Experiencia de cambio de marcas comerciales de lamotrigina en una paciente ambulatoria del Hospital Vilardebó / Experience of changing commercial brands of lamotrigine in an outpatient of the Vilardebó Hospital

Se desarrolló una experiencia en una pacientede cambio entre dos marcas comerciales de lamotrigina: Lamictal (referencia) y Epilepax (test). Esto fue motivado por notificaciones sobre sospecha de falta de eficacia de una de las citadas presentaciones farmacéuticas utilizada en el Hospital Vilardebó. Se realizó la comparación de las curvas salivales de lamotrigina versus tiempo para las dos marcas, determinándose parámetros clínicos, farmacocinéticos y de seguridad. La experiencia de cambio entre las dos marcas en la paciente no evidenció diferencias en ninguno de los parámetros mencionados.

An experience was developed in a patient of change between two commercial brands of lamotrigine: Lamictal (reference) and Epilepax (test). This was motivated by notifications on suspicion of lack of efficacy of one of the aforementioned pharmaceutical presentations used in the Vilardebó Hospital. The comparison of salivary curves of lamotrigine versus time for the two brands was made, determining clinical, pharmacokinetic and safety parameters. The experience of change between the two brands in the patient did not show any differences in any of the mentioned parameters.

Notas de farmacología: estudios de disolución de medicamentos del sistema nervioso central / Pharmacology notes: drug dissolution studies of the central nervous system

El propósito de los estudios in vitro es comparar las características de liberación del principio activo contenido en una forma farmacéutica sólida oral mediante la cantidad, o porcentaje de la dosis, disuelta en función del tiempo en condiciones controladas y validadas. Se realizó una comparación de disolución in vitro de flunitrazepam (Rohypnol®, Somnidual® e Inervon®) y de lamotrigina (Lamictal® y Epilepax®). Para los perfiles de disolución de flunitrazepam, una de las marcas comerciales tuvo un perfil de disolución muy diferente a las otras dos marcas. Para el caso de lamotriginano existió diferencia para aquellos pH que se consideran fundamentales para la disolución del comprimido en el tracto gastrointestinal. Los resultados obtenidos de los estudios in vitro son simplemente orientadores, permiten tan solo guiar la puesta en marcha del ensayo de bioequivalencia entre el test evaluado in vitro y la referencia utilizada en el mismo ensayo. No obstante, estos resultados pueden constituirse en un elemento de apoyo a la presunción de bioinequivalencia como causa de un evento adverso (ineficacia o toxicidad) detectado en los programas de farmacovigilancia actualmente en marcha.

Experiencia Uruguaya en Atención Farmacéutica activa en la comunidad / Uruguayan experience in community-wide active pharmaceutical care

Objetivo: realizar una actividad de difusión a la población sobre el uso racional de medicamentos, mediante la inserción de los estudiantes en el equipo de salud y analizar los datos farmacoterapéuticos obtenidos de esta actividad educativa. Métodos: en la vía pública se instaló una carpa de Atención Farmacéutica durante tres días donde participaron químicos farmacéuticos y médicos, quienes impartieron charlas sobre diferentes temas de salud preponderantes en la población uruguaya. Asimismo, los alumnos de Atención Farmacéutica, como parte de su formación práctica, participaron de esta actividad mediante la realización de entrevistas a los transeúntes, llenado de fichas de perfiles farmacoterapéuticos y de consumo de plantas medicinales, elaboradas para este fin, y la entrega de folletos informativos. A partir de las fichas farmacoterapéuticas se desarrolló un trabajo de investigación. Resultados: los alumnos del curso participaron de forma activa en el llenado de las fichas farmacoterapéuticas y mantuvieron una comunicación fluida con los asistentes a la carpa y con los profesionales de la salud. Se completaron 117 fichas farmacoterapéuticas (90 mujeres y 27 hombres). El 60 por ciento de los entrevistados consumía plantas medicinales. Sesenta personas recibían cuatro o más especialidades farmacéuticas. Las drogas antihipertensivas resultaron las más utilizadas. Veintitrés personas presentaban hipotiroidismo y dos personas de este grupo recibían litio para trastorno bipolar. Entre el grupo de mujeres: 18 tomaban ansiolíticos, 12 antidepresivos, 7 hipnóticos y 2 antisicóticos. Diecinueve personas manifestaron tener colesterol alto y 14 recibían medicación. Catorce presentaban artrosis y 10 estaban en tratamiento con analgésicos. Nueve personas presentaban gastritis, grupo este con un alto consumo de café y mate. Seis mujeres mayores de 50 años, declararon tener osteoporosis y solo tres recibían medicación a base de calcio y vitamina D. Conclusiones: la experiencia tuvo aceptación por el público y muestra una vez más la necesidad de la población de una educación sanitaria responsable(AU)

Objective: to conduct a health promotion activity for the population on the rational use of drugs, in which students participate with the rest of the health team and to analyze pharmacotherapeutic data collected in this educational activity. Methods: a pharmaceutical care tent was put up on a public area for three days where physicians and pharmacists participated, giving talks on various prevailing health issues that affect the Uruguayan population. Also, a number of pharmaceutical care students, as part of their practical training, participated in this activity by interviewing passers-by, filling out forms of pharmacotherapeutic profiles and of consumption of herbal medicines and giving people some information leaflets. A research study was carried out from the data collected in these pharmacotherapeutic forms. Results: the students actively participated in filling out the pharmacotherapeutic profiles and keeping fluent communication with the audience and with health professionals. One hundred and seventeen pharmacotherapeutic forms were completed (90 women and 27 men). Sixty percent of the interviewed people consumed herbal medicines. Sixty people received four or more medicines. Antihypertensive drugs were the most commonly used. Twenty three people had hypothyroidism and two people in this group were treated with lithium for bipolar disorder. In the female group 18 took anxiolytics, 12 antidepressants, 7 hypnotic drugs and 2 antipsychotic drugs. Nineteen people reported high cholesterol condition and 14 of them took medication. Fourteen had osteoarthritis and 10 were under painkiller treatment. Nine people had gastritis and this group showed high consumption rates of coffee and mate. Six women over 50 years old reported having osteoporosis and only 3 of them took calcium-based medication and vitamin D. Conclusions: the experience was well-accepted by the public and once again, the need for responsible health education of the population was demonstrated(AU)

Therapeutic carbamazepine (CBZ) and valproic acid (VPA) monitoring in children using saliva as a biologic fluid / Monitoramento terapêutico de carbamazepina e ácido valproico em saliva de crianças

OBJECTIVE: The aim of the study was to analyze retrospectively carbamazepine (CBZ) and valproic acid (VPA) salivary data collected from epileptic children during a 3-year period. METHODS: Saliva samples stimulated by citric acid were assayed by FPIA method. One hundred and three patients (aged 1-14 years) were in CBZ or VPA monotherapy or in CBZ-VPA combined therapy. RESULTS: VPA salivary levels were linearly related with daily dose, but a non-linear relationship was found for CBZ, in patients under monotherapy. VPA did not alter saliva CBZ concentration. Conversely, CBZ reduced VPA salivary levels. Non-responsive children displayed higher VPA concentrations. CBZ levels in uncontrolled patients showed non-significant difference in relation with controlled subjects even though their daily doses were higher. CONCLUSION: Citric acid stimulated saliva is reliable enough to perform therapeutic drug monitoring. Saliva drug levels in non-responsive patients would be explained according to the generalized efflux transporter overexpression hypothesis.

OBJETIVO: O objetivo deste estudo foi avaliar retrospectivamente por 3 anos a partir de dados salivares, as terapias com carbamacepina (CBZ) e ácido valproico (VPA) em pacientes pediátricos. MÉTODOS: Foram avaliadas amostras de saliva estimuladas com ácido cítrico por método FPIA em 103 pacientes (idades 1-14 anos) em monoterapia com CBZ ou VPA ou terapia combinada CBZ-VPA. RESULTADOS: Níveis salivares de VPA se relacionaram linearmente com a dose diária, e a relação não linear foi encontrada em pacientes com CBZ. VPA não alterou as concentrações salivares de CBZ, porém a CBZ reduziu os níveis salivares de VPA em pacientes com terapia combinada. Pacientes refratários apresentaram altas concentrações de VPA. Os níveis de CBZ em pacientes não controlados não apresentaram diferenças significativas em relação aos pacientes controlados quando as doses diárias foram mais elevadas. CONCLUSÃO: Saliva estimulada com ácido cítrico é adequada para o monitoramento terapêutico. Níveis da droga na saliva em pacientes que não responderam ao tratamento pode ser explicado pelo transporte de efluxo generalizado.

Actual bioavailability of divalproex sodium extended-release tablets and its clinical implications

Divalproex sodium extended-release dosage form (divalproex-ER) has been promoted as innovative formulation for the treatment of epilepsy and manic disorders, and for migraine headache prevention, with the advantage of being dosing once a day. Due to a significant decreasing in the peak-trough fluctuation of plasma valproic acid levels, in comparison with the twice-daily dosing of conventional delayed-release formulations (divalproex-DR), concentration-dependent side effects would be prevented. However the main constraint for divalproex-ER usage is the need to be administered in a higher daily dose, because of its lower bioavailability, in order to prevent eventual breakthrough seizures when patients are switched from the twice-daily divalproex DR regimen. Taking into account free plasma drug levels, divalproex ER/DR relative bioavailability could be assessed as low as 75 percent in fasting condition. In order to overcome the need of increase divalproex-ER daily dose, maintenance of the twice-daily regimen is suggested. Divalproex-ER administered every 12 hours not only increases steady state trough concentration to a higher value in comparison with divalproex-DR, avoiding inefficacy of the treatment, but also achieves the safest manner to treat patients with valproic acid because of reaching practically a plateau profile of drug levels.

Divalproato de sodio de liberación prolongada (divalproex-ER) es un producto innovador que ha sido promovido tanto para el tratamiento de la epilepsia y de los desórdenes maníacos como también para la prevención de la migraña, con la ventaja de poder administrarse una sola vez al día. Dado que la fluctuación de niveles plasmáticos de ácido valproico resulta menor que la originada por la administración dos veces al día del producto convencional de liberación retardada (divalproex-DR), se estarían previniendo los efectos secundarios dependientes de la concentración del fármaco. Sin embargo, y considerando la menor biodisponibilidad del producto, el uso de divalproex-ER tiene el principal inconveniente de necesitar una mayor dosis diaria a los efectos de evitar una eventual reaparición de crisis cuando los pacientes cambian de tratamiento desde divalproex-DR. Teniendo en cuenta los niveles plasmáticos libres del fármaco, la biodisponibilidad relativa divalproex ER/DR podría afirmarse que sea aún más baja, tanto como 75 por ciento cuando los estudios son realizados en ayunas. A los efectos de no incrementar la dosis diaria de divalproex-ER se sugiere mantener un régimen de administración cada 12 horas. La administración de divalproex-ER dos veces al día no sólo incrementa las concentraciones de valle, respecto a divalproex-DR, sino que logra un perfil de niveles de ácido valproico prácticamente de meseta, lográndose así un tratamiento eficaz y con la mayor seguridad para los pacientes.

Systemic and presystemic conversion of carbamazepine to carbamazepine-10, 11-epoxide during long term treatment / Conversão da carbamazepina para 10, 11-epóxido-carbamazepina no tratamento prolongado

INTRODUCTION: Carbamazepine (CBZ) undergoes biotransformation, being CYP3A4 the major cytocrome P450 (CYP) enzyme catalyzing the carbamazepine-10,11-epoxide (EPOX) formation, which is quantitatively the most important pathway in CBZ metabolism. There is evidence of dose-dependent elimination of this drug due to its autoinduction capacity. Moreover, published data showed an incomplete bioavailability of CBZ since its absorption increases when grapefruit juice was administered. Both CYP3A4 and MRP2 (located in the enterocyte) are autoinduced during long term use of CBZ. As the other enzymes involved in CBZ metabolism are negligible in the gut, presystemic biotransformation through CYP3A4 could be responsible for the bioavailability of the drug as well as EPOX formation. OBJECTIVE: The purpose of our study was to assess the importance of presystemic formation of EPOX during the autoinduction of CBZ versus the daily administered dose. PATIENTS AND METHODS: 40 adults (average age: 28 years) and 29 children (average age: 9 years) receiving CBZ as monotherapy were included in the study. CBZ and EPOX plasma concentrations were analyzed by a previous validated HPLC method. RESULTS AND CONCLUSION: The results obtained confirmed the metabolic induction after chronic administration and provided new elements to suggest a strong contribution of dose-dependent bioavailability in the non linear kinetics of CBZ.