Drugs may be administered by various routes. The choice of the route in a given patient depends on the tissue or organ to be treated, the characteristics of the drug and urgency of the situation, etc. Knowledge of the advantages and disadvantages of the different routes of administration is essential. The routes can be broadly divided into Enteral, Parenteral, and Local.

1. Prof. Amol B. Deore
Department of Pharmacology
MVP’s Institute of Pharmaceutical Sciences, Nashik
ROUTES OF DRUG ADMINISTRATION

2. Introduction
The choice of the route in a given patient depends
 on the tissue or organ to be treated,
 the characteristics of the drug and
 urgency of the situation

3. Classification of routes of drug administration

4. ROUTES OF DRUG ADMINISTRATION
Parenteral
1. Inhalational
2. Intravenous
3. Intramuscular
4. Intradermal
5. Subcutaneous
6. Jet injection
7. Intracardiac
8. Intra-spinal
9. Intra-medullary
10. Intra-arterial
11. Intra-articular
12. Intraperitoneal
13. Intrathecal
14. Intra-pleural
15. Retrobulbar
16. Transdermal
17 Transmucosal
Enteral
1. Oral
2. Sublingual
3. Rectal
Local
1. Skin topical
2. Intranasal
3. Ocular drops
4. Transdermal

5. ENTERAL ROUTES

6. Enteral route sub-types
Oral
Sublingual
Rectal

7. Oral route
 Most drugs can be administered by orally.
 for their systemic effect.
 In the form of tablets, capsules, powders, solutions, syrups
or suspensions etc.
 Drugs pass through the stomach and be absorbed in the
intestinal tract.
 Orally dosage forms are usually easy to take/
 usually less expensive than other dosage forms.

8. Oral administration of tablet

9. Advantages of oral route
• Most commonly used method
• Safe, convenient and painless procedure.
• Economical as sterilization of drug products is not essential
• Easy to administer the dosage.
• No need of any assistant or special technique.
• Self-medication is possible.
• Drug withdrawal is easily possible in case of overdose
• Useful in children as well as adult patients.
• Prolong duration of action.

10. Disadvantages of oral route
 Onset of action is slower (30-90 min)
 Polar drugs can't be given as they are not absorbed
 Inactivation by digestive juices (penicillin-G, insulin,
oxytocin).
 Acid sensitive drugs (penicillin-G).
 Presence of food in stomach
 first pass metabolism (for example- morphine,
isoprenaline).

11. Disadvantages (to be continued)
 Bad taste and unpleasant smell and irritant drugs
 Unconscious and uncooperative patients.
 During emesis and diarrhea.
 Antibiotics like tetracycline cause brown color staining
on teeth as well as nails in infants.

12. SUBLINGUAL
 Placing a drug under your tongue (sublingual cavity) to
dissolve and absorb.
 The cheek and sublingual cavity have network of blood
capillaries.
 drugs can be absorbed directly into the bloodstream
 Patients must be instructed not to swallow the tablet
and water should not be taken immediately after the
tablet to ensure proper sublingual absorption.

13. Sublingual administration of tablet

14. Products: Sublingual tablets

15. Advantages of sublingual route
 Quick onset of action (3-5 min).
 Rapid drug absorption
 important during emergencies such as during a heart
attack, angina pectoris etc.
 Drugs do not go through the digestive system, so they
aren’t metabolized through your liver.
 Drug withdrawal easily possible
 Sterilization of dosage form not required.

16. Disadvantages of sublingual route
• Drugs with bitter taste, unpleasant odour and irritant
• Not suitable in unconscious patients.
• Drug rapidly absorbed and reaches to certain organs like
heart, liver, kidney, brain and lungs.
• Hence there are chances of organ toxicity
• Higher molecular weight drugs can't be absorbed (for
example- insulin).

17. RECTAL ROUTE
 Rectal administration involves administration of medication
and other fluids,
 which are absorbed by the rectum's blood vessels, and
absorb into the body's circulatory system, which distributes
the drug to the body organs.
 The rectal route of administration is useful for patients
with any digestive tract motility problem,
 such as dysphagia, ileus, or bowel obstruction that would
interfere with the progression of the medication through
the tract.

18. Rectal administration
• A suppository, a drug delivery system inserted into the
rectum.
• An enema, the act of introducing a liquid-drug solution
into the rectum and sometimes into the colon.
• A specialized catheter designed for rectal
administration of medications and liquids.

19. For example- Rectal administration
for Local action
• Bisacodyl and glycerin suppositories, enemas, ointments
for systemic action
• aminophylline and indomethacin suppositories

20. Inserting a Rectal Suppository

21. PARENTERAL ROUTES

22. PARENTERAL ROUTES
 Means to avoid the gastrointestinal tract.
 Drugs are directly delivered into tissue fluids or blood.
 Injectable drugs enter into the body directly.
 Not required to gastrointestinal absorption of drugs.
 Requires skilled medical personnel
 Requires a syringe and needle or a catheter with aseptic
precautions.
 rapid onset of action
 must be sterile (free from living microbes).

23. Parenteral routes and their angle of needle insertion

26. INTRAVENOUS
• The drug is injected into one of the superficial
• it directly reaches the circulation
• immediately available for action.
• Drugs can be given IV as: a bolus, slow injection and slow
infusion

27. IV administration of drug injection

28. Site of injection:
• bulged cubital
or cephalic
veins of arm
Angle of needle
insertion
• 20-30˚
Dosage form:
• aqueous
solution
Onset of action
• 30-60 seconds
(most rapid
onset of action)
For examples: glucose, normal saline, dopamine and
noradrenaline drips

29. IV administration of drug injection

30. Advantages of IV route
• Drug directly enters into the systemic circulation and no
first pass metabolism
• Permits 100 % drug bioavailability
• Quicker onset of action
• Permits accurate dose of drugs
• Low dose is needed to achieve greater therapeutic
effects
• Generally about one litre of saline solution is infused
over 3 to 4 hours.

31. • Large volume of fluids can be infused at a uniform rate
• Most useful route in emergencies because the drug is
immediately available for action
• Can be given in unconscious, uncooperative patients those
are having nausea, vomiting and diarrhea
• Hypertonic solutions and GIT irritant drugs can be infused

32. Disadvantages of IV route
• Strict aseptic conditions are needed
• Self-medication is not possible. Patient has to depend upon
other skilled person for administration of drug
• Painful and risky
• Drug withdrawal is very critical in cases of overdose or
poisoning
• Introduction of any air or particulate matter produce
embolism which is deadly (fatal)

33. • Identification of cubital and cephalic vein little bit difficult
in obese (overweight), infant or old age patients.
• Accidents like venous thrombosis and thrombophlebitis
• Tissue necrosis around the site of action
• not suitable for oily preparations
• not suitable for suspensions and insoluble preparations

34. INTRADERMAL
• In this route, the drug is injected into the (top few layers) of
the skin. Ideally, the drug is placed within the dermis.
• The intradermal route is used almost exclusively for
diagnostic agents.
• Site of injection: skin
• Angle of needle insertion: 30˚
• Dosage form: solution, suspension

35. Intradermal administration of drug injection

36. Advantages of Intradermal route
• Certain drugs given intradermaly for allergic testing eg.
Penicillin, cephalosporin etc.
• Certain vaccines administered by intradermal route
• for example- BCG vaccine, small pox, diphtheria, hepatitis,
scarlet fever vaccine
• The mantoux skin test for diagnosis of tuberculosis
performed by injecting tuberculin intradermaly.

37. Disadvantages of Intradermal route
• Onset of action is very slow but prolong duration of action
• Volume of injection is very small i.e. 0.1 to 0.3 mL

38. SUBCUTANEOUS ROUTE
 the injection of the drug under the skin into the fatty layer,
but not into the muscle.
 reliable and patients can be trained for self-administration.
 absorption is slow and largely uniform making the drug
long-acting.

39. epinephrine pen injection Insulin pen injection

40. • Site of injection: Abdomen: at or under the level of the
belly button, back or side of the upper arm and front of the
thigh
• Dosage form: solution, suspension
• Onset of action: 15-30 min
For example: Insulin, metoclopramide, heparin,
dexamethasone

41. Subcutaneous administration of drug injection

42. INTRAMUSCULAR ROUTE
• used when drugs are injected deeply into muscle tissue.
• If the drug is in aqueous (water) solution, absorption is
rapid.
• if the drug is in an oily liquid or in the form of a suspension,
it can prolong the release of the drug.
• Deltoid muscle of buttock and Vastus muscle of the thigh
is common site

43. Site of injection: Deltoid, triceps, gluteus or rectus femoris
muscle
Angle of needle insertion: 90˚
Dosage form: aqueous solution, oily solution, suspension,
irritants, colloids
Onset of action: 10-20 min
Volume of injection: less than 10 mL
For example: injection of antibiotics, vitamin B12

45. IM administration of drug injection

46. Advantages of IM route
• Drug absorption is rapid.
• Oil soluble drugs, mild irritants, depot preparations,
suspensions and colloids can be injected.

47. Disadvantages of IM route
• Very painful and may even result in an abscess.
• Irritant solutions can damage the nerve if injected near a nerve.
• Chances of abscess at the site of injection
• an abscess is a painful collection of pus, usually caused by a bacterial
infection
• Chances of nerve damage leading to partial paralysis of muscle
supplied by it
• Large volumes can't be given (maximum 5 – 10 mL)

48. INHALATION ROUTE
• Inhalation is a means of administration of medications through the
respiratory system in the form of a gas, vapor, etc.
• In this way drugs can pass directly to the lungs.
• major types: vaporization, gas inhalation, and nebulization.
• Vaporization is the process by which a drug is changed from a liquid
or solid to a gas or vapor by the use of heat (such as in steam
inhalation).
• Equipment used for inhalation route include ventilator, inhaler,
nebulizer, inhalation pump, metered dose container and oral pump.

50. • Volatile liquids and gases are given by inhalation, e.g. general
anesthetics.
• In addition, drugs can be administered as solid particles, i.e. solutions
of drugs can be atomized and the fine droplets are inhaled as aerosol,
e.g. salbutamol.
• These inhaled drugs and vapors may act on the pulmonary epithelium
and mucous membranes of the respiratory tract and are also
absorbed through these membranes.
• For example: general anesthetics, aerosol of salbutamol and
ipratropium bromide

51. Ventilator

52. Metered Dose inhalers

53. Advantages of inhalation route
• certain critical emergency cases like bronchial asthma, hypoxia,
apnea, angina pectoris, trauma, surgery and general anesthesia
• Hepatic first pass metabolism is avoided
• Rapid onset of action takes place (1-3 min)
• This route has minimum side effects
• Almost instantaneous absorption of the drug is achieved because of
the large surface area of the lungs.

54. Disadvantages of inhalation route
• Special equipments are required
• Irritation of the respiratory tract may take place
• Cooperation of the patient is required
• Irritant gases may enhance pulmonary secretions—should be
avoided.
• This is an important route of entry of certain drugs of abuse.

55. LOCAL/TOPICAL

56. • Topical drugs are applied to a surface area of the body.
• Topically applied drugs serve two purposes:
Local effect and Systemic effect.
• For local effect, the drug is intended to relieve itching, burning,
or other skin conditions without being absorbed into the
bloodstream.
• For systemic effect, the drug is absorbed through the skin into
the blood circulation.
• ointments, creams, lotions, Transdermal patches, powders, eye
drops, ear drops, and shampoos.

59. Prof. Amol Deore