[Caffeine: a nutrient, a drug or a drug of abuse]. / Cafeína: un nutriente, un fármaco, o una droga de abuso.

Coffee, tea, chocolate and caffeinated drinks are the main sources of caffeine, which is consumed in almost all ages and socioeconomic levels. Caffeine acts as a non-selective adenosine receptor antagonist in the central nervous system. Its main effects are as psychostimulant, acting in addition on the respiratory, muscular and cardiovascular systems. Basically, caffeine is metabolized by the hepatic cytochrome P-450 1A2 enzymes (CYP1A2). Several drugs can interact with its metabolism. The observed interindividual differences of its effects can be explained by variations in its metabolism. The main therapeutic use of caffeine is bronchodilator in respiratory diseases. Other possible uses are under investigation. Acute or chronic consumption of caffeine can induce several adverse effects, including intoxication that can be lethal. Finally, caffeine can be considered a drug of abuse. It has positive reinforcing actions, produces tolerance, and a withdrawal syndrome after stopping its consumption. Caffeine can cause different mental disorders such as dependence, which is not included in the DSM-IV-R, withdrawal syndrome and intoxication. Depending on its use, caffeine can be considered a nutrient, a drug or a drug of abuse.

Estudios controlados en humanos de éxtasis / Controlled trials of ecstasy administration in humans

Objetivo: recopilar y analizar la información sobre los efectos de la MDMA obtenida en estudios controlados en humanos. Método: la mayoría de ensayos analizados han sido de diseño enmascarado a doble ciego, cruzados, con asignación aleatoria a la secuencia de tratamientos, y controlados con placebo y/o fármaco patrón. Resultados: además del incremento de la presión y frecuencia cardíaca, la MDMA incrementa el consumo miocárdico de oxígeno sin efectos inotrópicos y puede incrementar el intervalo QTc en el ECG. El aumento de temperatura no fue significativo frente a placebo. Produce euforia, bienestar y activación. No se han descrito ni alucinaciones ni ilusiones. En el EEG aumenta la actividad beta y disminuye la alfa. Aumenta de forma dosis-dependiente las concentraciones de ACTH, cortisol, prolactina, dihidroepiandrosterona y vasopresina. Inmunológicamente su efecto parece ser inmunosupresor. Su farmacocinética parece ser no-lineal con tendencia a la acumulación a dosis alta. Conclusiones: los estudios controlados han permitido conocer mejor la MDMA, profundizando en sus efectos subjetivos, y aportando datos originales en cuanto a cambios hormonales e inmunológicos. Se necesitan más estudios para determinar científicamente los efectos y toxicidad de la MDMA (AU)

Objective: to compile and analyse knowledge about the pharmacodynamics and pharmacokinetics of MDMA from controlled clinical trials in humans. Methods: the typical design of the trials was masked (double blind), randomized, cross-over, and controlled with placebo and/or an active drug. Results: MDMA increases the heart rate, arterial blood pressure, oxygen consumption by the heart and produced an enlargement of the QTC interval in the ECG. No statistical differences were found with placebo in the increase of body temperature. MDMA induce euphoria, wellbeing and activation. Neither ilusions nor hallucinations were described. An increase of beta activity and a decrease of alpha activity in the EEG was seen. A dose-dependent increase in the plasma levels of ACTH, cortisol, prolactin, dehydroepiandrosterone and vasopresine was observed. Immunogically, MDMA posses an immunosupresor effect. Its pharmacokinetic properties seems to be non-lineal, with a tendency to accumulation at high doses. Conclusion: the results obtained in these controlled clinical trials increase our previous knowledge on MDMA and add new data related to its hormonal and immunological effects. Further studies are needed in order to better understand the effects and toxicity of MDMA (AU)