Antiepileptic drugs and other medications: what interactions may arise?

Drug-microbiota interactions: an emerging priority for precision medicine

Individual variability in drug response (IVDR) can be a major cause of adverse drug reactions (ADRs) and prolonged therapy, resulting in a substantial health and economic burden. Despite extensive research in pharmacogenomics regarding the impact of individual genetic background on pharmacokinetics (PK) and pharmacodynamics (PD), genetic diversity explains only a limited proportion of IVDR. The role of gut microbiota, also known as the second genome, and its metabolites in modulating therapeutic outcomes in human diseases have been highlighted by recent studies. Consequently, the burgeoning field of pharmacomicrobiomics aims to explore the correlation between microbiota variation and IVDR or ADRs. This review presents an up-to-date overview of the intricate interactions between gut microbiota and classical therapeutic agents for human systemic diseases, including cancer, cardiovascular diseases (CVDs), endocrine diseases, and others. We summarise how microbiota, directly and indirectly, modify the absorption, distribution, metabolism, and excretion (ADME) of drugs. Conversely, drugs can also modulate the composition and function of gut microbiota, leading to changes in microbial metabolism and immune response. We also discuss the practical challenges, strategies, and opportunities in this field, emphasizing the critical need to develop an innovative approach to multi-omics, integrate various data types, including human and microbiota genomic data, as well as translate lab data into clinical practice. To sum up, pharmacomicrobiomics represents a promising avenue to address IVDR and improve patient outcomes, and further research in this field is imperative to unlock its full potential for precision medicine.

The Effectiveness of Lamotrigine and Its Blood Levels for Pediatric Epilepsy

This study was conducted to evaluate the effectiveness of lamotrigine (LTG) over 2 years and the usefulness of measuring its blood levels during the follow-up of patients with epilepsy. We measured peak blood LTG levels of 32 patients with epilepsy (9.16 ± 3.34 years old; mean ± SD). The blood levels were measured at 6 months, 1 year, and 2 years after reaching the LTG maintenance dosage. The effectiveness of LTG was evaluated to determine the seizure reduction rate. The patients were classified as effective cases (mean of own seizure reduction rates >50%) and ineffective cases (≤50%). The results were that the dosage and blood level showed positive correlations in the case of combination use with sodium valproate (VPA) (r = 0.690), carbamazepine and/or phenobarbital (r = 0.940), and others (r = 0.548). In several groups, the blood levels and efficacies did not show any positive correlations. In the cases of combination use with VPA, the blood levels of effective cases and ineffective cases were significantly different (P = 0.001). The optimal range was 8-11.5 μg/mL based on the average and SD values in the effective cases. No patients had any side effects. In conclusion, no precise definition of the therapeutic range was possible because of the incomplete correlation between the blood level and seizure frequency. We recommend the optimal range of LTG as a therapeutic target without any side effects, and it was established that the range in the combination with VPA was 8-11.5 μg/mL.

A Drug Regimen for Progressive Familial Cholestasis Type 2

Progressive familial cholestasis type 2 is caused by a genetically determined absence or reduction in the activity of the bile salt export pump (BSEP). Reduction or absence of BSEP activity causes a failure of bile salt excretion, leading to accumulation of bile salts in hepatocytes and subsequent hepatic damage. Clinically, patients are jaundiced, suffer from severe intractable pruritus, and evidence progressive liver dysfunction. A low level of serum γ-glutamyl transpeptidase, when associated with the described signs and symptoms, is often an early identifier of this condition. Treatment options to date include liver transplantation and the use of biliary diversion. We report a multidrug regimen of 4-phenylbutyrate, oxcarbazepine, and maralixibat (an experimental drug owned by Shire Pharmaceuticals, Dublin, Republic of Ireland) that completely controlled symptoms in 2 siblings with partial loss of BSEP activity.

Co-morbidity and clinically significant interactions between antiepileptic drugs and other drugs in elderly patients with newly diagnosed epilepsy

PURPOSE

A study was conducted to investigate the frequency of potential pharmacokinetic drug-to-drug interactions in elderly patients with newly diagnosed epilepsy. We also investigated co-morbid conditions associated with epilepsy.

METHOD

From the register of Kuopio University Hospital (KUH) we identified community-dwelling patients aged 65 or above with newly diagnosed epilepsy and in whom use of the first individual antiepileptic drug (AED) began in 2000-2013 (n=529). Furthermore, register data of the Social Insurance Institution of Finland were used for assessing potential interactions in a nationwide cohort of elderly subjects with newly diagnosed epilepsy. We extracted all patients aged 65 or above who had received special reimbursement for the cost of AEDs prescribed on account of epilepsy in 2012 where their first AED was recorded in 2011-2012 as monotherapy (n=1081). Clinically relevant drug interactions (of class C or D) at the time of starting of the first AED, as assessed via the SFINX-PHARAO database, were analysed.

RESULTS

Hypertension (67%), dyslipidemia (45%), and ischaemic stroke (32%) were the most common co-morbid conditions in the hospital cohort of patients. In these patients, excessive polypharmacy (more than 10 concomitant drugs) was identified in 27% of cases. Of the patients started on carbamazepine, 52 subjects (32%) had one class-C or class-D drug interaction and 51 (31%) had two or more C- or D-class interactions. Only 2% of the subjects started on valproate exhibited a class-C interaction. None of the subjects using oxcarbazepine displayed class-C or class-D interactions. Patients with 3-5 (OR 4.22; p=0.05) or over six (OR 8.86; p=0.003) other drugs were more likely to have C- or D-class interaction. The most common drugs with potential interactions with carbamazepine were dihydropyridine calcium-blockers, statins, warfarin, and psychotropic drugs.

CONCLUSIONS

Elderly patients with newly diagnosed epilepsy are at high risk of clinically relevant pharmacokinetic interactions with other drugs, especially if exposed to carbamazepine, but these interactions can be controlled via rational drug choices and with prediction of the possible drug-to-drug interactions. Patients on dihydropyridine calcium-channel blockers, statins, warfarin, and risperidone face the highest risk of interactions.