Definition and Classification of routes of drug administration. Along with an explanation of it. Advantages and Disadvantages of different routes of administration. Intravenous routes give faster onset of action than any other route. 100% bioavailability is possible in the case of IV. The choice of route depends upon the patient condition.

1. Lecture No. 03
Routes
of
Administration
▪ By
▪ Mr. Sagar K. Gangurde
▪ M. Pharm (PHARMACOLOGY)
▪ Lecturer
▪ SGSS College of Pharmacy, Manur, Kalwan.
ROUTES OF DRUGS ADMINISTRATION

2. Routes of Drug Administration
1
2
3
ENTERAL ROUTE
PARENTERAL ROUTE
TOPICAL ROUTE / LOCAL APPLICATION

3. ROUTES OF DRUG ADMINISTRATION
A route of administration is the path by which a drug,
fluid, poison, or other substance is taken into the body.
OR
The route through which the drug, fluid, poison or other
substance administered or introduced into the body is called
Routes of Administration.

4. CLASSIFICATION OF ROA
Enteral
1. Oral Route
2. Sublingual Route
3. Enema
Topical/ Local application
1. Intravenous
2. Intramuscular
3. Intradermal
4. Intra-arterial
5. Intra-articular
6. Intrathecal
7. Subcutaneous
8. Intramedullary
9. Intraperitoneal
Parenteral
Injections Inhalation

5. Enteral Route
The word enteral is derived from the word Enteron means
Intestine. There are three main divisions of enteral route and are as
follows: -
1. Oral Route- Drug kept in mouth and swallowed.
2. Sublingual Route/ Buccal Route- Drug kept below the tongue and
allow to dissolve in saliva.
3. Enema- Drugs administered in rectum through anus.

6. Oral Route
Dosage forms like tabs, capsules or liquid etc. can be taken through this route. Drugs in solid or liquid form such as tablet or syrup is
kept in mouth cavity and swallowed with water or milk. After the administration of drug by oral route, absorption of a drug takes place in
stomach or intestine.
Advantages: -
1. Most commonly preferred & used route for drug administration.
2. Does not required any special skill for administration.
3. Self medication is possible.
4. Very convenient and economical from infants to aged patients.
5. Does not required any complicated process like sterilization.
Disadvantages: -
1. Onset of action is very slow.
2. Not useful in emergency cases.
3. Irritant, unpalatable drugs can not be given by this route.
4. Can’t be used in cases of unconscious & uncooperative patients.
5. This route does not suitable in conditions like nausea, vomiting & diarrhoea.
6. After oral administration certain drugs like testosterone are destroyed in the liver cells i.e. Hepatic first pass metabolism bcoz of that
100% bioavailability is not possible.
7. High doses are effective
8. Some drugs like penicillin, insulin are destroyed by
gastric juice hence can not be given by this route.

7. Sublingual Route
Also called as Buccal Route. In this case, the tablet medicament is placed below the tongue or chewed in
mouth and spread over the buccal mucosa. Thus, the active medicaments gets absorbed through buccal mucous
membrane and then it directly passed into the systemic circulation. For ex., Angina pectoris – Nitroglycerine tablet,
Bronchial Asthma – Isoprenaline.
Advantages: -
1. Rapid onset of action.
2. Useful in emergency cases like angina pectoris.
3. Adverse effect of the drug can be prevented simply by spitting the tablet.
4. Also, one can spit the drug after getting desired effect or action.
5. Degradation of drug in stomach or liver is avoided because the drug directly reaches the systemic circulation.
6. Overdose can be avoided.
Disadvantages: -
1. The only disadvantage of this route is that the drugs having direct or toxic effect on heart should be carefully
administered to avoid any such effects.

8. Enema
This route involves administration of liquid medicament through the rectum for systemic effect. This route
is used in the cases of patient having recurrent vomiting or the patient is unconsciousness. There are two types of
enema: -
1. Evacuant Enema: -
This route is used to remove faecal matter and also flatulence. Maximum quantity of liquid administered
at a time is 600 ml. Eg. Soap water Enema.
In that, the water stimulates rectum while soap lubricates the pathway. This type of enema used before
surgical operations, delivery & GIT investigations by X-ray etc.
2. Retention Enema: -
In this case, the administered liquid medicaments get retained in the rectum to obtained local effects.
For ex., Prednisolone enema in Ulcerative colitis.
Sometimes drug may absorbed through mucous membrane & shows systemic effects.
For ex., Paraldehyde enema to produce basal anesthesia.
Quantity of fluid administered is 100-200 ml.

9. Parenteral Route
It includes the routes of administration of drugs other
than alimentary tract. The word parenteral is derived from two
Latin words i.e. Par means Beyond / Other and Enteron means
Intestine.
Thus parenteral routes means the drugs are
administered beyond the intestine i.e. the drugs are taken other
than oral route is known as Parenteral route of administration.
In this case the drugs in the suspension or solutions are
injected in the body with the help of needle & syringe (Injections)
or the drug in the form of vapours or fine droplets are inhaled in
respiratory tract (Inhalation).
Parenteral route can be divided into: - 1) Injections & 2)
Inhalation.

10. Advantages: -
1. Rapid onset of action.
2. This route is preferred in uncooperative or unconscious patient.
3. This route is also suitable in conditions like nausea & vomiting.
4. Useful in emergency cases.
5. Degradation of drugs by Hcl in stomach can be avoided so that 100% bioavailability is possible.
6. Accuracy of dosage is possible.
7. Low doses are effective.
8. Irritant or unpalatable drugs can be given.
Disadvantages: -
1. The preparations has to be sterilized in order to avoid possibility of infections.
2. It is a costly route.
3. Self medication is not possible as it requires a special technical skill for administration of a drug.
4. Injections are painful at site of administration.
5. Very difficult to reverse or control the effect of drug once it administered.

11. A) Injections: -
Injections are broadly categorized into:
1. Intravenous (IV).
2. Intramuscular (IM).
3. Intradermal (ID).
4. Subcutaneous (SC).
5. Intraarterial.
6. Intrathecal.
7. Intra-articular.
8. Intramedullary.
9. Intra-cardiac.
10. Intraperitoneal.

12. Intravenous Injections
In this route the drug is directed injected into the vein.
Median basilic vein near the anterior surface of the elbow.

13. Advantages: -
1. Rapid onset of action.
2. This route gives 100% bioavailability.
3. This route is preferred in uncooperative or unconscious patient.
4. This route is also suitable in conditions like nausea & vomiting.
5. Useful in emergency cases.
6. Degradation of drugs by Hcl in stomach can be avoided so that 100% bioavailability is possible.
7. Accuracy of dosage is possible.
8. Low doses are effective.
9. Irritant or unpalatable drugs can be given.
Disadvantages: -
1. The preparations has to be sterilized in order to avoid possibility of infections.
2. Drugs with oily vehicles or those precipitated in a blood constituents should not be given by this route.
3. Self medication is not possible as it requires a special technical skill for administration of a drug.
4. Injections are painful at site of administration.
5. Very difficult to reverse or control the effect of drug once it administered.

14. Intramuscular Injections
In this route the drug is deeply injected into the
muscular tissue (Skeletal Muscle).
Gluteal Muscle
Deltoid Muscle

15. Advantages: -
1. The drug administered by IM route includes soluble substances, mild irritants, suspensions
and colloids.
2. The absorption from this route is uniform and rapid as compare to subcutaneous route.
3. First pass effect can be avoid.
4. Degradation of drug by stomach can be avoided.
Disadvantages: -
1. The volume of drug injection should be upto 10 ml means only upto 10 ml drug can be
given.
2. Pain at the site of injection and chances of abscess formation.
3. Chances of nerve damage.
4. This route also ensures uniform and slow absorption of drugs.

16. Intradermal Injections
In this route the drug is injected in the layer of skin. It is given between inner layer or dermis & outer
layer or epidermis. Small volume can be injected through this route usually 0.1 to 0.2 ml. Fine short (26 Gauze)
needle is used. This route is used as diagnostic purpose s/a to check drug allergy like penicillin given ID to
observe its allergic reactions. Also used for Schick test for diphtheria, Dick test for Scarlet fever and Tuberculin
Test. This route is also used for introduction of vaccines like BCG.

17. Subcutaneous Injections
The drugs are injected below the skin in loose subcutaneous tissues. Only non-irritant
substances can be injected by this route. There is slow absorption of the drug in this route as compare to
IM & IV.

18. There are three different types of drug can be inject through this route: -
1. Hypodermoclysis: - Preferred when the vein is not found or difficult to
puncture the vein. Eg. In Neonants.
2. Hypospray/ Jet Injection: - Drug can be inject with high velocity through
small orifice present on skin. Due to drug inject by high velocity they did not
required the needle.
3. Implants: - A sustained release dosage form use when the long term
treatment is required. Implants can be placed at subcutaneous tissue by
performing minor surgery.

19. Intra-Arterial Injections
Drugs are directly injected into the arteries. Similar to the intravenous injection
and are occasionally used for an immediate effect in a peripheral area.
For ex., Tolazoline hydrochloride a peripheral vasodilator used to improve
circulation the extremities when arterial flow is restricted by arterial spasm, gangrene
etc.
This route is also used for arteriography (Radio-opaque subs). Anti-cancer drugs
are given by this route.

20. Intra-Thecal Injections
Also called as Intraspinal
Injections.
These are made into the
subarachnoid space that surround the
spinal cord. The space between the
arachnoid and pia matter is called Sub-
arachnoid space.

21. Intra-Articular Injections
In this route the drugs are injected into
synovial fluid (Into the joint). This route is
employed for the treatment of local
conditions which can achieve high local
concentration of the drugs.
Eg., Hydrocortisone acetate given by
this route to treat Rheumatoid Arthritis.
It requires perfectly sterile drug for the
injection to avoid possibility of infection

22. Intra-Medullary Injections
When IV administration is
not possible, the drugs are directly
injected into bone marrow. Rapid
onset of action. It is employed
particularly in infants and restless
patients.

23. Intra-Cardiac Injections
In this route, the drugs are directly injected into the cardiac muscles (Heart
Muscles) or ventricles. It can be used in emergencies, although they are rarely used in
modern practice. The procedure is performed by inserting a long spinal needle into the
ventricular chamber.
Intra-Peritoneal Injections
Drugs are injected into peritoneal
cavity which offers a large absorbing surface
area. These are rarely used. It is used to give
the fluid like glucose, saline solution to infants.

24. INHALATIONS
In case of inhalation route the drug may be administered as aerosol system or in
the form of vapours.
Certain drugs may be sprayed in the form of minute droplets which are
deposited over mucous membrane. Thus producing local effect.
Eg., Adrenaline spray- In the treatment of asthma. The drugs can be
administered as gaseous or in the form of smoke.
Eg., CO2 gas, volatile general anesthetics- Absorption by this route is rapid, easy
and high local as well as systemic concentration of the drug can be achieved.

25. Local / Topical Application
These preparations are meant for their action at the site of application on local affected area.
Eg., Dusting powder, paste, lotions, drops, ointments, plaster etc.
Occasionally the drugs may be utilize for their systemic action i.e. by induction or applied by rubbing.
Eg., Cod liver oil.
Advantages: -
1. Easy route of administration of certain medicament.
2. Are useful when prolonged effect of the drug is designed.
3. These preparations decrease the possibility of systemic absorption of medicaments.
Disadvantage: -
1. Drugs in the form of watery solutions are sometimes absorbs in the blood which may lead to the desired
toxic effect when applied on the mucous membrane.