There are several routes of drug administration that determine how quickly a drug acts and is absorbed in the body. Oral administration is the most common and involves swallowing drugs, but this can result in first-pass liver metabolism. Sublingual and buccal routes under the tongue and cheek provide rapid absorption bypassing the liver. Parenteral routes like intravenous injection place drugs directly in the bloodstream for immediate effect. Other routes include intramuscular, rectal, inhalation and topical application to skin or mucous membranes. Proper administration depends on the drug properties and patient needs.

1. ROUTES OF DRUG
ADMINISTRATION

2. Oral Medications (p.o.)
• Pills Must Dissolve/Breakdown
• Syrups/Suspensions are more rapid onset
• Most Absorbed in Small Intestine
• compressed tablet
– must be “scored” to divide

3. Sustained Release Oral
• Do Not Break
• Enteric Coated
• Beads or Granules
• Matrix i.e. Slow K
• Repeat action i.e.
Chlor-Trimetron
• Osmotic Pump i.e.
Acutrim

4. Sublingual / Buccal
• Rapid absorption and response
• Highly vascular areas
• Avoids “First Liver Bypass”

6. Rectal
• Advantages
– nausea, NPO, difficulty swallowing
– avoids first liver bypass
• Disadvantages
– Maybe erratic absorption
– May cause irritation

8. Definition:
A route of administration is
the path by which a drug,
fluid, poison or other
substance is brought into
contact with the body.

9. Routes of Drug Administration
The route of administration (ROA) that
is chosen may have a profound effect
upon the speed and efficiency with
which the drug acts
Important
Info

10. • The possible routes of drug entry into
the body may be divided into two
classes:
–Enteral
–Parenteral

11. Classification
Routes of administration can broadly be divided into:
• Topical: Drugs are applied topically to the skin or mucous
membranes, mainly for local action.
• Oral: used for systemic (non-local) effect, substance is given via
the digestive tract.
• Parenteral: A drug administered parenterally is one injected via
a hollow needle into the body at various sites and to varying
depth.
• Rectal: Drugs given through the rectum by suppositories or
enema.
• Inhalation: The lungs provide an excellent surface for
absorption when the drug is delivered in gaseous, aerosol or
ultrafine solid particle form.

12. ROUTES OF ADMINISTRATION

13. Enteral Routes
• Enteral - drug placed directly in the GI tract:
–sublingual - placed under the
tongue
–oral - swallowing (p.o., per os)
–rectum - Absorption through the
rectum

14. 1- Topical route:
I Skin
A-Dermal – cream, ointment (local action)
B- Transdermal- absorption of drug through skin (i.e systemic action)
I. stable blood levels(controlled drug delivery system)
II. No first pass metabolism
III. Drug must be potent or patch becomes too large
II Mucosal membranes
•eye drops (onto the conjunctiva)
• ear drops
• intranasal route (into the nose)

15. 2- Oral route:
- By swallowing.
- It is intended for systemic effects resulting
from drug absorption through the various
epithelia and mucosa of the gastrointestinal
tract.

16. Advantages:
1- Convenient - portable, no pain, easy to take.
2- Cheap - no need to sterilize, compact, multi-dose bottles,
automated machines produce tablets in large quantities.
3- Variety - tablets, capsules, suspensions, mixtures .
2 -Oral route (Cont.)

17. Disadvantages:
1- Sometimes inefficient - low solubility drugs may
suffer poor availability e.g. Griseofulvin
2- First-pass effect - drugs absorbed orally are
transported to the general circulation via the liver. Thus
drugs which are extensively metabolized will be
metabolized in the liver during absorption. e.g.
propranolol
2- Oral route (Cont.)

18. First-pass Effect
• The first-pass effect is the term used for the
hepatic metabolism of a pharmacological
agent when it is absorbed from the gut and
delivered to the liver via the portal
circulation. The greater the first-pass effect,
the less the agent will reach the systemic
circulation when the agent is administered
orally

19. First-pass Effect cont.
Magnitude of first pass hepatic effect:
Extraction ratio (ER)
ER = CL liver / Q ; where Q is hepatic
blood flow (usually about 90 L per hour.
Systemic drug bioavailability (F) may be
determined from the extent of absorption
(f) and the extraction ratio (ER):
F = f x (1 -ER)

20. First pass effect:
First pass effect

21. - The first pass effect is the term used for the
hepatic metabolism of a pharmacological
agent when it is absorbed from the gut and
delivered to the liver via the portal circulation.
- The greater the first pass effect, the lower
the bioavailability of the drug(the rate and
extent of the drug reaching systemic
circulation).
First pass effect (Cont.):

22. 3- Food - Food and G-I motility can affect drug absorption.
Often patient instructions include a direction to take with
food or take on an empty stomach.
- Absorption is slower with food(milk and milk products) for
tetracyclines and penicillins, etc. However, for
propranolol bioavailability is higher after food, and for
griseofulvin absorption is higher after a fatty meal.
2-Oral route (Cont.):

23. 4- Sometimes may have adverse reactions –
e.g. Antibiotics may kill normal gut flora and
allow overgrowth of fungal varieties. Thus,
antifungal agent may be included with an
antibiotic.
5- Not suitable for unconscious patient -
Patient must be able to swallow solid
dosage forms. Liquids may be given by tube.
2- Oral route (Cont.)

24. 6- May cause irritation to gastric mucosa,
nausea and vomiting.
7- Effect too slow for emergencies.
2-Oral route (Cont.)

25. Oral
• Advantages
– Convenient - can be self- administered, pain
free, easy to take
– Absorption - takes place along the whole
length of the GI tract
– Cheap - compared to most other parenteral
routes

26. Oral
• Disadvantages
– Sometimes inefficient - only part of the drug may
be absorbed
– First-pass effect - drugs absorbed orally are initially
transported to the liver via the portal vein
– irritation to gastric mucosa - nausea and vomiting

27. Oral
• Disadvantages cont.
– destruction of drugs by gastric acid and digestive
juices
– effect too slow for emergencies
– unpleasant taste of some drugs
– unable to use in unconscious patient

28. 3- Buccal/Sublingual route:
• Some drugs are taken as smaller tablets which are held in
the mouth (buccal tablet) or under the tongue
(sublingual tablet).
• Buccal tablets are often harder tablets [4 hour
disintegration time], designed to dissolve slowly.
• E.g Nitroglycerin, as a softer sublingual tablet [2 min
disintegration time], may be used for the rapid relief of
angina.

29. Advantages
1- Avoid hepatic first pass - The liver is by-passed thus there is
no loss of drug by first pass effect for buccal administration.
Bioavailability is higher.
2- Rapid absorption - Because of the good blood supply to the
area, absorption is usually quite rapid.
3- Drug stability - pH in mouth relatively neutral (gf. stomach -
acidic). Thus a drug may be more stable.
3- Buccal/Sublingual route (Cont.)

30. Disadvantages
1- Holding the dose in the mouth is
inconvenient.
2- Small doses only can be accommodated
easily.
3- Buccal/Sublingual route (Cont.)

31. Sublingual/Buccal
Some drugs are taken as smaller tablets which
are held in the mouth or under the tongue.
• Advantages
– rapid absorption
– drug stability
– avoid first-pass effect

32. Sublingual/Buccal
• Disadvantages
– inconvenient
– small doses
– unpleasant taste of some drugs

33. 4- Parenteral route:

34. A- Intravascular (IV, IA):
- placing a drug directly into blood stream.
-May be - Intravenous (into a vein) or - intraarterial (into an artery).
Advantages
1- precise, accurate and immediate onset of action, 100% bioavailability.
Disadvantages
1- risk of embolism.
2- high concentrations attained rapidly leading to greater risk of adverse
effects.
4- Parenteral route (Cont.)

35. 4- Parenteral route (Cont)
B-Intramuscular :(into the skeletal muscle).
Advantages
1- suitable for injection of drug in aqueous solution (rapid action)
and drug in suspension or emulsion (sustained release).
Disadvantages
1- Pain at injection sites for certain drugs.

36. C- Subcutaneous (under the skin), e.g. insulin.
D- Intradermal, (into the skin itself) is used for skin testing some
allergens.
E- Intrathecal (into the spinal canal) is most commonly used for spinal
anesthesia .
F- Intraperitoneal, (infusion or injection into the peritoneum) e.g.
peritoneal dialysis in case of renal insuffeciency.
4- Parenteral route (Cont)

37. 5-Rectal route:
Most commonly by suppository or enema.
Advantages
1- By-pass liver - Some of the veins draining the rectum lead directly to the
general circulation, thus by-passing the liver. Reduced first-pass effect.
2- Useful - This route may be most useful for patients unable to take drugs
orally (unconscious patients) or with younger children.
- if patient is nauseous or vomiting

38. Disadvantages
1- Erratic absorption - Absorption is often
incomplete and erratic.
2- Not well accepted.
5- Rectal route (Cont.)

39. 6- Inhalation route:
- Used for gaseous and volatile agents and aerosols.
- solids and liquids are excluded if larger than 20 micron. the particles
impact in the mouth and throat. Smaller than 0.5 micron , they aren't
retained.
Advantages
A- Large surface area
B- thin membranes separate alveoli from circulation
C- high blood flow
- As result of that a rapid onset of action due to rapid access
to circulation.

40. Disadvantages
1- Most addictive route of administration because it hits the
brain so quickly.
2- Difficulties in regulating the exact amount of dosage.
3- Sometimes patient having difficulties in giving themselves a
drug by inhaler.
6- Inhalation route (Cont.)

41. 1. unconscious patients and children
2. if patient is nauseous or vomiting
3. easy to terminate exposure
4. absorption may be variable
5. good for drugs affecting the bowel such
as laxatives
6. irritating drugs contraindicated
Rectal

42. Parenteral Routes
– Intravascular (IV, IA)- placing a drug directly into
the blood stream
– Intramuscular (IM) - drug injected into skeletal
muscle
– Subcutaneous - Absorption of drugs from the
subcutaneous tissues
– Inhalation - Absorption through the lungs

45. Intravascular
Absorption phase is bypassed
(100% bioavailability)
1.precise, accurate and almost immediate onset of
action,
2. large quantities can be given, fairly pain free
3. greater risk of adverse effects
a. high concentration attained rapidly
b. risk of embolism
c. OOPS factor or !@#$%

46. Intramuscular
1. very rapid absorption of drugs in aqueous
solution
2.repository and slow release preparations
3.pain at injection sites for certain drugs

47. Subcutaneous
1. slow and constant absorption
2. absorption is limited by blood flow,
affected if circulatory problems exist
3. concurrent administration of
vasoconstrictor will slow absorption

48. 1.gaseous and volatile agents and aerosols
2.rapid onset of action due to rapid access to
circulation
a.large surface area
b.thin membranes separates alveoli from
circulation
c.high blood flow
Particles larger than 20 micron and the particles impact
in the mouth and throat. Smaller than 0.5 micron and
they aren't retained.
Inhalation

49. Inhalation cont.
• Respiratory system. Except for IN, risk hypoxia.
• Intranasal (snorting) Snuff, cocaine may be partly oral via post-
nasal dripping. Fairly fast to brain, local damage to septum.
Some of the volatile gases also appear to cross nasal membranes.
• Smoke (Solids in air suspension, vapors) absorbed across lung
alveoli: Nicotine, opium, THC, freebase and crack cocaine,
crystal meth.Particles or vapors dissolve in lung fluids, then
diffuse. Longer action than volatile gases. Tissue damage from
particles, tars, CO.
• Volatile gases: Some anaesthetics (nitrous oxide, ether) [precise
control], petroleum distillates. Diffusion and exhalation
(alcohol).
• Lung-based transfer may get drug to brain in as little as five
seconds.

50. Topical
•Mucosal membranes (eye drops, antiseptic,
sunscreen, callous removal, nasal, etc.)
•Skin
a. Dermal - rubbing in of oil or ointment
(local action)
b. Transdermal - absorption of drug through
skin (systemic action)
i. stable blood levels
ii. no first pass metabolism
iii. drug must be potent or patch
becomes to large

51. • intravenous 30-60 seconds
• intraosseous 30-60 seconds
• endotracheal 2-3 minutes
• inhalation 2-3 minutes
• sublingual 3-5 minutes
• intramuscular 10-20 minutes
• subcutaneous 15-30 minutes
• rectal 5-30 minutes
• ingestion 30-90 minutes
• transdermal (topical) variable (minutes to hours)
Route for administration
-Time until effect-

52. Time-release preparations
• Oral - controlled-release, timed-release,
sustained-release
– designed to produce slow,uniform absorption
for 8 hours or longer
– better compliance, maintain effect over night,
eliminate extreme peaks and troughs

53. Time-release preparations
• Depot or reservoir preparations -
parental administration (except IV), may
be prolonged by using insoluble salts or
suspensions in non-aqueous vehicles.

54. The ROA is determined by the
physical characteristics of the
drug, the speed which the drug is
absorbed and/ or released, as well
as the need to bypass hepatic
metabolism and achieve high
conc. at particular sites
Important
Info

55. No single method of drug
administration is ideal for all
drugs in all circumstances

56. Oral Drugs
• Oral medications should be poured and
measured at eye level to ensure accuracy.

57. Parenteral Drugs
• Although the physician will determine the
dose and route of a parenteral drug, the
nurse is responsible for choosing the correct
gauge and length of the needle to be used.

58. Equipment to Administer Parenteral
Drugs
• Syringes (three basic parts: the hub, the
barrel, the plunger).
• Needles (three basic parts: the hub, the
cannula, or shaft, and the bevel).
• Ampules (glass containers of single-dose
drugs).
• Vials (glass, single- or multiple-dose rubber-
capped drug containers).

59. Intradermal Injection
• Injections typically used to diagnose
tuberculosis, identify allergens, and
administer local anesthetics.

60. Subcutaneous Injection
• Injections into the subcutaneous tissue,
between the dermis and the muscle.
• Commonly used in the administration of
medications such as insulin and heparin.

61. Intramuscular Injection
• Used to promote rapid drug absorption and
to provide an alternate route when the drug
is irritating the subcutaneous tissue.

62. Intravenous Therapy
• Requires parenteral fluids (hypotonic fluid,
isotonic fluid, hypertonic fluid)
• Special equipment needed:
– Administration set.
– IV pole.
– Filter.
– Regulators to control IV flow rate.
– Established venous route.

63. Blood Transfusion
• To replace blood loss (deficit) with whole
blood or blood components.
• Special equipment needed:
–Administration set.
–IV pole.
–Filter.
–Regulators to control IV flow rate.
–Established venous route.

64. The Importance of Monitoring
• The nurse must always carefully monitor
client reactions to medications and ensure
that clients are appropriately educated as to
the actions, side effects, and
contraindications of all medications they are
receiving.
• Clients receiving IV therapy or blood
transfusions require constant monitoring for
complications.

65. Topical Medications
• Eye medications.
• Ear medications.
• Nasal instillations.
• Respiratory
inhalants.
• Rectal instillations.
• Vaginal instillations.

66. Transdermal
• Absorbed through the skin at a slow, steady
rate
• Method:
– BSI
– Clean administration site
– Apply medication
– Leave medication in place for required time.
Monitor the patient for desirable or adverse
effects.

67. Mucous Membranes
• Absorbed through the mucous membranes at
a moderate to rapid rate

68. Place the pill or direct spray between the underside of the tongue and the floor
of the oral cavity.
Sublingual Medication
Administration

69. Place the medication between the patient’s cheek and gum.
Buccal Medication Administration

70. Use a medication dropper to place the
prescribed dosage on the conjunctival sac.
Eye Drop Administration

71. Nasal Medication Administration

72. Manually open the ear canal and administer the appropriate dose.
Aural Medication Administration

73. Pulmonary Drug Administration
• Medications are administered into the
pulmonary system via inhalation or injection.

74. Small volume nebulizer

75. Nebulizer with
attached face mask,
bag-valve mask, and
endotracheal tube

76. Metered dose inhaler

77. Endotracheal Tube
• Several medications can be administered
through an endotracheal tube:
– Lidocaine
– Epinephrine
– Atropine
– Naloxone

78. Enteral Drug Administration
• The delivery of any medication that is
absorbed through the gastrointestinal tract

79. Gastrointestinal tract