The document discusses the various routes of drug administration including local and systemic routes. Local routes deliver drugs to specific localized areas without systemic absorption, including topical, deeper tissues, and arterial supply routes. Systemic routes deliver drugs via absorption into blood circulation to achieve widespread distribution throughout the body, including oral, sublingual/buccal, rectal, inhalation, nasal, cutaneous, and parenteral routes. Parenteral routes involve injection directly into tissues or bloodstream, such as intramuscular, subcutaneous, intravenous, and intradermal injections. Factors such as drug properties, site of action, absorption rate, first-pass metabolism, desired speed of effect, dosage accuracy, and patient condition determine

1. ROUTES OF DRUG
ADMINISTRATION
Presented By:
Ritu Gupta
PG 1ST Year
Dept of Conservative
Dentistry and
Endodontics,
PDA, Bhopal (M.P.)

2. CONTENTS
• Introduction
• Factors governing choice
of route
• Classification
• Local routes
1. Topical
2. Deeper tissues
3. Arterial supply
• Systemic routes
1. Oral
2. Sublingual/ buccal
3. Rectal
4. Inhalation
5. Nasal
6. Cutaneous
7. Parenteral
-intramuscular
-subcutaneous
-intravenous
-intradermal injection
• References

3. • Most drugs can be administered by a variety of
routes.
• The choice of appropriate route in a given
situation depends both on drug as well as patient
related factors
• Mostly common sense considerations, feasibility
and convenience dictate the route to be used
• Routes can be broadly divided into
those for
a) local action b) systemic action

4. FACTORS GOVERNING CHOICE OF ROUTE
1. Physical and chemical properties of the drug (solid,
liquid, gas: solubility, stability, pH, irritancy)
2. Site of desired action - localized and approachable or
generalized and not approachable
3. Rate and extent of absorption of the drug from
different routes
4. Effect of digestive juices and first pass metabolism on
the drug
5. Rapidly with which the response is desired (routine
treatment or emergency)
6. Accuracy of dosage required (i.v. and inhalational can
provide fine tuning)
7. Condition of the patient (unconscious, vomiting)

5. CLASSIFICATIO
N
SYSTEMIC LOCAL
ENTERAL PARENTERAL • Skin topical
• Intranasal
• Ocular drops
• Mucosal throat,
vagina, mouth, ear
• Inhalational
• Transdermal
• Oral
• Sublingual
• Rectal
• Inhalational
• Injections
• Transdermal
1. Intravenous
2. Intramuscular
3. Subcutaneous
4. Intra-arterial
5. Intra-articular
6. Intrathecal
7. intradermal

7. LOCAL ROUTES
• These routes can only be used for localized
lesions at accessible sites and for drugs whose
systemic absorption from these sites is
minimal or absent
• Thus, high concentrations are attained at
desired site without exposing the rest of the
body
• Systemic side effects or toxicity are
consequently absent or minimal

8. • TOPICAL : refers to external application of the
drug to the surface for localized action
Oral cavity : as ointment or
jelly
e.g. 5% lignocaine hydrochloride
GI Tract : non absorbable drugs
given orally e.g. neomycin,
Vancomycin (for sterilization of
gut before surgery)

9. Bronchi :inhalation of
drugs e.g. salbutamol,
cromolyn sodium
Eye, ear, nose : as
drops, ointments and
sprays (for infection,
allergic conditions,
etc.) e.g. gentamicin
eye/ear drops

10. • DEEPER TISSUES
a) Certain deep areas can be
approached by using a
syringe and needle, but the
drug should be in such a
form that systemic
absorption is slow
•Infiltration around a
nerve or intrathecal
injection (lidocaine)

11. • Intra-articular
injection
(hydrocortisone
acetate in knee joint)
• Retrobulbal injection
(hydrocortisone
acetate behind the
eyeball)

12. • ARTERIAL SUPPLY
1. Close intra arterial injection is used for contrast
media in angiography
2. Anti-cancer drugs can be infused in femoral or
brachial artery to localize the effect for limb
malignancies.

13. SYSTEMIC ROUTES
• The drug administered through systemic routes is
intended to be absorbed into the blood stream
and distributed all over, including the site of
action , through circulation

14. Vascular pathway of drugs absorbed from various systemic
routes of administration and sites of first pass metabolism
NOTE: Total drug absorbed
orally is subjected to first
pass metabolism in
intestinal wall and liver,
while approximately half of
that absorbed from rectum
passes through liver. Drug
entering from any systemic
route is exposed to first
pass metabolism in lungs,
but its extent is minor for
most drugs

15. 1. ORAL
• Oldest and commonest mode of drug
administration
• Safer, convenient, does not need assistance,
noninvasive , often painless and is cheaper
• Both solid dosage forms and liquid dosage forms
can be given orally

16. LIMITATIONS OF ORAL ROUTE
• Action of drugs is slower and thus not suitable for
emergencies
• Unpalatable drugs(chloramphenicol) are difficult to
administer; drug may be filled in capsules to
circumvent this
• May cause nausea and vomiting
• Cannot be used for uncooperative/ unconscious /
vomiting patient
• Absorption of the drug may not be variable and
erratic; certain drugs are not absorbed
(streptomycin)
• Others are destroyed by digestive juices (penicillin
G, insulin)or in liver (GTN, Testosterone, lidocaine)

17. 2. SUBLINGUAL / BUCCAL
• The tablet/pellet containing the drug is placed
under the tongue(sublingual) or between the gums
and cheek region (buccal mucosa).
• The drug absorbed through the sublingual/buccal
mucous membrane and enters the systemic
circulation directly through internal jugular veins(
systemic veins) rather than the portal veins thus
bypassing first pass metabolism
• Absorption is relatively rapid- action can be
produced within minutes
• Though, it is somewhat inconvenient, one can spit
the drug after the desired effect has been obtained

19. • Liver is bypassed and drugs with
high first pass metabolism can be
absorbed directly into systemic
circulation
• Drug stability maintained because
the pH of saliva is relatively neutral
Advantages
• Only lipid soluble and non
irritating drugs can be so
administered
• May lose part of drug dose if
swallowed
Disadvantages

20. • Drugs given sublingually are GTN,
buprenorphine, desamino-oxytocin

21. 2010
Available for
Montelukast sodium to
treat asthms, alleric
conditions
Dodou K. Research and Development in buccal and sublingual drug delivery systems. The
Pharmaceutical Journal Apr 2018 : Vol 288 ; p446
2010

22. Dodou K. Research and Development in buccal and sublingual drug delivery systems. The
Pharmaceutical Journal Apr 2018 : Vol 288 ; p446
BEMA ( Bio-Erodible Mucoadhesive)

23. 3. RECTAL
• Certain irritant and unpleasant drugs
can be put into rectum as suppositories
or retention enema for systemic effect
• As an enema (administration of rectum
on liquid form)
- Evacuant enema (for evacuation of
bowel)
- Retention enema (for e.g. ,
methylprednisolone in ulcerative
colitis)
• As a suppository (administration of the
drug in a solid form into the rectum)
E.g. Glycerin for constipation

24. • ADVANTAGES:
1. Ideal if patient is having recurrent vomiting or is
unconscious
2. Partially bypasses first pass effect
3. Bypasses destruction by stomach acid
• DISADVANTAGES:
1. Inconvenient and embarrassing
2. Absorption is slower, irregular and often
unpredictable, though diazepam solution and
paracetamol suppository are rapidly and
dependably absorbed from the rectum in children
3. Rectal inflammation can result from irritant drugs

25. 4. INHALATION
• Volatile liquids and gases are given by inhalation for
systemic action e.g. general anesthesia
• Absorption takes place from the vast surface of
alveoli- action is very rapid
• When administration is discontinued the drug
diffuses back and is rapidly eliminated in expired air
• Thus, controlled administration is possible with
moment adjustment
• Disadvantage: irritant vapors (ether) cause
inflammation of respiratory tract and increase
secretion

26. GENERAL ANESTHESIA
METERED DOSE INHALER
Ibrahim M et al. Inhalation drug delivery devices : Technology Update. Med devices
(Auckl) 2015; 8: 131-139

27. 5. NASAL
• The mucous membrane of the nose can readily
absorb many drugs; digestive juices and liver are
bypassed
• However, only certain drugs like GnRH agonists,
calcitonin and desmopressin applied as a spray or
nebulized solution have been used by this route
• This route was tried for some other peptide drugs
like insulin, as well as to bypass the blood- brain
barrier

28. FDA APPROVED June 2014
 Rapid acting inhaled insulin
 Should be used prior to meals or within 20 min of starting meals
 Not substitute for long acting insulin , has to be taken along with it for type 1 diabetes

30. • eFlow®rapid Nebuliser System
• Modern inhalation therapy –
twice as fast 1
• eFlow®rapid Nebuliser System is an efficient device for the treatment of
respiratory diseases. During development, special care was taken to develop an
efficient, safe and fast inhalation treatment with the following characteristics:
• Short inhalation times
• Silent operation for discreet use
• Light, small, mobile – with mains or battery operation
• Easy to clean, can be disinfected – offers a high degree of hygienic safety
• Display provides feedback during inhalation

31. 6. CUTANEOUS
• Highly, lipid soluble drugs can be applied over the
skin for slow and prolonged absorption
• The liver is also bypassed
• The drug can be incorporated in an ointment and
applied over specified area of skin
• Absorption of the drug can be enhanced by rubbing
the preparation , by using an oily base and by an
occlusive dressing

32. TRANSDERMAL THERAPEUTIC SYSTEMS (TTS)
• These are devices in the form of adhesive
patches of various shapes and sizes (5-20 sq
cm)which deliver the contained drug at a
constant rate into systemic circulation via the
stratum corneum
• Sites of application : chest, abdomen, upper arm,
lower arm, buttock or mastoid region
(if mild local irritation, erythema occurs; can b
minimized by changing the site of application each
time by rotation)
• For different drugs, TTS have been designed to
last for 1-3 days

34. • Transdermal patches of GTN, fentanyl, nicotine ,
estradiol are available in India
• Isosorbide dinitrate, hyoscine and clonidine are
marketed elsewhere
• Advantages :
1. TTS provide smooth plasma concentrations of the
drug without fluctuations
2. Minimize inter-individual variations (drug is
subjected to little first pass metabolism) and side
effects
3. More convenient
4. Patient compliance is better
• Disadvantage : expensive

35. Special Drug –Delivery Systems
• Intraoral lignocaine patch : patch containing
lignocaine is used to anaesthetize the oral
mucosa (DentiPatch®)
Hersh EV, Houpt MI, Cooper SA, Feldman RS, Wolff MS, Levin LM. Analgesic efficacy and
safety of an intraoral lidocaine patch. J Am Dent Assoc 1996;127:1626-34.

36. 7. PARENTERAL
(Par- beyond, enteral- intestinal)
• Refers to administration by injection which takes the
drug directly into tissue fluid or blood without having
to cross the enteral mucosa
• Advantages:
1. Faster and surer drug action(valuable in
emergencies)
2. Gastric irritation and vomiting are not provoked
3. Can be employed even in unconscious ,
uncooperative or vomiting patient
4. No chances of interference by food or digestive
juices
5. Liver is bypassed

37. • Disadvantages :
1. The preparation has to be sterilized and is
costlier
2. Technique is invasive and painful
3. Assistance of another person is mostly needed
(though self injection is possible, e.g. insulin by
diabetics)
4. Chances of local tissue injury
5. In general, parenteral route more risky than oral

39. i) Intramuscular (i.m.)
• Drug is injected in one of the large skelatal
muscles- deltoid ,triceps, gluteus maximus, rectus
femoris, etc.
• Muscle is less richly supplied with sensory nerves
(mild irritants can be injected) and is more
vascular (absorption of drugs in aqueous solution
is faster)
• Less painful
• Depot preparations (oily solutions,
aqueous suspensions ) can be
injected by this route.

40. Intra muscular injections
should be avoided in
anticoagulant treated patients,
because it can produce local
hematoma

41. ii) Subcutaneous (s.c.)
• Drug is deposited in the loose subcutaneous
tissue which is richly supplied by nerves (irritant
drugs cannot be injected) but is less vascular
(absorption is slower than i.m.)
• Only small volumes can be injected
• Self injection is possible
• Repository(depot) preparations that are aqueous
suspensions can be injected for prolonged action
This route should be avoided in shock patients
who are vasoconstricted – absorption will be
delayed

42. Special forms of s.c. route
DERMOJET :
• Needle not used
• High velocity jet of drug solution
is projected from microfine
orifice using a gun like
implement
• Painless
• Suited for mass inoculations
PELLET IMPLANTATION :
• Drug in form of solid pellet is
introduced with a trochar and
canula
• Provides sustained release of
drug over weeks and months
• e.g. DOCA(Deoxy corticosterone
acetate), testosterone

44. SIALISTIC (NON-BIODEGRADABLE)
AND BIO-DEGRADABLE IMPLANTS
• Crystalline drug is packed in
tubes or capsules made of
suitable materials and
implanted under the skin
• Slow and uniform leeching of
drug over months providing
constant blood levels
• Tried for hormones and
contraceptives ( e.g.
NORPLANT)

45. iii) Intravenous (i.v.)
• Drug is injected as bolus or infused slowly over
hours in one of the superficial veins
• Advantages :
1. Drug reaches directly into the blood stream and
effects are produced immediately (great value in
emergency)
2. Intima of veins is insensitive and drug gets
diluted with blood, therefore, even highly
irritant drugs can be injected
3. Dose of drug required is smallest (bioavailability
is 100%) and even large volumes can be infused

46. • Disadvantages:
1. Thrombophlebitis of injected vein and necrosis
of adjoining tissues if extravasation occurs
[these complications can be minimized by
diluting the drug or injecting it into a running i.v.
line]
2. Chances of causing air embolism
3. Most risky route, vital organs like
heart, brain, etc. get exposed
to high concentrations
of the drug

47. THROMBOPHLEBITIS

48. iv) Intradermal injection
• Drug is injected into the skin raising a bleb
(e.g. BCG vaccine , sensitivity testing) or
scarring/ multiple puncture of the epidermis
through a drop of drug is done.
• This route is employed for specific purposes
only

50. REFERENCES
• Rang et al . Pharmacology. 5th edition . Noida (India) : Elsevier Science
Limited ; 2005
• Tripathi KD. Essentials of Medical Pharmacology. 8/e. New Delhi
(India) : Jaypee Brothers Medical Publishers (P) Ltd; 2019
• Dhikav V et al. Pharmacology for Dental Students. 1st edition. Delhi :
AITBS Publishers and Distributors (Regd) ; 2003
• Dodou K. Research and Development in buccal and sublingual drug
delivery systems. The Pharmaceutical Journal Apr 2018 : Vol 288 ;
p446
• Ibrahim M et al. Inhalation drug delivery devices : Technology Update.
Med devices (Auckl) 2015; 8: 131-139
• Hersh EV, Houpt MI, Cooper SA, Feldman RS, Wolff MS, Levin LM.
Analgesic efficacy and safety of an intraoral lidocaine patch. J Am Dent
Assoc 1996;127:1626-34.

51. THANK YOU!!