Metaprolol is a Beta-Blocker. It is not a blood thinner. It works to inhibit part of the parasympathetic nervous system. It is generally used to treat such things as high blood pressure, fast heart rates, and to help the heart contract harder to put out more blood volume. Some common "Blood Thinnners" are Heparin, Lovenox, Warfarin (Coumadin), and Pradaxa. More information about Metaprolol can be found at the manufacturer's website.
No, it does not. Betaloc is a trade name for metaprolol tartrate. It is used to treat high blood pressure, migraines and heart disease. The forumla for metaprolol is C15H25NO3 -- no S for sulfur. The tartrate group is a common food acid that is just added to increase solubility and has no medical effect. The formula for tartrate is C4H4O6, once again, no S for sulfur. Most medicines contain only a tiny amount of the active drug, the rest is a relatively inert material, called the excipient, that is mainly there to make the pill big enough to handle without tweezers and a magnifying glass. It is slightly possible that the excipient might contain sulfur but it is unlikely to be more than a tiny trace. The most common excipients are carbohydrates (cellulose and derivatives, starches or sugars), chalk, waxy magnesium stearate, and vegetable oils and waxes. None of these contain sulfur.