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Farhan M, Rani P, Moledina F, George T, Tummala HP, Mallayasamy S. Application of Physiologically Based Pharmacokinetic Modeling of Lamotrigine Using PK-Sim in Predicting the Impact of Drug Interactions and Dosage Adjustment. J Pharmacol Pharmacother 2022. [DOI: 10.1177/0976500x221111455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background Physiologically based pharmacokinetic (PBPK) models are helpful as mechanistic representations of pharmacokinetic parameters. There were no reports of lamotrigine (LTG) PBPK models developed in open source platforms like PK-Sim. Objectives The present work was aimed to build a LTG PBPK model and compare it to the clinical data from South Asian Indian patients and use this model to understand the drug interactions of LTG and explore the optimal doses. Methods and Material The PBPK model was developed using the PK-Sim software platform and qualified with LTG plasma concentration data from an Indian study. The European population database was chosen as the patient setting in the software. Physicochemical data of LTG and enzyme kinetic data were incorporated from the literature. Dosing protocols were as per the previous study. Interaction models for drug interactions with carbamazepine and valproate were also simulated. Results Most of the model predicted concentration-time profiles of LTG at steady-state were well within the observed concentrations. The developed models were suitably qualified. The drug interaction model was used to assess the impact of induction and inhibition of the pharmacokinetic profile of LTG. Conclusions The predicted plasma concentrations of the developed PBPK models using the European population database were very similar to the data from Indian patients. The developed LTG PBPK models are applicable in predicting the impact of drug interactions and can yield appropriate LTG doses to be administered.
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Affiliation(s)
- Mohammed Farhan
- Department of Pharmacy Practice, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Prathvi Rani
- Department of Pharmacy Practice, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Fatimazahra Moledina
- Department of Pharmacy Practice, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Thomas George
- Department of Pharmacy Practice, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Hari Prabhath Tummala
- Department of Pharmacy Practice, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Surulivelrajan Mallayasamy
- Department of Pharmacy Practice, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
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Marino SE, Birnbaum AK, Leppik IE, Conway JM, Musib LC, Brundage RC, Ramsay RE, Pennell PB, White JR, Gross CR, Rarick JO, Mishra U, Cloyd JC. Steady-state carbamazepine pharmacokinetics following oral and stable-labeled intravenous administration in epilepsy patients: effects of race and sex. Clin Pharmacol Ther 2012; 91:483-8. [PMID: 22278332 PMCID: PMC4038037 DOI: 10.1038/clpt.2011.251] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Carbamazepine is a widely prescribed antiepileptic drug. Owing to the lack of an intravenous formulation, its absolute bioavailability, absolute clearance, and half-life in patients at steady state have not been determined. We developed an intravenous, stable-labeled (SL) formulation in order to characterize carbamazepine pharmacokinetics in patients. Ninety-two patients received a 100-mg infusion of SL-carbamazepine as part of their morning dose. Blood samples were collected up to 96 hours after drug administration. Plasma drug concentrations were measured with liquid chromatography-mass spectrometry, and concentration-time data were analyzed using a noncompartmental approach. Absolute clearance (l/hr/kg) was significantly lower in men (0.039 ± 0.017) than in women (0.049 ± 0.018; P = 0.007) and in African Americans (0.039 ± 0.017) when compared with Caucasians (0.048 ± 0.018; P = 0.019). Half-life was significantly longer in men than in women as well as in African Americans as compared with Caucasians. The absolute bioavailability was 0.78. Sex and racial differences in clearance may contribute to variable dosing requirements and clinical response.
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Affiliation(s)
- S E Marino
- Center for Clinical and Cognitive Neuropharmacology, University of Minnesota, Minneapolis, Minnesota, USA.
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Lerche MH, Meier S, Jensen PR, Hustvedt SO, Karlsson M, Duus JØ, Ardenkjaer-Larsen JH. Quantitative dynamic nuclear polarization-NMR on blood plasma for assays of drug metabolism. NMR IN BIOMEDICINE 2011; 24:96-103. [PMID: 20862657 DOI: 10.1002/nbm.1561] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 02/09/2010] [Accepted: 04/14/2010] [Indexed: 05/29/2023]
Abstract
Analytical platforms for the fast detection, identification and quantification of circulating drugs with a narrow therapeutic range are vital in clinical pharmacology. As a result of low drug concentrations, analytical tools need to provide high sensitivity and specificity. Dynamic nuclear polarization-NMR (DNP-NMR) in the form of the hyperpolarization-dissolution method should afford the sensitivity and spectral resolution for the direct detection and quantification of numerous isotopically labeled circulating drugs and their metabolites in single liquid-state NMR transients. This study explores the capability of quantitative in vitro DNP-NMR to assay drug metabolites in blood plasma. The lower limit of detection for the anti-epileptic drug (13)C-carbamazepine and its pharmacologically active metabolite (13)C-carbamazepine-10,11-epoxide is 0.08 µg/mL in rabbit blood plasma analyzed by single-scan (13)C DNP-NMR. An internal standard is used for the accurate quantification of drug and metabolite. Comparison of quantitative DNP-NMR data with an established analytical method (liquid chromatography-mass spectrometry) yields a Pearson correlation coefficient r of 0.99. Notably, all DNP-NMR determinations were performed without analyte derivatization or sample purification other than plasma protein precipitation. Quantitative DNP-NMR is an emerging methodology which requires little sample preparation and yields quantitative data with high sensitivity for therapeutic drug monitoring.
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Barakat NS, Radwan MA. In Vitro Performance of Carbamazepine Loaded to Various Molecular Weights of Poly (D, L-Lactide-Co-Glycolide). Drug Deliv 2008; 13:9-18. [PMID: 16401588 DOI: 10.1080/10717540500308992] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
The purpose of this study was to develop and assess the in vitro characteristics of carbamazepine-loaded microspheres. A solvent evaporation method was used to incorporate carbamazepine (CBZ) into poly (D,L-lactide-co-glycolide) (PLGA) with different molecular weights. The optimum conditions for CBZ-PLGA microspheres preparation were considered and the in vitro release of CBZ of PLGA microspheres were followed up to 24 hr in USP dissolution medium. The effect of using different ratios of PLGA microspheres, prepared with different molecular weights, for optimizing CBZ release also was investigated. CBZ encapsulation efficiency was 68 to 82% for all prepared formulations. Thermograms of CBZ-PLGA microspheres suggest that CBZ was totally entrapped with the PLGA polymer. The presence of Pluronic F-68 has improved the encapsulation of CBZ, resulted in better and smoother microspheres surfaces and enhanced its release pattern. CBZ release profiles were biphasic patterns; after an initial burst, a constant CBZ release rate was observed up to 24 hr. The release from these PLGA-based spherical matrices was consistent with the diffusion mechanism. CBZ dissolution T(50%) was significantly affected (> 3-fold) by increasing the lactide percent from 33.3 to 66.6% from different microspheres mixtures. The present study provides evidence that the encapsulation of CBZ to PLGA microspheres, either as a single polymer or mixture of two, was a successful attempt to control the release of CBZ.
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Affiliation(s)
- Nahla S Barakat
- Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
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Tutor-Crespo MJ, Hermida J, Tutor JC. Relative proportions of serum carbamazepine and its pharmacologically active 10,11-epoxy derivative: effect of polytherapy and renal insufficiency. Ups J Med Sci 2008; 113:171-80. [PMID: 18509811 DOI: 10.3109/2000-1967-225] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The proposed action mechanism and pharmacological activity of carbamazepine (CBZ) and its major metabolite, carbamazepine-10,11-epoxide (CBZE), are the same. The aim of our study was the investigation of the effect of concomitant antiepileptic treatment and renal insufficiency on the relative proportions of serum CBZ and CBZE. METHODS Serum trough steady-state CBZ and CBZE concentrations were determined by high-performance liquid chromatography (HPLC) in 140 epileptic patients treated with CBZ in monotherapy (n=100) and polytherapy with phenytoin, phenobarbital and valproate (n=40). The levels of CBZ were also determined using the Dade Behring enzyme multiplied immunoassay technique (EMIT). The glomerular filtration rate (GFR) was estimated from serum cystatin C using the Dade Behring nephelometric immunoassay. RESULTS The CBZE/CBZ and CBZ+CBZE/CBZEMIT ratios were significantly increased in 7 cases (3 in monotherapy and 4 in polytherapy) with GFR<60 mL/min/1.73m2 in relation to the patients treated in monotherapy or polytherapy having normal or mildly decreased renal function (p<0.001). CONCLUSIONS In patients with moderate to severe renal insufficiency the relative proportion of CBZE with respect to the parent drug is significantly increased. In these cases, the CBZ concentrations obtained using the EMIT, or other immunoassays having low CBZE cross-reactivity, may have an inadequate diagnostic efficiency.
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Affiliation(s)
- María J Tutor-Crespo
- Unidad Monitorización Fármacos, Laboratorio Central, Hospital Clínico Universitario, 15706 Santiago de Compostela, Galicia, Spain
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Budakova L, Brozmanova H, Grundmann M, Fischer J. Simultaneous determination of antiepileptic drugs and their two active metabolites by HPLC. J Sep Sci 2007; 31:1-8. [DOI: 10.1002/jssc.200700253] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Parant F, Bossu H, Gagnieu MC, Lardet G, Moulsma M. Cross-reactivity assessment of carbamazepine-10,11-epoxide, oxcarbazepine, and 10-hydroxy-carbazepine in two automated carbamazepine immunoassays: PETINIA and EMIT 2000. Ther Drug Monit 2003; 25:41-5. [PMID: 12548143 DOI: 10.1097/00007691-200302000-00006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This study was conducted to compare the cross-reactivity of two commercially available carbamazepine (CBZ) immunoassays (PETINIA and EMIT 2000) with carbamazepine-10,11-epoxide (CBZ-E), the active metabolite of CBZ. Oxcarbazepine (OCBZ) and its main metabolite 10-hydroxy-carbazepine (HCBZ) have a chemical structure closely related to that of CBZ. The cross-reactivities of these two drugs were also investigated. In the first part of the study, Lyphocheck blank human serum and Chemonitor quality controls (containing CBZ without CBZ-E) were spiked with variable amounts of CBZ-E. The apparent CBZ levels were measured by PETINIA and EMIT 2000 methods. The interference from OCBZ and HCBZ was directly assessed by measuring the apparent CBZ levels in Chromsystems Trileptal quality controls (containing OCBZ and HCBZ). In the second part of the study, the CBZ levels of serum samples from 49 patients, including 2 patients with massive CBZ ingestion, were measured by immunoassays and compared with a high-pressure liquid chromatography (HPLC) reference technique allowing the simultaneous measurement of CBZ and CBZ-E. The antibody used in the PETINIA assay cross-reacts (about 90%) with CBZ-E. In one case of CBZ poisoning (CBZ and CBZ-E levels measured by HPLC were 26.2 and 18.2 mg/L, respectively), CBZ level measured by PETINIA was falsely elevated (42.5 mg/L). In contrast, the specificity of EMIT 2000 was satisfactory (29.5 mg/L). The two immunoassays tested showed low cross-reactivity with OCBZ and HCBZ. In conclusion, it appears that the CBZ-E metabolite present in samples can falsely increase CBZ levels measured by the PETINIA assay.
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Affiliation(s)
- François Parant
- Laboratory of Biochemistry, Pharmacology and Toxicology, Edouard Herriot Hospital, Lyon, France.
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Hermida J, Bóveda MD, Vadillo FJ, Tutor JC. Comparison between the Cobas Integra immunoassay and high-performance liquid chromatography for therapeutic monitoring of carbamazepine. Clin Biochem 2002; 35:251-4. [PMID: 12074835 DOI: 10.1016/s0009-9120(02)00299-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVES Carbamazepine (CBZ) is metabolized by the cytochrome P450 into carbamazepine-10,11-epoxide (CBZepox), a metabolite with similar pharmacological activity to the parent drug. Recently it has been indicated that most current immunoassays for the determination of CBZ are unable to quantitatively measure its active epoxide. An evaluation of the Cobas Integra immunoassay for the determination of CBZ was carried out, and the results are compared with those obtained for CBZ+CBZepox using high-performance liquid chromatography (HPLC) in patients on monotherapy and polytherapy. DESIGN AND METHODS Steady-state serum trough concentrations of CBZ were determined in 119 epileptic patients using the Cobas Integra immunoassay and HPLC. In 91 cases CBZ was administered in monotherapy and in 28 cases in polytherapy with other anticonvulsant drugs. RESULTS The study of within- and between-run imprecisiom for the Cobas Integra immunoassay led to clinically acceptable coefficients of variation. A high correlation was found between the concentrations of CBZ obtained using the immunoassay and HPLC (r = 0.981, p < 0.001). In both the group of patients on monotherapy and those on polytherapy, the levels of CBZepox were greater than the clinically acceptable error for CBZ; consequently, there is a clinically significant difference between the total of CBZ+CBZepox concentrations (HPLC) and the concentrations of CBZ (immunoassay). In the group of patients under monotherapy, a high correlation coefficient was obtained between the levels of CBZ and CBZ+CBZepox (r = 0.975, p < 0.001) with an standard error of the estimate similar to the clinically acceptable value. CONCLUSIONS For the patients on monotherapy, it is possible to make a clinically valid estimation of CBZ+CBZepox from the concentration of CBZ obtained by means the immunoassay. In patients on polytherapy, the analytical determination of CBZepox could be of interest in cases where CBZ+CBZepox would be higher than the critical level of CBZ.
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Affiliation(s)
- Jesús Hermida
- Laboratorio Central, Hospital Clínico Universitario, Santiago de Compostela, Spain
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Abstract
We investigated the clinical effects and plasma levels of zonisamide (ZNS) in children with cryptogenic localization-related epilepsies. ZNS is absorbed slowly from the gastrointestinal tract, and its biological half-life is long as compared with that of other common antiepileptic drugs. The peak-to-trough plasma level ratios during a day were as small as 1.28 +/- 0.15 in children taking a daily dose of 8 mg/kg of ZNS once a day as a single drug. The plasma level (microg/ml) to dose (mg/kg/day) ratios estimated by the trough and peak plasma levels both increased with advancing age, but the peak-to-trough plasma level ratios were maintained almost uniformly throughout the pediatric age period. A wide range of the plasma levels was associated with complete freedom from seizures. The range of the plasma levels in patients who did not respond to ZNS was higher than that in the controlled group. However, the clinical effects of ZNS were in agreement with the range of generally accepted therapeutic plasma levels of ZNS, 15-40 microg/ml. Any patient who receives polytherapy is at risk to develop 1 or more drug interactions. Concurrent administration of carbamazepine (CBZ) decreases plasma concentrations of ZNS. However, ZNS does not alter plasma concentrations of CBZ or its primary metabolite, carbamazepine-10,11-epoxide (CBZ-E). It is evident that the concurrent administration of lamotrigine (LTG) affects plasma concentrations of CBZ-E, while plasma CBZ levels remain unaltered. However, the effect of LTG on plasma concentrations of CBZ-E is small, and none of the study patients showed toxic plasma concentrations of CBZ-E or associated clinical toxicity. Drug-protein binding interactions are another source of side effects. A simultaneous administration of valproic acid increases the total plasma CBZ-E levels relative to the CBZ dose associated with the raised free fractions of CBZ and CBZ-E. The high free plasma concentrations of CBZ-E above 1.5 microg/ml may be responsible for the side effects.
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Affiliation(s)
- H Miura
- Department of Pediatrics, Kitasato University School of Medicine, Kanagawa, Japan
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Abstract
Carbamazepine (CBZ) is widely used in the treatment of epilepsy, frequently in combination with other anticonvulsants. Its metabolite, carbamazepine-10,11-epoxide, is pharmacologically active and is increased with concurrent use of valproate and other anticonvulsants. This pharmacokinetic interaction may be particularly important because CBZ, its epoxide, phenytoin, and lamotrigine all act on fast voltage-dependent sodium channels. Over a 2-month period, routine serum requests for CBZ (n=47) (excluding known cases of overdose) were also analyzed for CBZ epoxide, phenytoin, and lamotrigine using a simultaneous high performance liquid chromatographic (HPLC) method. Valproate was measured using fluorescence polarization immunoassay (FPIA). With concurrent phenytoin and lamotrigine administration, there was a relative increase in CBZ epoxide and a significant decrease in the ratio of CBZ to epoxide (from more than 5 to 3). If valproate was also present, the concentration of parent and metabolite increased significantly, causing potential toxicity. Two patients in this latter group had significant clinical toxicity, with parent CBZ concentrations in the reference range; a third patient suffered from poor control of seizures. This study illustrates the importance of awareness of the contribution of active metabolites in therapeutic drug monitoring and raises questions about the role of the routine monitoring of such metabolites.
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Affiliation(s)
- J M Potter
- Division of Chemical Pathology, Queensland Health Pathology Services, Royal Brisbane Hospitals Campus, Herston, Australia
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Besag FM, Berry DJ, Pool F, Newbery JE, Subel B. Carbamazepine toxicity with lamotrigine: pharmacokinetic or pharmacodynamic interaction? Epilepsia 1998; 39:183-7. [PMID: 9577998 DOI: 10.1111/j.1528-1157.1998.tb01356.x] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE To determine whether the toxicity that occurs in some patients when lamotrigine (LTG) is added to carbamazepine (CBZ) is the result of either a pharmacokinetic or a pharmacodynamic interaction. METHODS Escalating LTG doses were added to ongoing CBZ treatment in 47 patients. All patients had blood samples collected for drug concentration measurement, including the epoxide metabolite of CBZ, before starting LTG treatment and after stabilising at each dose escalation. Patients also were examined for signs of toxicity. RESULTS After LTG was introduced, nine patients demonstrated clinical signs of CNS toxicity, mainly diplopia and dizziness. There was no significant (p = 0.05) change in the serum concentrations of either CBZ or its epoxide metabolite when LTG was added either to the group as a whole or to the nine patients who experienced adverse CNS effects. LTG serum concentrations also were below the level at which the common signs of LTG toxicity, such as nausea, vomiting, or unsteadiness, are more likely to occur. In seven of the nine patients who exhibited CNS toxicity, CBZ serum concentrations were >8 mg/L on LTG introduction. CONCLUSIONS Toxicity is more likely to occur when LTG is added to CBZ if the initial CBZ level is high, typically >8 mg/L. This appears to be the result of a pharmacodynamic interaction. A reduction of CBZ dose usually resolves the toxicity, allowing the LTG dose to be escalated to maximal effect. It is not usually necessary to stop either drug.
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Delgado Iribarnegaray MF, Santo Bueldga D, García Sánchez MJ, Otero MJ, Falcão AC, Domínguez-Gil A. Carbamazepine population pharmacokinetics in children: mixed-effect models. Ther Drug Monit 1997; 19:132-9. [PMID: 9108639 DOI: 10.1097/00007691-199704000-00003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The aim of the authors' study was to investigate the factors affecting carbamazepine (CBZ) clearance (CL) in children with epilepsy. The factors evaluated were total body weight (TBW), age, dose, sex, and phenobarbital (PB) and valproic acid (VA) comedication. A total of 387 steady-state serum concentration samples was analyzed. These were collected during CBZ therapy from 201 children, aged 1-14 years and weighting 9-78 kg. Population CL was calculated by using NONMEM, with a one-compartment model with first-order absorption and elimination. The absorption rate, bioavailability, and volume of distribution were set at values found in the literature. The model found best to describe the data was CL = (0.0122 TBW + 0.0467 Dose) Age0.331 (1.289 PB). The interindividual variability in CL had a variation coefficient (CV) of 11.8%, and the residual error, described by using an additive model, was 1.5 mg/l. The results show that CL increases linearly with TBW and nonlinearly with age; thus older children have a lower CL with respect to TBW than do younger ones. Likewise CL was seen to increase with the increase in the CBZ dose, suggesting a dose-dependent autoinduction of CBZ metabolism. Concomitant PB administration affected CL: however, sex and VA comedication did not affect it significantly. The final regression model for CL, was validated in a different group of 74 children. The standarized prediction error (SPE) was not significantly different from zero (SPE = 0.028), indicating that the model proposed for CL can be used to make accurate dosage recommendations. With these population estimates, CBZ doses that would be suitable for pediatric patients of different ages are proposed.
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Affiliation(s)
- M F Delgado Iribarnegaray
- Department of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, University of Salamanca, Spain
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Rosenfeld WE, Liao S, Kramer LD, Anderson G, Palmer M, Levy RH, Nayak RK. Comparison of the steady-state pharmacokinetics of topiramate and valproate in patients with epilepsy during monotherapy and concomitant therapy. Epilepsia 1997; 38:324-33. [PMID: 9070595 DOI: 10.1111/j.1528-1157.1997.tb01124.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE The steady-state pharmacokinetics of valproate (VPA) and topiramate (TPM) were compared during VPA monotherapy, concomitant VPA and TPM therapy, and TPM monotherapy to evaluate pharmacokinetic interactions. METHODS After a 3-week baseline period, 12 patients receiving VPA monotherapy (500 to 2,250 mg every 12 h) received TPM at three escalating doses (from 100 to 200 to 400 mg every 12 h), each for 2 weeks. Thereafter, the VPA dose was tapered by 25% weekly. Blood and urine samples were collected over 12-h intervals during VPA monotherapy and at the end of each stage of TPM dose escalation and TPM monotherapy. RESULTS All patients reached TPM monotherapy, and nine achieved satisfactory seizure control for > or = 2 weeks without VPA. TPM plasma peak concentration (C(max)) and area under the concentration-versus-time curve during a 12-h dosing interval (AUC(0-12)) were slightly higher (17%; n = 8) during TPM monotherapy than during concomitant VPA therapy. TPM oral and renal clearances (n = 8) were 25.9 +/- 4.6 and 11.6 +/- 3.2 ml/min during TPM monotherapy and were 29.8 +/- 4.2 and 12.4 +/- 2.7 ml/min during VPA concomitant therapy. VPA AUC(0-12) decreased (11.3%; n = 10) with the addition of TPM 400 mg every 12 h. VPA oral clearance was 12.8 +/- 4.1 ml/min during monotherapy and was 13.8 +/- 4.0, 14.1 +/- 3.9, and 14.5 +/- 5.2 ml/min during coadministration of TPM 100, 200, and 400 mg every 12 h, respectively. Cognitive dysfunction, observed in some patients receiving high doses of VPA with TPM, reversed or improved with VPA dose reduction and discontinuation. The lower-than-normal prestudy platelet count measured in one patient increased to normal levels when VPA was discontinued. CONCLUSIONS Because changes in TPM and VPA pharmacokinetics were small, it is unlikely that their concomitant use will have a significant impact on the clinical condition of the patient.
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Affiliation(s)
- W E Rosenfeld
- The Comprehensive Epilepsy Care Center for Children and Adults at St. Luke's Hospital, St. Louis, Missouri 63017, USA
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Effect of valproate and felbamate on carbamazepine and its metabolites in epileptic children. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0896-6974(96)00068-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Svinarov DA, Pippenger CE. Relationships between carbamazepine-diol, carbamazepine-epoxide, and carbamazepine total and free steady-state concentrations in epileptic patients: the influence of age, sex, and comedication. Ther Drug Monit 1996; 18:660-5. [PMID: 8946662 DOI: 10.1097/00007691-199612000-00006] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Steady-state plasma carbamazepine (CBZ), carbamazepine-epoxide (CBZE), and carbamazepine-diol (CBZD) concentrations were quantified by high-performance liquid chromatography in 435 specimens divided into two groups: CBZ monotherapy (n = 78) and CBZ polytherapy (n = 357). Distributions of concentrations of CBZ and its metabolites were derived, their protein binding investigated, and the differences of concentration/dose (mumol/L/mg/kg/day or 1/clearance) ratios were calculated as a measure for the influence of sex, age, and comedication on CBZ metabolism. Concentrations of CBZ ranged from 2.5 to 82.9 mumol/L (mean +/- SD, 22.3 +/- 10.9 mumol/L), 73% being within the therapeutic range (17-51 mumol/L), 24% being less than the therapeutic range, and 3% greater than the therapeutic range. Concentrations of CBZE ranged from 0.85 to 16.6 mumol/L (mean +/- SD, 5.17 +/- 2.56 mumol/L), and those of CBZD were between 0.77 and 36.4 mumol/L (mean +/- SD, 11.3 +/- 5.4 mumol/L). A multiplicative regression best fitted the concentration/dose plots of CBZ and CBZE and an exponential regression for CBZD. Dose correlated best with the second biotransformation product, CBZD. Free fractions were 0.22 +/- 0.03 for CBZ, 0.40 +/- 0.06 for CBZE, and 0.68 +/- 0.11 for CBZD. Sex was found to be of minor importance for CBZ disposition. A gradual, high-amplitude age increase of CBZ dose ratio was observed in the monotherapy group, with global difference of approximately 3.6 times, while CBZE dose ratio increased approximately 2-fold, and CBZD dose ratio increased to the smallest extent of 1.5 times. In the polytherapy group, a smaller global age increase for CBZ dose ratio of 3.4 times was found, but the respective increase for dose ratios of metabolites was greater compared with the monotherapy patients: 2.3 times for CBZE and 1.8 times for CBZD. Comedication of other antiepileptic drugs induced significant decrease of CBZ dose ratio only, but no changes of dose ratios of the metabolites were registered. The influence of valproic acid was represented in a particular pattern. We conclude that these findings could provide valuable information for CBZ metabolism and disposition in epileptic patients with respect to the efforts to ensure the best possible individualization of CBZ therapy.
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Affiliation(s)
- D A Svinarov
- Department of Clinical Laboratory, Alexander Hospital, Faculty of Medicine, Sofia, Bulgaria
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Abstract
In separate studies, potential pharmacokinetic interactions of topiramate (TPM) with phenytoin (PHT), carbamazepine (CBZ), and valproate (VPA) were evaluated. TPM was added to the baseline antiepileptic drug (AED) at a dosage of up to 800 mg/day, after which the baseline drug was discontinued, when possible. Addition of TPM produced no change in plasma levels of CBZ or CBZ epoxide (CBZ-E). Modest increases in PHT plasma levels in six of 12 patients treated with PHT and TPM, and a small mean decrease in VPA levels noted in patients receiving VPA with TPM, were considered unlikely to require adjustments in the dosage of the concomitant AED when TPM is added or discontinued. When patients were changed from concomitant therapy with PHT or CBZ to TPM monotherapy, TPM clearance was reduced by approximately 50%, suggesting that an adjustment in TPM dose may be required when PHT or CBZ is discontinued from TPM-treated patients. A slight increase in plasma TPM levels during monotherapy compared to concomitant therapy with VPA was considered clinically insignificant and not likely to require TPM dosage adjustment. In another study, oral clearance of digoxin was slightly increased when TPM was added, resulting in a small decrease in peak plasma levels of digoxin. In vitro studies conducted to date on a number of specific cytochrome P450 isoforms show an effect of TPM only on the CYP2Cmeph isoform. The risk for clinically meaningful changes in plasma levels of traditional AEDs when TPM is added to or discontinued from concomitant regimens appears to be minimal. However, adjustments in TPM dosages are likely to be needed when potent enzyme inducers, such as PHT or CBZ, are added or discontinued. TPM has a relatively low propensity for clinically significant drug interactions, and its pharmacokinetic and drug interaction profiles represent a clear advance over those of the traditional AEDs.
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Affiliation(s)
- B F Bourgeois
- Epilepsy Center and Neurophysiology Laboratory, St. Louis Children's Hospital and Washington University, Missouri, USA
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17
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Kodama Y, Kuranari M, Kodama H, Tsutsumi K, Fujii I, Takeyama M. Comparison of equations for predicting bound serum concentrations of carbamazepine and carbamazepine-10, 11-epoxide after polytherapy in patients with epilepsy. J Clin Pharmacol 1995; 35:995-1002. [PMID: 8568018 DOI: 10.1002/j.1552-4604.1995.tb04016.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In a previous study, an equation with in vivo population binding parameters of carbamazepine and carbamazepine-10, 11-epoxide (CBZ-E) to serum proteins for the relation between unbound and bound serum concentrations was defined. A review by Pynnönen indicates that the average bound/unbound plasma fraction ratio is 3.0 for carbamazepine and 1.0 for CBZ-E. In this study, the ability of equations with in vivo population binding parameters of the previous study (method 1) or with the average bound/unbound plasma fraction ratio of 3.0 of Pynnönen (method 2) to predict the bound serum carbamazepine concentration was retrospectively evaluated using 85 serum samples from 46 patients with epilepsy taking carbamazepine polytherapy. In 21 serum samples from 16 patients, the ability of these equations to predict bound serum CBZ-E concentration was also determined with in vivo population binding parameters from the previous study (method A) or with the average bound/unbound plasma fraction ratio of 1.0 of Pynnönen (method B). Mean prediction error, mean absolute prediction error (MAE), and root mean squared error (RMSE) were calculated for each method, and these values served as a measure of prediction bias and precision. Method 1 showed a bias to overpredict bound serum carbamazepine. The MAE and RMSE were significantly smaller with method 2 (MAE = 2.4 mumol/L; RMSE = 3.2 mumol/L) than with method 1 (MAE = 4.1 mumol/L; RMSE = 4.8 mumol/L). Method 2 was superior to method 1 in terms of accuracy and precision. For bound CBZ-E prediction, method B had a bias to underprediction. The MAE and RMSE were smaller with method A (MAE = 0.581 mumol/L; RMSE = 0.796 mumol/L) than with method B (MAE = 0.724 mumol/L; RMSE = 0.905 mumol/L). Method A was superior to method B in terms of accuracy and precision.
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Affiliation(s)
- Y Kodama
- Department of Clinical Pharmacy, Oita Medical University, Japan
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18
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Kodama Y, Kuranari M, Kodama H, Fujii I, Takeyama M. Evaluation of equations for unbound serum concentration prediction of carbamazepine and carbamazepine-10,11-epoxide in polytherapy pediatric patients with epilepsy. J Pharm Sci 1995; 84:835-9. [PMID: 7562433 DOI: 10.1002/jps.2600840710] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We retrospectively evaluated the ability of equations with in vivo population binding parameters of our previous study (Method 1) or an average unbound fraction of 0.25 of Pynnönen (Method 2) to predict the unbound serum carbamazepine (CBZ) concentration in 50 serum samples from 28 polytherapy pediatric patients with epilepsy. In 12 serum samples from 10 patients, the ability of equations for unbound serum carbamazepine-10,11-epoxide (CBZ-E) concentration prediction was also determined in predictive performance with in vivo population binding parameters of our previous study (Method A) or an average unbound fraction of 0.5 of Pynnönen (Method B). Mean prediction error, mean absolute prediction error (MAE), and root mean squared error (RMSE) were calculated for each method, and these values served as a measure of prediction bias and precision. Method 1 shows a bias to underpredict unbound serum CBZ. The MAE and RMSE were lower in Method 2 (MAE = 0.696 microM, RMSE = 0.912 microM) than in Method 1 (MAE = 0.946 microM, RMSE = 1.138 microM). Method 2 is superior to Method 1 in accuracy and precision. The effects of antiepileptic co-medications on predictive performance of Method 1 are relatively larger in a co-medicated group of serum samples with valproic acid (n = 33, MAE = 0.994 microM, RMSE = 1.211 microM) than in a group of serum samples without valproic acid co-medication (n = 17, MAE = 0.853 microM, RMSE = 0.979 microM).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- Y Kodama
- Department of Clinical Pharmacy, Oita Medical University, Japan
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19
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Liu H, Delgado MR. Interactions of phenobarbital and phenytoin with carbamazepine and its metabolites' concentrations, concentration ratios, and level/dose ratios in epileptic children. Epilepsia 1995; 36:249-54. [PMID: 7614908 DOI: 10.1111/j.1528-1157.1995.tb00992.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The effects of phenytoin (PHT) or phenobarbital (PB) comedication on the concentrations, concentration ratios, and level/dose ratios of carbamazepine (CBZ) and its metabolites were investigated. The hetero-induction effects of CBZ metabolism by PHT or PB were clearly demonstrated. Serum CBZ level/dose ratios in patients with CBZ polytherapy were decreased while CBZ-10,11-epoxide (CBZ-E) and trans-10,11-dihydroxy-10,11-dihydro-CBZ (CBZ-H) concentrations were increased as compared with those of patients receiving CBZ alone. The concentration ratios of CBZ-H/CBZ and CBZ-E/CBZ were also greater in patients receiving CBZ+PHT or CBZ+PB than in patients receiving CBZ alone. In addition, positive correlations between serum PHT concentration and CBZ-H/CBZ or CBZ-E/CBZ concentration ratios were observed. There were no significant differences in CBZ-H/CBZ-E concentration ratios, the free fractions of CBZ and its metabolites, and CBZ-E or CBZ-H level/dose ratios among the three groups of patients. Because this approach investigates the in vivo relation between the substrates and products of the enzymes involved in CBZ biotransformation, more detailed information about the drug interactions was obtained. The results suggest that the PHT has a potent induction effect on CBZ epoxidase, whereas PB is a moderate inducer.
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Affiliation(s)
- H Liu
- Department of Research, Texas Scottish Rite Hospital for Children, Dallas 75219, USA
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20
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Liu H, Delgado MR. A comprehensive study of the relation between serum concentrations, concentration ratios, and level/dose ratios of carbamazepine and its metabolites with age, weight, dose, and clearances in epileptic children. Epilepsia 1994; 35:1221-9. [PMID: 7988515 DOI: 10.1111/j.1528-1157.1994.tb01793.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We made a comprehensive study of the relation between age, weight, carbamazepine (CBZ) dose, total clearance (TC), and intrinsic clearance (IC) and concentrations, concentration ratios, and level/dose ratios of CBZ, carbamazepine-10,11-epoxide (CBZ-E) and trans-10,11-dihydroxy-10,11- dihydro-carbamazepine (CBZ-H) in a group of epileptic children receiving CBZ monotherapy. Body weight and age showed negative correlations with TC, IC, CBZ dose, and CBZ-E/CBZ and CBZ-H/CBZ concentration ratios, and had positive relation with CBZ, CBZ-E, and CBZ-H level/dose ratios. These results indicate decreased CBZ metabolism with patient maturity. Correlations between CBZ dose with TC, IC, and the concentration ratios of CBZ-E/CBZ, CBZ-H/CBZ-E, and CBZ-H/CBZ were positive. CBZ dose also had negative associations with CBZ and CBZ-E level/dose ratios, indicating dose-dependent autoinduction of CBZ metabolism. Our data suggest that weight, age, and CBZ dose have less influence on epoxide-hydrolase activities than on epoxidase activities. The CBZ-E/CBZ concentration ratio can be used as an indicator of the degree of autoinduction of CBZ metabolism, even in patients receiving CBZ monotherapy.
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Affiliation(s)
- H Liu
- Department of Laboratory, Texas Scottish Rite Hospital for Children, University of Texas Southwestern Medical Center, Dallas 75219
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So EL, Ruggles KH, Cascino GD, Ahmann PA, Weatherford KW. Seizure exacerbation and status epilepticus related to carbamazepine-10,11-epoxide. Ann Neurol 1994; 35:743-6. [PMID: 8210232 DOI: 10.1002/ana.410350616] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Over a 3-year period, we encountered 6 adults whose seizure control unexpectedly deteriorated with the occurrence of partial status epilepticus and daily multiple seizures. Analysis of the case histories and subsequent clinical follow-up for 1 1/2 to 3 years disclosed the following evidence that demonstrates the role of carbamazepine-epoxide in the development of the seizure exacerbation: (1) There were high serum carbamazepine-epoxide concentrations while serum carbamazepine concentrations were lower than or the same as baseline levels; (2) all patients were taking drugs that are known to increase serum carbamazepine-epoxide concentrations; (3) status epilepticus failed to respond to intravenous phenytoin loading; (4) seizure exacerbation in all patients was corrected by withholding carbamazepine dose; (5) seizure exacerbation recurred in 1 patient who resumed the same dose of carbamazepine; and (6) there were no prior status epilepticus or daily multiple seizures despite previous toxicities with other antiepileptic drugs in 3 patients. Our experience shows that inconspicuous elevation of carbamazepine-epoxide levels during polytherapy may precipitate a distinct state of drug toxicity characterized by severe exacerbation of seizures. Mental retardation may be a predisposition to this condition.
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Affiliation(s)
- E L So
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
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22
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Abstract
Therapeutic drug monitoring (TDM) is practiced for a number of frequently used drugs in infants and children. It is believed that monitoring drug levels will increase the probability of a therapeutic response and minimize the probability of adverse drug sequelae. Dose adjustments are based on measured drug levels interpreted relative to published therapeutic ranges which may or may not reflect the true relationship with either therapeutic or adverse effects. Potential errors derive from many sources, some amenable to solutions based on current knowledge, others awaiting improved understanding of the causes and consequences of unreliable therapeutic ranges.
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Affiliation(s)
- S M Tange
- Department of Biochemistry, Montreal Children's Hospital, McGill University, Quebec, Canada
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23
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Liu H, Delgado MR. The influence of polytherapy on the relationships between serum carbamazepine and its metabolites in epileptic children. Epilepsy Res 1994; 17:257-69. [PMID: 8013448 DOI: 10.1016/0920-1211(94)90056-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The influence of polytherapy on the relationships between the age, weight, carbamazepine (CBZ) dose, total clearance, and intrinsic clearance, with concentrations, concentration ratios, and level/dose ratios of CBZ, carbamazepine-10,11-epoxide (CBZ-E) and trans-10,11-dihydroxy-10,11-dihydro-carbamazepine (CBZ-H) are investigated. Three groups of patients with CBZ monotherapy, or receiving CBZ polytherapy by taking CBZ and valproic acid (VPA) or CBZ plus other antiepileptic drugs (AEDs) were studied. The significant correlations between serum CBZ concentrations and CBZ dose in patients taking CBZ alone were no longer significant in patients with polytherapy, and the positive associations between serum CBZ-E concentrations and CBZ dose were lost in patients with CBZ + VPA. Only the concentrations of CBZ-H had significant correlations with CBZ dose in all three groups of patients. Results from this relationship study indicate a heteroinduction effect of other AEDs on CBZ metabolism, and a relatively weak influence on CBZ-E elimination. Data also suggest that there is a block in the biotransformation from CBZ-E to CBZ-H in patients taking CBZ + VPA, presumably caused by the inhibition effect of VPA on epoxide hydrolase. Therapeutic drug monitoring of CBZ will benefit from the knowledge obtained from the relationship study.
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Affiliation(s)
- H Liu
- Department of Research, Texas Scottish Rite Hospital for Children, University of Texas Southwestern Medical Center, Dallas 75219
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Collins DM, Gidal BE, Pitterle ME. Potential interaction between carbamazepine and loxapine: case report and retrospective review. Ann Pharmacother 1993; 27:1180-7. [PMID: 8251682 DOI: 10.1177/106002809302701003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
OBJECTIVE To report a potential interaction between carbamazepine (CBZ), an anticonvulsant medication, and loxapine, an antipsychotic. CBZ is being increasingly used to treat a variety of psychiatric disorders. Because of this, the potential for multiple-drug therapy and subsequent drug interactions is increased. METHODS We prospectively monitored plasma CBZ and carbamazepine epoxide (CBZE) concentrations in a single patient during and after withdrawal of loxapine comedication. Additionally, we retrospectively evaluated four patients who had received concomitant therapy with CBZ and loxapine. RESULTS Plasma CBZE/CBZ ratios decreased from 0.76 to 0.18 following discontinuation of loxapine. Absolute CBZE plasma concentrations also decreased from 1.7 to 0.6 micrograms/mL after loxapine therapy was stopped. Retrospectively screened patients who were receiving concomitant loxapine-CBZ therapy all had unusually elevated CBZE/CBZ plasma concentration ratios (0.75-1.91). CONCLUSIONS These cases suggest that an interaction occurs between loxapine and CBZ. Possible mechanisms include either induction of CBZ metabolism to its epoxide metabolite, or inhibition of the enzymatic metabolism of CBZE (epoxide hydrolase).
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Affiliation(s)
- D M Collins
- University of Wisconsin Hospitals and Clinics, Madison
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25
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Abstract
Approximately 20 to 30% of patients with active intractable epilepsy are commonly treated with polytherapy antiepileptic drug regimens, and these patients may experience complicated drug interactions. Furthermore, because of the long term nature of treatment, the possibility of drug interactions with drugs used for the treatment of concomitant disease is high. Classically, clinically significant drug interactions, both pharmacokinetic and pharmacodynamic, have been considered to be detrimental to the patient, necessitating dosage adjustment. However, this need not always be the case. With the introduction of new drugs (e.g. vigabatrin and lamotrigine) with known mechanisms of action, the possibility exists that these can be used synergistically. The most commonly observed clinically significant pharmacokinetic interactions can be attributed to interactions at the metabolic and serum protein binding levels. The best known examples relate to induction (e.g. phenobarbital, phenytoin, carbamazepine and primidone) or inhibition [e.g. valproic acid (sodium valproate)] of hepatic monoxygenase enzymes. The extent and direction of interactions between the different antiepileptic drugs are varied and unpredictable. Interactions in which the metabolism of phenobarbital, phenytoin or carbamazepine is inhibited are particularly important since these are commonly associated with toxicity. Some inhibitory drugs include macrolide antibiotics, chloramphenicol, cimetidine, isoniazid and numerous sulphonamides. A reduction in efficacy of antibiotic, cardiovascular, corticosteroid, oral anticoagulant and oral contraceptive drugs occurs during combination therapy with enzyme-inducing antiepileptic drugs. Discontinuation of the enzyme inducer or inhibitor will influence the concentrations of the remaining drug(s) and may necessitate dosage readjustment.
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Affiliation(s)
- P N Patsalos
- University Department of Clinical Neurology, Institute of Neurology, London, England
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26
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Chapron DJ, LaPierre BA, Abou-Elkair M. Unmasking the significant enzyme-inducing effects of phenytoin on serum carbamazepine concentrations during phenytoin withdrawal. Ann Pharmacother 1993; 27:708-11. [PMID: 8329787 DOI: 10.1177/106002809302700605] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
OBJECTIVE We report on two patients who appeared to exhibit profound induction of carbamazepine metabolism during cotherapy with phenytoin. Gradual withdrawal of phenytoin confirmed this impression. DESIGN Two case studies. RESULTS Two patients receiving carbamazepine and phenytoin as combination anticonvulsant therapy were admitted for comprehensive rehabilitation. A 23-year-old man had therapeutic serum phenytoin concentrations, but his serum carbamazepine concentrations were so low that they were nonquantifiable. Doubling the daily carbamazepine dosage did not yield quantifiable serum concentrations. When the daily phenytoin dosage was tapered from 500 to 200 mg, the carbamazepine concentration rose to 10.0 micrograms/mL. No further changes in serum carbamazepine concentrations were observed when the phenytoin was discontinued. A 49-year-old man was receiving large daily dosage of phenytoin (600 mg) and carbamazepine (2300 mg). In the process of tapering and discontinuing phenytoin, the patient became lethargic and confused. These signs and symptoms suggested carbamazepine toxicity. The patient was eventually stabilized on a carbamazepine dosage of 1200 mg/d, which produced a serum concentration of 8.4 micrograms/mL. When this patient had been receiving concurrent phenytoin therapy, approximately twice as much carbamazepine (2300 mg) was required to maintain a similar serum concentration. CONCLUSIONS Phenytoin is a potent inducer of carbamazepine metabolism. Whenever phenytoin dosages are tapered and discontinued in patients receiving these medications concomitantly, frequent serum carbamazepine monitoring is recommended during the ensuing deinduction phase.
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Affiliation(s)
- D J Chapron
- School of Pharmacy, University of Connecticut, Storrs
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Lucarelli C, Villa P, Lombaradi E, Prandini P, Brega A. HPLC method for the simultaneous analysis of valproic acid and other common anticonvulsant drugs in human plasma or serum. Chromatographia 1992. [DOI: 10.1007/bf02276848] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Petit P, Lonjon R, Cociglio M, Sluzewska A, Blayac JP, Hue B, Alric R, Pouget R. Carbamazepine and its 10,11-epoxide metabolite in acute mania: clinical and pharmacokinetic correlates. Eur J Clin Pharmacol 1991; 41:541-6. [PMID: 1815966 DOI: 10.1007/bf00314982] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The study was designed to investigate the antimanic profile of carbamazepine as a first-line drug in affective or schizoaffective disorders, to correlate the clinical efficacy with the plasma level of carbamazepine and its 10,11-epoxide metabolite, and to test the potential value of monitoring the salivary level. It was administered alone for 3 weeks to 21 acute manic inpatients. During the first week, the dosage was rapidly increased to 800 mg/day in order to produce steady-state plasma levels of carbamazepine on Day 7. The individual dose was then adjusted to maintain the therapeutic range of 8-12 mg/l. Plasma and saliva levels of the drug and its metabolite, as well as clinical status were assessed weekly. Overall, there was 62% globally improved patients and 77% in affective disorders. The improvement of manic symptoms was significantly lower in schizoaffective than in affective disorders, whereas the dropout rate and the need for antipsychotic medication was higher in the former group. The antimanic response was significantly correlated with the plasma levels both of carbamazepine and its epoxide metabolite, with a time-lag consistent with a delayed drug effect. Drug and metabolite concentrations in saliva were close to their plasma free fraction and were strongly correlated with their plasma levels, suggesting the potential value of salivary drug monitoring.
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Affiliation(s)
- P Petit
- Service de Psychologie Médicale et Psychiatrie de l'Adulte, C.H.R.U., Montpellier, France
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Sunaoshi W, Miura H, Takanashi S, Shirai H, Hosoda N. Influence of concurrent administration of sodium valproate on the plasma concentrations of carbamazepine and its epoxide and diol metabolites. THE JAPANESE JOURNAL OF PSYCHIATRY AND NEUROLOGY 1991; 45:474-7. [PMID: 1762252 DOI: 10.1111/j.1440-1819.1991.tb02525.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- W Sunaoshi
- Department of Pediatrics, Kitasato University School of Medicine, Sagamihara, Japan
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