Eficácia e segurança da Fampridina comparada com placebo no tratamento de disfunções motoras em adultos portadores de esclerose múltipla: revisão rápida de evidências / Effectiveness and safety of Fampridine compared with placebo in the treatment of motor dysfunctions in adults with multiple sclerosis: quick evidence review

Tecnologia: Fampridina Indicação: Tratamento de disfunções motoras em pacientes portado-res de esclerose múltipla. Pergunta: A Fampridina é eficaz e segurança para o tratamento de disfunções motoras em adultos portadores de esclerose múltipla comparada ao placebo? Méto-dos: Levantamento bibliográfico foi realizado na base de dados PUBMED, seguindo estratégias de buscas predefinidas. Foi feita avaliação da qualidade metodológica das revisões sistemáticas com a ferramenta AMSTAR-2 (Assessing the Methodological Quality of Systematic Reviews Version 2). Resultados: Foram selecionados três estudos que atenderam aos critérios de inclu-são. Conclusão: A fampridina foi eficaz e segura para tratar disfunções motoras em dosagens específicas. Conforme os resultados dos estudos analisados, a fampridina pode melhora de modo significativo e contínuo a capacidade de deambular dos portadores EM. Além disso, pode ser eficaz para tratar habilidades manuais e cognitiva

Technology: Fampridine. Indication: Treatment of motor disorders in patients with multiple sclerosis. Question: Is Fampridine effective and safe for the treatment of multiple sclerosis in adults with functional limitations compared to placebo? Methods: A bibliographic survey was carried out in the PUBMED database, following predefined search strategies. The methodological quality of systematic reviews was evaluated using the Assessing the Methodological Quality of Systematic Reviews Version 2 tool. Results: Three studies that met the inclusion criteria were selected. Conclusion: Fampridine was effective and safe to treat motor disorders at specific dosages. According to the results of the analyzed studies, fampridine can significantly and continuously improve the ability to walk in MS patients. Also, it can be effective for treating manual and cognitive skills

Informe de evaluación científica basada en la evidencia disponible: esclerosis múltiple / Scientific evaluation report based on available evidence: multiple sclerosis

INTRODUCCIÓN: La Esclerosis Múltiple (EM) suele presentarse en cerca del 80% de los casos a través de episodios recurrentes y remitentes, los cuales con el tiempo podrán desarrollar a una forma progresiva y persistente. Un 10 a 15% de los casos, evidencia un cuadro sin remisiones desde su inicio. Durante el año 2010, se incorporó bajo modalidad Garantía Explícita en Salud la Esclerosis Múltiple Remitente Recurrente (EMRR), garantizando en su tratamiento fármacos inmunomoduladores de primera línea, Interferones intramusculares, subcutáneos y el Acetato de Glatiramer. Además, cuentan con cobertura a través de la Ley Ricarte Soto desde el año 2015 aquellos pacientes refractarios a la terapia habitual. TECNOLOGÍAS SANITARIAS ANALIZADAS: Alemtuzumab, Ocrelizumab, Fampridina, Teriflunomida, Dimetilfumarato. EFICACIA DE LOS TRATAMIENTOS: Se extrajo la evidencia de 2 revisiones sistemáticas que reportan 3 Ensayos Controlados Aleatorizados (ECA) para teriflunomida y dimetilfumarato. Adicionalmente, se incluyó información de 1 y 5 ECAs para el tratamiento de alemtuzumab y ocrelizumab, respectivamente. Teriflunomida logra un mayor número de pacientes con ausencia de brotes a los 12 meses. En cuanto a la progresión de la discapacidad asociada a la enfermedad, teriflunomida probablemente no es mejor que placebo para disminuir el número de pacientes libres de progresión de la discapacidad a 2 años. Alemtuzumab probablemente logra un menor número de pacientes con brotes a los 2 años, en comparación a Interferón B, mientras que los pacientes que reciben dimetilfumarato tienen una menor probabilidad de tener brotes que los pacientes tratados con placebo. Ocrelizumab para la Esclerosis Múltiple Primaria Progresiva (EMPP), se compara contra placebo y no se encuentran efectos relevantes en la mayor parte de outcomes (pacientes con confirmación de progresión, SF-36), salvo en indicadores específicos como el número de lesiones activas en T2 ó el volumen cerebral. Para pacientes con EMRR al compararse con Interferón beta-1, se evidencia una reducción de la progresión confirmada a la semana 12, 24 y 96, y reduce la tasa anualizada de brotes a la semana 96. Finalmente, en pacientes con EMRR al comparar ocrelizumab versus placebo, éste podría reducir el número de pacientes con brotes a la semana 24. EVALUACIÓN ECONÓMICA: En cuanto a la discordancia de los estudios revisados se logra establecer que dependiendo de la perspectiva tomada en cuenta para el dimetilfumarato, se establece la efectividad o no del tratamiento, dependiendo ésto también de los tratamientos que se les compare. Donde sí existe consenso es que comparando el dimetilfumarato con acetato de glatiramer, el primero es costoefectivo. En cuanto a ocrelizumab, ambas investigaciones encontradas, desde la perspectiva del pagador, consideran que este tratamiento es costo-efectivo. Por último, teriflunomida fue costoefectivo para una investigación realizada en Finlandia desde la perspectiva del pagador. En cuanto a las recomendaciones de agencias, se aprecia que: alemtuzumab y dimetilfumarato tienden a ser recomendados, no así teriflunomide. Ocrelizumab al momento se encuentra en análisis por las agencias. En cuanto al análisis presupuestal, se encontró que los costos de los mismos para la esclerosis múltiple remitente recurrente, en 1ª línea, serían de un nivel muy alto en relación al fondo disponible. En cuando a la esclerosis múltiple primaria progresiva, el impacto de ocrelizumab para el año 2018 es de MM$4.440. Además, se realizó una comparación de cuál sería el impacto diferencial en esclerosis múltiple remitente recurrente en 2ª línea, en comparación por lo ya cubierto por la ley, de incluir Ocrelizumab o Alemtuzumab. CONCLUSIÓN: Para dar cumplimiento al artículo 28° del Reglamento que establece el proceso destinado a determinar los diagnósticos y tratamientos de alto costo con Sistema de Protección Financiera, según lo establecido en los artículos 7° y 8° de la ley N°20.850, aprobado por el decreto N° 13 del Ministerio de Salud, se concluye que el presente informe de evaluación se considera favorable, de acuerdo a lo establecido en el Título III, de las Evaluaciones Favorables de la Norma Técnica N° 0192 de este mismo Ministerio.

4-Aminopyridine inhibits the neuromuscular effects of nitric oxide and 8-Br-cGMP

The effects induced by nitric oxide (NO) in different tissues depend on direct and/or indirect interactions with K+ channels. The indirect interaction of NO is produced by activation of guanylyl cyclase which increases the intracellular cGMP. Since NO, cGMP and 4-aminopyridine alone induce tetanic fade and increase amplitude of muscular contractions in isolated rat neuromuscular preparations, the present study was undertaken to determine whether or not the neuromuscular effects of NO and 8-Br-cGMP can be modified by 4-aminopyridine. Using the phrenic nerve and diaphragm muscle isolated from male Wistar rats (200-250 g), we observed that L-arginine (4.7 mM) and 8-Br-cGMP (18 æì©, in contrast to D-arginine, induced an increase in the amplitude of muscle contraction (10.5 0.7 percent, N = 10 and 8.0 0.7 percent, N = 10) and tetanic fade (15 2.0 percent, N = 8 and 11.6 1.7 percent, N = 8) at 0.2 and 50 Hz, respectively. N G-nitro-L-arginine (4 mM, N = 8 and 8 mM, N = 8) antagonized the effects of L-arginine. 4-Aminopyridine (1 and 10 æì© caused a dose-dependent increase in the amplitude of muscle contraction (15 1.8 percent, N = 9 and 40 3.1 percent, N = 10) and tetanic fade (17.7 3.3 percent, N = 8 and 37.4 1.3 percent, N = 8). 4-Aminopyridine (1 æì¬ N = 8) did not cause any change in muscle contraction amplitude or tetanic fade of preparations previously paralyzed with d-tubocurarine or stimulated directly. The effects induced by 4-aminopyridine alone were similar to those observed when the drug was administered in combination with L-arginine or 8-Br-cGMP. The data suggest that the blockage of K+ channels produced by 4-aminopyridine inhibits the neuromuscular effects induced by NO and 8-Br-cGMP. Therefore, the presynaptic effects induced by NO seem to depend on indirect interactions with K+ channels

Sensitivity of Leishmania spp. to glibenclamide and 4-Aminopiridine: a tool for the study of drug resistance development

We have demonstrated that Leishmania spp. grown as promastigotes, are sensitive to the K+ channel inhibitors 4-aminopyridine and glibenclamide. Their host cells, the macrophages, are not affected by similar concentrations of the drugs. We have also initiated the molecular characterization of the mechanisms involved in the development of drug resistance to glibenclamide by the parasite. Therefore, we have selected experimentally and begun to characterize the Venezuelan Leishmania (Leishmania) strain, NR resistant to glibenclamide [NR(Gr)]. The analysis of genomic DNA evidenced the existence of a fragment which apparently is amplified in NR(Gr). The fragment recognized by the pgpA probe, related to the Leishmania P-glycoprotein family and which was originally isolated from L. tarentolae, showed a size polymorfism between the sensitive and the resistant strain. These results suggest that the development of resistance to glibenclamide in the strain NR(Gr) might be associated with the amplification of the ItpgpA or related gene(s).

Release and uptake of glutamate as related to excitatoxicity

It has been established that neurons exposed to high concentrations of glutamate or other excitatory amino acids degenerate and die. Neuronal damage appears to be due to the activation of different types of glutamate receptors, among which the ionotropic N-methyl-D-aspartate (NMDA) type seems particularly involved, since its channel is permeable to Ca2+ and an increase in the cytoplasmic concentration of this cation promotes a chain of events leading to cell death. The mechanism of such glutamate receptor-mediated neurodegeneration has been defined as excitotoxicity, and several pieces of evidence suggest that this mechanism might contribute to the neuronal death associated with certain neurological disorders, such as ischemia, cerebral trauma and some chronic neurodegenerative diseases. A relevant question is whether the origin of endogenous extracellular glutamate is important for the induction of excitotoxicity. An excess of glutamate release, or a deficiency in its clearance from the synaptic cleft, which depends mainly on its transport by high affinity carriers, are potential sources for the accumulation of extracellular glutamate. In the present article some experimental results from our laboratory, aimed at obtaining information on this question, are reviewed. These experiments include the use of 4-aminopyridine, a convulsant drug that enhances the release of glutamate, and of some inhibitors of glutamate transport, in vivo and in neuronal cell cultures. The results obtained indicate that an increase of endogenous extracellular glutamate due to these procedures is not sufficient to induce neuronal death, at least under the experimental condition used.

Modulation of baroreceptor activity by ionic and paracrine mechanisms: an overview

1. The primary mechanism of activation of baroreceptors is mechanical deformation during vascular stretch. In addition, baroreceptor activity is modulated by ionic mechanisms and by neurohumoral and paracrine factors that act directly on the nerve endings. 2. Ionic mechanisms play a major role in causing baroreceptor activity to decline during a sustained increase in arterial pressure (adaptation) and in the suppression of activity that occurs after pressure returns to basal levels (post-excitatory depression). Activation of a 4-aminopyridine-sensitive K+ channel contributes to adaptation, whereas activation of an electrogenic sodium pump is responsible for post-excitatory depression. 3. Factors released from vascular endothelium exert powerful effects on baroreceptor sensitivity. Prostacyclin increases baroreceptor sensitivity and contributes to baroreceptor activation during vascular stretch. Nitric oxide, endothelin and oxygen-derived free radicals suppress baroreceptor activity particularly at high levels of arterial pressure. The sympathetic neurotransmitter norepinephrine modulates baroreceptor activity: a) indirectly through its vasoconstrictor action, b) directly by binding to alpha-adrenergic receptors on the nerve endings, and c)through release of a cyclooxygenase metabolite, possibly prostacyclin, from endothelium. 4. Endothelial dysfunction contributes to baroreceptor impairment in atherosclerosis and in chronic hypertension. Loss of the excitatory influence of prostacyclin and increased formation of free radicals and possibly endothelin contribute to the baroreceptor dysfunction. Platelets aggregating at sites of endothelial damage in the carotid sinus release a stable diffusible factor that impairs baroreceptor sensitivity. 5. Therapeutic interventions may alter baroreceptor sensitivity through paracrine mechanisms. Treatment of hypertension or atherosclerosis may improve baroreceptor sensitivity by restoring endothelial function. Antiplatelet agents may enhance baroreceptor sensitivity. Antidepressant agents may decrease baroreceptor sensitivity by inhibiting prostacyclin and/or stimulating nitric oxide formation, which may contribute to dysregulation of the circulation in patients treated for depression.

A review on drugs and toxins affecting presynaptic K+ currents and phasic quantal transmitter release at motor nerve terminals

Esta revisión reúne la información disponible sobre los agentes farmacológicos y toxina sque bloquean los diferentes tipos de corrientes de K+ presinápticas, y discute la importancia relativa de estas corrientes en el control de la liberación fásica y cuántica del transmisor. Los agentes farmacológicos y toxinas que bloquean la corriente rápida de K+ voltaje-dependiente (IKf), aumentan la liberación fásica de actilcolina evocada por el impulso nervioso. Este efecto es debido al aumento del influjo de Ca2+ durante la despolarización de la membrana presináptica. El bloqueo selectivo de la correinte de K+ calcio-dependiente IK(Ca) no produce ningún cambio en la liberación fásica del transmisor, lo cual indica que en condiciones fisiológicas esta corriente no tiene un papel significaivo en la repolarización de la membrana presináptica. La contribución de la corriente lenta de K+ voltaje-dependiente (IKs) en la liberación fásica de acetilcolina no ha sido aún dilucidada. En conclusión, IKf, IK(Ca) e IKs pueden modular la entrada de Ca2ñ en las terminaciones nerviosas motoras; sin embargo, en condiciones fisiológicas solamente IKf tiene una importancia clave, ya que controla el indlujo transitorio de Ca2+ que es responsable d ela liberación fásica del neurotransmisor