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A river and its surrounding riparian vegetation are two dynamical systems that interact through several hydrological, geomorphological, and ecological processes. This work focuses on the role played by vegetation on meandering river morphodynamics: River planform evolution forces the riparian vegetation dynamics, which, in turn, affect the mechanical characteristics of the river banks and influence the meandering dynamics of the river itself. It follows that despite the fact that a traditional engineering approach considers vegetation as a static element the study of river morphodynamics should be coupled with the riparian vegetation evolution. To this end, a fluid dynamic model of meandering rivers is here coupled with a process-based model for the riparian biomass dynamics. The feedback of vegetation on river morphology is provided by a relation that links the biomass density to the bank erodibility. The numerical results highlight (1) the remarkable effects of the vegetation dynamics on meander evolution and (2) the role of the temporal scales of vegetation growth and decay in relation to typical morphodynamic scales. In particular, the differences with respect to the constant erodibility case can be of the order of tens or hundreds of meters (10-20% of the meander wavelength), and peculiar meander shapes that do not show the usual marked upstream skewness emerge. [ABSTRACT FROM AUTHOR]

In June 2005, a team of experts participated in a workshop with the objective of reaching agreement on several important aspects of valproate in the treatment of elderly patients with epilepsy. Epilepsy in the elderly is relatively common and its incidence increases for each decade after age 60. The aetiology and manifestations of epilepsies in the elderly are complex because of comorbidity and other underlying risk factors. A consensus was reached that elderly patients who present with a seizure disorder should be referred rapidly to a specialist and that diagnosis should be improved by using a multidisciplinary team of cardiologists, neurologists and epilepsy experts (syncope, falls and seizure specialists). This is especially important to avoid mistreatment with antiepileptic drugs (AEDs). There was consensus that the elderly are generally more susceptible to the adverse effects of AEDs than younger adults. For these reasons, in older persons AEDs should be started at low dosages, and titrated slowly according to clinical response. Some of the most troublesome side effects of AEDs in the elderly include sedation and cognitive side effects, as well as osteoporosis. Drug–drug interactions should be given special consideration. There was consensus that the pharmacokinetics of all AEDs are altered in the elderly, and that the most significant change common to all AEDs is a moderate reduction in renal and metabolic clearance. Predicting pharmacokinetic changes in the individual, however, can be very difficult because multiple factors contribute to a high inter-patient variability. There was agreement on the advantages and disadvantages of the use of valproate in the elderly, and consensus that valproate is a useful option in this population. There was no consensus, however, on whether valproate should be considered among the preferred first-line treatments in the elderly. [ABSTRACT FROM AUTHOR]

Adverse effects of antiepileptic drugs (AEDs) are common, can have a considerable impact on quality of life and contribute to treatment failure in up to 40% of patients. The adverse effect profiles of AEDs differ greatly and are often a determining factor in drug selection because of the similar efficacy rates shown by most AEDs. The most common adverse effects are dose dependent and reversible. Cognitive impairment is of particular concern, especially for patients who work or study. Idiosyncratic effects, such as skin rashes, and chronic effects, such as weight gain, can lead to high rates of treatment discontinuation and complicate clinical management. Nearly all conventional AEDs increase the risk of congenital malformations when taken during pregnancy, with valproate posing a potentially greater risk, whereas the potential teratogenicity of new generation AEDs is largely unknown. Most conventional AEDs have a poor record when it comes to drug interactions, largely because of their tendency to interfere with hepatic drug metabolism. Some newer AEDs have no effect on hepatic drug metabolizing enzymes and are renally excreted, resulting in a lower potential for drug interactions. However, further research is needed to confirm the apparent improvement in tolerability offered by some of the newer AEDs. [ABSTRACT FROM AUTHOR]

The antipyrine clearance and the urinary excretion of D-glucaric acid (D-GA) were determined in 122 patients receiving chronic anticonvulsant drug treatment and in 21 drug-free control subjects. Patients treated with carbamazepine (CBZ), phenytoin (DPH), primidone (PMD) and phenobarbitone (PB), either alone or in combination, showed higher values of antipyrine clearance and excreted larger amounts of D-GA as compared to controls. While antipyrine clearance values did not differ significantly from one drug group to another, D-GA excretion was significantly higher in patients treated with CBZ than in those treated with DPH. In patients treated with sodium valproate antipyrine clearance did not differ from control values. There was a trend for D-GA excretion to be higher in these patients but the difference was not statistically significant. Significant positive correlations were found between the dosage of CBZ, DPH, PMD and PB and both indices of enzyme induction. These data demonstrate a dose-dependent degree of enzyme induction in patients receiving therapeutic doses of these anticonvulsants. The relative potency at average dose levels for antipyrine clearance was PB (1), DPH (0.92), CBZ (0.84), PMD (0.82) and for log D-GA excretion was PB (1), CBZ (0.96), PMD (0.95), DPH (0.90). [ABSTRACT FROM AUTHOR]

Infections are probably the most common preventable cause of epilepsy worldwide. There are concerns that endemic infections and infestations, such as malaria and neurocysticercosis, could be responsible for the increased incidence of epilepsy in the developing world. Cases of epilepsy associated with neurocysticercosis are also being seen increasingly in developed countries due to migration from, and travel to, endemic areas. When prescribing antimicrobial agents in patients with epilepsy a number of issues need to be considered, such as potential adverse effects on seizure control and interactions with concomitant antiepileptic drugs (AEDs). Some antimicrobial agents, including penicillins, cephalosporins, carbapenems, quinolones and antimalarials, can have proconvulsant activity and may precipitate seizures, even in patients who do not have epilepsy. Moreover, many antimicrobials increase or decrease the plasma levels of AEDs, whereas some AEDs may adversely affect the efficacy of antimicrobials. [ABSTRACT FROM AUTHOR]

Although older generation antiepileptic drugs (AEDs) such as carbamazepine, phenytoin and valproic acid continue to be widely used in the treatment of epilepsy, these drugs have important shortcomings such as a highly variable and nonlinear pharmacokinetics, a narrow therapeutic index, suboptimal response rates, and a propensity to cause significant adverse effects and drug interactions. In an attempt to overcome these problems, a new generation of AEDs has been introduced in the last decade. Compared with older agents, some of these drugs offer appreciable advantages in terms of less variable kinetics and, particularly in the case of gabapentin, levetiracetam and vigabatrin, a lower interaction potential. Lamotrigine, topiramate, zonisamide and felbamate protect against partial seizures and a variety of generalized seizure types, vigabatrin is effective against partial seizures (with or without secondary generalization) and infantile spasms, while the use of oxcarbazepine, tiagabine and gabapentin is mainly resticted to patients with partial epilepsy (and, in the case of oxcarbazepine, also primarily generalized tonic-clonic seizures). Levetiracetam, the latest AED to be introduced, has been found to be effective in partial seizures, but its potentially broader efficacy spectrum remains to be determined in clinical studies. Currently, the main use of new generation AEDs is in the adjunctive therapy of patients refractory to older agents. However, due to advantages in terms of tolerability and ease of use, some of these drugs are increasingly used for first-line management in certain subgroups of patients. Due to serious toxicity risks, felbamate and vigabatrin should be prescribed only in patients refractory to other drugs. [ABSTRACT FROM AUTHOR]

Aims The aim of the study was to characterize further the role of CYP3A4 in the metabolism of tricyclic antidepressants. Methods The effect of oral ketoconazole (200 mg day−1 for 14 days) on the kinetics of a single oral dose of imipramine (100 mg) and desipramine (100 mg) was evaluated in two groups of six healthy male subjects. Results Ketoconazole administration was associated with a decrease in imipramine apparent oral clearance (from 1.16±0.21 to 0.96±0.20 l h−1 kg−1, mean±s.d.; 'of2\P<0.02), a prolongation in imipramine half-life (from 16.7±3.3 to 19.2±5.4 h, 'of2\P<0.05) and a decrease in area under the curve of metabolically derived desipramine (from 3507±1707 to 3180±1505 nmol l−1 h, P<0.05), whereas concentrations of 2-hydroxy-imipramine were unaffected. In the subjects given desipramine, no significant changes in desipramine and 2-hydroxy-desipramine kinetics were observed during ketoconazole treatment. Conclusions These findings indicate that ketoconazole, a relatively specific inhibitor of CYP3A4, inhibits the N-demethylation of imipramine without affecting the 2-hydroxylation of imipramine and desipramine. This interaction, confirms that CYP3A4 plays a role in the demethylation of tricyclic antidepressants. [ABSTRACT FROM AUTHOR]

1To assess the effect of enzyme inducing anticonvulsants on ethosuximide pharmacokinetics, plasma ethosuximide concentrations after a single oral dose (500 mg) of the drug were compared in 12 healthy control subjects and 10 epileptic patients receiving chronic therapy with phenobarbitone, phenytoin and/or carbamazepine. 2Compared with controls, epileptic patients showed markedly shorter ethosuximide half-lives (29.0±7.8 vs 53.7±14.3 h, means±s.d., P<0.001) and higher apparent oral clearance (CL/ F) values (15.3±3.8 vs 9.2±1.9 ml kg−1 h−1, P<0.001). The apparent volume of distribution ( V/F) of ethosuximide was slighty lower in the patients than in controls (0.6±0.1 vs 0.7±0.1 l kg−1, P<0.05). 3These findings provide evidence that ethosuximide elimination is increased by enzyme inducing anticonvulsants, the effect probably being mediated by stimulation of cytochrome CYP3A activity. 4The enhancement of ethosuximide clearance in patients comedicated with enzyme inducing anticonvulsants is likely to be clinically relevant. Higher ethosuximide dosages will be required to achieve therapeutic drug concentrations in these patients. [ABSTRACT FROM AUTHOR]

1. The pharmacokinetics and metabolism of primidone at steady-state were studied in 10 elderly patients aged 70-81 years and eight control subjects aged 18-26 years. 2. Primidone half-lives and clearance values (mean +/− s.d.) were similar in the elderly and in the young (12.1 +/− 4.6 vs 14.7 +/− 3.5 h and 34.8 +/− 9.0 vs 33.2 +/− 7.2 ml h-1 kg-1 respectively. 3. The serum concentrations of the metabolites phenylethylmalonamide (PEMA) and phenobarbitone relative to those of parent drug were higher in the elderly than in the young, the difference being significant (P less than 0.01) in the case of PEMA. 4. The renal clearances of primidone, phenobarbitone and PEMA were moderately decreased in the elderly but this reduction was statistically significant only for PEMA. Elderly patients excreted a reduced proportion of unchanged primidone and an increased proportion of PEMA in urine. 5. Ageing is associated with a greater accumulation of PEMA, which is unlikely to have a major clinical significance. [ABSTRACT FROM AUTHOR]

1. Somatosensory (SEP) brainstem auditory (BAEP) and visual (VEP) evoked potentials were determined before and after add-on administration of vigabatrin (GVG) in patients with epilepsy. 2. At pre- treatment assessment SEP and BAEP parameters were usually found to be within normal limits, while P100 latencies of the VEP were abnormally prolonged in a considerable proportion of patients. 3. In a double- blind, placebo-controlled trial in 22 patients GVG (1-3 g day-1 stratified according to body weight) given for 7 weeks did not modify any of the evoked potential parameters evaluated. 4. Eighteen patients were evaluated prospectively at regular intervals during long-term GVG (2-4 g day-1) therapy with a mean follow up of 24 months (range 13-42 months). SEP, BAEP and especially VEP parameters showed some interindividual variability, but the within patient variation was relatively small. No consistent important changes were seen in association with GVG, although a possible trend towards a shortening of BAEP latencies and P100 latencies was observed. 5. The relevance of these findings with respect to GVG safety is discussed. [ABSTRACT FROM AUTHOR]

The antipyrine clearance and the urinary excretion of D-glucaric acid (D-GA) were determined in 122 patients receiving chronic anticonvulsant drug treatment and in 21 drug-free control subjects. Patients treated with carbamazepine (CBZ), phenytoin (DPH), primidone (PMD) and phenobarbitone (PB), either alone or in combination, showed higher values of antipyrine clearance and excreted larger amounts of D-GA as compared to controls. While antipyrine clearance values did not differ significantly from one drug group to another, D-GA excretion was significantly higher in patients treated with CBZ than in those treated with DPH. In patients treated with sodium valproate antipyrine clearance did not differ from control values. There was a trend for D- GA excretion to be higher in these patients but the difference was not statistically significant. Significant positive correlations were found between the dosage of CBZ, DPH, PMD and PB and both indices of enzyme induction. These data demonstrate a dose-dependent degree of enzyme induction in patients receiving therapeutic doses of these anticonvulsants. The relative potency at average dose levels for antipyrine clearance was PB (1), DPH (0.92), CBZ (0.84), PMD (0.82) and for log D-GA excretion was PB (1), CBZ (0.96), PMD (0.95), DPH (0.90). [ABSTRACT FROM AUTHOR]

The kinetics and dynamics (inhibition of exercise tachycardia) of two controlled-release preparations of propranolol (Elanolol and Inderal LA) were examined in six normal volunteers. Conventional propranolol (Inderal) was also studied for comparison purposes. As compared to conventional propranolol (120 mg), single doses of Elanol (120 mg) and Inderal LA (160 mg) produced a smoother serum level profile, with lower and delayed peak times. Dose-corrected AUC0-24 values were greater after Elanol than after Inderal LA (651 +/- 147 vs 402 +/- 159 ng ml-1 h, means +/- s.e. mean, P greater than 0.05). The profile of inhibition of exercise tachycardia mirrored closely that of the serum levels. At steady state, all regimens studied (Inderal 40 mg three times daily; Elanol 120 mg once daily; Inderal LA 160 mg once daily) ensured relatively sustained serum levels and a stable degree of pharmacological effect. Dose-corrected AUC0-24 values were 797 +/- 148 ng ml-1 h after Inderal, 908 +/- 113 ng ml-1 h after Elanol and 602 +/- 122 ng ml-1 after Inderal LA. The bioavailability of Inderal LA was significantly lower than that of the other preparations. These results demonstrate that long-acting formulations of propranolol can be developed which are not necessarily associated with reduced bioavailability secondary to enhanced first-pass metabolism. [ABSTRACT FROM AUTHOR]

The plasma protein binding of phenytoin was studied in nine epileptic patients before and during addition of sodium valproate to the drug therapy. The free phenytoin fraction in plasma was significantly greater during sodium valproate treatment. The mean free fraction rose from 0.135 +/- 0.019 (s.d.) to 0.182 +/- 0.030. Total plasma phenytoin concentration fell significantly from a range of 4.3-26.2 micrograms/ml to 3.4-19.8 micrograms/ml during sodium valproate treatment. Neither the free plasma concentration nor the saliva concentration of phenytoin was significantly altered by sodium valproate. No significant correlation was found between plasma valproic acid concentrations and the change in phenytoin binding. We conclude that valproic acid displaces phenytoin from plasma protein binding sites but does not inhibit its metabolism. [ABSTRACT FROM AUTHOR]

The unbound fraction of valproic acid (VPA) was found to be significantly lower in cord serum (6.0 +/- 0.8%) than in maternal serum collected before oxytocin (12.2 +/- 2.7%) or after delivery (9.9 +/- 2.3%). The difference was probably due to the concentration of free fatty acids (acting as displacing agents) being higher in maternal serum. The transplacental binding gradient explains the clinical observation that total VPA levels at delivery are higher in the newborn than in the mother. [ABSTRACT FROM AUTHOR]

The kinetics of a single oral dose of sodium valproate was studied in six healthy elderly patients (age 68-89 years) and six young control subjects (age 24-26 years). The profiles of total plasma valproic acid (VPA) concentrations were very similar in the elderly and in the young. Half-lives (15.3 +/- 0.7 s.e. mean in the elderly vs 13.0 +/- 1.0 h in the young), volumes of distribution (0.16 +/- 0.01 l/kg in the elderly vs 0.14 +/- 0.01 l/kg in the young) and clearance (7.5 +/- 0.9 ml h-1 kg-1 in the elderly vs 7.7 +/- 0.6 ml h-1 kg-1 in the young) did not differ significantly between the two groups. Free VPA concentrations were significantly increased in the elderly. The clearance of the free drug (intrinsic clearance) was reduced from 127.0 +/- 12 ml h-1 kg-1 (control value in the young) to 77.7 +/- 5.5 ml h-1 kg-1 (P less than 0.02). Free VPA fraction was 9.5 +/- 0.6% in the elderly and 6.6 +/- 0.5% in the young (P less than 0.02). These findings suggest that the pharmacokinetic alterations of VPA in old age are complex and include at least two separate mechanisms: a decrease in plasma protein binding and a reduction of drug metabolizing capacity resulting in decreased clearance of free drug by the liver. [ABSTRACT FROM AUTHOR]

The kinetics at steady state of prednisone and its metabolite prednisolone were determined in nine nephrotic children during the active phase of the disease and in remission. There were no differences in serum prednisone levels between the two occasions. Prednisone levels were lower than prednisolone levels. Total serum prednisolone levels were significantly lower during the active phase than in remission (AUC: 2452 +/- 207 vs 3392 +/- 293 ng ml-1 h respectively). Half-life values were similar on both occasions. The binding of prednisolone to serum proteins was markedly impaired during the active phase as compared to the remission. Free fraction values correlated positively with total drug concentration. A negative correlation between free fraction and serum albumin level was found during the active phase. Free prednisolone levels during the active phase did not differ significantly from those observed during remission (AUC: 937 +/- 128 vs 847 +/- 81 ng ml-1 h respectively). These data indicate that pharmacokinetic changes are unlikely to be responsible for alterations in steroid responsiveness in nephrotic patients with hypoalbuminaemia. [ABSTRACT FROM AUTHOR]

1 The effect of pregnancy on the binding of phenytoin and phenobarbitone to serum proteins was studied in normal women and in drug treated epileptic women. 2 The binding of both drugs was reduced during pregnancy. The reduction correlated positively with the gestational age and negatively with the serum albumin concentration. 3 In spite of the increase in unbound fraction, both the total and free serum concentrations of phenytoin were decreased in late pregnancy. [ABSTRACT FROM AUTHOR]

1 The disposition kinetics of lignocaine and antipyrine were compared in eight normal subjects and in eleven patients receiving chronic therapy with antiepileptic drugs. The urinary excretion of D-glucaric acid (D-GA) was measured in 16 subjects. 2 In patients treated with antiepileptic drugs antipyrine clearance and D-GA excretion were significantly increased, whereas lignocaine biovailability was significantly reduced. 3 When all the subjects included in the study were considered, a significant positive correlation could be found between the apparent oral clearance of lignocaine (Dose/area under the blood concentration curve) and both antipyrine clearance (r = 0.73) and D-GA excretion (r = 0.74). 4 When normal subjects and epileptic patients were considered separately, a significant positive correlation could be confirmed between the apparent oral clearance of lignocaine and both antipyrine clearance (r = 0.71) and D-GA excretion (r = 0.76) in normal subjects, and between antipyrine clearance and D-GA excretion (r = 0.75) in epileptic patients. 5 These results suggest that the reduction of the oral availability of lignocaine in epileptic patients is secondary to induction of first-pass metabolism of the latter drug. [ABSTRACT FROM AUTHOR]

The kinetics of sodium valproate (di- n-propyl-acetate, Depakine®) have been studied in six healthy volunteers after administration of single oral and intravenous doses (800 mg)., Kinetic parameters were similar for both routes of administration. In all subjects absorption was rapid and complete. Half-lives ranged from 11-15 h. Apparent volumes of distribution were relatively low (0.147 ± 0.0041/kg) and showed little variation amongst individuals., The factors responsible for the poor correlation between dosage and serum levels during chronic treatment and therapeutic implications are discussed. [ABSTRACT FROM AUTHOR]

The effects of single intravenous doses of diazepam, clonazepam, lorazepam, frusemide, mexiletine and (+)-propranolol on the frequency of electroencephalographic (EEG) interictal spike discharges were assessed in three double-blind placebo-controlled trials in fourteen epileptic patients., Diazepam (5 mg) produced a significant mean decrease of spike discharges to about one third of the control frequency. The effect developed rapidly and persisted for the duration of the study (up to 25 min after injection). A larger dose (10 mg) failed to produce a further reduction in the frequency of the spike discharges., Clonazepam (0.5 mg), frusemide (40 mg) and lorazepam (2 mg) appeared to be as effective as diazepam in reducing spike discharges, although the effect of the latter drug seemed to develop with some delay., Mexiletine (100 mg) and (+)-propranolol (50 mg) did not reduce paroxysmal EEG discharges, their effects being not significantly different from that of saline., EEG spike counting after intravenous administration of single test-doses appeared to be both a simple and promising technique for the rapid preliminary evaluation of the clinical efficacy of new anti-epileptic drugs. [ABSTRACT FROM AUTHOR]

Highlights the Fourth European Congress of Epileptology 2000 in Florence, Italy. Sessions of the congress; Recognition of doctors, J.P.S. Cunha and Averio Portugal as Best Contribution in Clinical Epileptology awardee; Purpose of the conference.

The effect of the valpromide isomer valnoctamide (VCD, 200 mg three times daily for 8 days), an over-the-counter tranquillizer, on the elimination kinetics of a single oral dose of carbamazepine-10, 11- epoxide (CBZ-E, 100 mg) was investigated in healthy subjects. During VCD treatment, the half-life of CBZ-E was prolonged significantly compared with control (19.7 +/- 6.7 h vs 6.9 +/- 2.0 h, means +/- s.d., P less than 0.01), and its oral clearance decreased four-fold (from 109.6 +/- 30.7 to 28.8 +/- 11.1 ml h-1 kg-1, P less than 0.01). These findings indicate that VCM, like valpromide, strongly inhibits epoxide hydrolase in vivo. [ABSTRACT FROM AUTHOR]

The single oral dose pharmacokinetics of carbamazepine-10, 11-epoxide (CBZ-E) were investigated in six normal volunteers during a control session and during concurrent treatment with valpromide (VPM) (300 mg twice daily for 8 days). VPM caused a prolongation of the CBZ-E half- life from 6.4 +/- 1.4 to 20.5 +/- 6.3 h and decreased CBZ-E clearance from 73.5 +/- 20.0 to 23.5 +/- 4.0 ml h-1 kg-1 (P less than 0.01). These results suggest that the elevation of plasma CBZ-E levels in patients receiving carbamazepine and VPM in combination is due to inhibition of epoxide hydrolase in the liver. [ABSTRACT FROM AUTHOR]

The serum levels of carbamazepine (CBZ) and its 10,11-epoxide metabolite (CBZ-E) were determined in seven subjects after a single dose of CBZ (400 mg) in the control state and during co-administration of erythromycin (500 mg three times daily for 10 days). Erythromycin treatment was associated with a decrease in CBZ clearance and a prolongation of CBZ half-life, while CBZ-E levels were markedly reduced. These data provide evidence that erythromycin inhibits the conversion of CBZ to its epoxide metabolite. [ABSTRACT FROM AUTHOR]

The effect of a high potency antacid on the oral bioavailability of a single dose of famotidine (40 mg) was evaluated in normal volunteers according to a randomized cross-over design. Ingestion of the antacid concurrently with famotidine resulted in a significant reduction of peak plasma famotidine concentration (from 156 ± 22 to 104 ± 7, P < 0.05) and area under the famotidine plasma concentration curve (from 956 ± 125 to 607 ± 56, P < 0.02). No significant interaction was observed when the antacid was ingested 2 hours after famotidine administration. [ABSTRACT FROM AUTHOR]

The effect of cholestyramine (4 g qid for 5 days) on the kinetics of phenytoin (400 mg orally) was investigated in normal subjects. Apart from a trend toward faster phenytoin absorption, the serum level profile of the drug during concurrent cholestyramine coadministration was similar to that observed in a control session. Areas under the serum phenytoin concentration curves were virtually identical in the two occasions. It is concluded that cholestyramine does not significantly affect the bioavailability of a single dose of phenytoin. [ABSTRACT FROM AUTHOR]

Objective: A previous European cost-utility study reported that use of buccal midazolam in the community setting for the treatment of prolonged seizures (ie, seizures lasting ≥5 minutes) in children was associated with an overall €12 507 399 reduction in annual costs charged to the Italian national health service compared with rectal diazepam. We re-evaluated these findings by applying a more conservative approach., Methods: The Italian Delphi panel reconvened to apply a more conservative assessment of available reports. A decision-tree model was used, allowing for different treatment pathways depending on whether or not a caregiver administers treatment, an ambulance is required for transport of the child to hospital, and an inpatient stay is required. Direct medical costs were derived from Italian healthcare system data. Estimates of the annual number of prolonged tonic-clonic seizures expected in the country were based on studies which assessed seizure duration using video-EEG recordings and medical records., Results: Although drug acquisition costs were greater for buccal midazolam than for rectal diazepam, the acquisition cost difference was outweighed by larger cost savings resulting mostly from a reduction in hospital admissions. Assuming that 1.2% of tonic and/or clonic seizures occurring in children and adolescents over a 12-month period are prolonged, the annual nationwide reduction in costs from preferring buccal midazolam to rectal diazepam was estimated at €3 577 587.9., Conclusions: In this more conservative revised analysis, the high cost of buccal midazolam is still counteracted by greater cost savings compared with rectal diazepam, but cost reduction was less than previously estimated., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Lamotrigine (LTG) is one of the most widely used antiepileptic drugs. Confusion still exists in the literature as to the relative influence of age, body weight, and concomitant drug therapy on LTG pharmacokinetics. So, the objective of this study is to evaluate the influence of patient-related factors and comedication on LTG apparent oral clearance (CL/F). A therapeutic drug-monitoring database was used to identify steady-state plasma LTG concentrations in 210 patients. LTG CL/F values were calculated for each patient according to the equation CL/F (L/h per kg) = LTG daily dose (mg/kg)/Css (steady state concentration) (mg/L) × 24 h. A linear-regression model was used to assess the influence of gender, dose, age, and body weight in LTG CL/F. The influence of comedication on LTG CL/F was investigated by applying the Bonferroni post-test. The lowest LTG CL/F was found in patients comedicated with valproate (VPA) (mean, 0.0183 L/h per kg), followed by patients receiving VPA + enzyme inducers (0.0271 L/h per kg), patients on LTG monotherapy (0.0298 L/h per kg) and patients comedicated with enzyme inducers (0.056 L/h per kg) LTG CL/F correlated significantly with LTG dose (P < 0.01), but showed no significant relationship with gender, weight, and age. LTG CL/F is influenced by the type of antiepileptic comedication. The correlation with dose may be a spurious finding related to the fact that physicians, in adjusting dosage according to clinical response, are more likely to use larger doses in patients with high clearance values., (© 2016 John Wiley & Sons Australia, Ltd.)

Some patients with difficult-to-treat epilepsy benefit from combination therapy with two or more antiepileptic drugs (AEDs). Additionally, virtually all epilepsy patients will receive, at some time in their lives, other medications for the management of associated conditions. In these situations, clinically important drug interactions may occur. Carbamazepine, phenytoin, phenobarbital and primidone induce many cytochrome P450 (CYP) and glucuronyl transferase (GT) enzymes, and can reduce drastically the serum concentration of associated drugs which are substrates of the same enzymes. Examples of agents whose serum levels are decreased markedly by enzyme-inducing AEDs, include lamotrigine, tiagabine, several steroidal drugs, cyclosporin A, oral anticoagulants and many cardiovascular, antineoplastic and psychotropic drugs. Valproic acid is not enzyme inducer, but it may cause clinically relevant drug interactions by inhibiting the metabolism of selected substrates, most notably phenobarbital and lamotrigine. Compared with older generation agents, most of the recently developed AEDs are less likely to induce or inhibit the activity of CYP or GT enzymes. However, they may be a target for metabolically mediated drug interactions, and oxcarbazepine, lamotrigine, felbamate and, at high dosages, topiramate may stimulate the metabolism of oral contraceptive steroids. Levetiracetam, gabapentin and pregabalin have not been reported to cause or be a target for clinically relevant pharmacokinetic drug interactions. Pharmacodynamic interactions involving AEDs have not been well characterized, but their understanding is important for a more rational approach to combination therapy. In particular, neurotoxic effects appear to be more likely with coprescription of AEDs sharing the same primary mechanism of action.

The understanding of neurobiological mechanisms of epileptogenesis is essential for rational approaches for a possible disease modification as well as treatment of underlying causes of the epilepsies. More effort is necessary to translate results from basic investigations into new approaches for clinical research and to better understand a relationship with findings from clinical studies. The following report is a condensed synapsis in which molecular mechanisms of epileptogenesis, pharmacological modulation of epileptogenesis, evidence based therapy, refractoriness and prediction of outcome is provided in order to stimulate further collaborative international research.

Aims: This serendipitous study revealed an unexpected effect of Jufeng grape juice on the CYP1A2-mediated metabolism of phenacetin. Investigation of the inhibition of CYP1A2 by grapefruit juice was involved but a translation error led to the grape juice substitution., Methods: Twelve healthy subjects took a single oral dose of phenacetin (900 mg) on two randomized occasions together with 200 ml water or grape juice. Plasma phenacetin and paracetamol concentrations were assessed by h.p.l.c., Results: Ingestion of grape juice was associated with reduced plasma phenacetin concentrations, while paracetamol levels were unaffected. Paracetamol to phenacetin AUC ratios increased from 13.9+/-3.1 to 24.3+/-3.8 after ingestion of grape juice., Conclusions: These findings suggest enhanced first-pass metabolism of phenacetin, due to CYP1A2 activation by grape juice or to desaturation of CYP1A2 isoenzymes secondary to a slower rate of phenacetin absorption.

1. After a hiatus of over 20 years, several new antiepileptic drugs (vigabatrin, lamotrigine, gabapentin, oxcarbazepine, topiramate, felbamate, zonisamide and tiagabine) have reached or approached the registration phase. 2. Compared with older agents, many new drugs exhibit simpler pharmacokinetics. This is especially true for vigabatrin and gabapentin, which are renally eliminated and have a low interaction potential. 3. Unlike most of the older agents, vigabatrin, lamotrigine, gabapentin and tiagabine are devoid of significant enzyme inducing or inhibiting properties. Topiramate, oxcarbazepine and felbamate may induce the metabolism of steroid oral contraceptives. In addition, felbamate also acts as a metabolic inhibitor. 4. To date, the efficacy of new drugs has been evaluated extensively only under add-on conditions in patients with partial seizures (with or without secondary generalization) refractory to conventional treatment. However, there is evidence that lamotrigine, zonisamide, felbamate and, possibly, topiramate may also be effective in generalized epilepsies. 5. In placebo-controlled studies, typically between 15 and 40% of patients with difficult-to-treat partial epilepsy have shown an improvement (defined as a 50% or greater decrease in seizure frequency) after addition of a new drug. Only a small minority of these patients achieved complete seizure control. 6. Compared with older agents, some of the new drugs may have a better tolerability profile. Felbamate, however, has been associated with a high risk of aplastic anaemia and hepatotoxicity. 7. At present, the main use of the new agents is in patients refractory to first-line drugs such as carbamazepine or valproate, and further studies are required to characterize their activity spectrum as well as their potential value in monotherapy. In most patients, new drugs cannot be recommended for first-line use until evidence is obtained that potential advantages in tolerability or ease of use outweigh the drawback of their high cost.

Most patients with newly diagnosed epilepsy can be optimally controlled by prescribing a single anti-epilepsy drug, selected on the basis of its efficacy and safety profile. In about one-third of patients, however, seizures persist during monotherapy, despite the intake of the maximally tolerated drug dose. In such cases, substantial therapeutic benefit may be achieved by prescribing appropriate drug combinations. Safe use of multiple drug therapy requires a good knowledge of clinical pharmacology, particularly an awareness of potentially adverse drug interactions. As many older anti-epilepsy drugs have similar modes of action, their interaction may not always be of clinical benefit, because drug side-effects may also be additive. There is, however, evidence that specific combinations may be particularly advantageous; for example, valproate and ethosuximide in the management of refractory absence seizures. Compared with older drugs, some of the recently developed agents possess different and more selective mechanisms of action, which may result in enhanced therapeutic benefit when specific combinations are used. Preliminary observations do suggest that, in some cases, the efficacy exhibited by certain new drugs could be explained in terms of their pharmacological effect being 'complementary' to that of concurrently used agents.

The effects of Viloxazine (VLX, 100 mg b.i.d. for 10 days) on the steady-state plasma concentrations of Oxcarbazepine (OXC), its active metabolite 10, 11-dihydro-10-hydroxy-carbazepine (MHD) and the corresponding diol (DHD) were studied in a randomized, double-blind cross-over placebo-controlled trial in 6 epileptic patients stabilized on a fixed dosage of OXC. Administration of VLX resulted in an 11% increase in the plasma concentration of MHD (p = 0.003) associated with a 31% fall in DHD levels (p = 0.0001). Plasma concentrations of unchanged OXC were unaffected by VLX. No changes in seizure frequency nor signs of drug toxicity were observed during the study. Although VLX may inhibit the conversion of MHD to the inactive diol, the interaction is unlikely to be of clinical significance.

The possibility that vigabatrin (VGB) decreases serum phenytoin (PHT) concentration by lowering the oral bioavailability of PHT was investigated in 21 patients with epilepsy. Each patient was switched from oral to intravenous PHT for 5 days before and after combined treatment with VGB. After VGB (2-3.5 g day(-1) for at least 5 weeks), serum PHT concentrations decreased slightly from 87 +/- 25 to 76 +/- 31 micromol l(-1) (means +/- s.d., P < 0.05), but in a subgroup of seven patients the decrease was more prominent (from 72 +/- 22 to 49 +/- 17 micromol l(-1), P < 0.005). At baseline (before VGB), serum PHT remained unaffected (85 +/- 30 micromol l(-1)) after switching PHT dosage to the intravenous route, indicating that the oral availability of the drug was virtually complete. During VGB treatment, serum PHT was also unchanged (74 +/- 34 micromol l(-1)) after switching from oral to intravenous therapy, and this was also true for the subgroup of patients showing a prominent interaction (48 +/- 18 micromol l(-1)). The urinary recoveries of PHT and its metabolites pHPPH and mHPPH remained constant throughout the study. It is concluded that the oral availability of PHT is unaffected by VGB and that the VBG-induced decrease in serum PHT is mediated by alternative mechanisms.