The oral administration route is the eldest method of drug delivery. Amongst the variety of medication delivery routes, oral administration is reported to be the most preferred route for both the clinician and the patient (Shojaei, 1998). This method has several considerable advantages relating to convenience, safety and cost that make it probably the most often used one.
Firstly, oral administration involves no pain and is characterized by relative ease for the clinician and the patient. Secondly, since this method does require any additional expenses for either the production of orally administered drugs or their administration to patients, it is reasonably considered to be the cheapest. Thirdly, this method offers a great variety of choices for the clinician who can, depending on the patient’s needs, administer fast or slow-release tablets, suspensions/mixtures or solid medications, etc (Singh &. Kim, 2006). Mobility and absence of the need to sterilize or use specific devices/machines also contribute to the popularity of the oral administration route.
While the advantages of the oral route are significant, it also has several essential shortcomings relating, for the most part, to the fact that drugs administered orally move through the digestive tract. Firstly, some orally administered medications begin to absorb in the mouth and stomach though typically absorptions begin from the small intestine. On its way to the target organ, the medication passes through the intestinal wall and is further transported to the liver. Both these pathways chemically alter many medications which result in decreased amounts of medication carried to the target site. Therefore, such medications are distributed orally in larger doses to compensate for the loss due to the liver and intestinal wall-related metabolism, while, for example, intravenous administration of the same medications does not involve any chemical alterations and, subsequently, smaller doses are needed to have the same effect. .