This presentation describes various routes of drug administration. However, this presentation is not inclusive.

1. Routes of Drug
Administration for BNS 1st
Year
Dr. Pravin Prasad
1stYear Resident, MD Clinical Pharmacology
Maharajgunj Medical Campus, Kathmandu, Nepal
9th December, 2015 (Mangsir 23, 2072),Wednesday

2. Expected Outcomes
• Define Route of Administration
• Determining Factors
• Classification
• Understand the salient features of various Routes of Administration

3. Introduction
• A route of administration is the path by which a drug, fluid,
poison or other substance is brought into contact with the body.
• Jonas: Mosby's Dictionary of Complementary and Alternative Medicine,
2005, Elsevier.
• No single method of drug administration is ideal for all drugs in
all circumstances
• Knowledge of advantage and disadvantage of different routes of
administration is of importance in order to choose a route by
which a therapeutic agent may be given

4. Choosing a Route of Drug Administration
Factors Examples
Physical & chemical properties of drug solid/liquid/gas; solubility, stability, pH, irritancy
Site of desired action localized and approachable or generalized and
non approachable
Rate & extent of absorption from various
routes
Effect of digestive juices & first pass effect
Rapidity of the desired response emergency/routine
Accuracy of dosage
Condition of the patient unconscious, vomiting

5. Classifying Routes of Administration
• On the basis of where effects are seen
• Systemic
• Local
• On the basis of access to blood
• Intra-vascular
• Extra-vascular
• On the basis of location at which substance is applied
• On the basis of where target of action is
Fundamental
Reason:
Bioavailability

6. Route of administration on the basis of access to blood
Intravascular Extravascular
Intravenous Oral Intra-bone
Intra-arterial Sub-lingual/ buccal Intra-articular
Intra-cardiac Intramuscular Intra-pleural
Percutaneous/Subcutaneous Intra-peritoneal
Intradermal Inhalation
Transdermal drug delivery system Nasal
Epidural Rectal
Intra-Spinal Vaginal
Intra-cranial Ocular

7. Route of administration on the basis of exposure of
body
Systemic
Enteral
Oral
Parenteral
Rectal
Sub-lingual/
Buccal
Intra-
venous
Intra-
muscular
Sub-
cutaenous

8. Route of administration on the basis of
exposure of body
Local
Inhalational
Application to
Epithelial Surface
Cutaenous
Administration
Nasal
Sprays
Intra-
vitreal
Intra-
thecal
Eye
Drops
Rectal

9. Oral Administration
• Absorption mainly takes place from the intestine.
• Drugs administered orally that act locally:
• Vancomycin- eradicates toxin forming C. difficile in pseudomembranous colitis
• Mesalazine and Olsalazine in the treatment of inflammatory bowel disease
• Factors Affecting Absorption on Oral Administration:
• Gut content
• Gastro-intestinal motility
• Splanchnic blood flow
• Surface Area for Absorption
• Particle size and formulation
• Physicochemical factors, drug interactions
Physiological

10. Oral Administration of Drugs
Advantages
• Safe
• Convenient- self- administered, pain free,
noninvasive and easy to take
• Economical- compared to other parentral routes
• Usually good absorption- takes place along the
whole length of the GI tract
• No need for sterilization
Disadvantages
• Slow absorption and action - can not used in
emergency
• Irritable and unpalatable drugs- nausea and
vomiting
• Cannot be used uncooperative, vomiting and
unconscious patients
• Some drugs destroyed, some drugs are not
absorbed like streptomycin
• First-pass effect
• Food–Drug interactions and Drug-Drug
interactions

11. Bioavailability and Bioequivalence
Bioavailability
• Indicates the fraction (F) of an orally
administered dose that reaches the systemic
circulation as intact drug
• Depends on:
• Drug preparation
• Host factors: enzyme activities at intestine and
liver(first pass metabolism), gastric pH, motility
• Bioavailability of the same preparation can
vary.
Bioequivalence
• Bioavailability does not take rate of absorption
into account, hence the concept of
‘Bioequivalence’ emerged
• Bioequivalence includes:
• Maximum concentration achieved Cmax
• Time taken from dosing to reach maximum
concentration, tmax
• Area Under Curve AUC(0-∞)
• Values of each parameters must be between
80% and 125%

12. Rectal Administration of Drugs
• Drugs that are administered rectally as a suppository.
• Can serve as local as well as systemic route of administration of
drugs.
• Unreliable absorption
• Preferable in patients who are vomiting, post-operative, difficult to
establish intravenous access (child having seizures)

13. Rectal Administration of Drugs
Advantages
• Used in children
• Little or no first pass effect (ext
haemorrhoidal vein)
• Used in vomiting or unconscious
• Higher concentrations rapidly
achieved
Disadvantages
• Inconvenient
• Absorption is slow and erratic
• Irritation or inflammation of
rectal mucosa can occur

14. Sublingual and Buccal Administration of Drugs
• When rapid response is required
• Drug unstable at gastric pH
• Drug rapidly metabolised by the liver
• Absorbed drugs directly reach systemic circulation, bypassing
portal circulation, hence escapes first pass metabolism.

15. Sublingual and Buccal Administration of Drugs
Advantages
• Drug absorption is quick
• Quick termination
• First-pass avoided
• Can be self administered
• Economical
Disadvantages
• Unpalatable & bitter drugs
• Irritation of oral mucosa
• Large quantities not given
• Few drugs are absorbed

16. Parenteral Route of Drug Administration
• A) Intradermal
• Inj into skin
• B) Subcutaneous -
• Absorption of drugs from the subcutaneous
tissues
• C) Intramuscular (IM)
• Drug injected into skeletal muscle
• D) Intravascular (IV)-
• Placing a drug directly into the blood stream

17. Intravenous Administration of Drugs
• Fastest route of administration of drugs
• Peak concentration reaching tissues depends on rate of administration
• Bolus dosing: can cause high peak plasma levels-uncertain absorption from
other sites
• Infusion dosing: avoids fallacy of the bolus administration.

18. Intravenous Administration of Drugs
Advantages
•Most common route for drugs not
absorbed orally.
•Avoids first-pass metabolism;
absorption bypassed
•Permits a rapid effect and a maximal
degree of control over the circulating
levels of the drug. Titration of dose with
response.
•Large quantities can be given
Disadvantages
•Cannot be easily removed
•May induce hemolysis or cause
other adverse reactions by the too-
rapid delivery of high
concentrations of drug
•Thrombophlebitis of vein and
necrosis of adjoining tissue if
extravasation occurs

19. • Large skeletal muscle are used for intra-muscular administration- Deltoid,
triceps, gluteus maximus, rectus femoris
• SubcutaenousAdministration: drug is deposited in loose subcutaneous tissue
• Faster absorption than oral administration
• Rate limiting factors:
• Diffusion through the tissue
• Removal by local blood flow.
Intramuscular and Subcutaenous
Administration of Drugs

20. Intramuscular and Sub-cutaenous Administration
Route of Administration Advantages Disadvantages
Intra-muscular • Absorption reasonably uniform
• Rapid onset of action
• Mild irritants can be given
• First pass avoided, Gastric factors
avoided
• Only up to 10ml drug given
• Local pain and abscess
• Expensive
• Infection
• Nerve damage
• Local hematoma can occur
in anticoagulant treated pt.
Sub-cutaneous • Less blood supply: slow
absorption
• Depot preparation can be used
• Risk associated with intravascular
injection avoided
• Should be avoided in shock
patient
• Only small volume can be
injected

21. Local Route of Drug Administration
Routes of Drug Administration for BNS 1stYear

22. Local Application: Application to Epithelial
Surface
•Cutaenous Adminstration:
• Usually absorption poor over intact skin.
• Advantages:
• Steady rate of drug delivery
• Pre Systemic metabolism avoided
• Disadvantages:
• Only applicable for Lipid soluble drugs
• Relatively Expensive

23. Formulations forTopical Applications
Common Types Special types
Liquids
Lotions Shake lotions, Gels
Solutions Paints, Tinctures
Semisolid Creams, Ointments
Solids Pastes, Powders
Miscellaneous
Delivery System
Colloidion, Microsponges,
Liposomes

24. Different Formulations of Topical Preparation
Lotion
Shake
Lotion
Paste
Cream/ Ointment/
Emulsion

25. Transdermal Route of Drug Administration
• Achieves systemic effects by application of drugs to the skin, usually
via a transdermal medicated adhesive patch.
• The rate of absorption depends on the physical characteristics of the
drug (lipid soluble) and skin at the site of application.
• Slow effect (prolonged drug action)
• Site – Upper arm, chest, abdomen, mastoid region
• First pass effect avoided
• Absorption- increase by oily base, occlusive dressing, rubbing
preparation

26. Local Application: Application to Epithelial
Surface
•Eye/Ear Drops:
• Eye Drops: Absorption through conjunctival sac epithelium
• Ear Drops: Absorption through epithelial lining of External ear
• Relatively brief contact time with absorbing surface
• Sterile; require aseptic handling
• Desirable for local effects: lacks systemic reactions.

27. Administration By Inhalation
•SystemicAdministration of drugs: GeneralAnaesthetics (volatile and
gaseous)
• Large surface area and large blood flow: rapid exchange of drugs, possible
to adjust plasma levels rapidly
•LocalAdministration of drugs: corticosteroids, β2 agonist, Nasal
Decongestants
•Nasal Sprays:
• Peptide hormone analouge: Anti Diuretic Hormone, Gonadotrophin,
Calcitonin
• Absorption via Nasal Mucosa and then through nasal associated lymphoid
tissue

28. Local Application: Application to Epithelial
Surface

29. Intrathecal and Intravitreal Administration of
Drugs
•Intrathecal administration:
• Injection into sub-arachnoid space
• Minimises systemic adverse effects
•Intravitreal administration:
• Administered by Opthalmologist
• Ranibizumab for wet age-related macular degeneration.

30. Topical Therapy: Pros and Cons
Advantages Disadvantages
Delivery onto the target organ at
an optimal concentration
Time consuming
Rapid onset of action
Depends largely on patient’s
compliance and patience
Systemic effects are less More expensive

31. Other Topical Preparations
• Medicated plaster, dressings,
strips
• Suppository
• Douche
• MedicatedVaginal Rings
• Intra-uterine devices
• Intra-nasal drug delivery
• Inhaled Drug Delivery
• Transdermal Patch

32. Dosage forms forVariousTopical Routes
• Mouth and pharynx: Paints, lozenges, mouth washes, gargles.
• Eyes, ears and nose: As drops, ointments, irrigation, nasal spray.
• Gastrointestinal tract: As non-absorbable drugs given orally e.g. aluminium
hydroxide, kaolin, neomycin.
• Bronchi and lungs: As inhalations, aerosols (nebulised solution or fine
powder)- e.g. salbutamol, cromolyn sodium.
• Urethra: As jellies e.g. lidocaine, irrigating solutions.
• Vagina: As pessaries, vaginal tablets, inserts, cream, powders, douches.
• Anal canal: As ointment, suppositories.

33. That will be all for today!
•Any Queries?
•Next class
• Will be onThursday (24th Mangsir, 2072);
• Topic: Understanding Prescription
•Assignment for you: Prescriptions