Anticonvulsant effects of isopimpinellin and its interactions with classic antiseizure medications and borneol in the mouse tonic-clonic seizure model: an isobolographic transformation.

BACKGROUND: Overwhelming evidence indicates that some naturally occurring coumarins and terpenes are widely used in folk medicine due to their various therapeutic effects affecting the brain. Antiseizure medications (ASMs) are the principal treatment option for epilepsy patients, although some novel strategies based on naturally occurring substances are intensively investigated. This study was aimed at determining the influence of isopimpinellin (ISOP-a coumarin) when administered either separately or in combination with borneol (BOR-a monoterpenoid), on the antiseizure potencies of four classic ASMs (carbamazepine (CBZ), phenytoin (PHT), phenobarbital (PB), and valproate (VPA)) in the mouse model of maximal electroshock-induced (MES) tonic-clonic seizures. MATERIALS: Tonic-clonic seizures were evoked experimentally in mice after systemic (ip) administration of the respective doses of ISOP, BOR, and classic ASMs. Interactions for two-drug (ISOP + a classic ASM) and three-drug (ISOP + BOR + a classic ASM) mixtures were assessed isobolographically in the mouse MES model. RESULTS: ISOP (administered alone) had no impact on the anticonvulsant potencies of four classic ASMs. Due to the isobolographic transformation of data, the combination of ISOP + VPA exerted an antagonistic interaction, whereas the two-drug mixtures of ISOP + CBZ, ISOP + PHT, and ISOP + PB produced additive interactions in the mouse MES model. The three-drug combinations of ISOP + BOR with CBZ and PHT produced additive interactions, while the three-drug combinations of ISOP + BOR with PB and VPA exerted synergistic interactions in the mouse MES model. CONCLUSIONS: The most intriguing interaction was that for ISOP + VPA, for which the addition of BOR evoked a transition from antagonism to synergy in the mouse MES model.

Phenytoin's Pharmacological Interactions with Medicinal Herbs: A Review.

Physiologic changes due to aging, pregnancy, nutritional status, drug interactions, and can affect pharmacokinetics and pharmacodynamics of antiepileptic drugs. In this review article, the interactions between phenytoin and herbs recorded in the literature were summarized according to the Medline database (via PubMed). Our results revealed that, changes in phenytoin's bioavailability were reported for co-administration of herbs or herbal extracts. An increase in phenytoin blood levels was established with Piper nigrum, Mentat, and Lipidum sativum in in vitro and/or in vivo studies. In contrast, herbphenytoin interactions led to sub-therapeutic levels of phenytoin in other cases with herbs such as Cannabis, Ginkgo biloba, Morinda citrifolia, Nigella sativa, and Trigonella foenum graceum. In addition, the findings of other pharmcodynamic experiments showed that various herbs, including Zizyphus jujube, Terminalia chebula, Curcuma longa L, and Centella asiatica, improved the pharmacological impact of phenytoin. To reduce the patients' health risks, health professionals involved in their treatment are expected to be thoroughly educated about the interactions between phenytoin and medicinal plants.

Revealing how phenytoin triggers liver damage and the potential protective effects of Balanites Aegyptiaca fruit extracts: Exploring Nrf2/MAPK/ Beclin-1 signaling pathways.

Phenytoin-induced liver injury (PHT ILII) is a serious condition that may necessitate discontinuation of the drug. This study investigates the mechanisms of PHT ILII and evaluates the protective effects of Balanites Aegyptiaca (BA) fruit extracts on the liver. We focus on the Nrf2/MAPK/NF-κB/Beclin-1 signaling pathways involved in oxidative stress and inflammation from drug-induced liver injury. Phytochemical analyses of BA fruit extracts (Bu-F and EA-F) are conducted. Molecular docking techniques explore the interaction between phenytoin (PHT) and the Nrf2/MAPK/NF-κB/Beclin-1 pathways. Thirty-six male rats are divided into Control, Bu-F, EA-F, PHT, Bu-F/PHT, and EA-F/PHT groups, and they are observed for 45 days. EA-F extract is rich in phenolics/flavonoids, while Bu-F extract mainly contains saponins.PHT ILII causes histological damage in liver tissues and affects Nrf-2, MAPK, TNF-α, IL-1ß, Mcp-1, Beclin-1, iNOS expression, and liver function markers (ALT, AST, ALP). However, EA-F/Bu-F extracts effectively improve the histological structure and significantly reduce biochemical/immunohistochemical parameters, restoring them to near-normal levels. EA-F extract is particularly effective.In conclusion, the Nrf2/MAPK /Beclin-1 pathways play a critical role in the development of PHT ILII. BA fruit extracts show promise as hepato-protective agents, with the EA-F extract demonstrating superior efficacy. These results lay the groundwork for new treatments for PHT ILII and drug-induced liver injuries.

Enhancing Oil Solubility of BCS Class II Drug Phenytoin Through Hydrophobic Ion Pairing to Enable High Drug Load in Injectable Nanoemulsion to Prevent Precipitation at Physiological pH With a Potential to Prevent Phlebitis.

This work investigates the micellar titration of phenytoin (a weakly acidic drug) with cetyltrimethylammonium hydroxide (CTAH) to form a hydrophobic ion-pair to enhance oil solubility of phenytoin, followed by an effort to formulate nanoemulsion that could potentially prevent precipitation of phenytoin at physiological pH. The ion-pair formulated in nanoemulsion was evaluated for in vitro precipitation during serial dilution at physiological pH. The formation of ion-pair during titration was explained in context of pH-solubility data. The mathematical model successfully integrated ionization and micellization equilibria to reflect on dominant mechanisms for solubilization. The micellar phenomenon during titration was confirmed using Dynamic Light Scattering (DLS). The phase changes of the excess undissolved solids during titration were evident from X-Ray Powder Diffraction (XRPD) and Fourier Transform Infrared Spectroscopy (FTIR). This analysis confirmed the conversion of phenytoin into ionized state and its subsequent ionic interaction with CTAH forming hydrophobic ion-pair complex (HIP). The complete ion pair formation was evident at pHmax (8.8 to 9.2), and its 1:1 stoichiometry was confirmed using HPLC (Phenytoin and CTAH) and H1 NMR, hence could also be called as a lipophilic salt. The ion-pair (salt) was insoluble in water and showed remarkably high partition coefficient (log P) in octanol/water. As characterized by Hot Stage Microscopy (HSM), the melting point of the ion-pair complex was lowered to 150.8°C compared to the free acid (> 300οC), this was even further lowered to 81.1 °C when evaluated in castor oil. This led to approximately eight-fold higher solubility of hydrophobic ion pair (HIP) in castor oil compared to the free acid form. The high miscibility in castor oil was suitable to formulate a high drug load injectable dispersed system. This was successfully achieved with lecithin and polysorbate as emulsifiers without leaching drug into continuous phase at pH 7.4. This nanoemulsion (<300 nm, and > +30 mV zeta potential) remain stable when evaluated over a period of one month. A serial dilution study of the nanoemulsion was performed in PBS buffer, microscopic observations suggested no birefringence despite incubation at 25°C for several hours. This result indicated that Phenytoin remained strongly partitioned within dispersed oily phase with a higher drug loading when ion-paired phenytoin was used. The higher drug load could enable a small volume slow bolus injection to meet 50 mg/min or lower delivery rate criteria for Phenytoin in the clinical set up. This provided a pathway to further explore potential injectable nano-emulsion formulations that could alleviate typical phlebitis issue associated with the injectable phenytoin solution administration at physiological pH.

Cutaneous Hypersensitivity Reaction After Phenytoin Therapy in a Neonate: A Case Report and Review of Literature Elucidating the Potential Pharmacological Plausibility and Preventive Strategies.

BACKGROUND: Drug-induced hypersensitivity reaction is a potentially life-threatening condition reported among patients of different age groups. Phenytoin is a prototypic drug prescribed for the treatment of a variety of seizure disorders. Allergic reaction to phenytoin therapy in a newborn is relatively a rare clinical manifestation that is not frequently reported. OBJECTIVE: The objective of this study is to report a suspected case of hypersensitivity reaction in a newborn possibly due to phenytoin and the strategies to prevent these immune-mediated reactions. CASE REPORT: An early term newborn on the 4th day of life developed erythematous rashes over the abdominal region following phenytoin treatment for recurrent generalized tonic-clonic seizures. Prenatal history was uneventful except for the mother had preeclampsia during the third trimester of pregnancy. The suspected phenytoin was replaced with phenobarbitone to control seizure episodes. Subsequently, the rashes disappeared. The baby had also suffered from skin discolouration after phototherapy. Radiological investigations and cerebrospinal fluid culture were performed to detect the etiology of seizures. CONCLUSION: Hypersensitivity reaction to phenytoin in newborns is a rare clinical entity but may lead to serious lethal complications. Thus, stringent clinical monitoring of patients on phenytoin therapy is mandatory, especially in the pediatric population.

In vitro and in vivo anti-seizure activity of hydromethanolic extract and fractions of Pterolobium stellatum.

ETHNOPHARMACOLOGICAL RELEVANCE: In Ethiopia, the whole plant juice of Pterolobium stellatum is used to treat seizures and epilepsy. AIM OF THE STUDY: To investigate the antiseizure activity of hydromethanolic crude extract and fractions collected from leaves of P. stellatum using both in vitro, and in vivo seizure models in mice. MATERIALS AND METHODS: Fresh leaves of P. stellatum were collected from Awash Melka, Addis Ababa, Ethiopia. An 80% crude methanol extract was further fractionated to produce petroleum ether, chloroform, butanol, and aqueous fractions. Anti-seizure activity of the crude extract and fractions (petroleum ether, chloroform, butanol, and water) were assessed at a concentration of 0.7 mg/ml using the in vitro 0 Mg2+ model of seizures in mouse brain slices prepared from 14- to 21-day-old C57BL/6 mice. The maximal electroshock seizure (MES) model and the pentylenetetrazol (PTZ) seizure model for seizures were performed on male BALB/c mice using 400 mg/kg and 800 mg/kg of crude 80% methanol extract, as well as the four fractions described above. Diazepam and phenytoin were used as positive controls for PTZ and MES test respectively. RESULTS: Addition of 0.7 mg/ml of crude 80% methanol extract of P. stellatum prevented the onset of SLEs in most brain slices in the 0 Mg2+in vitro model of seizures, with similar efficacy to diazepam (3 µM). The same extract at 400 and 800 mg/kg was efficacious in reducing the hindlimb extension time in the MES model and delaying the onset of myoclonic convulsions in the PTZ model, although not to the same extent as phenytoin (10 mg/kg) or diazepam (5 mg/kg). The chloroform and water fractions of the crude extract also showed significant anti-seizure activity across all three models whilst the non-polar petroleum ether and butanol fractions did not. The UPLC-MS analysis indicated the presence of gallic acid, ellagic acid, kaempferol, myricitrin, isoquercitrin and quercitirin in the crude extract. Gallic acid and ellagic acid were observed in chloroform fraction and in the water fraction ellagic acid, kaempferol, myricitrin and isoquercitrin were detected. CONCLUSION: The crude hydromethanolic extract of P. stellatum has significant anti-seizure activity. The chloroform and aqueous fractions have antiseizure activity. The extracts have previously identified compounds with anticonvulsant activity which indicates the antiseizure potential of the plant.

Determination of the effectiveness of Dorema ammoniacum gum on wound healing: an experimental study.

OBJECTIVE: For a long time, natural compounds have been used to accelerate wound healing. In this study, the topical effects of ammoniacum gum extract on wound healing were investigated in white male rats. METHOD: Following skin wound induction in aseptic conditions, 48 Wistar rats were divided into six equal groups; phenytoin cream 1% (standard), untreated (control), Eucerin (control), and 5%, 10% and 20% ointments of Dorema ammoniacum gum extract (treatment groups). All experimental groups received topical drugs daily for 14 days. The percentage of wound healing, hydroxyproline content, histological parameters, and growth factors (endothelial growth factor (EGF), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-α) were measured in experimental groups. RESULTS: The areas of the wounds in the treatment groups were significantly decreased compared with the wound areas of control groups at 5, 7 and 10 days after wounding. On the 12th day, the wounds in the treatment groups were completely healed. Hydroxyproline contents were significantly increased in the treatment groups compared with the control groups (p<0.001). In histological evaluation, the re-epithelialisation, increasing thickness of the epithelial layer, granulation tissue and neovascularisation parameters in the treatment groups showed significant increases compared with the control groups. Also, serum levels of TGF-ß, PDGF, EGF and VEGF in the treatment groups were significantly increased compared to the control groups. CONCLUSION: The topical application of ammoniacum gum extract significantly increases the percentage of wound healing in rats and reduces the time of wound closure.

Treatment of benzodiazepine-resistant status epilepticus: Systematic review and network meta-analyses.

PURPOSE: Multiple interventions have been studied for benzodiazepine-resistant status epilepticus (SE) in children and adults. This review aimed to summarize the available evidence and provide estimates of comparative effectiveness and ranking of treatment effects. METHODS: All randomized controlled trials studying patients (>1 month of age) with benzodiazepine-resistant SE were included. Outcomes including seizure cessation within 60 min, seizure freedom for 24 h, death, respiratory depression warranting intubation and cardiovascular instability were studied. Conventional and network meta-analyses (NMA) were done. RESULTS: Seventeen studies were included (16 in NMA). Phenobarbital and high-dose levetiracetam were significantly superior to phenytoin with respect to seizure cessation within 60 min. Network ranking demonstrated that phenobarbital had the highest probability of being the best among the studied interventions followed by high-dose levetiracetam and high-dose valproate. Network meta-analysis was limited by predominant indirect evidence and high heterogeneity.On pairwise comparisons, phenobarbital was found to be associated with a higher risk of need for intubation and cardiovascular instability. Levetiracetam had a better safety profile than fosphenytoin. CONCLUSIONS: Based on low quality evidence, phenobarbital appears to be the most effective agent for seizure cessation within 60 min of administration in patients with benzodiazepine resistant status epilepticus. High-dose levetiracetam, high-dose valproate and fosphenytoin are probably equally effective. Choice of medication may be guided by effectiveness, safety concerns, availability, cost and systemic co-morbidities.

Topical administration of Juglans regia L. leaf extract accelerates diabetic wound healing.

BACKGROUND: Diabetic wounds are one of the most important issues in diabetic patients. It seems that Juglans regia L. leaf with antioxidant and anti-inflammatory potentials can be profitable for healing of diabetic wounds. The aim of present study was to investigate the topical administration of Juglans regia L. leaf extract in diabetic wound healing. METHODS: Seventy-five diabetic male rats were randomly divided into 5 groups (n = 15), including: untreated (Control) group, Eucerin group, 2% Juglans regia L. ointment (JRL 2%) group, 5% Juglans regia L. ointment (JRL 5%) group, and Phenytoin group as a reference drug. Sampling was performed at days 7, 14, and 21 after surgery. Evaluation tests included stereology, immunohistochemistry, molecular, and biomechanical. RESULTS: Our results showed that the wound closure rate, volumes of newly formed of epidermis and dermis, density of fibroblasts and blood vessels, collagen deposition, density of proliferation cells, expression levels of TGF-ß and VEGF genes, and biomechanical characteristics were significantly higher in extract groups compared to control and eucerin groups, however, these changes were considerable in the JRL 5% group (P < 0.05). This is while that the density of neutrophils and expression levels of TNF-α and IL-1ß genes in the extract groups, especially in the JRL 5% group, were significantly reduced compared to control and eucerin groups (P < 0.05). CONCLUSION: Topical administration of Juglans regia L. leaf extract, especially in 5% concentration, considerably accelerates diabetic wound healing.

The Prevention and Reversal of a Phenytoin-Resistant Model by N-acetylcysteine Therapy Involves the Nrf2/P-Glycoprotein Pathway at the Blood-Brain Barrier.

The transporter hypothesis is one of the most popular hypotheses of drug-resistant epilepsy (DRE). P-glycoprotein (P-gp), a channel protein at the blood-brain barrier (BBB), plays an important role in the transport of some anti-seizure drugs from brain tissue into vessels, which reduces drug concentrations and diminishes the effects of drug treatment. We performed this study to test whether P-gp is overexpressed in DRE and identify ways to prevent and reverse DRE. In this study, we established a phenytoin (PHT)-resistant mouse model and revealed that P-gp was overexpressed at the BBB in PHT-resistant mice. The P-gp inhibitor nimodipine decreased the resistance of phenytoin. Antioxidative preventive treatment with N-acetylcysteine (NAC) prevented the mice from entering a PHT-resistant state, and NAC therapy tended to reverse PHT resistance into sensitivity. We were also able to induce PHT resistance by activating the Nrf2/P-gp pathway, which indicates that oxidative stress plays an important role in drug resistance. Taken together, these findings suggest that antioxidative therapy may be a promising strategy for overcoming DRE.

The effect of hydroalcoholic extract of Psidium guajava L. on experimentally induced oral mucosal wound in rat.

BACKGROUND: The aim of this study was to evaluate the biological effects of hydroalcoholic extract of Psidium guajava L leaves and phenytoin as a standard agent on the induced oral mucosal wound. METHODS: Hundred seventy Sprague Dawley rats were grouped in 5 clusters randomly. Oral mucosal wounds were induced in all rats except for the control group. Phenytoin and guajava leaf extract were used as a mouthwash. Twelve rats from the 5 groups were euthanized on day 7th and 10th, and 10 rats from each group were sacrificed on the 14th day. Interleukin-6 and total antioxidant capacity were determined in the serum. The tissues were evaluated for pathological and stereological assessments. Phytochemical analyses were performed on the hydroalcoholic extract of Psidium guajava L to determine the antioxidant potency. RESULTS: Total phenolic content test and DPPH analysis demonstrated the high potential of antioxidant capacity of Psidium guajava L. Decreasing IL-6 and increasing TAC were seen in the guajava hydroalcoholic extract and phenytoin groups. The difference of IL-6 between the wound treated guajava group and the wounded group was significant. The wound treated guajava group and wound treated phenytoin group on the 14th day increased the number of fibroblast cells and volume density of sub-mucosae effectively to the same thickness to be considered as a healed sub-mucosae layer. The volume density of the epithelium changes showed statistically significant different responses based on gender. CONCLUSION: In conclusion, hydroalcoholic extract of Psidium guajava L leaves might exert theraputic effects on oral mucositis.

The interplay of epilepsy with impaired mitophagy and autophagy linked dementia (MAD): A review of therapeutic approaches.

The duration and, age of dementia have been linked to a higher risk of seizures. The exact mechanism that drives epileptogenesis in impaired mitophagy and autophagy linked dementia (MAD) is fully defined after reviewing the Scopus, Publon, and Pubmed databases. The epileptogenesis in patients with Alzheimer's disease dementia (ADD) and Parkinson's disease dementia (PDD) is due to involvement of amyloid plaques (Aß), phosphorylated tau (pTau), Parkin, NF-kB and NLRP3 inflammasome. Microglia, the prime protective and inflammatory cells in the brain exert crosstalk between mitophagy and inflammation. Several researchers believed that the inflammatory brain cells microglia could be a therapeutic target for the treatment of a MAD associated epilepsy. There are conventional antiepileptic drugs such as gabapentin, lamotrigine, phenytoin sodium, carbamazepine, oxcarbazepine, felbamate, lamotrigine, valproate sodium, and topiramate are prescribed by a psychiatrist to suppress seizure frequency. Also, the conventional drugs generate serious adverse effects and synergises dementia characteristics. The adverse effect of carbamazepine is neurotoxic and also, damages haemopoietic system and respiratory tract. The phenytoin treatment causes cerebellar defect and anemia. Dementia and epilepsy have a complicated relationship, thus targeting mitophagy for cure of epileptic dementia makes sense. Complementary and alternative medicine (CAM) is one of the rising strategies by many patients of the world, not only to suppress seizure frequency but also to mitigate dementia characteristics of patients. Therefore our present review focus on the interplay between epilepsy and MAD and their treatment with CAM approaches.

Evaluation of combination use of phenytoin cream 1% and fractional CO2 laser in treatment of stable nonsegmental vitiligo: A pilot study.

Vitiligo is an autoimmune disorder of melanocyte characterized by macular and depigmented patches. There are several treatment modalities for this disease, including the use of corticosteroids, calcineurin inhibitors, vitamin D analogous and topical phenytoin. Combination therapy utilizing fractional CO2 laser with different topical agents has been used to enhance treatment response with promising results. In this study, we aimed to evaluate the effect of fractional CO2 laser in combination with topical phenytoin. In this study, 25 patients (11 females and 14 males) with age of 18-59 (mean age of 31.12) with nonsegmental stable vitiligo were recruited with insufficient response to at least 1-year treatment with a monotherapy using topical corticosteroids, calcineurin inhibitors, and/or NB-UVB phototherapy. Patients were treated with a combination of fractional CO2 laser (10,600 nm, pulse energy 30-50 mJ, MIXEL, South Korea, Rating: 220VAC, 3A, 50/60 Hz) with monthly intervals for six sessions and application of phenytoin 1% cream twice daily. Photography was done before and after treatment with Wood's lamp. The severity of disease using VASI score was calculated and compared before and after treatment. The mean VASI score before treatment was 0.55, and sixth month after treatment increased to 1.97 (p-value < 0.001). Patients were divided into three groups based on the vitiligo subtype: acral, upper extremities, and trunk. VASI score was measured in each group: VASI score before and after treatment was 0.50 and 1.48 in acral areas, 0.45 and 2.04 in upper extremities and 0.79 and 3.39 in trunk, respectively. This study revealed that combination therapy with phenytoin and fractional CO2 laser is effective in treatment of vitiligo not only in the upper extremities and trunk, but also interestingly in the acral areas.

Clinical Evaluation of Levetiracetam in the Treatment of Epilepsy.

Objectives: Epilepsy is a chronic neurological disorder that is characterized by episodes of seizure. Methods: In this study, patients with status epilepticus in the Intensive Care Unit of the Department of Neurology of Qujing First People's Hospital were collected and treated with levetiracetam injection, continuous bedside EEG monitoring (cEEG) technology, and quantitative EEG (qEEG) technique. The inhibitory effects of different doses of levetiracetam injection and sodium valproate on abnormal discharge, the improvement of clinical symptoms, the incidence of adverse reactions, and prognosis were monitored, analyzed, and compared. Results: Compared with the experimental group of sodium valproate, 1000 mg/d levetiracetam group and 1500 mg/d levetiracetam group had a high probability of successful symptom control and a short control time. The patients had a low recurrence rate and a long recurrence time, and the probability of abnormal discharge in EEG was low. Conclusions: The recording results showed that levetiracetam could significantly inhibit the abnormal discharge of patients. Compared with sodium valproate, high-dose levetiracetam is a drug with a rapid effect, good effect, and long action time.

Topical phenytoin administration accelerates the healing of acetic acid-induced colitis in rats: evaluation of transforming growth factor-beta, platelet-derived growth factor, and vascular endothelial growth factor.

Ulcerative colitis (UC), limited to the colon's innermost lining, has become a global health problem. Immunomodulatory and monoclonal antibodies are used to treat UC despite their side effects and limitations. Phenytoin is used to heal wounds owing to its effects on growth factors, collagen, and extracellular matrix synthesis. This study aimed to evaluate the effect of topical phenytoin administration in UC. Phenytoin was administered in two doses during the treatment. Eighty male Wistar rats (230-280 g) were divided randomly into ten groups of sham, control, hydrocortisone, phenytoin 1%, and 3% groups in 6- or 12-day treatment protocols. The UC model was induced by the administration of acetic acid 4% into the colon. Animals were killed on the 7th and 13th postoperative days. The main outcome measures included body weight loss, microscopic score, and ulcer index measured using specific criteria. Growth factors were measured by western blotting. Results illustrated that body weight loss was reversed in the treatment groups. Ulcer index had decreased on 6- and 12-day treatment protocols. Microscopic scores in 6-day enema treatment significantly decreased compared to the control groups. Transforming growth factor-beta (TGFß) significantly increased in a time-dependent manner and platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) significantly increased in a time- and dose-dependent manner in phenytoin 1% and 3% in the 6- and 12-day protocols. Phenytoin dose- and time-dependently reversed weight loss. In addition, histopathological parameters included microscopic scores, and the ulcer index was decreased through the induction of growth factors TGFß, PDGF, and VEGF and consequently accelerated ulcer healing.

Potential herb-drug interaction risk of thymoquinone and phenytoin.

Thymoquinone is a main bioactive compound of Nigella sativa L. (N.sativa), which has been used for clinical studies in the treatment of seizures due to its beneficial neuroprotective activity and antiepileptic effects. It has been evidenced that thymoquinone may inhibit the activity of cytochrome P450 2C9 (CYP2C9). However, little is known about the effect of thymoquinone or N.sativa on the pharmacokinetic behavior of phenytoin, a second-line drug widely used in the management of status epilepticus. In this study, we systematically investigated the risk of the potential pharmacokinetic drug interaction between thymoquinone and phenytoin. The inhibitory effect of thymoquinone on phenytoin hydroxylation activity by CYP2C9 was determined using UPLC-MS/MS by measuring the formation rates for p-hydroxyphenytoin (p-HPPH). The potential for drug-interaction between thymoquinone and phenytoin was quantitatively predicted by using in vitro-in vivo extrapolation (IVIVE). Our data demonstrated that thymoquinone displayed effective inhibition against phenytoin hydroxylation activity. Enzyme kinetic studies showed that thymoquinone exerted a competitive inhibition against phenytoin hydroxylation with a Ki value of 4.45 ± 0.51 µM. The quantitative prediction from IVIVE suggested that the co-administration of thymoquinone (>18 mg/day) or thymoquinone-containing herbs (N.sativa > 1 g/day or N.sativa oil >1 g/day) might result in a clinically significant herb-drug interactions. Additional caution should be taken when thymoquinone or thymoquinone-containing herbs are co-administered with phenytoin, which may induce unexpected potential herb-drug interactions via the inhibition of CYP2C9.

The role of efflux transporters and metabolizing enzymes in brain and peripheral organs to explain drug-resistant epilepsy.

Drug-resistant epilepsy has been explained by different mechanisms. The most accepted one involves overexpression of multidrug transporters proteins at the blood brain barrier and brain metabolizing enzymes. This hypothesis is one of the main pharmacokinetic reasons that lead to the lack of response of some antiseizure drug substrates of these transporters and enzymes due to their limited entrance into the brain and limited stay at the sites of actions. Although uncontrolled seizures can be the cause of the overexpression, some antiseizure medications themselves can cause such overexpression leading to treatment failure and thus refractoriness. However, it has to be taken into account that the inductive effect of some drugs such as carbamazepine or phenytoin not only impacts on the brain but also on the rest of the body with different intensity, influencing the amount of drug available for the central nervous system. Such induction is not only local drug concentration but also time dependent. In the case of valproic acid, the deficient disposition of ammonia due to a malfunction of the urea cycle, which would have its origin in an intrinsic deficiency of L-carnitine levels in the patient or by its depletion caused by the action of this antiseizure drug, could lead to drug-resistant epilepsy. Many efforts have been made to change this situation. In order to name some, the administration of once-daily dosing of phenytoin or the coadministration of carnitine with valproic acid would be preferable to avoid iatrogenic refractoriness. Another could be the use of an adjuvant drug that down-regulates the expression of transporters. In this case, the use of cannabidiol with antiseizure properties itself and able to diminish the overexpression of these transporters in the brain could be a novel therapy in order to allow penetration of other antiseizure medications into the brain.

Use of Saliva as an Alternative Matrix to Serum/Plasma for Therapeutic Drug Monitoring Using Reverse-Phase HPLC.

PURPOSE: This study was conducted to examine and verify the use of saliva as an alternative matrix for monitoring phenytoin drug levels in patients with epilepsy. Drug concentrations are measured to evaluate whether a suitable drug level has been achieved to minimize the risk for toxicity, inadequate efficacy, or therapy resistance and compliance issues. METHODS: Quantitative analysis was performed by using reverse-phase HPLC after sample pretreatment with acetonitrile. Seventy-eight patients who met the inclusion/exclusion criteria were examined in this study. Trough concentrations of both saliva and serum were taken at steady state. FINDINGS: Of the 78 patients enrolled, only 11 (14.1%) had normal levels. Twenty-eight patients (35.9%) had subtherapeutic levels, and 39 (50%) had toxic levels. Simultaneously, salivary phenytoin levels were analyzed; only 13 patients (17.3%) had therapeutic levels, 25 patients (33.3%) had subtherapeutic levels, and 37 (49.3%) had toxic levels. Among the study population, most of the patients were aged 31 to 40 years (25.6%) followed by the age group 21 to 30 years (19.2%). The lowest percentage of patients were in the age groups 71 to 80 years and >80 years (1.3%) each. This study found a statistically significant relationship between free serum and salivary phenytoin levels (P < 0.001). A very weak and insignificant correlation was observed between serum/salivary phenytoin levels and sex/age of the study population. The results of the present study support the use of saliva as an alternative to serum/plasma for monitoring phenytoin therapy. IMPLICATIONS: The free concentration of a drug represents the freely diffusible drug fraction, which is the therapeutically active form. Accordingly, the free drug concentration correlates to clinical efficacy and drug toxicity better than total concentration.

Effects of antiepileptic drugs' administration during pregnancy on the nerve cell proliferation and axonal outgrowth of human neuroblastoma SH-SY5Y nerve cells.

It has been suggested that the intelligence quotient of children born to pregnant women taking 1000 mg or more of valproic acid per day is lower than that of children born to pregnant women taking other antiepileptic drugs. However, the mechanism whereby intelligence quotient is decreased in children exposed to valproic acid during the fetal period has not yet been elucidated. Therefore, we used the human neuroblastoma cell line SH-SY5Y to evaluate the effects of antiepileptic drugs containing valproic acid on nerve cells. We assessed the anti-proliferative effects of drugs in these cells via WST-8 colorimetric assay, using the Cell Counting Kit-8. We also quantified drug effects on axonal elongation from images using ImageJ software. We also evaluated drug effects on mRNA expression levels on molecules implicated in nervous system development and folic acid uptake using real-time PCR. We observed that carbamazepine and lamotrigen were toxic to SH-SY5Y cells at concentrations >500 µM. In contrast, phenytoin and valproic acid were not toxic to these cells. Carbamazepine, lamotrigen, phenytoin, and valproic acid did not affect axonal outgrowth in SH-SY5Y cells. Sodium channel neuronal type 1a (SCN1A) mRNA expression-level ratios increased when valproic acid was supplemented to cells. The overexpression of SCN1A mRNA due to high valproic acid concentrations during the fetal period may affect neurodevelopment. However, since detailed mechanisms have not yet been elucidated, it is necessary to evaluate it by comparing cell axon elongation and SCN1A protein expression due to high-concentration valproic acid exposure.

Pharmacodynamic and pharmacokinetic interactions of hydroalcoholic leaf extract of Centella asiatica with valproate and phenytoin in experimental models of epilepsy in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Centella asiatica (CA) is commonly used herbal medicine for treatment of epilepsy. CA has CYP2C9, CYP2D6 and CYP3A4 enzymes inhibition property and used as an adjuvant therapy with conventional antiepileptic drugs (AEDs). That may be responsible for herb-drug interaction. AIM OF THE STUDY: The present study was planned to evaluate interactions profile of hydroalcoholic extract Centella asiatica (HECA) with antiepileptic drugs in experimental models of epilepsy in rats. MATERIALS AND METHODS: Wistar rats (175-200 g) were used. In the pharmacodynamic interaction study, seizures were induced using pentylenetetrazole (PTZ) (60 mg/kg, i.p.) and maximal electroshock seizure (MES) (70 mA for 0.2 s). The therapeutic and sub-therapeutic doses of valproate (VPA) and phenytoin (PHT) were co-administrated with HECA in PTZ and MES model of seizures respectively. Behavioural parameters were assessed using elevated plus maze test and passive avoidance paradigm. Rat brain oxidative stress parameters were also assessed. In the pharmacokinetic interaction study, the serum levels of the VPA and PHT were estimated at different time intervals by HPLC and pharmacokinetic parameters were analyzed by WinNonlin software. RESULTS: The VPA and PHT produced complete protection against seizures in their therapeutic doses but not with sub-therapeutic doses. However, co-administration of HECA with a sub-therapeutic dose of VPA and PHT enhanced the protection of seizures and significantly (p < 0.001) attenuated the seizure induced oxidative stress and cognitive impairment. It also significantly increased (p < 0.001) serum levels of VPA and PHT. The alterations in pharmacokinetic parameters (maximum serum concentration, area under the curve, clearance) of AEDs were also found with co-administration of HECA. CONCLUSION: The results suggested that co-administration of HECA could improve the therapeutic efficacy of VPA and PHT. But, alteration in pharmacokinetic parameters revel that needs critical medical supervision to avoid any toxic reactions.