A combination drug most commonly refers to a fixed-dose combination (FDC), which is a formulation including two or more active pharmaceutical ingredients (APIs) combined in a single dosage form, which is manufactured and distributed in certain respective fixed doses. Terms like "combination drug" or "combination drug product" can be common shorthand for a FDC product (since most combination drug products are currently FDCs), although the latter is more precise if in fact referring to a mass-produced product having a predetermined combination of drugs and respective dosages (as opposed to customized polypharmacy via compounding). And it should also be distinguished from the term "combination product" in medical contexts, which without further specification can refer to products that combine different types of medical products - such as device/drug combinations as opposed to drug/drug combinations. Note that when a combination drug product (whether fixed-dose or not) is a "pill" (i.e., a tablet or capsule), then it is also a kind of "polypill" or combopill.
Initially, fixed-dose combination drug products were developed to target a single disease (such as with antiretroviral FDCs used against AIDS). However, FDCs may also target multiple diseases/conditions, such as Caduet (atorvastatin/amlodipine) or Exforge (amlodipine/valsartan). In cases of FDCs targeting multiple conditions, such conditions might often be related — in order to increase the number of prospective patients who might be likely to utilize a given FDC product. This is because each FDC product is mass-produced, and thus typically requires having a critical mass of potentially applicable patients in order to justify its manufacture, distribution, stocking, etc.
Magnesium is an essential element in biological systems. Magnesium occurs typically as the Mg2+ ion. It is an essential mineral nutrient (i.e., element) for life and is present in every cell type in every organism. For example, ATP (adenosine triphosphate), the main source of energy in cells, must be bound to a magnesium ion in order to be biologically active. What is called ATP is often actually Mg-ATP. As such, magnesium plays a role in the stability of all polyphosphate compounds in the cells, including those associated with the synthesis of DNA and RNA.
Over 300 enzymes require the presence of magnesium ions for their catalytic action, including all enzymes utilizing or synthesizing ATP, or those that use other nucleotides to synthesize DNA and RNA.