Oral ( per os - PO):
Many medications are taken by mouth, and enter the bloodstream through the digestive system. This process often takes as long as 1 hour. One of the advantages of using this route is that ii is noninvasive. Patients are often much happier to take a pill than to have a needle stuck in them. It is also less expensive to use enteral medications than to use parenteral. The main disadvantage of this administration route is the unpredictability of medication absorption. If the patient has vomiting or diarrhea, the amount of medication that is absorbed will be altered. Some medications, referred to as orally disintegrating tablets (OTDs), are put directly onto the tongue, where they dissolve. This is an alternative administration form for patients who may have difficulty swallowing. Some forms of medications are adversely affected by stomach acids, so dissolving them directly on the tongue avoids breakdowm by gastric acids. An example of this type of medication is ondansetron (Zofran), which is used to treat nausea and vomiting.