General Pharmacology:
Route of Drug Administration:
There are two major routes of administration.
A- Enteral
B- Parenteral
A- Enteral:
1- Oral:
Giving a drug by mouth is the most common route of administration,
but it is also the most variable, & involves the most complicated pathway to
the tissues. Some drugs are absorbed from the stomach; however, the
duodenum is the major site of entry to the systemic circulation because of its
larger absorptive surface.
2- Sublingual:
Placement under the tongue allows a drug to diffuse into the
capillary network & therefore to enter the systemic circulation directly.
Administration of an agent by this route has the advantage that the drug
bypasses the intestine & liver & thus avoids first pass metabolism.
3- Rectal:
Fifty percent of the drainage of the rectal region by passes the
portal circulation; thus, the biotransformation of drugs by the liver is
minimized. Both the sublingual & the rectal routes of administration have the
additional advantage that they prevent the destruction of the drug by
intestinal enzymes or by low pH in the stomach. The Rectal route is also
useful if the drug induces vomiting when orally or if the patient is already
vomiting.
B- Parenteral:
Route of Drug Administration:
There are two major routes of administration.
A- Enteral
B- Parenteral
A- Enteral:
1- Oral:
Giving a drug by mouth is the most common route of administration,
but it is also the most variable, & involves the most complicated pathway to
the tissues. Some drugs are absorbed from the stomach; however, the
duodenum is the major site of entry to the systemic circulation because of its
larger absorptive surface.
2- Sublingual:
Placement under the tongue allows a drug to diffuse into the
capillary network & therefore to enter the systemic circulation directly.
Administration of an agent by this route has the advantage that the drug
bypasses the intestine & liver & thus avoids first pass metabolism.
3- Rectal:
Fifty percent of the drainage of the rectal region by passes the
portal circulation; thus, the biotransformation of drugs by the liver is
minimized. Both the sublingual & the rectal routes of administration have the
additional advantage that they prevent the destruction of the drug by
intestinal enzymes or by low pH in the stomach. The Rectal route is also
useful if the drug induces vomiting when orally or if the patient is already
vomiting.
B- Parenteral:
