Administration Of CBZ Research Articles

ID 343 – Oral carbamazepine controlled temporal complex partial status epilepticus

Objective Temporal complex partial status epilepticus TCPSE is a condition usually manifest as variable periods of confusion with a prolonged epileptic episode. In our case report on two patients with TCPSE we study the response to carbamazepine after failure of first and second line therapy. Methods Clinical case report. Results Case 1: A 39-year old women with cryptogenic epilepsy, was treated with phenobarbital PB 100 mg/day. Prolonged disturbed consciousness over 3 days, after abrupt withdrawal of PB. Experiencing visual and auditory hallucinations. EEG showed continuous left temporal spike/wave and slow waves discharges. Normal brain MRI. No response to intravenous Diazepam 0.15 mg/kg and PB 15 mg/kg after four days. Clinical improvement and ictal EEG pattern resolved after oral Carbamazepine CBZ treatment 600 mg/day. Case 2: A 61-year old women with symptomatic complex partial seizure disorder, secondary to CNS lymphoma. Was treated with PB 100 mg/day and CBZ600 mg/day. Confusion with agitation and experiencing visual hallucinations, after abrupt withdrawal of CBZ. EEG revealed continuous temporal slow waves. CT scanning was unchanged from imaging studies six month earlier. No response to intravenous Diazepam 0.1 mg/kg and PB 15 mg/day after three days. Improvement in her clinical delirium and EEG pattern after oral CBZ treatment 600 mg/day. Conclusion CBZ was effective and safe in controlling TCPSE in our patients. Oral administration of CBZ is an effective alternative.

Teratogenic Effect of Carbamazepine Administration in Pregnant Rats

Background: Carbamazepine (Tegretol) is an anticonvulsant and mood stabilizing drug used primarily in the treatment of epilepsy and bipolar disorder, as well as trigeminal neuralgia. It has been assigned to pregnancy category D by the U.S Food and Drug Administration (FDA). CBZ can cause fetal harm when administered to pregnant women. Epidemiological data suggested that there may be an association between the use of CBZ during pregnancy and congenital malformations, specifically spina bifida and developmental disorders. The possible malformation-specific risks with CBZ use during pregnancy need to be considered, so the present work was conducted to evaluate the genotoxicity of two doses of CBZ (3.6 mg and 10.8 mg/ 100g body weight/ day) in pregnant female rats and their fetuses. Chromosomal aberration in bone marrow cells and histopathological examination of liver and kidney of pregnant rats were also determined. Materials and Methods: Fourty five pregnant Sprague Dawley rats were randomly divided into the groups. The first was administered oral doses of distilled water and served as control. The other two groups were administered oral doses of CBZ suspended in distilled water equivalent to 3.6 mg and 10.8 mg/100g body weight/day respectively for 15 day from the 6th day to the 20th day of gestation. Females were sacrificed on the 20th day of gestation. Results: Administration of CBZ 3.6 mg and 10.8 mg /100g body weight to pregnant rats from the 6th till the 20thday of gestation. Decreased fetal body weight, crown-rump length, increased resorbed and dead fetuses were observed compared to the control ones. Moreover, CBZ-high dose group(10.8mg/100g) causedmalformations that could be described as severe growth retardation. At the same time, bone marrow metaphases of CBZ-treated pregnant rats revealed structural chromosomal aberrations. Whereas, histopathological examination of liver and kidney of pregnant rats treated with both doses of CBZshowed cellular alterations.Conclusion:It has been found that usage of antiepileptic CBZ during gestational period may create risk, associated with maternal toxicity, hepato- and nephrotoxicity and chromosomal aberrations in pregnant rats, with intrauterine growth retardation which was manifested by low body weight, length reduction and malformations. These alterations were dose dependent. The benefits of taking CBZ must be weighed against the potential risks to boththe developing fetus and the mother.

Abuse Potential of Carbamazepine for Euphorigenic Effects

Euphoric effects following administration of CBZ alone have been never reported in any international journals and this is the first case report regarding to potential abuse of CBZ for euphoria. We hope this report will be a warning to physicians who will decide to prescribe CBZ, particularly in the patients who had a history of alcohol dependence as abuse potential of CBZ for euphoric effects has been frequently reported in the treatment of alcohol withdrawal.

Absence of interaction of cabazitaxel on the pharmacokinetics of midazolam: Results of a drug–drug interaction study in patients with advanced solid tumors.

126 Background: Cabazitaxel (Cbz) is approved in combination with prednisone/prednisolone for the treatment of men with hormone-refractory metastatic prostate cancer previously treated with a docetaxel-containing treatment regimen. In vitro studies showed that Cbz is mainly metabolized through CYP3A, resulting in inhibition of this family of enzymes. Midazolam (Mdz) is primarily metabolized by CYP3A4. We aimed to determine the effect of Cbz on CYP3A activity by comparing the pharmacokinetic (PK) properties of Mdz when administered alone and following co-administration with Cbz. Methods: An ongoing safety and PK study of Cbz in patients with metastatic or locally advanced solid tumors and varying degrees of hepatic impairment (NCT01140607) included a cohort with normal hepatic function to assess the effect of a single Cbz dose on the PK profile of a single dose of Mdz. This was an open-label, two-period, fixed-sequence study in patients aged between 45 and 60 years with advanced solid tumors and normal hepatic function. A single dose of Mdz (2 mg) was administered orally alone (Day –1) and at the end of a 1-hour infusion of Cbz (25 mg/m2) (Day 1), with a 24-hour interval between the two administrations of Mdz. Endpoints included AUC and AUClastof Mdz with and without Cbz administration, and safety evaluations. Results: Of the 13 patients enrolled and treated in the cohort, 11 patients were included in the PK analysis. Exposure (AUC and AUClast) and other PK parameters after a single administration of Mdz alone and in combination with Cbz (Day 1) were similar. The AUC ratio for Mdz administered alone or with Cbz was 0.97 (90% CI: 0.76–1.23). The AUClast ratio for Mdz administered alone or with Cbz was 1.04 (90% CI: 0.81–1.34). All 13 patients had ≥1 adverse event (AE), 11 (84.6%) experienced a Grade 3–4 AE, and 4 (30.8%) experienced a serious AE. The majority of Grade 3–4 AEs were haematological and no new or unexpected safety findings were observed. Conclusions: In this study, Cbz did not increase the plasma exposure of Mdz. This indicates that Cbz is not a CYP3A inhibitor in the clinical setting and can be administered in combination with drugs metabolized by CYP3A. Clinical trial information: NCT01140607.

Concomitant use of carbamazepine and olanzapine and the effect on some behavioral functions in rats

As shown in clinical studies, combinations of first generation normothymics (carbamazepine – CBZ) with atypical neuroleptics (olanzapine – OLA) lead to improvements in approximately half of patients treated for relapses of bipolar affective disease. Our previous studies have shown OLA to have an antidepressant effect when administered at a dose of 0.5mg/kg only upon single administration; the effect did not last throughout chronic administration, whereas CBZ administered at a dose of 30mg/kg showed an antidepressant effect only after 7 days of administration. As shown in our previous studies, both OLA and CBZ improve memory in rats but only after chronic administration. The improved antidepressant effect of many drugs, including OLA and CBZ used in combined therapy – as observed in our clinic – as well as confirmed evidence of OLA’s and CBZ’s positive effects on cognitive functions in humans and animals substantiated commencement of research on defining the effect of combined administration of OLA and CBZ on sedation (tested in a locomotor activity test), antidepressant effect (Porsolt test) and spatial memory (Morris test) in animals. The tests were performed on male Wistar rats. It was found that in combined administration of CBZ and OLA for 7 and 14 days, OLA would completely prevent the CBZ’s sedative effect. With combined administration of CBZ and OLA, both as a single dose and after prolonged treatment for 7 days, a significant reduction in immobility time was observed. Combined administration of CBZ and OLA did not improve memory in rats that received these drugs in a single dose, whereas statistically significant differences were observed in the chronic experiments. It can be assumed that the observed effects of combined administration of CBZ and OLA may be due to the pharmacokinetic interactions, but further studies are necessary to confirm these assumptions.

Drug resistance and hippocampal damage after delayed treatment of pilocarpine-induced epilepsy in the rat

Temporal lobe epilepsy (TLE) is the most common and pharmacoresistant form of epilepsy. Problems that cause pharmacoresistance may include delayed therapy due to late consultation, especially in developing countries. Our study aimed at unraveling consequences of delayed drug treatment using a rat model of TLE. Following pilocarpine-induced status epilepticus interrupted after 4 h, rats were continuously videorecorded for onset and recurrence of spontaneous convulsive seizures. The animals were then treated for 50 days with carbamazepine (CBZ; first-line drug in TLE and effective also in rats), starting at seizure onset (27.22 ± 3.38 days after status epilepticus) or 50 days later, and compared with epileptic untreated rats and non-epileptic CBZ-treated ones. Convulsive seizure frequency and duration, and hippocampal cell changes were evaluated. In particular, parvalbumin-containing hippocampal interneurons, astrocytes and microglia were characterized with immunohistochemistry and quantitative analyses. Prompt administration of CBZ suppressed seizures; delayed treatment only decreased frequency of convulsive seizures, which were also relatively prolonged. In hippocampal regions, histopathological damage, parvalbumin immunoreactivity loss, and glial activation were very marked after delayed treatment, and were reduced only slightly compared to untreated epilepsy, but enhanced compared to early treatment. The data on high frequency and duration of convulsive seizures in late-therapy rats indicate that delayed CBZ administration caused a high degree of drug resistance. This condition was subserved by severe damage in the hippocampus, presumably consequent to long-term seizure recurrence. Overall the data indicate that the paradigm of delayed treatment of limbic epilepsy could provide a model of drug-refractory TLE with hippocampal sclerosis.

Carbamazepine and oxcarbazepine decrease phenytoin metabolism through inhibition of CYP2C19

Multiple studies suggest that phenytoin concentrations increase with CBZ co-medication. This study evaluated the hypothesis that CBZ and/or its major metabolite (CBZE) inhibit CYP2C19-mediated phenytoin metabolism using human liver microsomes and cDNA-expressed CYP2C19. Oxcarbazepine (OXC), and its 10-monohydroxy metabolite (MHD) were also evaluated. CBZ and MHD inhibited CYP2C19-mediated phenytoin metabolism at therapeutic concentrations. Thus, administration of CBZ and OXC with CYP2C19 substrates with narrow therapeutic ranges should be done cautiously.

Polycystic ovaries, obesity and insulin resistance in women with epilepsy

In order to investigate the possible role of valproic acid therapy in the development of obesity, hyperinsulinism and polycystic ovaries (PCOs), we have studied metabolic parameters and ovarian morphology in epileptic women. A total of 105 women, who were treated for at least 2 years with valproate (n = 52) or carbamazepine monotherapy (n = 53), were included in the examination. Menstrual disturbances were reported by 29 (28 %) of the women, 12 (11 %) of the VPA treated women, and 17 (16 %) in the CBZ group. On ultrasound scan polycystic ovaries were found in 28 patients (27 %) of the whole study population, of whom 13 (12 %) received VPA and 15 (14 %) CBZ. The mean body mass index (BMI) was significantly higher in the VPA group (24.4 kg/m(2) +/- 4.1) than in CBZ treated patients (22.9 kg/m(2) +/- 2.4;p < 0.022), and serum triglycerides tended to be increased, while total cholesterol values (178.9 +/- 30.5) and LDL-cholesterol values (92.6 +/- 27.4) were significantly lower in the valproate group, than in the carbamazepine group (207.1 +/- 43.0 vs 115.1 +/- 42.0; p < 0.001). Postprandial insulin, C-peptide and proinsulin levels were significantly higher in VPA treated patients compared with those treated with CBZ, while no differences could be found in the fasting state. In conclusion we could thus demonstrate that the frequency of PCOs in 27 % of epileptic women seems to be similar to that in the general population with a frequency of 20-30 %. The development of PCOs did not reveal a difference with the administration of VPA or CBZ. With respect to the metabolic side-effects of VPA therapy our data indicate that VPA increases glucose stimulated pancreatic insulin secretion, which might be followed by an increase in body weight.

Epileptic nystagmus: A case study video‐EEG correlation

ABSTRACT Epileptic nystagmus (EN) is an uncommon phenomenon characterized by repetitive and rapid saccades, in association with epileptic discharges. We present a critical video‐EEG recording in a patient with occipital seizures that appeared clinically as EN. The subject, male, 70 years‐old, was examined because of generalized tonic‐clonic seizures, preceded by left cephalic version. These were controlled using i.v. PHT, but partial seizures persisted, which we recorded using video‐EEG. Clinically, we observed episodes of left conjugate deviation of the eyes, accompanied by horizontal nystagmoid movements, with a rapid leftward component and visual hallucinations. The patient did not lose consciousness. Ictal EEG: spike rhythm in the posterior right occipito‐temporal region extending to adjacent and contralateral regions, followed by post‐discharge of slow waves. The video‐EEG was interpreted as partial oculo‐clonic status epilepticus of right temporo‐occipital origin. Cranial MRI: old, bilateral hemorrhaging occipital contusions associated with previous cranial injury. The picture persisted for two days, and disappeared with administration of CBZ 600 mg/d. Our patient's nystagmus seemed to be related to the critical activity recorded in the right occipito‐temporal region. The co‐existence of visual hallucinations and the video‐EEG correlation support this possibility. This phenomenon is probably due to epileptic activation of the cortical center of saccadic movements, with a rapid phase of nystagmus, contralateral to the focus, and a slow ipsilateral phase in association with a defect in the gaze‐fixing system (“leaky neural integrator”) [published with videosequences].

Pharmacoepidemiologic investigation of a clonazepam-carbamazepine interaction by mixed effect modeling using routine clinical pharmacokinetic data in Japanese patients.

Nonlinear mixed effects modeling was used to estimate the effects of clonazepam-carbamazepine interaction on clearance values using 359 serum levels gathered from 183 pediatric and adult epileptic patients (age range, 0.3-26.8 years) during their clinical routine care. Patients received the administration of clonazepam and/or carbamazepine. The final model describing clonazepam clearance was CL = 179.0 x TBW(-0.231) x 1.22(CBZ), where CL is total body clearance (mL/kg/h) and TBW is total body weight (kg); CBZ = 1 for concomitant administration of carbamazepine and CBZ = zero otherwise. The final model describing carbamazepine clearance was CL = 92.7 x TBW(-0.394) x DOSE(0-397) x 0.795(CZP), where DOSE is the daily dose of carbamazepine (mg/kg/day); CZP = 1 for concomitant administration of clonazepam and CZP = zero otherwise. Concomitant administration of clonazepam and carbamazepine resulted in a 22% increase in clonazepam clearance and a 20.5% decrease in carbamazepine clearance.

Teratogenic effects of antiepileptic drugs: implications for the management of epilepsy in women of childbearing age.

Exposure to antiepileptic drug (AED) treatment in utero occurs in 1 of every 250 newborns. The absolute risk of major malformations in these infants is about 7-10%, approximately 3-5% higher than in the general population. Specific risk factors include high maternal daily dosage or serum concentrations of AED, low folate levels, polytherapy, and generalized seizures during pregnancy. Adverse pregnancy outcomes, including congenital heart malformations, facial clefts, spina bifida aperta, hypospadias, growth retardation, and psychomotor and mental retardation, are associated with, although not necessarily caused by, AED exposure. Specific cognitive defects, hypertelorism, and nail hypoplasia can be causally related to specific AED exposures. To prevent teratogenic side effects, the prospective mother should be treated with AEDs only when absolutely necessary. Monotherapy with the AED that is most effective in the lowest possible daily dose (divided into at least two or three administrations) should be prescribed. High-dose folate supplementation (4-5 mg/day) reduces the risk of a neural tube defect in a child whose sibling had such a defect, but its impact on the specific teratogenic risks of AEDs is unknown. A substantial proportion of fetal malformations may be secondarily prevented by prenatal diagnosis, consisting of a fetal structural ultrasound examination at weeks 18 and 20 of gestation and, with VPA or CBZ administration, an alpha 1-fetoprotein analysis of amniotic fluid at week 16. Determination of a specific defect prevention strategy depends largely on parental attitudes toward prenatal diagnosis and termination of pregnancy, which should be discussed before conception.(ABSTRACT TRUNCATED AT 250 WORDS)

Development and Reversal of Contingent Inefficacy and Tolerance to the Anticonvulsant Effects of Carbamazepine

The relationship of the timing of drug administration to anticonvulsant efficacy against amygdala kindled seizures was studied. During kindling development, rats received carbamazepine (CBZ, 15mg/kg) before (CBZ-before) or after each amygdala stimulation (CBZ-after). After kindling to full seizures, when all animals were given CBZ before the stimulation, only the CBZ-after group showed a good anticonvulsant response. The rats that had received CBZ before (during development of kindled seizures) remained unresponsive to CBZ treatment (contingent inefficacy). When drug-naive or CBZ-after animals repeatedly received CBZ before electrical stimulation, they developed tolerance to its anticonvulsant effects (contingent tolerance). The tolerance could be reversed by a period of treatment with CBZ-after or by kindling the animal drug-free, but not by CBZ administration alone or by time off from both drug and seizures. These findings suggest that inefficacy and tolerance to CBZ may be affected by the temporal contingencies of drug administration and that responsiveness can be reinstated by altering these contingencies.

The effect of dosage regimen on the efficacy of cambendazole against Trichinella spiralis

Systematic dose- and time-response trials were first conducted to determine a treatment regimen with cambdendazole (CBZ, 2-[4′-thiazolyl]-5- isopropoxycarbonylaminobenzimidazole) that would be therapeutically effective against adult Trichinella spiralis in experimentally-infected mice. CBZ proved to be highly effective against adult Trichinella in a 3-day treatment course during the enterai phase of experimental trichinellosis. When treatment began 72 h after the mice were inoculated with parasites, the number of adult worms recovered from the host intestine was greatly reduced by twice-daily oral doses of CBZ at 25 mg kg −1 body wt. The efficacy of the divided daily oral dosage treatment regimen that was effective against adult T. spiralis during the enteral phase of infection was then tested during the parenteral phases of trichinellosis. Gavage administration of CBZ at 25 mg kg −1 bis m die for 3 consecutive days during the invasive (days 14–16) and encystment (days 28–30) phases of infection significantly reduced (29 and 90 %, respectively) the number of larvae subsequently recovered from the host musculature on day 44 postinoculation.

Effects of cimetidine on carbamazepine auto- and hetero-induction in man.

The effect of cimetidine (CMT; 400 mg twice daily) and matching placebo on the enzyme-inducing properties of carbamazepine (CBZ; 200 mg at night for 15 days) was studied in seven healthy male volunteers. CMT alone had no significant effect on antipyrine kinetics, urinary 6 beta-hydroxycortisol excretion or leucocyte delta-aminolaevulinic acid synthase (ALA.S) activity. CBZ increased leucocyte ALA.S activity by 204% following 1 week's treatment (P less than 0.001). Thereafter, ALA.S activity fell despite continued CBZ administration. Concomitant CMT did not influence this response. Antipyrine clearance and urinary 6 beta-hydroxycortisol excretion were both increased by CBZ after 2 weeks' treatment (P less than 0.01). CMT blocked CBZ induction of antipyrine metabolism but the rise in urinary 6 beta-hydroxycortisol excretion was unaffected. Plasma CBZ concentrations 10, 14 and 18 h following the 8th and 15th doses were higher when CMT was taken concurrently (P less than 0.05). CBZ half-life fell by 36% and clearance rose by 29% (both P less than 0.001) with placebo and by 10% and 7% (both NS) when CMT was taken concurrently. CMT inhibits CBZ auto- and hetero-induction in man. Epileptic patients receiving CBZ chronically may be at risk of toxicity if CMT is also prescribed.

Brainstem noradrenergic system depression by cyclobenzaprine

A possible mechanism for CBZ's depressant action on the brainstem noradrenergic system was investigated in precollicularly decerebrated cats immobilized with Flaxedil (2 mg/kg, i.V.). Phenoxybenzamine (2 mg/kg, i.v.) was consistently observed to antagonize CBZ's suppression of both the flexor and extensor MSRs. Subsequent evidence for the brainstem noradrenergic system mediating the CBZ effect was established by extracellular recordings. Unitary discharges of LC neurons identified histologically were demonstrated to be inhibited chiefly by CBZ (1 mg/kg, i.V.). In some instances, the inhibition of spontaneous coerulear activity was found to parallel temporally the MSR response following CBZ administration. Coerulospinal neurons characterized by physiological criteria also revealed diminished activities following CBZ (0.5 mg/kg, i.V.). A decreased neuronal somatic excitability was also observed by the antidromically driven coerulospinal neurons following CBZ. It is concluded that CBZ's depressant action is mediated, at least in part, by the noradrenergic coerulospinal system. Other possible mechanisms of CBZ action are also discussed.