Routes of drug administra MBBS

1. 1

2. Most drugs can be administered by different of routes. The
choice of appropriate route in a given situation depends both
on the drug as well as patient related factors.
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3.  Physical and chemical properties of the drug.
 Site of desired action.
 Rate and extent of absorption of drug from different routes.
 Rapidity and intensity of action desired.
 Activation & Inactivation of drugs.
 Condition of the patient
 Amount of the drug to be administered.
 Age of the patient.
 Associated disease.
 patient’s/ doctor's choice (sometime)
 Gender
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4. Routes of drug
administration
Local Routes
Systemic
Routes
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5. Local
Routes
Topical
Cutaneous
Mucous
Membranes
Deeper
Tissues
Intra-
Articular
Periocular
Intra-
Thecal
Intra-
Cardiac
Intra-
Pleural
Intra-
Peritoneal
Intra-
Arterial
Intra-
Lesional
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6. Systemic
Routes
Enteral
Oral
Rectal
Sublingual or
Buccal
Parenteral
Inhalational
Intravenous
(i.v)
Intramuscular
(i.m)
Subcutaneous
(s.c)
Intra-osseous
Intra-dermal
Trans-dermal
Therapeutic
Systems
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7. Used for localized lesions of action and drugs whose systemic
absorption from these sites is minimal
or absent so less side effects.
I. Topical
II. Intra-arterial
III. Intra-lesional
IV. For deeper tissues
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8. Advantages of Local routes of
administration
Disadvantages of Local routes of
administration
Fast onset of action not all drugs Not always possible to apply
drug locally
Better concentration at site of
action
Local irritation
Less quantity required Sometimes systemic
absorption and toxicity can occur
Less systemic adverse drug
reactions
Repetitive administration can
cause local trauma and
damage
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9.  External application of drug to surface of skin or mucosal membranes
for localized action.
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10. Topical Application – Skin
 Absorption depends on surface area and lipid solubility of the
drug.
 Few drugs readily penetrate the skin.
 Toxicity by highly lipid soluble insecticides & corticosteroids.
Topical Application – Mucous Membranes
Applied to conjunctiva, vagina, urethra, urinary bladder, ear,
nose nasopharynx, oropharynx and anal canal.
Absorption is rapid.
Local anesthetics used for rapid effect but chances of systemic
toxicity also present.
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11. Topical application on skin and mucosal membranes in form
of lotions, ointments, creams, powders, sprays, paints, and
drops.
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12.  Used for administering contrast media in angiography.
 To localize the effects in a particular tissue or organ.
 Anticancer drugs ( e.g. Nitrogen mustard ) infused in femoral or
brachial artery for localized effect in limb malignancies.
 Also used for liver tumors, head and neck cancers.
III. Intralesional Route
 drugs is directly injected in a lesion e.g. steroid injection directly in
hypertrophied scar.
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13. a. Intra-articular route
 Drugs given directly into the joint space to
reduce pain, inflammation and maintaining
mobility of the joint in OA and RA.
 Ensures higher concentration of drug into
localized area.
 Repetitive injections may lead to trauma in
the joint.
 E.g. Hydrocortisone, steroids and gold
chloride
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14. b. Periocular and intravitreal
routes
 Used for drug delivery to retina and
surrounding areas.
Intravitreal route-
 provides high concentration in the
retina.
 But many side effects seen like
cataracts and retinal detachment .
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15. c. Intra-cardiac route
 Drug administered by a long needle into the heart through the fourth
intercostal space. E.g. Adrenaline in cardiac arrest.
 Injury to coronary artery, hemorrhage
d. Intra-pleural route
 Generally used for pleurodesis.
 Drugs used for this procedure are – bleomycin, tetracycline,
povidone iodine and slurry of talc.
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16. e. Intrathecal route
 Drug injected into the subarachnoid
space (L2-3 or L3-L4).
 Blood-brain and blood-CSF barrier
bypassed.
 Aseptic conditions required
 Chances of infection- meningitis
 Post injection- Spinal headache, nausea
and vomiting.
 Lignocaine used for spinal anesthesia in
lower abdomen and limb surgeries.
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17. Epidural route-
 Drug injected through vertebral
interspace between the dura and the
vertebra.
 Lignocaine used by this route as epidural
anesthesia.
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18. f. Intra-peritoneal route
 Rapid absorption due to large surface
area.
 Fluids can be given to correct
dehydration in children by this route.
 Peritoneal dialysis as an alternative to
haemodialysis.
 Chances of infections and trauma are
common by this route.
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19. Drugs given through these routes are absorbed into the blood
stream and distributed all over, including the site of action,
through the circulation.
Enteral routes
Parenteral routes
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20. Administration of drugs through the gastrointestinal tract
Oral
Sublingual/ buccal
Rectal
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21.  Most common route of drug
administration.
 Majority produce systemic
effect but some produce local
effects
 Doses form are capsule, tablet,
syrup, mixture, powder etc.
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22. Advantage :-
 Simple
 Safer.
 Cheaper.
 Convenient and prolonged used.
 Economical
 Painless
 Easy to adjust doses
 Can be self-administered.
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23.  Slower onset of action.
 Not suitable for emergency.
 Highly polar drugs like streptomycin
not absorbed from the GIT.
 Drugs like penicillin-G, insulin,
Oxytocin are destroyed by gastric juices.
 Drugs with extensive first pass metabolism not effective
e.g. morphine, isoprenaline.
 Patients with severer vomiting and diarrhea.
 Unconscious patients
 Uncooperative and unreliable patients.
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24. Drug placed under the tongue,
between lips and gingiva, buccal
mucosa.
Due to high vascularity in these
areas drug quickly absorbed into
systemic circulation.
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25. Advantage :-
 Rapid onset action.
 Quick termination of effect on spitting
 Bypasses the GIT and liver
 self-administered.
Disadvantage :-
 Irritant drugs cant be given
 Drugs with bad test.
 Drugs with high molecular weight cant be given e.g. insulin.
Examples: Isorbide dinitrate, NTG in angina
Isoprenaline in Br. Asthma
Nifedipine in Hypertension
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26. Advantage:-
 Irritant drugs given via this route as suppositories or enema for systemic
effect.
 Useful for patients having recurrent emesis, vomiting or unconscious.
 First-pass metabolism is by passed as major drug is absorbed from external
haemorrhoidal veins.
Examples:
 Diazepam in Febrile seizures in children
& Status Epilepticus
 Indomethacin in Rheumatoid Arthritis
 Dulcolax suppositories for local effects
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27. Disadvantage :-
 Absorption slow, irregular often
unpredictable
 Chances of rectal inflammation
 Inconvenient and embarrassing for
the patient
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28.  Administration by injection which takes drug directly into the tissue fluid or
blood without having to cross the intestinal mucosa.
 Intradermal
 Sub-cutaneous
 Intra muscular
 Intravenous
 Intramedullary
 Inhalational
 Transdermal Therapeutics Systems
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29.  Drug is injected into the dermal
layer of the skin.
 Only a small amount of drugs given
by this route 0.1ml adults & 0.05 ml
in infants.
 Absorption is slow.
 BCG vaccine and sensitivity testing
( Penicillin and ATS )
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30. Advantage :-
 Smooth but slower absorption over longer
periods.
 Depot preparation can also be given.
 Vaccines given by this route.
 Local anesthetics for local action.
Disadvantage :-
 Only small volumes can be given. (max. 2 ml )
 Cannot be used in shock as reduced peripheral
circulation decreases rate of absorption.
 Irritant drugs not administered.
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31. 31

32. Drug injected into deltoid muscle, gluteus
maximus and vastus lateralis.
Absorption faster from deltoid and vastus
lateralis than from gluteus maximus.
Massaging of area after injection increases
absorption due to vasodilatation
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33. Absorption more predictable and rapid as compared to oral
route.
Oily solutions, depot injections and mild irritants can be given.
Less painful
Depot preparations can be given
Soluble substances, mild irritants, suspensions & colloids can be
injected
The vascularity of muscle is good so absorption of drugs is more
rapid than SC route

34. Disadvantage :-
 Self administration not possible
 Aseptic precautions necessary
 Danger of injecting into blood stream
 The volume of injection should not be more than
10 ml
 Pain at injection site
 Irritation, abscess formation, tissue/ nerve
damage may occur
 Rapid absorption may even cause death
Examples :-
Various antibiotics, antiemetics, and depot
injections of testosterone and neuroleptics
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35.  Drug injected through the lumen of the vein,
generally the ante cubital vein.
Types :-
 Bolus injection: Initial large dose given
e.g. Corticosteroids
 Rapid injection
e.g. Adenosine
 Slow injections: over 10-15 mins
e.g. Aminophylline
 Infusions: 1-8 Hrs or more
e.g. Dopamine, dobutamine, dextrose etc.
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36. Advantage :-
 Most suitable route for emergencies.
 As drug is injected directly into the blood, bioavailability is 100 %
( by passes GIT metabolism and hepatic first pass mechanism ).
 Large volumes of drugs can be given
 Irritant drugs and hypertonic solution can be given.
 Route of choice for unconscious, uncooperative, emetic and diarrheal
patients.
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37. Disadvantage :-
Aseptic conditions required.
Painful and risky as once the drug is administered it cant be
recalled.
May cause thrombophlebitis and a risk of air embolism.
Fast injections may cause profound hypotension.
Self-medication not possible.
Oily preparations cant be given.
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38. Drug is injected directly into
the marrow of the bone (
antero-medial aspect of tibia,
anterior aspect of femur,
superior illiac crest ).
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39. Advantage :-
 Can be used in emergency situations
 Can be maintained for 24 to 48 hrs.
 Has almost same absorption rate as
intravenous access.
 Blood, bone marrow transplant, fluids
and antibiotics can be given by this
route.
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40. Disadvantage :-
Must be performed under
sterile conditions otherwise
there are chances of
osteomyelitis and cellulitis.
Risky and painful procedure.
Intraosseous route is
contraindicated in Ipsi-
lateral Fracture of bone and
osteogenesis imperfecta.
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41.  Drug is delivered directly to the respiratory tract
while inspiring through the mouth.
Advantage :-
 rapid onset of action due to rapid access to
circulation
*large surface area
*thin membranes separates alveoli
from circulation high blood flow
 Self administration possible.
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42. Disadvantage :-
 Bronchial Irritation
 Increased Bronchial and salivary secretions
 Poor ability to regulate the dose
Examples :-
* Drug aerosols given by MDI - Salbutamol, Terbutaline
* Dry powders from inhalers - Salbutamol
* Nebulization - Baclomethasone
* General anesthesia – Nitrous Oxide, Halothane
* For systemic effect - Oxygen
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43.  Adhesive patches which deliver the drug at a constant rate into the
circulation.
 Absorption occurs via skin by diffusion.
 Achieves therapeutic plasma concentrations without fluctuations.
 Single patch – 7 days ( longer duration of action ).
 Very convenient to use .
 little first pass effect .
 Local irritation.
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44. Sites- Chest, abdomen, upper arm,
lower back, mastoid area and pinna.
Transdermal patches –e.g.
* Gyceryl trinitrate / Nitroglycerin
* Nicotine
* Fentanyl
* Scopalamine
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