that existing dosing instructions-based on data from European patients-are appropriate in a Japanese population. METHODS: This was a nonrandomised, open-label trial. Six participants were allocated to each of five groups (normal renal function, mild, moderate and severe renal impairment and ESRD); 30 participants in total. Participants received a single dose of levetiracetam 500 mg (normal or mild), 250 mg (moderate or severe), or 500 mg followed by 250 mg post-haemodialysis (ESRD). Blood and urine samples were obtained serially for levetiracetam and metabolite determinations. Noncompartmental pharmacokinetic parameters were calculated and steady-state profiles were simulated using the superposition method. RESULTS: In this trial, levetiracetam total clearance decreased proportionally with creatinine clearance: 52, 31, 25, 20 and 11 mL/min/1.73 m(2) in healthy controls and in patients with mild, moderate, severe renal impairment, and ESRD, respectively. Simulated levetiracetam plasma profiles using the recommended dose adjustments were within the range for normal renal function. Overall, results from this trial were consistent with historical European data. CONCLUSION: These findings confirm that the dosing instructions are appropriate for Japanese patients with renal impairment including ESRD.

Augmented renal clearance of vancomycin and levetiracetam in a traumatic brain injury patient.

BACKGROUND: Increased creatinine clearance and subsequent elevated antimicrobial clearance is evident in many traumatic brain injury (TBI) patients due to augmented renal clearance (ARC). Little is known about the effects of ARC on other renally-eliminated medications, such as the anti-epileptic drug levetiracetam. METHODS: This is a case report of serum monitoring of vancomycin and levetiracetam in a 22 year old female with ARC after severe TBI. RESULTS: The patient exhibited ARC of vancomycin as evidenced by her low serum concentrations with standard vancomycin dosing. Her estimated creatinine clearance based on vancomycin clearance was 243.9 ml/min. Serum concentrations also suggested ARC of levetiracetam. No toxicities for either medication were noted, even after dose adjustment to account for possible ARC. CONCLUSIONS: Vancomycin and levetiracetam both appear to be subject to ARC after TBI. Clinicians should be mindful that standard dosing of these agents may not achieve typical target concentrations in this clinical scenario.

Higher evening antiepileptic drug dose for nocturnal and early-morning seizures.

We describe 17 children with nocturnal or early-morning seizures who were switched to a proportionally higher evening dose of antiepileptic drugs and were retrospectively reviewed for seizure outcome and side effects. Of 10 children with unknown etiology, clinical presentation was consistent with nocturnal frontal lobe epilepsy (NFLE) in 5 and benign epilepsy with centrotemporal spikes (BECTS) in 3. After a mean follow-up of 5.3 months, 15 patients were classified as responders; 11 of these became seizure free (5 NFLE, 1 BECTS, 5 with structural lesions) and 4 (2 BECTS, 2 with structural lesions) experienced 75-90% reductions in seizures. Among two nonresponders, seizures in one had failed to resolve with epilepsy surgery. Nine subjects (53%) received monotherapy after dose modification, and none presented with worsening of seizures. Two complained of transient side effects (fatigue/somnolence). Differential dosing led to seizure freedom in 64.7% (11/17) of patients, and 88.2% (15/17) experienced ≥ 50% reductions in seizures.

Quantification of levetiracetam in human plasma by liquid chromatography-tandem mass spectrometry: application to therapeutic drug monitoring.

A rapid, selective, reliable, precise, accurate, and reproducible tandem mass spectrometric (MS-MS) method for the quantification of levetiracetam (LEV) in human plasma using adenosine as an internal standard (IS) has been developed and validated. The drug and IS were extracted by solid phase extraction (SPE) technique and analyzed on Symmetry((R)) C(18) column (5 microm, 3.9 mm x 50 mm) using a mobile phase of methanol-water-formic acid (97:03:0.25, v/v/v) at a flow rate of 0.2 ml/min. Quantitation was achieved using a positive electrospray ionization (ESI+) interface employing multiple reaction monitoring (MRM) mode at MRM transitions m/z 171>126 and m/z 268>136 for LEV and IS, respectively. The method was validated over the concentration range of 1.0-40 microg/ml (r>0.99) with a limit of quantification of 1.0 microg/ml (R.S.D.%; 4.1 and Bias%; -9.0 to + 11.0%). Intra- and inter-run precision of LEV assay at three concentrations ranged from 0.6 to 8.9% with accuracy (bias) varied from -4.0 to 8.6% indicating good precision and accuracy. Analytical recoveries of LEV and IS from spiked human plasma were in the range of 91.7-93.4% and 80.2-84.1%, respectively. Stability of LEV in human plasma samples at different conditions showed that the drug was stable under the studied conditions. Matrix effect study showed a lack of matrix effect on mass ions of LEV and IS. The described method compared well with the commercial HPLC-UV method of Chromsystem (r(2)=0.99). The suitability of the developed method for therapeutic drug monitoring was demonstrated by measuring LEV in human plasma samples of epileptic patients treated with LEV.

[Fulminant liver failure in a patient on carbamazepine and levetiracetam treatment associated with status epilepticus]. / Fulminantes Leberversagen unter Therapie mit Carbamazepin und Levetiracetam nach einer Anfallserie.

A 22-year-old female with a history of developmental delay and seizures successfully treated with carbamazepine and levetiracetam developed fulminant hepatic failure and subsequently died. She had been admitted to the hospital following secondary generalized seizures of 35 min duration. A circulatory shock as well as intoxication was taken into consideration during the clinical course. Autopsy failed to reveal a macroscopically discernible cause of death. Significant findings on microscopic examination included acute tubular necrosis in the kidneys, pre-existing marked accumulation of neutral lipid within the hepatocytes as well as hyperacute liver damage with evidence of almost complete hepatocyte necrosis. Carbamazepine and levetiracetam were simultaneously determined from blood and tissues such as liver, lungs, muscle and kidneys by LC-MS/MS following addition of lamotrigine as an internal standard and liquid-liquid extraction. Validation data are given for levetiracetam. Both carbamazepine and levetiracetam were present in blood at concentrations within or below the therapeutic range, respectively. Moreover, tissue concentrations suggested long-term administration of anticonvulsant drugs, which is in accordance with the medical history. After excessive drug concentrations could be ruled out, the metabolic consequences of a prolonged carbamazepine therapy to cause severe hepatic injury in the present case are discussed. A mechanism of injury to the hepatocytes may be membrane damage by either an increased production of free radicals and/or a decreased free radical scavenging capacity. Following ischemia with reperfusion and during hyperthermia, large amounts of free radicals are formed. Induction of the mixed oxidase activity during longterm administration of carbamazepine may also increase production of free radicals, leaving the hepatic cell more vulnerable to oxidative injury.

Enantioselective analysis of levetiracetam and its enantiomer R-alpha-ethyl-2-oxo-pyrrolidine acetamide using gas chromatography and ion trap mass spectrometric detection.

A gas chromatographic-mass spectrometric method was developed for the enantioselective analysis of levetiracetam and its enantiomer (R)-alpha-ethyl-2-oxo-pyrrolidine acetamide in dog plasma and urine. A solid-phase extraction procedure was followed by gas chromatographic separation of the enantiomers on a chiral cyclodextrin capillary column and detection using ion trap mass spectrometry. The fragmentation pattern of the enantiomers was further investigated using tandem mass spectrometry. For quantitative analysis three single ions were selected from the enantiomers, enabling selected ion monitoring in detection. The calibration curves were linear from 1 microM to 2 mM for plasma samples and from 0.5 mM to 38 mM for urine samples. In plasma and urine samples the inter-day precision, expressed as relative standard deviation was around 10% in all concentrations. Selected ion monitoring mass spectrometry is suitable for quantitative analysis of a wide concentration range of levetiracetam and its enantiomer in biological samples. The method was successfully applied to a pharmacokinetic study of levetiracetam and (R)-alpha-ethyl-2-oxo-pyrrolidine acetamide in a dog.

Renal handling of drugs in the healthy elderly. Creatinine clearance underestimates renal function and pharmacokinetics remain virtually unchanged.

OBJECTIVE: It is commonly assumed that renal function, and in parallel the excretion of drugs, is considerably reduced in the elderly. Endogenous creatinine clearance or indirect estimates of this parameter are generally recommended for adapting drug dosage. The present study evaluates the validity of both assumptions. METHODS: We compared pharmacokinetics (and pharmacodynamics) of 50 mg atenolol, 800 mg piracetam and 25 mg hydrochlorothiazide plus 50 mg triamterene in ten healthy young [25 (2) years] and 11 healthy elderly subjects [68 (5) years]. Inulin (Cin) and para-aminohippurate [PAH (CPAH)] clearance (infusion clearance technique), endogenous (C(Cr)) and calculated (Cockroft-Gault) creatinine clearance, analysis of drugs and their metabolites (HPLC), were performed. Renal haemodynamics and the pharmacokinetics of beta-adrenergic blocking agent, diuretics and the nootropic agent piracetam, respectively, were measured on separate days. RESULTS: Cin was significantly (P < 0.01) lower in the healthy elderly subjects [104 (12) vs 120 (14) ml x min(-2) x 1.73 m(-2) in the young], but remained within the normal range (> 90 ml x min(-2) x 1.73 m(-2)). In contrast, C(Cr) was even lower in healthy elderly subjects [95 (24) vs 121 (20) ml x min(-1) in the young], and the Cockroft-Gault clearance underestimated true glomerular filtration rate (GFR) even more seriously [74 (17) vs 122 (16) ml min(-1)]. For atenolol the mean area under the curve (AUC) was similar in both groups [3.16 (0.48) microg x h(-1) x ml(-1) in the elderly vs 3.01 (0.30) in the young], as was the mean maximal plasma concentration [0.42 (0.07) vs 0.44 (0.06) microg x ml(-1)], but the proportion of the drug excreted in urine was marginally (P < 0.025) lower in the elderly. Similar results were obtained for hydrochlorothiazide, whereas no marked differences between the groups were found for triamterene and its metabolite. Furthermore, the pharmacodynamic action of diuretics was not significantly altered in the elderly. CONCLUSIONS: The true GFR of the healthy elderly remains within the normal range and is underestimated by creatinine clearance and more so by its surrogate (Cockroft-Gault clearance). In parallel, pharmacokinetics of renally excreted drugs are not affected in the healthy elderly to a clinically significant extent. For drugs with a narrow therapeutic window, indirect estimates of GFR appear to be an unreliable means for calculating correct dosage in the elderly.

High-performance liquid chromatographic and megabore gas-liquid chromatographic determination of levetiracetam (ucb L059) in human serum after solid-phase extraction.

For monitoring drug levels of the new potential anticonvulsant drug levetiracetam (ucb L059) in human serum, two assay methods were developed and compared. A solid-phase extraction procedure was followed by either reversed-phase HPLC separation and UV-detection or GLC separation using cold on-column injection on a megabore column and nitrogen-phosphorous detection. Absolute recovery of the drug exceeded 97%. Precision and accuracy values for the 16.0 micrograms/ml quality control sample were 2.4% and 101 +/- 5% (n = 10), respectively, for the GLC method. Precision and accuracy values for the 12.1 micrograms/ml quality control sample were 1.0% and 100 +/- 1% (n = 7), respectively, for the HPLC method. Agreement between both methods was excellent (r = 0.993). Both methods are suitable for pharmacokinetic studies and therapeutic drug monitoring as well. Serum level data for levetiracetam in a patient on chronic antiepileptic medication are presented.