The manner a drug enters the body is referred to as the route of administration. There are many different routes than can be utilized. The routes are: orally, otically, nasally, transdermal, rectally, vaginally; or injected through the skin in several ways. The drug has to enter the body and cannot do its specific job until it has entered the bloodstream. This process is also known as absorption. The administration route most used is the oral route. Taken orally the medication is dissolved in the intestines and absorbed into the bloodstream.
With injectables; the intestines are passed over and the “first pass” stage (The Pharmacy Techician Series: Fundamentals of Pharmacy Practice, 2006). Now we discuss the bioavailability. The bioavailability is “the degree to which a drug or other substance becomes available to the target tissue after administration” (The Free Dictionary, 2010). In clinical pharmacology the extent that a drug is available to the targeted tissue after administration refers to the rate and extent of absorption. In the case of oral drugs it refers to the extent and rate of absorption in the gastrointestinal tract (GI).
Bioavailability in other words means the amount of drug, rate of that drug that entered the body and when it is accessible to the body. Most drugs are eliminated after metabolism (chemically altered), or in their unaltered state. Water soluble drugs and their metabolites are eliminated through the urine, while some are eliminated by excretion in the bile. After the drug has entered the bloodstream it is in its molecular form and can cross cell membranes and has been metabolized. Once the drug has completed its job, it has to be eliminated.
It is the liver, kidneys, and lungs job to do the elimination process. The liver and kidneys are the primary elimination processors. Other ways of the body eliminating drugs after metabolism is through tears, breath, and sweat. “Without elimination, the medications could build to toxic levels in the body and do significant damage, up to and including death” (The Pharmacy Techician Series: Fundamentals of Pharmacy Practice, 2006). Once the drug has been administered it has to be metabolized by the body. After it has done its job or been sent to specific areas of the body it has to be eliminated.
Most drugs are eliminated primarily by the liver and kidneys. Elimination of drugs is a necessary process after the body has metabolized the drug. Without elimination of the drugs the body can build up toxic levels which could cause damage to internal organs and quite possibly death. References Johnston, M. (2006). The Pharmacy Technician Series: Fundamentals of Pharmacy Practice. Bioavailability. (2010, October). The Free Dictionary by Farlex Retrieved from http://medical-dictionary. thefreedictionary. com/bioavailability.