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Abstract
Epilepsy is a common neurological disease in both humans and domestic dogs, making dogs an ideal translational model of epilepsy. In both species, epilepsy is a complex brain disease characterized by an enduring predisposition to generate spontaneous recurrent epileptic seizures. Furthermore, as in humans, status epilepticus is one of the more common neurological emergencies in dogs with epilepsy. In both species, epilepsy is not a single disease but a group of disorders characterized by a broad array of clinical signs, age of onset, and underlying causes. Brain imaging suggests that the limbic system, including the hippocampus and cingulate gyrus, is often affected in canine epilepsy, which could explain the high incidence of comorbid behavioral problems such as anxiety and cognitive alterations. Resistance to antiseizure medications is a significant problem in both canine and human epilepsy, so dogs can be used to study mechanisms of drug resistance and develop novel therapeutic strategies to benefit both species. Importantly, dogs are large enough to accommodate intracranial EEG and responsive neurostimulation devices designed for humans. Studies in epileptic dogs with such devices have reported ictal and interictal events that are remarkably similar to those occurring in human epilepsy. Continuous (24/7) EEG recordings in a select group of epileptic dogs for >1 year have provided a rich dataset of unprecedented length for studying seizure periodicities and developing new methods for seizure forecasting. The data presented in this review substantiate that canine epilepsy is an excellent translational model for several facets of epilepsy research. Furthermore, several techniques of inducing seizures in laboratory dogs are discussed as related to therapeutic advances. Importantly, the development of vagus nerve stimulation as a novel therapy for drug-resistant epilepsy in people was based on a series of studies in dogs with induced seizures. Dogs with naturally occurring or induced seizures provide excellent large-animal models to bridge the translational gap between rodents and humans in the development of novel therapies. Furthermore, because the dog is not only a preclinical species for human medicine but also a potential patient and pet, research on this species serves both veterinary and human medicine.
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Affiliation(s)
- Wolfgang Löscher
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine, Hannover, Germany
- Center for Systems Neuroscience, Hannover, Germany
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Musuc AM, Anuta V, Atkinson I, Sarbu I, Popa VT, Munteanu C, Mircioiu C, Ozon EA, Nitulescu GM, Mitu MA. Formulation of Chewable Tablets Containing Carbamazepine-β-cyclodextrin Inclusion Complex and F-Melt Disintegration Excipient. The Mathematical Modeling of the Release Kinetics of Carbamazepine. Pharmaceutics 2021; 13:pharmaceutics13060915. [PMID: 34205629 PMCID: PMC8235681 DOI: 10.3390/pharmaceutics13060915] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 11/23/2022] Open
Abstract
Due to its low solubility, carbamazepine (CBZ) exhibits slow and incomplete release in the gastrointestinal tract and, hence, variable pharmacokinetics and pharmacodynamic effect. Lots of methods have been devised to improve its solubility, the large number of proposed solutions being a sign that the problem is not yet satisfactorily solved. The persistent problem is that predictable release kinetics, an increased rate but within defined limits, are required to avoid high absorption variability. This paper presents a synthesis of a carbamazepine-β-cyclodextrin inclusion complex (CBZ-β-CD), the characterization of the physical mixture, CBZ, β-CD and the CBZ-β-CD inclusion complex using Fourier transform infrared spectroscopy, scanning electron microscopy, simultaneous thermal analysis and X-ray diffraction, formulation of chewable tablets, determination of the dissolution of carbamazepine in medium containing 1% sodium lauryl sulfate (LSS), and in simulated saliva (SS), mathematical modeling of release kinetics. The kinetics of total CBZ release from tablets containing CBZ-β-CD and super-disintegrant F-Melt in both SS and LSS followed two steps: a burst release in the first minutes and a slower release in intervals up to 60 min. The release in the second phase has been well described by the Higuchi and Peppas models, which advocate a controlled release by combined diffusion and with some phenomena of swelling and relaxation of the matrix generated by the crospovidone component of the F-Melt excipient.
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Affiliation(s)
- Adina Magdalena Musuc
- “Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, 202 Spl. Independentei, 060021 Bucharest, Romania; (I.A.); (V.T.P.); (C.M.)
- Correspondence: (A.M.M.); (I.S.); (E.A.O.)
| | - Valentina Anuta
- Department of Physical and Colloidal Chemistry, Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, 020956 Bucharest, Romania;
| | - Irina Atkinson
- “Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, 202 Spl. Independentei, 060021 Bucharest, Romania; (I.A.); (V.T.P.); (C.M.)
| | - Iulian Sarbu
- Department of Pharmaceutical Physics and Biophysics, Drug Industry and Pharmaceutical Biotechnologies, Faculty of Pharmacy, “TituMaiorescu” University, 004051 Bucharest, Romania
- Correspondence: (A.M.M.); (I.S.); (E.A.O.)
| | - Vlad Tudor Popa
- “Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, 202 Spl. Independentei, 060021 Bucharest, Romania; (I.A.); (V.T.P.); (C.M.)
| | - Cornel Munteanu
- “Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, 202 Spl. Independentei, 060021 Bucharest, Romania; (I.A.); (V.T.P.); (C.M.)
| | - Constantin Mircioiu
- Department of Applied Mathematics and Biostatistics, Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, 020956 Bucharest, Romania;
| | - Emma Adriana Ozon
- Department of Pharmaceutical Technology and Biopharmacy, Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, 020956 Bucharest, Romania;
- Correspondence: (A.M.M.); (I.S.); (E.A.O.)
| | - George Mihai Nitulescu
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, 020956 Bucharest, Romania;
| | - Mirela Adriana Mitu
- Department of Pharmaceutical Technology and Biopharmacy, Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, 020956 Bucharest, Romania;
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3
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Brigo F, Leo A, Russo E, Striano P, Belcastro V. Intravenous carbamazepine for the treatment of epilepsy. Expert Opin Pharmacother 2018; 19:743-747. [DOI: 10.1080/14656566.2018.1462338] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Francesco Brigo
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
- Department of Neurology, Franz Tappeiner Hospital, Merano, Italy
| | - Antonio Leo
- Department of Science of Health, School of Medicine, University of Catanzaro, Catanzaro, Italy
| | - Emilio Russo
- Department of Science of Health, School of Medicine, University of Catanzaro, Catanzaro, Italy
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, DINOGMI-Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health University of Genoa, ‘G. Gaslini’ Institute, Genova, Italy
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Abstract
Status epilepticus (SE) represents the most severe form of epilepsy. It is one of the most common neurologic emergencies, with an incidence of up to 61 per 100,000 per year and an estimated mortality of 20 %. Clinically, tonic-clonic convulsive SE is divided into four subsequent stages: early, established, refractory, and super-refractory. Pharmacotherapy of status epilepticus, especially of its later stages, represents an "evidence-free zone," due to a lack of high-quality, controlled trials to inform clinical decisions. This comprehensive narrative review focuses on the pharmacotherapy of SE, presented according to the four-staged approach outlined above, and providing pharmacological properties and efficacy/safety data for each antiepileptic drug according to the strength of scientific evidence from the available literature. Data sources included MEDLINE and back-tracking of references in pertinent studies. Intravenous lorazepam or intramuscular midazolam effectively control early SE in approximately 63-73 % of patients. Despite a suboptimal safety profile, intravenous phenytoin or phenobarbital are widely used treatments for established SE; alternatives include valproate, levetiracetam, and lacosamide. Anesthetics are widely used in refractory and super-refractory SE, despite the current lack of trials in this field. Data on alternative treatments in the later stages are limited. Valproate and levetiracetam represent safe and effective alternatives to phenobarbital and phenytoin for treatment of established SE persisting despite first-line treatment with benzodiazepines. To date there are no class I data to support recommendations for most antiepileptic drugs for established, refractory, and super-refractory SE. Limiting the methodologic heterogeneity across studies is required and high-class randomized, controlled trials to inform clinicians about the best treatment in established and refractory status are needed.
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Affiliation(s)
- Eugen Trinka
- Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University Salzburg, Ignaz Harrerstrasse 79, 5020, Salzburg, Austria,
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Franco V, Iudice A, Grillo E, Citraro R, De Sarro G, Russo E. Perspective on the use of perampanel and intravenous carbamazepine for generalized seizures. Expert Opin Pharmacother 2014; 15:637-44. [PMID: 24437529 DOI: 10.1517/14656566.2014.879572] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Several antiepileptic drugs are available for the treatment of epileptic patients. However, the treatment of some seizure types and novel drug formulations deserve further advances in epilepsy research. AREAS COVERED The authors analyze the published evidence on the efficacy of perampanel against secondarily generalized seizures (SGS) and report the currently available development of intravenous (IV) formulations of carbamazepine (CBZ), commenting on their potential in the clinical setting. EXPERT OPINION Perampanel is the first noncompetitive AMPA receptor antagonist to be approved as adjunctive treatment in patients with partial-onset (focal) seizures (POS) with or without secondary generalization. Apart from its efficacy and safety on POS, a consistent body of evidence supports its efficacy in SGS at a minimum dose of 8 mg/day; however, such dose appears close to the best-tolerated dose. CBZ is a poorly water-soluble compound; many efforts to develop a parenteral formulation have not been successful so far. Novel IV CBZ formulations seem to exhibit favorable pharmacokinetics along with good tolerability in animal models and in patients taking oral CBZ. Further studies are needed to assess whether larger doses will be as well tolerated, allowing IV CBZ to be used as bridge therapy when the oral route is not feasible or in patients naïve to CBZ.
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Affiliation(s)
- Valentina Franco
- University of Pavia, Department of Internal Medicine and Therapeutics, Clinical Pharmacology Unit , Pavia , Italy
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6
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Bridging solubility between drug discovery and development. Drug Discov Today 2012; 17:486-95. [DOI: 10.1016/j.drudis.2011.11.007] [Citation(s) in RCA: 295] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/25/2011] [Accepted: 11/18/2011] [Indexed: 11/22/2022]
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Hemenway JN, Jarho P, Henri JT, Nair SK, VanderVelde D, Georg GI, Stella VJ. Preparation and physicochemical characterization of a novel water-soluble prodrug of carbamazepine. J Pharm Sci 2010; 99:1810-25. [DOI: 10.1002/jps.21952] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Bialer M. Pharmacodynamic and pharmacokinetic characteristics of intravenous drugs in status epilepticus. Epilepsia 2009; 50 Suppl 12:44-8. [DOI: 10.1111/j.1528-1167.2009.02348.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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9
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Pharmacokinetic study of a carbamazepine nanoemulsion in beagle dogs. Int J Pharm 2009; 378:146-8. [DOI: 10.1016/j.ijpharm.2009.05.055] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 05/16/2009] [Accepted: 05/25/2009] [Indexed: 11/22/2022]
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Kelmann RG, Kuminek G, Teixeira HF, Koester LS. Preliminary Study on the Development of Nanoemulsions for Carbamazepine Intravenous Delivery: An Investigation of Drug Polymorphic Transition. Drug Dev Ind Pharm 2008; 34:53-8. [DOI: 10.1080/03639040701506387] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
beta-cyclodextrin (beta-CD) and other cyclodextrins (CDs) have utility for solubilizing and stabilizing drugs; however, some are nephrotoxic when administered parenterally. A number of workers have attempted to identify, prepare, and evaluate various CD derivatives with superior inclusion complexation and maximal in vivo safety for various biomedical uses. A systematic study led to SBE-beta-CD (Captisol), a polyanionic variably substituted sulfobutyl ether of beta-CD, as a non-nephrotoxic derivative and HP-beta-CD, a modified CD developed by Janssen. SBE-beta-CD and HP-beta-CD have undergone extensive safety studies and are currently used in six products approved by the Food and Drug Administration (four for Captisol and two for HP-beta-CD). They are also in use in numerous clinical and preclinical studies. This article will focus on the issues that led to the development of these two CDs, their safety, characterization, and applications, and especially their ability to improve drug delivery. SBE-beta-CD interacts very well with neutral drugs to facilitate solubility and chemical stability, and because of its polyanionic nature, it interacts particularly well with cationic drugs. Complexes between SBE-beta-CD and HP-beta-CD and various drugs have been shown to rapidly dissociate after parenteral drug administration, to have no tissue-irritating effects after intramuscular dosing, and to result in superior oral bioavailability of poorly water-soluble drugs. The pharmacokinetics, tissue distribution, and cellular effects of some representative CDs, including SBE-beta-CD and HP-beta-CD, are reviewed. The safety profiles of CDs are discussed, with emphasis on the biological effects of some CDs on the gastrointestinal tract, kidney, and reproduction and development and the carcinogenic potential of CDs. In addition, human experience with CD derivatives, specifically SBE-beta-CD and HP-beta-CD, indicates that these two CDs are well tolerated in humans and have no adverse effects on the kidneys or other organs following either oral or intravenous administration.
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Affiliation(s)
- Valentino J Stella
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas 66047, USA.
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Affiliation(s)
- Meir Bialer
- Department of Pharmaceutics, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel.
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Structural behaviour of 2-hydroxypropyl-beta-cyclodextrin in water: molecular dynamics simulation studies. Pharm Res 2007; 25:1092-9. [PMID: 18161014 DOI: 10.1007/s11095-007-9506-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Accepted: 11/19/2007] [Indexed: 10/22/2022]
Abstract
PURPOSE To investigate the effect of 2-hydroxypropyl side group substitutions on the structure of beta-cyclodextrin (CD) in water. METHODS Molecular dynamics simulations were carried out on four HPBCDs that broadly represent a range of degree of substitutions in order to investigate the effect of substitution of beta-cyclodextrin with 2-hydroxypropyl groups at various O2 and O6 positions of the glucose units. RESULTS The 2-hydroxypropyl side groups located at the O2 positions widen the cavity entrance at the secondary OH position of the CD molecule. These groups are spatially more spread out but dynamically more restricted, due to the formation of a hydrogen bond network between the hydroxyl groups of the side chains and the glucose units. On the other hand, the 2-hydroxypropyl groups at the O6 positions are dynamically more flexible. CONCLUSIONS The extent and the location of the substitution can affect the cavity structure of the CD molecule, and thus possibly the molecular encapsulation capabilities.
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Buggins TR, Dickinson PA, Taylor G. The effects of pharmaceutical excipients on drug disposition. Adv Drug Deliv Rev 2007; 59:1482-503. [PMID: 18198495 DOI: 10.1016/j.addr.2007.08.017] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Many new chemical entities are poorly soluble, requiring the use of co-solvents or excipients to produce suitable intravenous formulations for early pre-clinical development studies. There is some evidence in the literature that these formulation components can have significant physiological and physicochemical effects which may alter the distribution and elimination of co-administered drugs. Such effects have the potential to influence the results of pre-clinical pharmacokinetic studies, giving a false impression of a compound's intrinsic pharmacokinetics and frustrating attempts to predict the drug's ultimate clinical pharmacokinetics. This review describes the reported effects of commonly used co-solvents and excipients on drug pharmacokinetics and on physiological systems which are likely to influence drug disposition. Such information will be useful in study design and evaluating data from pharmacokinetic experiments, so that the potential influence of formulation components can be minimised.
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Preparation, characterization and in vivo conversion of new water-soluble sulfenamide prodrugs of carbamazepine. Bioorg Med Chem Lett 2007; 17:6629-32. [DOI: 10.1016/j.bmcl.2007.09.045] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Revised: 09/11/2007] [Accepted: 09/12/2007] [Indexed: 11/18/2022]
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Kelmann RG, Kuminek G, Teixeira HF, Koester LS. Carbamazepine parenteral nanoemulsions prepared by spontaneous emulsification process. Int J Pharm 2007; 342:231-9. [PMID: 17582711 DOI: 10.1016/j.ijpharm.2007.05.004] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2006] [Revised: 04/07/2007] [Accepted: 05/07/2007] [Indexed: 11/17/2022]
Abstract
Carbamazepine (CBZ), a widely used anticonvulsant drug, is a poorly soluble drug with no parenteral treatment available for patients. This study was aimed at developing a nanoemulsion for CBZ intravenous delivery. The spontaneous emulsification method was used to prepare different formulations containing 2mg/mL CBZ. Likewise, a 2(2) full factorial experimental design was applied to study the influence of two independent variables (type of oil and type of lipophilic emulsifier) on emulsion physicochemical characteristics. The nanoemulsions were evaluated concerning droplet size, zeta potential, viscosity, drug content and association to oily phase. The formulation, which presented the best characteristics required for intravenous administration was selected and refined with respect to the lipophilic emulsifier content (increase from 5% to 6% of soy lecithin). This formulation was characterized and kept its properties in a satisfactory range over the evaluated period (3 months), i.e. droplet size around 150 nm, drug content around 95% and zeta potential around -40 mV. The transmission electron microscopy revealed emulsion droplets almost spherical in shape with an amorphous core, whereas the in vitro release profile assessed by dialysis bags demonstrated a release kinetics square root time dependent, with 95% of ca. having been released within 11h.
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Affiliation(s)
- Regina G Kelmann
- Universidade Federal de Santa Catarina, Campus Universitário-Trindade, Centro de Ciências da Saúde, Departamento de Ciências Farmacêuticas, Bloco K, Laboratório de Controle de Qualidade, sala 207, 88040-900 Florianópolis, SC, Brazil
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Löscher W. The pharmacokinetics of antiepileptic drugs in rats: consequences for maintaining effective drug levels during prolonged drug administration in rat models of epilepsy. Epilepsia 2007; 48:1245-58. [PMID: 17441999 DOI: 10.1111/j.1528-1167.2007.01093.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rodent models of chronic epilepsy with spontaneous recurrent seizures likely represent the closest parallel to the human condition. Such models may be best suited for therapy discovery for pharmacoresistant epilepsy and for antiepileptogenic or disease-modifying therapeutics. However, the use of such rodent models for therapy discovery creates problems with regard to maintaining effective drug levels throughout a prolonged testing period. This is particularly due to the fact that rodents such as rats and mice eliminate most drugs much more rapidly than humans. Thus, knowledge about elimination rate of a test drug in a laboratory species is essential for development of a treatment paradigm that allows maintaining adequate drug levels in the system over the period of treatment. Currently, the most popular models of epilepsy with spontaneous seizures are poststatus epilepticus models of temporal lobe epilepsy in rats. Such models are both used for studies on antiepileptogenesis and drug resistance. For validation of these models, current antiepileptic drugs (AEDs) have to be used. In this article, the elimination rates of these AEDs and their effective plasma levels in rats are reviewed as a guide for developing treatment protocols for chronic drug testing. The advantages and disadvantages of several technologies for drug delivery are discussed, and some examples for calculation of adequate treatment protocols are given. As shown in this review, because of the rapid elimination of most AEDs in rats, it is no trivial task to maintain effective steady-state AED levels in the plasma throughout the day over multiple days to ensure that there will be adequate levels in the system for the purpose of the experiment. However, the use of an adequate dosing regimen that is based on elimination rate is an absolute prerequisite when using rat models for discovery of new antiepileptogenic therapies or therapies for pharmacoresistant epilepsy, because otherwise such models may lead to erroneous conclusions about drug efficacy.
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Affiliation(s)
- Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, and Center for Systems Neuroscience, Hannover, Germany.
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Koester LS, Bertuol JB, Groch KR, Xavier CR, Moellerke R, Mayorga P, Dalla Costa T, Bassani VL. Bioavailability of carbamazepine:β-cyclodextrin complex in beagle dogs from hydroxypropylmethylcellulose matrix tablets. Eur J Pharm Sci 2004; 22:201-7. [PMID: 15158905 DOI: 10.1016/j.ejps.2004.03.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2003] [Revised: 02/19/2004] [Accepted: 03/02/2004] [Indexed: 11/26/2022]
Abstract
The bioavailability of a carbamazepine:beta-cyclodextrin (CBZ:betaCD) complex from hydroxypropylmethylcellulose (HPMC) matrix tablets was evaluated in beagle dogs. A solubility study demonstrated the improvement of CBZ aqueous solubility by adding increasing amounts of betaCD. The 1:1 CBZ:betaCD molar ratio was chosen to produce the complex, which was obtained by spray-drying. Matrix tablets were prepared by direct compressing either a CBZ:betaCD complex or a physical mixture of both substances with HPMC. Both matrix formulations displayed a controlled-release profile when compared to the reference formulation (Tegretol CR 200). CBZ presented a significantly higher bioavailability from matrix tablets containing the CBZ:betaCD complex than that obtained from Tegretol CR 200). Although a high inter-subject variability was observed, the results pointed to the feasibility of using betaCD in order to modulate CBZ release and absorption, as well as to reduce the drug dosage maintaining the same plasma levels.
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Affiliation(s)
- Letícia S Koester
- Programa de Pós-Graduação em Ciências Farmacêuticas, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Ipiranga 2752, 90610-000 Porto Alegre, RS, Brazil
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Wray-Cahen D, Caperna TJ, Steele NC. Methyl-beta-cyclodextrin: an alternative carrier for intravenous infusion of palmitate during tracer studies in swine (Sus scrofa domestica). Comp Biochem Physiol A Mol Integr Physiol 2001; 130:55-65. [PMID: 11672683 DOI: 10.1016/s1095-6433(01)00369-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Fatty acid-free albumin has been the standard carrier for intravenous infusion of fatty acids to study in vivo lipid metabolism. However, subjects can have adverse reactions to infusion of albumin. We sought an alternative to albumin as a carrier for intravenous infusion of fatty acids, using the pig as a model. Cyclodextrins are naturally occurring water-soluble molecules that can serve as carriers for lipid-soluble compounds. 13C-palmitate was complexed to either 20% methyl-beta-cyclodextrin, 20% 2-hydroxypropyl-beta-cyclodextrin, or 5% porcine albumin (isotopic purity of infusates: 99.22+/-0.06%). 13C-palmitate-albumin was infused under fed conditions and 13C-palmitate-methyl-beta-cyclodextrin was infused under fasted and fed conditions in 50-kg pigs. Palmitate remained in solution at 4 degrees C in methyl-beta-cyclodextrin, but precipitated at 25-30 degrees C in 2-hydroxypropyl-beta-cyclodextrin. Pigs infused with 13C-palmitate-methyl-beta-cyclodextrin maintained normal body temperature and appetite; those infused with 13C-palmitate-albumin became anorexic and exhibited other negative side effects to albumin. Palmitate oxidation rates under fed conditions were similar using either 13C-palmitate-methyl-beta-cyclodextrin or 13C-palmitate-albumin complexes. Fasting increased 13C-palmitate-methyl-beta-cyclodextrin oxidation by approximately eight-fold. These data suggest that methyl-beta-cyclodextrin may be a suitable substitute for albumin in fatty acid metabolism studies in swine.
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Affiliation(s)
- D Wray-Cahen
- USDA-ARS, Livestock and Poultry Science Institute, Growth Biology Laboratory, Beltsville, MD 20705, USA.
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Abstract
Since their discovery, cyclodextrins and their ability to form inclusion complexes have fascinated chemists, formulators and recently, entrepreneurs. This mini-review has as its objective, a critical assessment of the current status of cyclodextrins in the formulation and delivery of pharmaceuticals and commentary on their potential future uses. The emphasis will be on answers to common questions often asked of pharmaceutical scientists working in this area. Why use cyclodextrins for drug solubilization and stabilization when alternative techniques are available? Why the greater interest in modified cyclodextrins and not the parent cyclodextrins? If a drug forms a strong cyclodextrin inclusion complex, how is the drug released in vivo? Dose the injection of a cyclodextrin/drug complex alter the pharmacokinetics of the drug? Are there drug products on the market which contain cyclodextrins? What is the regulatory status of cyclodextrins? Although definitive answers to all these questions are not possible at this time, many of these questions are answerable, and educated and informed responses are possible for the rest.
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Affiliation(s)
- V J Stella
- Higuchi Biosciences Center for Drug Delivery Research, University of Kansas, Lawrence 66047, USA
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Brewster ME, Anderson WR, Meinsma D, Moreno D, Webb AI, Pablo L, Estes KS, Derendorf H, Bodor N, Sawchuk R, Cheung B, Pop E. Intravenous and oral pharmacokinetic evaluation of a 2-hydroxypropyl-beta-cyclodextrin-based formulation of carbamazepine in the dog: comparison with commercially available tablets and suspensions. J Pharm Sci 1997; 86:335-9. [PMID: 9050802 DOI: 10.1021/js9602913] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Complexation of carbamazepine with 2-hydroxypropyl-beta-cyclodextrin was performed to provide improved formulations of this widely used antiepileptic drug. Based on this approach, liquid dosage forms were configured for both parenteral and oral use. Intravenous administration of an aqueous carbamazepine x 2-hydroxypropyl-beta-cyclodextrin (CBZ x HPbetaCD) complex at a CBZ dose of 20 mg/kg was well tolerated and generated high initial drug levels that fell monoexponentially as a function of time, yielding a plasma elimination half-life of 38 min. Oral studies were completed with three preparations: a commercially available tablet and suspension, as well as a CBZ x HPbetaCD oral solution. Oral administration of tablets gave erratic and slow absorption, leading to maximum CBZ concentrations (C(max)) of <2 microg/mL, which were manifested only at 2.5 h after drug dosing. The absolute bioavailability of CBZ from the tablets was approximately 25%. Both the suspension and CBZ x HPbetaCD solution gave a significantly improved profile. Thus, the liquid oral dosage forms approximately doubled the oral bioavailability of CBZ compared with the tablets.
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Löscher W, Hönack D. Intravenous carbamazepine: comparison of different parenteral formulations in a mouse model of convulsive status epilepticus. Epilepsia 1997; 38:106-13. [PMID: 9024191 DOI: 10.1111/j.1528-1157.1997.tb01084.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE A drawback of carbamazepine (CBZ), a major antiepileptic drug (AED) with clinical efficacy against partial and generalized convulsive seizures, is its isolubility in aqueous vehicles, which is generally considered a contraindication to parenteral administration in epileptic patients. However, CBZ can be dissolved in glycofurol, a solvent used clinically as a vehicle for parenteral preparations of drugs such as diazepam (DZP) and phenytoin (PHT). Furthermore, aqueous CBZ solutions can be prepared by complexing CBZ with 2-hydroxypropyl-beta-cyclodextrin (HP beta CD), an inert beta-cyclodextrin derivative believed to have acceptable tolerability for human use. Such solutions of CBZ have been proposed to be suitable for intravenous administration in treatment of convulsive (grand mal) status epilepticus (CSE). METHODS A series of five generalized tonic-clonic seizures (GTCS) in 30 min was induced by repeated transauricular electrical stimulation in mice. In this model of convulsive (grand mal) SE, the anticonvulsant potency of intravenous CBZ dissolved in aqueous dilutions of either HP beta CD or glycofurol was evaluated. RESULTS In both solutions, CBZ rapidly suppressed seizures after intravenous bolus injection. Potent anticonvulsant activity was obtained as early as 30 s after injection, and peak effects were observed at approximately 3 min. ED50 for blockade of GTCS throughout the 30-min period of repeated electrical stimulation was approximately 7 mg/kg, similar to the potency of DZP in this model. Whereas the HP beta CD/CBZ solutions were tolerated by the animals, with no pronounced behavioral or motor adverse effects, the glycofurol/CBZ solutions induced marked sedation and motor impairment, indicating interactions between drug and solvent. Determination of CBZ in plasma and brain demonstrated that the rapid onset of anticonvulsant action after intravenous bolus injection was related to rapid drug penetration into brain tissue. CONCLUSIONS An intravenous formulation of CBZ achieved through complexing with HP beta CD might be suitable for parenteral use in acute clinical conditions such as SE, particularly because CBZ has the advantage of being almost free of respiratory or cardiovascular adverse effects.
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Affiliation(s)
- W Löscher
- Department of Pharmacology, Toxicology and Pharmacy, School of Veterinary Medicine, Hannover, Germany
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Rajewski RA, Stella VJ. Pharmaceutical applications of cyclodextrins. 2. In vivo drug delivery. J Pharm Sci 1996; 85:1142-69. [PMID: 8923319 DOI: 10.1021/js960075u] [Citation(s) in RCA: 565] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The objective of this Review is to summarize and critique recent findings and applications of both unmodified and modified cyclodextrins for in vivo drug delivery. This review focuses on the use of cyclodextrins for parenteral, oral, ophthalmic, and nasal drug delivery. Other routes including dermal, rectal, and pulmonary delivery are also briefly addressed. This Review primarily focuses on newer findings concerning cyclodextrin derivatives which are likely to receive regulatory acceptance due to improved aqueous solubility and safety profiles as compared to the unmodified cyclodextrins. Many of the applications reviewed involve the use of hydroxypropyl-beta-cyclodextrins (HP-beta-CDs) and sulfobutylether-beta-cyclodextrins (SBE-beta-CDs) which show promise of greater safety while maintaining the ability to form inclusion complexes. The advantages and limitations of HP-beta-CD, SBE-beta-CD, and other cyclodextrins are addressed.
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Affiliation(s)
- R A Rajewski
- Higuchi Biosciences Center for Drug Delivery Research, Lawrence, KS, USA
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