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Pharmaceutics Oct 2023Regulatory agencies worldwide expect that clinical pharmacokinetic drug-drug interactions (DDIs) between an investigational new drug and other drugs should be conducted...
Regulatory agencies worldwide expect that clinical pharmacokinetic drug-drug interactions (DDIs) between an investigational new drug and other drugs should be conducted during drug development as part of an adequate assessment of the drug's safety and efficacy. However, it is neither time nor cost efficient to test all possible DDI scenarios clinically. Phenytoin is classified by the Food and Drug Administration as a strong clinical index inducer of CYP3A4, and a moderate sensitive substrate of CYP2C9. A physiologically based pharmacokinetic (PBPK) platform model was developed using GastroPlus to assess DDIs with phenytoin acting as the victim (CYP2C9, CYP2C19) or perpetrator (CYP3A4). Pharmacokinetic data were obtained from 15 different studies in healthy subjects. The PBPK model of phenytoin explains the contribution of CYP2C9 and CYP2C19 to the formation of 5-(4'-hydroxyphenyl)-5-phenylhydantoin. Furthermore, it accurately recapitulated phenytoin exposure after single and multiple intravenous and oral doses/formulations ranging from 248 to 900 mg, the dose-dependent nonlinearity and the magnitude of the effect of food on phenytoin pharmacokinetics. Once developed and verified, the model was used to characterize and predict phenytoin DDIs with fluconazole, omeprazole and itraconazole, i.e., simulated/observed DDI AUC ratio ranging from 0.89 to 1.25. This study supports the utility of the PBPK approach in informing drug development.
PubMed: 37896246
DOI: 10.3390/pharmaceutics15102486 -
Cleveland Clinic Journal of Medicine Sep 2022
Topics: Humans; Phenytoin; Gingival Overgrowth; Anticonvulsants
PubMed: 37907437
DOI: 10.3949/ccjm.89a.21107 -
Tzu Chi Medical Journal 2022Phenytoin (PHT) was first synthesized as a barbiturate derivative and was approved in 1953 by the Food and Drug Administration. This work aimed to review the... (Review)
Review
Phenytoin (PHT) was first synthesized as a barbiturate derivative and was approved in 1953 by the Food and Drug Administration. This work aimed to review the pathophysiology, epidemiology, clinical presentation, and treatment of PHT-associated movement disorders (MDs). Studies were searched in relevant databases (ScienceDirect, Google Scholar, Excerpta Medica, Latin American and Caribbean Health Sciences Literature, Medline, and Scientific Electronic Library Online) and were selected by two reviewers irrespective of language between 1963 and 2021. Papers of PHT-induced ataxia alone or tremor were excluded. In total, 127 reports with 219 individuals who developed MDs associated with PHT were encountered. MDs found: 126 dyskinesias, 49 myoclonus, 19 dystonia, 14 parkinsonism, 6 tics, 3 stuttering, and 2 restless legs syndrome. The mean age was 35 years (standard deviation [SD]: 23.5) and the predominant sex was male (53.4%). The mean PHT dose when the MD took place was 370.4 mg (SD: 117.5). A serum PHT concentration was reported in 103 cases, ranging from 4 to 110 μg/mL (median: 27.7 μg/mL). No significant relationship was found between PHT dose and age or PHT level. The mean onset time of PHT-associated MD was 23.4 months (SD: 4.4). The mean recovery time after MD management was 3.7 weeks (SD: 1.1). Regarding management, the most common form was PHT withdrawal in 90.4%. 86.3% of the individuals recovered fully. PHT-induced MD was extensively reported in the literature. Only general terms were used in the majority of the reports. The mechanisms underlying the adverse events caused by PHT probably depend on the presence of predisposing factors.
PubMed: 36578637
DOI: 10.4103/tcmj.tcmj_74_22 -
International Journal of Environmental... Jan 2021Cerebellar degeneration has been associated in patients with epilepsy, though the exact pathogenic mechanisms are not understood. The aim of this systematic review was... (Review)
Review
INTRODUCTION
Cerebellar degeneration has been associated in patients with epilepsy, though the exact pathogenic mechanisms are not understood. The aim of this systematic review was to identify the prevalence of cerebellar degeneration in patients with epilepsy and identify any pathogenic mechanisms.
METHODOLOGY
A systematic computer-based literature search was conducted using the PubMed database. Data extracted included prevalence, clinical, neuroradiological, and neuropathological characteristics of patients with epilepsy and cerebellar degeneration.
RESULTS
We identified three consistent predictors of cerebellar degeneration in the context of epilepsy in our review: temporal lobe epilepsy, poor seizure control, and phenytoin as the treatment modality. Whole brain and hippocampal atrophy were also identified in patients with epilepsy.
CONCLUSIONS
Cerebellar degeneration is prevalent in patients with epilepsy. Further prospective studies are required to confirm if the predictors identified in this review are indeed linked to cerebellar degeneration and to establish the pathogenic mechanisms that result in cerebellar insult.
Topics: Atrophy; Brain; Epilepsy; Epilepsy, Temporal Lobe; Humans; Magnetic Resonance Imaging; Prospective Studies
PubMed: 33435567
DOI: 10.3390/ijerph18020473 -
Journal of Postgraduate Medicine 2022Levetiracetam is a new generation antiseizure medication which binds to synaptic vesicle protein SV2A and inhibits the release of neurotransmitters. Gingival hyperplasia...
Levetiracetam is a new generation antiseizure medication which binds to synaptic vesicle protein SV2A and inhibits the release of neurotransmitters. Gingival hyperplasia is a common side effect of conventional antiseizure medications like phenytoin, but very rare with the newer ones. A 14-year-old boy was started on levetiracetam 250 mg twice daily after a generalized seizure. Five days later he presented with gingival swelling and painful oral aphthae, without lymphadenopathy or systemic symptoms. Blood investigations were normal. After one-month of stopping the drug, the lesions cleared. This case highlights the importance of maintaining good oral hygiene and periodic dental review in patients on antiseizure medications.
Topics: Adolescent; Anticonvulsants; Gingival Hyperplasia; Humans; Levetiracetam; Male; Phenytoin; Seizures
PubMed: 35848684
DOI: 10.4103/jpgm.jpgm_1059_21 -
Tuberculosis Research and Treatment 2020There is an urgent need for better and safer therapeutic interventions for tuberculosis (TB). We assessed the effects of FDA-approved ion transport modulators, namely,...
There is an urgent need for better and safer therapeutic interventions for tuberculosis (TB). We assessed the effects of FDA-approved ion transport modulators, namely, ambroxol HCl, amiloride HCl, diazoxide, digoxin, furosemide, hydrochlorothiazide (HCTZ), metformin, omeprazole, pantoprazole, phenytoin, verapamil, and drug X and Y on the growth of free and intracellular BCG. Free and intracellular BCG were cultured in the presence or absence of the test drugs for 3 to 9 days and then quantified. For both free and intracellular bacteria, cultures that were exposed to furosemide, phenytoin, or drug Y yielded lower bacteria counts compared to drug-free controls ( < 0.05). The same was observed with diazoxide, HCTZ, verapamil, and drug X, but only for intracellular BCG ( < 0.05). To assess the effects of the drugs on bactericidal activity of rifampicin, free and intracellular BCG were treated with rifampicin alone or in combination with each of the thirteen test drugs for 3 to 9 days. For extracellular bacteria, higher bacteria clearance rates were observed in cultures exposed to rifampicin in combination with amiloride HCl, diazoxide, digoxin, furosemide, HCTZ, metformin, pantoprazole, phenytoin, drug X, or drug Y than those exposed to rifampicin alone, indicating that rifampicin had a synergistic effect with these test drugs. Rifampicin was also synergistic with ambroxol HCl, diazoxide, digoxin, furosemide, HCTZ, omeprazole, pantoprazole, phenytoin, verapamil, and drug X against intracellular BCG. The antimycobacterial properties exhibited by the ion transport modulators in this study make them viable candidates as adjuncts to the current anti-TB regimens.
PubMed: 33294223
DOI: 10.1155/2020/3767915 -
Cureus Jul 2023Toxic epidermal necrolysis (TEN) is a rare fatal mucocutaneous blistering disorder that can have varied underlying triggers. The percentage of body surface area (BSA)...
Toxic epidermal necrolysis (TEN) is a rare fatal mucocutaneous blistering disorder that can have varied underlying triggers. The percentage of body surface area (BSA) that is impacted by erosive blistering is what separates it from Steven Johnson syndrome (SJS), both of which have the same underlying pathogenesis and are thought to exist on a continuum of disease with TEN being the more serious of the two. Medications are the most frequent cause of TEN/SJS and typically cause disease in both adults and children within eight weeks; however, the median exposure window is four days to four weeks. Nonsteroidal anti-inflammatory drugs, allopurinol, anticonvulsants including lamotrigine, phenytoin, levetiracetam and carbamazepine, antimicrobial sulfonamides, and the antiviral nevirapine are examples of medications that frequently cause TEN/SJS. Here, we are reporting a case of phenytoin-induced TEN highlighting the patient's excellent response to immunomodulating treatment despite 100% involvement of the BSA.
PubMed: 37644929
DOI: 10.7759/cureus.42654 -
Cureus Sep 2023The administration of multiple antiepileptic drugs (AEDs) is standard practice for neurological intensive care unit (ICU) patients who cannot obtain seizure control with... (Review)
Review
The administration of multiple antiepileptic drugs (AEDs) is standard practice for neurological intensive care unit (ICU) patients who cannot obtain seizure control with monotherapy. Phenytoin and levetiracetam continue to be highly utilized AEDs for ICU patients due to their efficacy and relatively low cost. However, there is no randomized control trial to date that assesses the efficacy outcomes of the concurrent use of these two medications for ICU patients in convulsive or silent status epilepticus that combats the toxicity with increasing dosages of a single drug by itself. Here, we have analyzed several studies published over the past two decades to better understand whether the concomitant use of these two medications is more efficacious in treating unremitting seizures in ICU patients. Several factors influence which AED is a better fit for ICU patients due to the complexity of their clinical state. Risk for drug interactions, increased incidence of renal and hepatic impairment, and higher need for patient monitoring are daily barriers that determine AED use. After analysis of past research, while the efficacy of concurrent use of levetiracetam and phenytoin is still not fully clear, we offer the "Arrowhead Rationale" for such dual therapy in a subset of patients at our tertiary care trauma and stroke center in Southern California.
PubMed: 37790049
DOI: 10.7759/cureus.44547