Types
Advantages
Routes of Administration,
Disadvantage
Routes of Drugs Administration
ENTERAL
It involves drug administration via alimentary tract.
(1) Oral
(a) Most convenient, & most acceptable.
(b) Used for local as well as systemic actions of drugs
(c) Dosage forms do not require sterile techniques for
administration.
(d) Delivery of drug into circulation is slow, so
that rapid, high blood conc. are avoided &
adverse effects are less.
Disadvantages
(a) Rate of absorption is variable.
(b) Irritation of mucosal surfaces can occur.
(c) Extensive hepatic metabolism (first-pass
effect) may occur before the drug reaches its
site of action.
(d) Onset of action is delayed, thus unsuitable in
emergency situations.
(e) Impractical in unconscious or uncooperative pts.
(f) Drugs destroyed by digestive enzymes (insulin,
pituitary hormones) or by gastric acidity
(benzyl penicillin) can not be administered.
(2) Sublingual (Beneath Tongue)
Advantages
(a) Rapid absorption & effect (eg, glyceryl trinit-rate in
angina).
(b) Effect can be terminated by spitting out tablet.
Disadvantages
(a) Inconvenient for frequent use.
(b) Irritation of oral mucosa, & excessive salivation.
(3) Rectal
Advantages
(a) Drug irritant to stomach can be given by
suppository (eg aminophylline, indomethacin).
(b) Suitable in vomiting, motion sickness,
migraine, or when a pt can not swallow, &
when cooperation is lacking.
(c) Used for local effects, eg in proctitis, or colitis, &
for bowel evacuation.
Disadvantages
(a) Psychological in that the pt may be embarrassed.
(b) Rectal inflammation may occur with repeated use.
PARENTERAL
It involves drug administration via injection into a
blood vessel, soft tissue, or a body cavity.
Examples
(1) Intravenous (IV).
(2) Intramuscular (IM).
(3) Intradermal (ID).
(4) Subcutaneous (SC).
(5) Intraperitoneal (IP).
(6) Intra-arterial (IA).
(7) Intracardiac (IC).
(8) Intrathecal (IT).
(9) Intra-articular or joint (IJ).
(10)Intra-bone marrow (IBM).
Advantages
(1) Drugs get to the site of action more rapidly, providing a
rapid response, which may be required in an emergency.
(2) Dose can be more accurately delivered.
(3) Can be used when alimentary route is not feasible (eg in
unconscious pts).
(4) Suitable for drugs that are not absorbed from GIT, or are
too irritant to be given by other routes.
Disadvantages
(1) More rapid absorption can lead to increased
adverse effects.
(2) A sterile formulation, & an antiseptic technique are
required.
(3) Local irritation may occur at the site of injection.
MISCELLANEOUS ROUTES
(1) Inhalational
It involves drug administration directly into the
respiratory tract.
Advantages
Drugs as gases or aerosols can be rapidly taken up or
eliminated.
Disadvantages
(a) Special apparatus is needed.
(b) Drug must be non-irritant for conscious pts.
(2) Topical
It involves application of drugs over skin or mucus
membrane, to produce local effects.
Advantages
High local conc. can be achieved without systemic
effects.
Disadvantages
Absorption can occur, esp. when there is tissue
destruction, that results in systemic effects