Nachfolgendes ist aus ´Mosby´s Medical, nursing & allied health dictionary´ (2002) - demnach auf Englisch, aber das tut dem Fachenglisch ja ganz gut ;-)
Magnesium is the second most abundont cation of the intracellular fluids in the body. It is essential for many enzyme activities and the interaction of intracellular particles and binding of macromolecules to subcellular organelles, such as the binding of messenger ribonucleic acid to ribosomes. It is also imp;ortant to neurochemical transmissions and muscular excitability. The body of the average 145-pound adult contains about 2000 mEq of magnesium, about 50% of which is in the bones, 45% existing as intracellular cations, and about 5% in the extracellular fluid. Absorption of magnesium occurs in the upper small bowel by means of an active process closely related to the transport system for calcium. Magnesium is excreted mainly by the kidney. Renal excretion of magnesium increases during diuresis induced by ammonium chloride, glucose, and organic mercurials. Magnesium affects the central nervous, neuromuscular, and cardiovascular systems. (...) Excess magnesium (hypermagnesemia) in the body can slow the heartbeat, and concentrations greater than 15 mEq/L can produce cardiac arrest in diastole. Excess magnesium also causes vasodilation by direct effects on the blood vessels and by ganglionic blockade. Hypermagnesemia is usually caused by renal insufficiency and is manifested by hypotension, electrocardiographic changes, muscle weakness, sedation, and a confused mental state.
Habe auch folgenden ´abstract´ zum Thema gefunden http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WB0-4FRD3M8-20&_coverDate=07%2F31%2F1988&_alid=442804000&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=6696&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b0145d273455bf7ff514713ce58960d7 - also eine Ueberdosis (auch im Sinne von Suizid) ist durchaus moeglich, aber ob das mit Brausetabletten einfach so geht weiss ich auch nicht. Wenn Du sagst, dass Du Dich erst 4 Tage nach Einnahme schlapp fuehlst, ist es wohl eher unwahrscheinlich, dass dies vom Magnesium verursacht wurde (siehe ´abstract´)