Drugs versus Biologics. 1  A biologic is manufactured in a living system such as a microorganism, or plant or animal cells. 2  Most biologics are very large, complex molecules or mixtures of molecules.enerics Drugs versus Follow-On Biologics. 1  To be approved as a generic, a drug must have the same active ingredient, strength, dosage form, and route of administration as the reference drug, and it must also be bioequivalent..
Viruses (e.g., adenovirus, astrovirus, rotavirus, Norwalk virus) are the most common cause of diarrhea in the United States. The most common ones in children are rotavirus and in adults are norovirus. Escherichia coli, Clostridium difficile, and Campylobacter, Salmonella, and Shigella spp. are common bacterial causes.
1 Chronic cases of infectious diarrhea may be seen in immunocompromised patients (as seen in HIV diarrhea) or associated with a Clostridium difficile infection (as seen in antibiotic-associated diarrhea).  Malabsorption syndromes are another common cause of watery stool or watery diarrhea. In these cases, there is failure of the small intestine to absorb nutrients, which is further compounded by decreased water absorption in the large intestine.