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No. of bitstreams: 2 Dissertação - Beatriz Pacheco de Souza - 2018.pdf: 1691107 bytes, checksum: d58fa98c4c4c1e53256c98918c5d381f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-05-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Epilepsy is one of the most common problems in the neurological clinic, affecting up to 1% of the world population, moreover, individuals with epilepsy have a higher mortality than the general population. Thus, the interest in investigating cardiac changes in patients with epilepsy has been increasing, and some studies have associated the use of antiepileptic drugs (AEDs) with cardiovascular disorders. In this context, there are hypotheses that patients using specific AEDs, sodium channel blockers, have an increased risk of cardiovascular disease (CVD). In our study, we sought to evaluate cardiovascular responses in epileptic rats submitted to chronic administration of carbamazepine (CBZ) or lamotrigine (LTG). Baseline cardiovascular parameters [Systolic blood pressure (SBP); Diastolic blood pressure (DBP); Mean arterial pressure (MAP) and heart rate (HR)] were recorded through cannulation of the femoral artery and electrode implant after sixty days of treatment with AED or vehicle [(150mg / kg (vo)]. The animals were submitted to a baroreflex test with bolus administration of phenylephrine (PHE - 5μg) and sodium nitroprusside (NPS - 10μg) via cannulation of the femoral vein and later submitted to a challenge with isoproterenol. Through the recording of baseline cardiovascular parameters, we also analyzed the heart rate variability (HRV) and the number of extrasystoles. After all procedures in vivo, samples of the heart were retained for histological analyzes of cardiac tissue. The division of the groups was performed in controls without epilepsy (CNT), epileptics (EP), epileptics treated with CBZ (CBZ) and epileptics treated with LTG (LTG). In our results the epileptic rats presented all the baseline cardiovascular parameters higher than the parameters of animals without epilepsy. CBZ treatment reduced resting HR, SBP and MAP compared to untreated epileptic animals. Treatment with LTG also reduced resting HR compared to the EP group. We also observed that the EP group had a greater cross-sectional area (CSA) of cardiomyocytes when compared to the other groups and an increased accumulation of perivascular collagen in comparison to CNT and CBZ groups. In this way, we can suggest that chronic use of AEDs may influence cardiovascular responses and cardiac microstructure. / A epilepsia é um dos problemas mais comuns na clínica neurológica, chegando a afetar até 1% da população mundial, além disso, indivíduos com epilepsia possuem uma mortalidade maior que a população geral. Com isso, o interesse em pesquisar alterações cardíacas em pacientes com epilepsia vem sendo crescente, e alguns estudos têm associado o uso de drogas antiepilépticas (DAEs) com distúrbios cardiovasculares. Neste contexto, há hipóteses de que pacientes em uso de DAEs específicas, bloqueadoras de canais para sódio, possuem aumento do risco de doença cardiovascular (DCV). Em nosso estudo, buscamos avaliar as respostas cardiovasculares em ratos epilépticos submetidos à administração crônica de carbamazepina (CBZ) ou lamotrigina (LTG). A divisão dos grupos foi dada em controles sem epilepsia (CNT), epilépticos (EP), epilépticos tratados com CBZ (CBZ) e epilépticos tratados com LTG (LTG). Os parâmetros cardiovasculares basais [Pressão arterial sistólica (PAS); Pressão arterial diastólica (PAD); Pressão arterial média (PAM) e Frequência cardíaca (FC)] foram registrados através de uma canulação da artéria femoral e do implante de eletrodos após sessenta dias de tratamento com DAEs ou veículo [(150mg/kg (v.o.)]. Durante o registro os animais foram submetidos a um teste de barorreflexo com administração em bolus de fenilefrina (PHE - 5μg) e nitroprussiato de sódio (NPS - 10μg) via canulação da veia femoral e posteriormente submetidos a um desafio com isoproterenol. Através do registro dos parâmetros cardiovasculares basais, também foi analisada a variabilidade da frequência cardíaca (VFC) e o número de extrassístoles. Após todos os procedimentos in vivo amostras do coração foram retiradas para análises histológicas do tecido cardíaco. Em nossos resultados os ratos epilépticos apresentaram todos os parâmetros cardiovasculares basais maiores que os parâmetros de animais sem epilepsia. O tratamento com CBZ reduziu a FC de repouso, PAS e PAM em comparação com animais epilépticos sem tratamento. O tratamento com LTG também reduziu a FC de repouso em comparação com o grupo EP. Também observamos que o grupo EP possui área de secção transversa (AST) de cardiomiócitos maior quando comparado aos demais grupos e maior acúmulo de colágeno perivascular em comparação aos grupos CNT e CBZ. Desta forma, podemos sugerir que o uso crônico de DAEs pode influenciar em respostas cardiovasculares e na microestrutura cardíaca.

Abstract Interruption of cerebral blood flow during hypothermic circulatory arrest (HCA) predisposes neurons to glutamate excitotoxicity. Reperfusion is followed by leukocyte infiltration, which results in an inflammatory reaction in the brain tissue. In the first study, the presynaptic glutamate release inhibitor lamotrigine (L) and the leukocyte-depleting filter (LF) were studied to determine if their combination could mitigate brain injury after HCA (I). The aim of the second study was to evaluate the possible neuroprotective effect of a 14-hour period of mild (32°C) hypothermia after HCA (II). Recent experimental research has demonstrated the neuroprotective properties of erythropoietin (EPO) and fructose-1,6-bisphosphate (FDP), whose effects during and after HCA were evaluated in the third and the fourth studies (III, IV). A chronic porcine model was used. The animals were randomly assigned to the study groups as follows: 8 animals in the L+LF group, 8 in the L group, and 8 in the control group (I); 10 animals in the hypothermia group and 10 in the normothermia group (II); 10 animals in the EPO group and 10 in the control group (III), and 12 animals in the FDP group and 12 in the control group (IV). Monitoring of hemodynamics, metabolism, temperature, electroencephalogram (EEG), brain microdialysis, intracranial pressure (II-IV), and brain tissue oxygen (II-IV) was carried out. A daily behavioral assessment was performed until death or until elective sacrifice on the seventh postoperative day, after which the brain was prepared for a histopathologic examination. The results of these studies indicate that lamotrigine has a neuroprotective effect during HCA. This is observed in terms of EEG burst recovery, behavioral and histopathologic outcome, and brain microdialytic findings. The combined use of lamotrigine and leukocyte filtration may further improve survival. A 14-hour period of mild hypothermia after HCA is associated with a poor outcome. However, it may preserve its efficacy when used for no longer than 4 hours. Administration of EPO before HCA proved ineffective in reducing mortality or brain histopathologic injury. Findings from brain microdialysis, brain tissue oxygen tension, and neuronal apoptosis, however, suggest that the drug has neuroprotective properties. Administration of FDP before and after HCA is associated with better survival, behavioral outcome, and brain histopathologic scores. The metabolic and brain microdialytic findings also suggest that this drug has supportive effects on myocardial and brain metabolism.

Abstract Ischaemic cerebral injury follows a well attested sequence of events including three phases, i.e. depolarization, biochemical cascade and reperfusion injury. Glutamate excitotoxicity plays an important role in the development of ischaemic brain injury following prolonged hypothermic circulatory arrest (HCA), and leukocyte infiltration and a cytokine-mediated inflammatory reaction are known to play a pivotal role in the reperfusion phase. The aim of this series of experimental studies was to develop biochemical and reperfusion-related strategies to improve brain protection. We tested the hypotheses that the Na+ channel blocker lamotrigine (I) or the N-Methyl-D-Aspartate-receptor antagonist memantine (III) could improve the cerebral outcome after HCA and studied whether a leukocyte-depletion filter (L-DF; LeukoGuard LG6®, Pall Biomedical, Portsmouth, U.K) could mitigate brain injury (II). The aim of the fourth study was to find out whether lamotrigine combined with the leukocyte-depleting filter can potentiate cerebral protection (IV). A chronic porcine model was used, in which haemodynamic, electrophysiological, metabolic and temperature monitoring were performed for four hours after the instigation of rewarming and S-100β measured up to 20 hours. Cytokines were measured, microdialysis was performed, and daily behavioural assessments were made until death or elective sacrifice on the seventh postoperative day, upon which a histopathological analysis of the brain was carried out. The rate of EEG burst recovery was higher in the lamotrigine-treated animals, the median being 40% of the baseline compared with 17% in the placebo group at 4 hours after the start of rewarming (p = 0.02) and 80% compared with 20% at 4 hours (p = 0.01). Complete behavioural recovery was seen in 5/8 of cases (63%) after lamotrigine administration, compared with 1/8 (13%) in the placebo group (p = 0.02). The median behavioural score among the animals that survived for 7 days was higher in the lamotrigine group (8) than in the controls (7) (p = 0.02). Mortality was 2/10 in the L-DF group and 5/10 in the controls, the median behavioural score on day 7 being higher in the L-DF group (8.5 vs. 3.5 p = 0.04). The median of the total histopathological score was 6.5 in the L-DF group and 15.5 in the control group (p = 0.005). In the memantine group 5/10 animals survived seven days, as compared with 9/10 in the placebo group, and the median behavioural score on day 7 was 3.5 compared with 7.5 in the placebo group (p = 0.39). The median of the total histopathological score was 16 in the memantine group and 14 in the placebo group (p = 0.25). In the LD-F + lamotrigine group 7/8 animals survived for seven days, as compared with 4/8 in the lamotrigine only group and 3/8 among the controls. EEG burst recovery 7 hours after the start of rewarming was highest in the LDF + lamotrigine group, the median being 94% (p = 0.024 vs. controls), compared with 81% in the lamotrigine group and 64% in the control group. The median behavioural score on day 7 was 9 in the LD-F + lamotrigine group (p = 0.004 vs. controls), 4 in the lamotrigine group and 0 in the control group, while the median of total histopathological score was 14 (p = 0.046 vs controls), 14.5 (p = 0.062 vs. controls) and 21, respectively. The control group had the highest intracerebral lactate, glutamate and glycerol levels after HCA. In conclusion, the results indicate that the NA+ channel blocker lamotrigine improves the neurological outcome after a prolonged period of HCA but that the NMDA receptor antagonist memantine does not have this property in the present setting. The leukocyte-depleting filter mitigates brain injury after a prolonged period of HCA, and lamotrigine can potentiate this effect.

No / Rationale Phencyclidine (PCP), a glutamate/N-methyl-d-aspartate (NMDA) receptor antagonist, has been shown to induce a range of symptoms similar to those of patients with schizophrenia, while d-amphetamine induces predominantly positive symptoms. Previous studies in our laboratory have shown that PCP can selectively impair the performance of an operant reversal-learning task in the rat. Furthermore, we found that the novel antipsychotic ziprasidone, but not the classical antipsychotic haloperidol, could prevent the PCP-induced deficit. Objectives The aim of the present study was to validate the model further using the atypical antipsychotic clozapine and then to investigate the effects of lamotrigine, a broad-spectrum anticonvulsant that is known to reduce glutamate release in vitro and is able to prevent ketamine-induced psychotic symptoms in healthy human volunteers. A further aim was to compare effects of PCP and d-amphetamine in the test and investigate the effects of the typical antipsychotic haloperidol against the latter. Methods Female hooded-Lister rats were food deprived and trained to respond for food in a reversal-learning paradigm. Results PCP at 1.5 mg/kg and 2.0 mg/kg and d-amphetamine at 0.5 mg/kg significantly and selectively impaired performance in the reversal phase of the task. The cognitive deficit induced by 1.5 mg/kg PCP was attenuated by prior administration of lamotrigine (20 mg/kg and 30 mg/kg) or clozapine (5 mg/kg), but not haloperidol (0.05 mg/kg). In direct contrast, haloperidol (0.05 mg/kg), but not lamotrigine (25 mg/kg) or clozapine (5 mg/kg), prevented a similar cognitive impairment produced by d-amphetamine (0.5 mg/kg). Conclusions Our findings provide further data to support the use of PCP-induced disruption of reversal learning in rodents to investigate novel antipsychotic drugs. The results also provide evidence for different mechanisms of PCP and d-amphetamine-induced disruption of performance in the test, and their different sensitivities to typical and atypical antipsychotic drugs.

A associação de ácido valpróico/ divalproato de sódio e lamotrigina tem se mostrado eficaz no tratamento das epilepsias refratárias, tendo como limitador ao seu uso os efeitos adversos, principalmente numa população de crianças e adolescentes, onde esses efeitos são maximizados. Este estudo clínico tem como objetivo avaliar as propriedades farmacológicas da associação valproato/divalproato de sódio e lamotrigina em uma população pediátrica refratária ao tratamento medicamentoso usando método de introdução e escalonamento mais lento do que o preconizado, com seguimento prolongado. Para tal, foi estudado um grupo de 51 crianças e adolescentes com epilepsia de difícil controle, com idades de 4 a 16 anos (mediana de 8 anos), sendo 27 (52,9%) meninas. Dezesseis (31,4%) crianças apresentavam epilepsia generalizada; 35 (68,6%), epilepsia parcial. A associação valproato/divalproato de sódio e lamotrigina foi eficaz no primeiro ano de acompanhamento para 39 (76,5 %) pacientes. No segundo ano de tratamento, esta associação foi eficaz para 36 (70,6%) pacientes. Houve melhora dos drop attacks em 22 pacientes (88,5%), mas não houve especificidade em relação à síndrome ou crise epiléptica. Efeitos adversos observados foram rash, em quatro (7,8%) pacientes, com descontinuidade do tratamento, e tremores sutis em seis (11,7%), resolvidos com a diminuição da dose da lamotrigina. A descontinuidade ocorreu em 12 (23,5%) pacientes, sendo que a maior razão foi o rash cutâneo, seguido pela perda da eficácia ao tratamento, em oito (15,7%) pacientes. Concluímos que, com a proposta de introdução mais lenta da lamotrigina, os efeitos adversos são minimizados (principalmente os referentes ao sistema nervoso central), assim como há melhora das crises debilitantes, que comprometem a qualidade de vida desses pacientes, tendo como resultado uma maior adesão ao esquema terapêutico. Além disso, pontuamos que a eficácia terapêutica se mantém com doses mais baixas de lamotrigina, mesmo após o primeiro ano de tratamento / The association lamotrigine and sodium valproate/divalproex sodium has been shown to be effective in the treatment of refractory epilepsy, having as a limiting factor for its use, adverse effects, especially in a population of children and adolescents where these effects are maximized. This clinical study aims to evaluate the pharmacological properties of this association in a pediatric population refractory to medical treatment using a method of introduction and titration slower than the usually recommended, with extended follow-up. For this purpose, we studied a group of 51 children and adolescents, with refractory epilepsy, ranging from 4 to 16 years old (median 8 years), with 27 (52.9%) girls. Sixteen (31.4%) children presented generalized and 35 (69.6%) focal epilepsy. The association sodium valproate/ divalproex sodium and lamotrigine was effective in the first year of followup in 39 (76.5%) patients. In the second year of treatment this combination was effective in 36 (70.6%) patients. An improvement of drop attacks was observed in 22 (88.5%) patients, but there was no specificity as to the epileptic syndrome or seizure type. Adverse effects were rash, leading to discontinuation in four (7.8%), and subtle tremors, that resolved with reduction of the dose of lamotrigine in six (11.7%) patients. In twelve (23.5%) patients treatment was withdrawn, because of rash (7.8%) and loss of efficacy, in eight (15.7%) patients. We concluded that with the proposed slower introduction of lamotrigine, adverse effects are minimized, especially in the central nervous system, as well as better obtained control of debilitating seizures, affecting quality of life, and resulting in better adherence to the therapeutic scheme. Furthermore, we point out that the therapeutic efficacy is maintained with lower doses of lamotrigine, even after the first year of treatment

A associação de ácido valpróico/ divalproato de sódio e lamotrigina tem se mostrado eficaz no tratamento das epilepsias refratárias, tendo como limitador ao seu uso os efeitos adversos, principalmente numa população de crianças e adolescentes, onde esses efeitos são maximizados. Este estudo clínico tem como objetivo avaliar as propriedades farmacológicas da associação valproato/divalproato de sódio e lamotrigina em uma população pediátrica refratária ao tratamento medicamentoso usando método de introdução e escalonamento mais lento do que o preconizado, com seguimento prolongado. Para tal, foi estudado um grupo de 51 crianças e adolescentes com epilepsia de difícil controle, com idades de 4 a 16 anos (mediana de 8 anos), sendo 27 (52,9%) meninas. Dezesseis (31,4%) crianças apresentavam epilepsia generalizada; 35 (68,6%), epilepsia parcial. A associação valproato/divalproato de sódio e lamotrigina foi eficaz no primeiro ano de acompanhamento para 39 (76,5 %) pacientes. No segundo ano de tratamento, esta associação foi eficaz para 36 (70,6%) pacientes. Houve melhora dos drop attacks em 22 pacientes (88,5%), mas não houve especificidade em relação à síndrome ou crise epiléptica. Efeitos adversos observados foram rash, em quatro (7,8%) pacientes, com descontinuidade do tratamento, e tremores sutis em seis (11,7%), resolvidos com a diminuição da dose da lamotrigina. A descontinuidade ocorreu em 12 (23,5%) pacientes, sendo que a maior razão foi o rash cutâneo, seguido pela perda da eficácia ao tratamento, em oito (15,7%) pacientes. Concluímos que, com a proposta de introdução mais lenta da lamotrigina, os efeitos adversos são minimizados (principalmente os referentes ao sistema nervoso central), assim como há melhora das crises debilitantes, que comprometem a qualidade de vida desses pacientes, tendo como resultado uma maior adesão ao esquema terapêutico. Além disso, pontuamos que a eficácia terapêutica se mantém com doses mais baixas de lamotrigina, mesmo após o primeiro ano de tratamento / The association lamotrigine and sodium valproate/divalproex sodium has been shown to be effective in the treatment of refractory epilepsy, having as a limiting factor for its use, adverse effects, especially in a population of children and adolescents where these effects are maximized. This clinical study aims to evaluate the pharmacological properties of this association in a pediatric population refractory to medical treatment using a method of introduction and titration slower than the usually recommended, with extended follow-up. For this purpose, we studied a group of 51 children and adolescents, with refractory epilepsy, ranging from 4 to 16 years old (median 8 years), with 27 (52.9%) girls. Sixteen (31.4%) children presented generalized and 35 (69.6%) focal epilepsy. The association sodium valproate/ divalproex sodium and lamotrigine was effective in the first year of followup in 39 (76.5%) patients. In the second year of treatment this combination was effective in 36 (70.6%) patients. An improvement of drop attacks was observed in 22 (88.5%) patients, but there was no specificity as to the epileptic syndrome or seizure type. Adverse effects were rash, leading to discontinuation in four (7.8%), and subtle tremors, that resolved with reduction of the dose of lamotrigine in six (11.7%) patients. In twelve (23.5%) patients treatment was withdrawn, because of rash (7.8%) and loss of efficacy, in eight (15.7%) patients. We concluded that with the proposed slower introduction of lamotrigine, adverse effects are minimized, especially in the central nervous system, as well as better obtained control of debilitating seizures, affecting quality of life, and resulting in better adherence to the therapeutic scheme. Furthermore, we point out that the therapeutic efficacy is maintained with lower doses of lamotrigine, even after the first year of treatment

The studies on cocrystals and salts presented in the the chapters clearly bring out the influence of intermolecular interactions as the main evaluators of the cocrystal-salt regime. The observations made in Chapter 2 indicate that in case if the cocrystal formation is through hydrogen bonds the location of the proton decides the nature of the complex in the energy landscape. The observation that the coformer controls the topology of intermolecular space as demonstrated in Chapter 3 provides insights into the importance of directionality rather than strength of intermolecular interactions. Indeed halogen bonding in cocrystals gain importance in this context.

Posttraumatic stress disorder (PTSD) is classified as an anxiety disorder and the characteristic symptoms (re-experiencing, avoidance as well as numbing of general responsiveness and hyperarousal) of this disorder develop in response to a traumatic event. The disorder is characterised by hypothalamic-pituitary-adrenal (HPA) axis abnormalities linked with changes in cortisol moreover, the hippocampus and cortex also play a role in the neurobiology. With regard to the neurochemistry of this disorder it is known that gamma amino butyric acid (GABA) is involved however, the precise role of GABA in PTSD and how stress changes GABA concentrations in the brain are still not fully understood. Another aspect regarding PTSD that has not been clearly defined is the treatment of PTSD. Classic anxiolytics such as diazepam is expected to relieve the anxiety linked with PTSD. Studies with this group of drugs have however not produced the concrete evidence needed to establish it as a treatment of choice for PTSD and subsequently other classes of drugs have been investigated as possible treatment options for PTSD. Among these is lamotrigine, which in a clinical study was found to be effective in alleviating symptoms of PTSD. Moreover, a possible pharmacokinetic-pharmacodynamic relationship for each of these drugs has also not been elucidated. In order to elude on some of these uncertainties, an animal model of PTSD, time dependent sensitisation (TDS), was used. GABA levels in the rat hippocampus and frontal cortex were determined at two different time intervals following the TDS procedure (1 day and 7 days post re-stress). High performance liquid chromatography (HPLC) with electrochemical (EC) detection was used to determine gamma amino butyric acid (GABA) concentrations. To investigate the possible anxiolytic effects of diazepam and lamotrigine in this model, as well as a possible pharmacokinetic-pharmacodynamic relationship for each drug, pharmacokinetic profiles for both drugs were established in order to find the times of peak and trough levels of each drug. Blood samples were collected at different time intervals after drug administration either from the tail vein of rats (lamotrigine) or directly from the heart (diazepam). Subsequently, drug concentrations at each time interval were determined by means of HPLC with ultraviolet (UV) detection. The behaviour of rats was analysed using the elevated plus-maze (EPM) at peak or trough concentrations of the drugs and this was performed after either acute administration of the drug, or after a 14 day chronic treatment regime. GABA levels in the hippocampus were not found to change statistically significantly in response to stress at either 1 day or 7 days post re-stress. In the frontal cortex, however, GABA levels increased in response to stress at 1 day post re-stress, with a statistically insignificant, but strong trend towards an increase, at 7 days post re-stress. With regard to the pharmacokinetic profiles, the peak concentration of diazepam was found to occur at 60 minutes, with lamotrigine's peak at 120 minutes. The behavioural studies indicated that acute treatment with diazepam 3 mg/kg resulted in a statistically significant increase in both ratio open arm entries and ratio time spent in the open arms at peak level of the drug. After acute treatment with diazepam 3 mg/kg a statistically significant decrease in ratio time spent in open arms was also found when the ratio time spent in open arms at peak level of the drug and the ratio time spent in open arms at trough level of the drug was compared. In response to chronic treatment with diazepam 3 mg/kg for 14 days, test animals exhibited an increase in the ratio open arm entries at trough level of the drug, with a statistically insignificant yet definite trend towards an increase at peak level. Acute treatment with lamotrigine 10 mg/kg resulted in no statistically significant change in EPM parameters. In response to chronic treatment, however, a statistically significant increase was found in ratio time spent in open arms at peak level of the drug, with a statistically insignificant trend towards an increase at trough level. From the results of this study, we may therefore conclude that GABA-levels in the brain are definitely affected, but in different ways, following TDS-stress. A pharmacokinetic-pharmacodynamic relationship between the drugs' levels and aversive behaviour could also be established. Furthermore it appears that more sustained anxiolytic effects are evident following chronic treatment with both drugs than with acute administration of these drugs. / Thesis (M.Sc. (Pharmacology))--North-West University, Potchefstroom Campus, 2006

A lamotrigina é um fármaco relativamente novo que tem se mostrado útil no tratamento de diferentes crises epilépticas. Este fármaco encontra-se no mercado na forma de comprimidos e, apesar de seu amplo uso na terapêutica, não há descrição de métodos analíticos em códigos oficiais para o controle de qualidade da lamotrigina em sua forma farmacêutica. Estudos de estabilidade não foram encontrados na literatura científica, apenas dados fornecidos pela indústria. No FDA (2006) estão descritas as condições para o teste de dissolução dos comprimidos de lamotrigina, mas não há relatos sobre a forma de quantificação dos mesmos. Desta forma, o presente trabalho teve como objetivos o desenvolvimento e validação de métodos analíticos qualitativos e quantitativos, realização de estudo preliminar de estabilidade e o desenvolvimento e validação de método de dissolução para o controle de qualidade da lamotrigina em comprimidos.A caracterização da substância química de referência foi realizada através de calorimetria diferencial exploratória (DSC) e espectrofotometria na região do infravermelho (IV). A cromatografia em camada delgada (CCD), espectrofotometria de absorção no ultravioleta (UV) e cromatografia líquida de alta eficiência (CLAE) foram utilizadas para identificação da lamotrigina em comprimidos. Para a quantificação dos comprimidos, foram utilizadas a espectrofotometria de absorção no ultravioleta (UV) e cromatografia líquida de alta eficiência (CLAE). O estudo preliminar de estabilidade térmica foi realizado submetendo-se as amostras ao calor seco de 80ºC. A fotoestabilidade foi avaliada em soluções de lamotrigina armazenadas em câmara de luz a 254 nm por um período de até quinze dias, demonstrando que o fármaco é sensível à luz. As amostras também foram submetidas à hidrólise ácida por um período de 54 horas, observando-se decaimento no teor do fármaco. Foi desenvolvido e validado um método de dissolução simples e rápido para o controle de qualidade dos comprimidos de lamotrigina. / Lamotrigine is a relative new antiepileptic drug that seems useful in the treatment of different seizures. Lamotrigine can be found in the market in tablets. Despite being used in therapeutics, methods for quality control of lamotrigine in tablets are not available in the official codes. Stability studies were just informed by the producer. FDA (2006) described the conditions of dissolution test to lamotrigine in tablets, but there is nothing about the quantification method. In this way, the aim of this work was the development and validation of analytical methods, preliminary study of stability and the development and validation of a dissolution method to quality control of lamotrigine in tablets. The characterization of the reference standard was carried out by differential scanning calorimetry (DSC) and infrared spectroscopy (IR). Thin-layer chromatography (CCD), ultraviolet spectroscopy (UV) and high performance liquid chromatography (HPLC) was performed to lamotrigine qualitative analysis. UV and HPLC were performed to lamotrigine quantitative analysis. The sample solutions were submitted under UV-light at 254 nm during 15 days, showing degradation and decrease in the labeled amount. Thermal degradation was carried by dry heat at 80°C in solid powder. The solution samples was also submitted to acid condition with HCL 1 M during 54 hours. Rapid and simple dissolution method to routine quality control of lamotrigine was developed and validated.

Thesis (M.Sc. (Pharmacology))--North-West University, Potchefstroom Campus, 2006.