Extremely high unbound flucloxacillin concentrations in a patient with acute septic renal failure during continuous venovenous hemofiltration: Therapeutic drug monitoring to optimize treatment.

A 75-year-old female orthopedic patient with spondylodiscitis was admitted to the intensive care unit, where she developed severe acute renal injury (AKI) due to a Staphylococcus aureus bloodstream infection. Continuous venovenous hemofiltration (CVVH) was initiated as renal replacement therapy. According to physician experience and based on (inter)national guidelines and the severity of the infection, treatment with intravenous (IV) flucloxacillin at an initial continuous dose of 9 g/24h was started. The dose was increased to 12 g/24h because endocarditis could not be excluded. Therapeutic drug monitoring (TDM) was used to monitor flucloxacillin levels which are related to antibiotic efficacy and toxicity. Total and unbound flucloxacillin concentrations were measured following 24 hours of continuous infusion at three time points before regional citrate anticoagulation (RCA)-CVVH was initiated, at three time points in plasma, pre-filter, and post-filter, and in ultrafiltrate samples during RCA-CVVH treatment and 1 day following cessation of CVVH treatment. Extremely high total (up to 299.8 mg/L) and unbound (up to 155.1 mg/L) flucloxacillin concentrations were found in the plasma. This led to a dose decrease to 6 g/24h and subsequently to 3 g/24h. Antimicrobial target attainment against S. aureus was achieved by dosing IV flucloxacillin based on TDM. Based on these findings, we conclude that current dosing guidelines for flucloxacillin during renal replacement therapy need revision. We suggest a starting dose of 4 g/24h, which should be adjusted based on the TDM of the unbound flucloxacillin concentration.

Efficacy and tolerability of brivaracetam in patients with intellectual disability and epilepsy.

Patients with intellectual disability (ID) are often excluded from clinical trials, and little is known about the best approach to treat their epilepsy. Brivaracetam (BRV) is a new antiepileptic drug (AED) for adjunctive treatment in patients with focal-onset seizures with or without secondary generalization. We analyzed the efficacy and tolerability of BRV in patients with ID and epilepsy who either had or had not previously received treatment with levetiracetam (LEV). Data on efficacy and tolerability were retrospectively collected. After the initial start of BRV in our tertiary epilepsy center, we analyzed medical records at 0, 3, 6 and 12 months of follow-up. 116 patients were included (mean age = 34.9 years, 44% female). All had complete data of 3-month follow-up, 76 of 6-month follow-up, and 39 patients of 1-year follow-up. Median starting dose of BRV was 50.0 mg/day and the mean number of concomitant AEDs was 2.6. Seizure reduction and no side effects were reported in more than half of all patients. The most reported side effects were somnolence, dizziness and aggression. Retention rates for BRV were 84.4%, 75.5% and 58.1% after 3, 6 and 12 months, respectively. Seizure reduction and side effects did not differ significantly between the groups with or without previous LEV treatment. We demonstrate that BRV is effective and well tolerated in patients with epilepsy and ID, even in those where previous LEV treatment failed.

Therapeutic Drug Monitoring of Antiepileptic Drugs in Women with Epilepsy Before, During, and After Pregnancy.

During pregnancy, the pharmacokinetics of an antiepileptic drug is altered because of changes in the clearance capacity and volume of distribution. These changes may have consequences for the frequency of seizures during pregnancy and fetal exposure to antiepileptic drugs. In 2009, a review was published providing guidance for the dosing and therapeutic drug monitoring of antiepileptic drugs during pregnancy. Since that review, new drugs have been licensed and new information about existing drugs has been published. With this review, we aim to provide an updated narrative overview of changes in the pharmacokinetics of antiepileptic drugs in women during pregnancy. In addition, we aim to formulate advice for dose modification and therapeutic drug monitoring of antiepileptic drugs. We searched PubMed and the available literature on the pharmacokinetic changes of antiepileptic drugs and seizure frequency during pregnancy published between January 2007 and September 2018. During pregnancy, an increase in clearance and a decrease in the concentrations of lamotrigine, levetiracetam, oxcarbazepine's active metabolite licarbazepine, topiramate, and zonisamide were observed. Carbamazepine clearance remains unchanged during pregnancy. There is inadequate or no evidence for changes in the clearance or concentrations of clobazam and its active metabolite N-desmethylclobazam, gabapentin, lacosamide, perampanel, and valproate. Postpartum elimination rates of lamotrigine, levetiracetam, and licarbazepine resumed to pre-pregnancy values within the first few weeks after pregnancy. We advise monitoring of antiepileptic drug trough concentrations twice before pregnancy. This is the reference concentration. We also advise to consider dose adjustments guided by therapeutic drug monitoring during pregnancy if the antiepileptic drug concentration decreases 15-25% from the pre-pregnancy reference concentration, in the presence of risk factors for convulsions. If the antiepileptic drug concentration changes more than 25% compared with the reference concentration, dose adjustment is advised. Monitoring of levetiracetam, licarbazepine, lamotrigine, and topiramate is recommended during and after pregnancy. Monitoring of clobazam, N-desmethylclobazam, gabapentin, lacosamide, perampanel, and zonisamide during and after pregnancy should be considered. Because of the risk of teratogenic effects, valproate should be avoided during pregnancy. If that is impossible, monitoring of both total and unbound valproate is recommended. More research is needed on the large number of unclear pregnancy-related effects on the pharmacokinetics of antiepileptic drugs.

Review on the relevance of therapeutic drug monitoring of levetiracetam.

Therapeutic Drug Monitoring (TDM) of anti-epileptic drugs (AEDs) is not routinely performed, although this can guide the dosage regimen to achieve greater efficacy and safety. Levetiracetam (LEV) has been introduced as an AED with an almost perfect pharmacokinetic (PK) profile. Nonetheless, recent research challenges this statement and therefore we aimed to explore factors that modify LEV PK. Age and enzyme-inducing drugs (EIDs) appear to be major factors influencing the PK profile of LEV. Therefore, 30-50% lower dosages should be used in the elderly (> 65 years of age) and the dosing regimen should be guided by monitoring SDC (TDM). In contrast, higher LEV dosages are necessary in children aged between 2 months and 12 years (compared to adults) due to a 30-70% increase of LEV clearance (CL). Higher dosages are also required if a patient receives EIDs, again due to a higher CL of LEV (range 24-60%). This could also be true for pregnant women. LEV TDM is currently not common in the clinical setting due to the wide therapeutic range and the low prevalence of side-effects. However, LEV dose should on the one hand be increased in certain physiological situations (pregnancy, neonates) and patients on EIDs (especially carbamazepine). On the other hand, dose reductions are necessary when the LEV CL is impaired (elderly). Nevertheless, current data to support regular LEV TDM are lacking. Prospective research is needed to explore the importance of LEV TDM in elected patient groups; i.e. neonates, elderly, patients on EIDs and pregnant women.

Effect of low-intensity acenocoumarol on frequency and severity of migraine attacks.

OBJECTIVE: To investigate the effect of low-intensity acenocoumarol treatment (target INR 1.5 to 2.0) on the frequency and severity of migraine attacks. BACKGROUND: The positive effect of anticoagulation on migraine has been described in case reports and observational studies. METHODS: We conducted a randomized, open, crossover study in migraine patients. After a run-in period of 8 weeks, all patients received acenocoumarol or propranolol during a period of 12 weeks and, after a washout period of 2 weeks, propranolol or acenocoumarol during a second period of 12 weeks. RESULTS: Nineteen patients fulfilling the criteria were included. In 12 patients with complete data collection, only one good responder could be noted. In the other patients, treatment with low-intensity acenocoumarol did not show improvement of migraine symptoms compared with the run-in period. Treatment with propranolol showed a trend towards improvement compared with the run-in period. No serious adverse events were observed. CONCLUSIONS: Overall, low-intensity acenocoumarol treatment has no prophylactic effect in migraine patients.

A thromboembolic predisposition and the effect of anticoagulants on migraine.

OBJECTIVE: To investigate the presence of thromboembolic risk factors and the effect of low-dose acenocoumarol therapy on migraine in patients who spontaneously reported a reduction of their migraine attacks during previous therapeutic use of anticoagulants. BACKGROUND: The positive effect of anticoagulants on migraine has been described in case reports and observational studies. It remains unclear whether this concerns only a select group of migraineurs with certain common characteristics. METHODS: In 4 migraineurs with a self-reported reduction of attack frequency during previous use of anticoagulants (international normalization ratio [INR], 2.5:4.0), the presence of thromboembolic risk factors and the effect of low-dose acenocoumarol therapy (INR, 1.5:2.0) on migraine attacks were prospectively investigated in an open study. RESULTS: All patients had one or more thromboembolic risk factors. Two patients, both with factor V Leiden heterozygosity, experienced a clear improvement of migraine during low-dose acenocoumarol therapy. CONCLUSIONS: Our findings support the hypothesis that migraine, as a phenotype, has different underlying mechanisms, amongst which a thromboembolic tendency. In this group of patients, oral anticoagulants may be a suitable form of migraine prophylaxis, but this needs further clinical investigation.