An assignment on the different modes of drug administration. Hope it helps pharmacy students.

1. UNIVERSITY OF
MAURITIUS
Bachelor of Pharmacy – Year 2
PHARMACOLOGY 1
TITLE:
Modes of Administration of Drugs along with
their Advantages & Disadvantages.
Presented by:
NARAINO MAJIE Nabiilah - 1216824
Date of Submission: 3rd September 2013

2. Routes of administration
The route of administration is the way through which the dosage form is administered into
the body for treatment of various diseases and disorders. Various routes of administrations
play a marked role in the bioavailability of the active drug in the body. Bioavailability is the
proportion of an administered drug that reaches the systemic circulation and is therefore
available for distribution to the intended site of action. Drugs that are given by direct IV
injection are said to have 100% bioavailability. Some drugs that are particularly well
absorbed by the gastrointestinal mucosa may have bioavailability comparable to that of an IV
dose – for example the antibiotic ciprofloxacin. Most drugs do not have this availability by
the oral route so the dose given orally is usually higher than that given parenterally. The route
of administration and its formulation (tablet, capsule, liquid) can clearly influence the
bioavailability of a drug. (P. Verma et al, 2010)
There are various routes of administration available, each of which has associated advantages
and disadvantages. All the routes of drug administration need to be understood in terms of
their implications for the effectiveness of the drug therapy and the patient’s experience of
drug treatment. Before administering a drug to a patient, these two factors should be
considered:
1. Pharmacodynamics (effect of drug on body)
2. Pharmacokinetics (effect of body on drug)
Pharmacodynamics deal with the site/mechanism of action, potency and efficacy while
Pharmacokinetics deal with absorption, distribution, metabolism, excretion of the drug after
consumption.
The different routes of administration are listed below:
A. Systemic Route
1. Enteral Route 2. Parenteral Route
 Oral
 Sublingual
 Rectal
 Intravenous
 Intramuscular
 Subcutaneous
 Inhalation

3. B. Local Route
C. Topical
D. Deeper Tissues
E. Arterial Supply
Systemic Route of Administration
Systemic administration is a route of administration of medication, nutrition or other
substance into the circulatory system so that the entire body is affected. Administration can
take place via enteral administration (absorption of the drug through the gastrointestinal tract)
or parenteral administration (generally injection, infusion, or implantation).
A. Enteral Routes:
It is the placement of drug directly into any part of the Gastro Intestinal Track (GIT).
I. Oral
The drug is taken through the mouth and it is absorbed from the gastro-intestinal tract.
e.g. Both solid dosage forms (e.g. tablets, capsules, powders) and liquid dosage forms
(e.g elixirs, syrups, emulsions, mixtures) can be given orally.
Advantages:
(i) It is safer, more convenient.
(ii) No assistance is required for administration.
(iii) It is painless.
(iv) The medicament need not be sterile and so is cheaper.
Disadvantages:
(i) Action is slower and thus not suitable for emergencies.
(ii) Unpalatable drugs are difficult to administer.
(iii) May cause nausea and vomiting.
(iv) Cannot be used for uncooperative / unconscious / vomiting patients.
(v) Certain drugs are not absorbed (e.g. streptomycin).
(vi) Some drugs are destroyed by digestive juices (e.g. penicillin G, insulin) or in liver
(e.g. testosterone).

4. II. Sublingual or Buccal
The tablet or pellet containing the drug is placed under the tongue (sublingual) or
crushed in the mouth and spread over the buccal mucosa. The drug is absorbed
through the buccal mucosa. e.g. isoprenaline, clonidine. (Stuti Gupta Singh et al,
2012)
Advantages:
(i) Absorption is relatively rapid - action can be produced in a minute.
(ii) One can spit the drug after the desired effect has been obtained.
(iii) The liver is bypassed and drugs with high first-pass metabolism can be absorbed
directly into the systemic circulation.
Disadvantages:
(i) Only lipid soluble and non-irritating drugs can be administered in this way.
(ii) Drugs with bad taste or objectionable odour are not possible to administer on the
tongue.
III. Rectal
The drug containing dosage form is either inserted or put into the rectum as
suppositories or retention enema. One part of the absorbed drug passes to the liver,
another part to the systemic circulation. (P. Verma et al, 2010)
Advantages:
(i) Drugs having bad taste or odour can be given through this route.
(ii) Drug that degrades in acidic pH of the gastric juice can be given through this
route.
(iii) This route can also be used when the patient is having recurrent vomiting.
Disadvantages:
(i) Administration of drug through this route is rather inconvenient and embarrassing.
(ii) Absorption is slower, irregular and often unpredictable.
(iii) Drug absorbed into external haemorrhoidal veins (about 50%) by-passes liver, but

5. not that absorbed into internal haemorrhoidal veins.
(iv) Rectal inflammation can result from highly irritant drugs.
e.g. Aminophylline, diazepam, ergotamine and few other drugs are sometimes given
rectally.
B. Parenteral Routes:
It is the administration of drugs by injection or by inhalation through the lungs. (
Shubhika Kwatra et al, 2012)
1. Intravenous
The drug is injected as a bolus or infused slowly over hours in one of the superficial
veins.
Advantages:
(i) The drug directly reaches the blood stream and effect is produced immediately,
hence, this route can be used in emergencies.
(ii) The inside of the veins is insensitive and drug gets diluted with blood quickly,
therefore, even highly irritant drugs can be injected intravenously.
(iii) Large volumes can be infused (e.g. normal saline).
(iv) It is useful in unconscious patients.
(v) Desired blood concentration can be achieved.
Disadvantages:
(i) Drugs that precipitate in the blood cannot be administered. Only aqueous solution
can be administered.
(ii) If the needle puncture the vessel then thrombophlebitis of the injected vein and
necrosis of the adjoining tissues may occur.
(iii) No drug can be given in depot form - so the action is not prolonged compared to
other parenteral administrations.
(iv) Once administered, withdrawal of the drug is not possible.

6. 2. Intramuscular injection
The drug is injected in one of the large skeletal muscles.
Advantages:
(i) Muscle is less richly supplied with sensory nerves, hence mild irritants can be
injected.
(ii) Muscle is more vascular hence absorption is faster than subcutaneous route.
(iii) It is less painful.
(iv) Depot preparations can be injected by this route and the action of the drug may be
prolonged.
Disadvantages:
(i) Since deep penetration is needed hence self-medication is not possible.
(ii) Large volume cannot be given.
3. Subcutaneous injection
The drug is injected under the skin. The drug is deposited in the loose subcutaneous
tissue which is richly supplied by nerves.
Advantages:
(i) Self injection is possible because deep penetration is not required.
(ii) Oily solutions or aqueous suspensions can form a depot which will release drug
slowly for a prolonged period.
Disadvantages:
(i) Since skin is richly supplied by nerve-endings hence irritant drugs cannot be
injected.
(ii) This route should be avoided in shock patients. e.g. Insulin injection.
4. Inhalation
The drug is administered through nose or mouth, carried by the air to reach the lungs
where alveoli, rich with capillary vessels are present and the drug is diffused into the
blood stream. Thus systemic action is obtained.

7. Advantages:
(i) Absorption takes place from the vast surface of alveoli - hence action is very rapid.
(ii) When administration is discontinued the drug diffuses back and is rapidly
eliminated in expired air. Thus controlled administration is possible with time to time
adjustment.
(iii) Bypasses the liver.
Disadvantages:
(i) Irritant vapours (ether) cause inflammation of respiratory tract and increase
secretion.
e.g. Volatile liquids and gases are given by inhalation- such as general anaesthetics,
amylnitrite.
Local Route of Administration
These routes can only be used for localized lesions at accessible sites. Systemic absorption of
the drug from these routes is minimal or absent. Thus high concentrations are attained at the
desired site without exposing the rest of the body. (P. Verma et al, 2010)
1. TOPICAL
This refers to external application of the drug to the surface for localized action.
(a) Skin: Drug is applied as ointment, cream, lotion, paste, powder, dressing etc.
(b) Mucous membrane: The dosage form depends on the site:
(i) Mouth and pharynx: Paints, lozenges, mouth washes, gargles.
(ii) Eyes, ears and nose: As drops, ointments, irrigation, and nasal spray.
(iii) Gastrointestinal tract: As non absorbable drugs given orally e.g. aluminum
hydroxide, kaolin, neomycin.
(iv) Bronchi and lungs: As inhalations, aerosols (nebulized solution or fine
powder) - e.g. salbutamol
(v) Urethra: As jellies e.g. lidocaine, irrigating solutions.
(vi) Vagina: As pessaries, vaginal tablets, inserts, cream, powders, douches.
(vii) Rectum: As ointment, suppositories.
2. DEEPER TISSUES
Certain deep areas can be approached by using a syringe and needle, but the drug

8. should be such that systemic absorption is slow;
e.g. intra-articular injection (hydrocortisone acetate)
3. ARTERIAL SUPPLY
In these cases the drug is injected into the artery that is supplying the blood to the
desired site (i.e., site for diagnosis or the cancerous tissues); the drug is conveyed
by the blood flow towards the tissue it is perfusing and not towards the heart, thus
systemic action is avoided and localized action is achieved.
Advantages of Topical Drug Delivery Systems:
 Avoidance of first pass metabolism.
 Convenient and easy to apply.
 Avoidance of the risks and inconveniences of intravenous therapy and of the
varied conditions of absorption, like pH changes, presence of enzymes, gastric
emptying time etc.
 Achievement of efficacy with lower total daily dosage of drug by continuous
drug input.
 Ability to easily terminate the medications, when needed.
 Ability to deliver drug more selectively to a specific site.
 Avoidance of gastro-intestinal incompatibility.
 Providing utilization of drugs with short biological half-life, narrow
therapeutic window.
 Improving physiological and pharmacological response.
 Improve patient compliance.
 Provide suitability for self-medication.
Disadvantages of Topical Drug Delivery Systems:
 Skin irritation of contact dermatitis may occur due to the drug and/or
excipients.
 Poor permeability of some drugs through the skin.
 Possibility of allergenic reactions.
 Can be used only for drugs which require very small plasma concentration for
action

9.  Enzyme in epidermis may denature the drugs
 Drugs of larger particle size not easy to absorb through the skin
Conclusion
The topical drug delivery system is generally used where the others system of drug
administration fails. ( Shubhika Kwatra et al, 2012). In the current scenario, Transdermal and
Parenteral are the leading routes of drug administration, other than the most common route-the
Oral route. They help overcome the bioavailability and absorption problems associated
with the Oral route. Thus, the efficacy of the therapy increases. Transdermal medication
delivers a steady infusion of drug over a prolonged period of time, thereby providing
controlled drug delivery and increasing patient compliance. When the drug is administered
parenterally or in the form of transdermal patches, it is not subjected much to first pass
metabolism and hence the bioavailability of the drug is more.
The preferable mode of administration also depends on the onset of Action (The length of
time needed for a medicine to give its action. This time varies for different types of routes of
administrations.)
Onset of action of different routes is as follows:-
•Intravenous 30-60 seconds
•Intraosseous 30-60 seconds
•Inhalation 2-3 minutes
•Sublingual 3-5 minutes
•Intramuscular 10-20 minutes
•Subcutaneous 15-30 minutes
•Rectal 5-30 minutes
•Oral 30-90 minutes
•Topical/transdermal (minutes to hours)
We can observe that the parenteral route is the fastest one and provides an immediate
response on usage.

10. References
(1) P. Verma, A.S. Thakur, K. Deshmukh, Dr. A.K. Jha, S. Verma, 2010, ROUTES OF
DRUG ADMINISTRATION, International Journal of
Pharmaceutical Studies and Research, Vol. I/ Issue I/July-September,2010/Pg.54-59
Electronic journal available on:
http://www.technicaljournalsonline.com/ijpsr/VOL%20I/IJPSR%20VOL%20I%20ISSUE
%20I%20JULY%20SEPTEMBER%202010/IJPSR%20VOL%20I%20ISSUE%20I%20A
rticle%208.pdf
[Accessed on 3rd September 2013]
(2) Shubhika Kwatra, Guncha Taneja, Nimisha Nasa, 2012, Alternative Routes of Drug
Administration- Transdermal, Pulmonary & Parenteral, Indo Global Journal of
Pharmaceutical Sciences; 2(4): 409-426
Electronic journal available on: http://iglobaljournal.com/wp-content/uploads/2013/02/9.-
Shubhika-Kwatra-et-al-2012.pdf
[Accessed on 3rd September 2013]
(3) Stuti Gupta Singh, Ravindra Pal Singh, Shivjee Kumar Gupta, Renu Kalyanwat,
Sudhir Yadav, 2011, Buccal Mucosa as a route for Drug Delivery: Mechanism, Design
and Evaluation, Research Journal of Pharmaceutical, Biological and Chemical
Sciences Volume 2 Issue 3:358-372
Electronic journal available on: http://www.rjpbcs.com/pdf/2011_2%283%29/43.pdf
[Accessed on 3rd September 2013]