Introduction to PK / Routes of Administration
Now in the previous video I told you that Pharmacokinetics is the study of the fate of drugs in the body. And that this includes the processes of absorption, distribution, metabolism and excretion.
In this video we will look at the absorption process and consider the different routes of administration
We should recognize that the skin is actually a very effective barrier to most drugs and chemicals.
For some drugs, it may be possible to obtain absorption by applying the drug on the skin. But absorption is usually inefficient and incomplete. This is called the transdermal route of administration.
The most effective way of getting drugs into the body is by means of an injection.
Both the transdermal and the injections are called parenteral routes on injections because they do not involve the gastrointestinal tract.
The intravenous route of administration is the most effective and complete because it directly introduces the drug into the circulation.
You can administer the drug under the skin. This is called the subcutaneous route of administration. Or into the muscle, in which case it is called the intramuscular route of administration. Both these routes of administration can result in erratic rates of absorption, and can even be incomplete.
The commonest route of administration is through the oral route.
Oral absorption is usually good and efficient, although the absorption is always incomplete. We refer to this as having a bioavailability of less than 1. We will discuss this in the next video, so just keep this thought in mind.
So, in summary, these are the common routes of administration – the oral route, and the non-oral, or parenteral routes, which are the injections and transdermal route.
Don’t go away just yet, because in the next video we will examine the concepts of bioavailability and bioequivalence.
See you then.