The document discusses various routes of drug administration. The choice of route depends on factors like the drug's properties, the desired site of action, absorption rate, and the patient's condition. Local routes like topical provide localized drug delivery while deeper tissue routes like injections target specific areas. Systemic routes include oral, sublingual, rectal, cutaneous, inhalation, nasal, and parenteral like subcutaneous, intramuscular, and intravenous injections. Each route has advantages and limitations for drug delivery and absorption. The most appropriate route is selected based on the drug and clinical situation.

1. Routes of Drug Administration
DR. SUBHASH R. YENDE
ASSISTANT PROFESSOR,
GURUNANAK COLLEGE OF PHARMACY,
NAGPUR
DR. SUBHASH R. YENDE, GNCP NAGPUR 1
Pharmacology-I General Pharmacology

2. Routes of drug administration
The choice of appropriate route is depends on drug as well as patient related
factors such as-
Physical and chemical properties of the drug
Site of desired action
Rate and extent of absorption of the drug
Effect of digestive juices and first pass metabolism
Rapidity with which the response is desired
Condition of the patient
DR. SUBHASH R. YENDE, GNCP NAGPUR 2

3. Routes of drug administration
Local Routes – Topical, Deeper tissue
1. Topical
External application of the drug to the surface for localized action
Drugs can be efficiently delivered to the localized lesions on skin,
oropharyngeal/ nasal mucosa, eyes, ear canal, anal canal or vagina in the
form of lotion, ointment, cream, powder, rinse, paints, drops, spray,
lozengens, suppositories or pessaries.
 action on g.i. mucosa (sucralfate), inhalation for action
on bronchi (salbutamol) are other forms of topical medication
DR. SUBHASH R. YENDE, GNCP NAGPUR 3
Local Action Systemic Action

4. 2. Deeper tissues
 approached by using a syringe and needle
 systemic absorption is slow,
 e.g. intra-articular injection (hydrocortisone acetate in knee joint),
Infiltration around a nerve or intrathecal injection (lidocaine),
retrobulbar injection (hydrocortisone acetate behind the eyeball)
DR. SUBHASH R. YENDE, GNCP NAGPUR 4

5. Systemic Routes
1. Oral
2. Sublingual or buccal
3. Rectal
4. Cutaneous
5. Inhalation
6. Nasal
7. Parenteral
Subcutaneous
Intramuscular
Intravenous
Intradermal injection
DR. SUBHASH R. YENDE, GNCP NAGPUR 5

6. 1. Oral route
Drug administered through oral cavity
Oldest and commonest mode of drug administration
Advantages:
• Safer, more convenient, noninvasive, often painless
• Need no assistance,
• Need no sterilization of medicament
• Cheaper
• Both solid and liquid dosage form can be given orally
DR. SUBHASH R. YENDE, GNCP NAGPUR 6

7.  Disadvantages or Limitations:
• Action of drugs is slower and thus not suitable for emergencies
• Unpalatable drugs (chloramphenicol) are difficult to administer
• May cause nausea and vomiting.
• Cannot be used for uncooperative/
unconscious/vomiting patient.
• Absorption of some drug may
be variable
• Drugs may destroyed by digestive
juices (penicillin G, insulin)
• First pass effect
• Food drug interaction
DR. SUBHASH R. YENDE, GNCP NAGPUR 7

8. 2. Sublingual or buccal route
Drug is placed under the tongue or
crushed in the mouth and spread
over the buccal mucosa
Advantages:
• Liver is bypassed and drugs with high first pass metabolism can be
absorbed directly into systemic circulation
• Absorption is relatively rapid
Disadvantages:
• Only lipid soluble and non-irritating drugs can be so administered
DR. SUBHASH R. YENDE, GNCP NAGPUR 8

9. 3. Rectal route
Drugs can be put into rectum as
suppositories or retention enema
for systemic effect
Advantages:
• Irritant and unpleasant drug can be administered
• Can be used for uncooperative/unconscious/vomiting patient
• 50% bypasses liver
Disadvantages:
• Inconvenient and embarrassing
• Absorption is slower, irregular and often unpredictable
• Rectal inflammation can result from irritant drugs
DR. SUBHASH R. YENDE, GNCP NAGPUR 9

10. 4. Cutaneous route
drugs can be applied over the skin for slow and prolonged absorption
• Liver is also bypassed
• Transdermal drug delivery systems (adhesive patches) are used
DR. SUBHASH R. YENDE, GNCP NAGPUR 10

11. 5. Inhalation route
Volatile liquids and gases are administered
Absorption takes place from the vast surface of alveoli
Advantages:
• Action is very rapid
Disadvantages:
• Back diffusion of drug
• Irritant vapours (ether) cause inflammation of respiratory tract and
increase secretion
5. Nasal route
The mucous membrane of the nose can readily absorb many drugs
Spray or nebulized solution have been used by this route
DR. SUBHASH R. YENDE, GNCP NAGPUR 11

12. 7. Parenteral route
Par—beyond, enteral—intestinal
Administration by injection which takes the drug directly into the
tissue fluid or blood without having to cross the enteral mucosa
Advantages:
• Drug action is faster (valuable in emergencies)
• Gastric irritation and vomiting are not provoked
• Can be given in unconscious, uncooperative or vomiting patient
• No chances of interference by food or digestive juices
• Liver is bypassed
DR. SUBHASH R. YENDE, GNCP NAGPUR 12

13. Disadvantages:
• The preparation has to be sterilized and is costlier
• The technique is invasive and painful
• Assistance of another person is mostly needed
• Chances of local tissue injury
• Parenteral route is more risky than oral
Important parenteral routes are:
DR. SUBHASH R. YENDE, GNCP NAGPUR 13

14. Subcutaneous (s.c.)
• The drug is deposited in the loose subcutaneous
tissue which is richly supplied by nerves
• Irritant drugs cannot be injected
• Only small volumes can be injected
• Self-injection is possible
• Depot preparations (oily solutions, aqueous suspensions) can be
injected
• Dermojet, Pellet implantation, Implants are some special forms of this
route
DR. SUBHASH R. YENDE, GNCP NAGPUR 14

15. Intramuscular (i.m.)
• The drug is injected in one of the large skeletal muscles—deltoid,
triceps, or rectus femoris
• Mild irritants can be injected and more vascular (absorption of drugs in
aqueous solution is faster)
• It is less painful
• Deep penetration is needed
• Depot preparations can be injected
DR. SUBHASH R. YENDE, GNCP NAGPUR 15

16. Intravenous (i.v.)
• The drug is injected as a bolus or infused slowly over hours in one of
the superficial veins
• The drug reaches directly into the blood stream and effects are
produced immediately
• Irritant drugs can be Injected by diluting the drug
or injecting it into a running i.v. line
• No depot preparations for this route
• Bioavailability of drug is 100%
• This is the most risky route beacouse vital organs like heart, brain, etc.
get exposed to high concentrations of the drug
DR. SUBHASH R. YENDE, GNCP NAGPUR 16

17. Intradermal injection
• The drug is injected into the skin raising a bleb (e.g. BCG vaccine,
sensitivity testing)
• This route is employed for specific purposes only
DR. SUBHASH R. YENDE, GNCP NAGPUR 17

18. Reference:
KD Tripathi. Essentials of Medical Pharmacology, 8th edition, 2019,
Jaypee Brothers Medical Publishers (P) Ltd. New Delhi.
Sharma H. L., Sharma K. K., Principles of Pharmacology, Paras
medical publisher
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