Routes of drug adminstration Factors for the choice of Drugs,details about various routes for drug administration

1. ROUTES OF DRUG ADMINSTRATION
Vijay Salvekar
Dept. of Pharmacology
GRY Institute of Pharmacy,Borawan

2. Route of administration:
• A route of administration in pharmacology and
toxicology is the path by which a drug, fluid,
poison, or other substance is taken into the body. -
Most of the drugs can be administered by different
routes.
• Drug- and patient-related factors determine the
selection of routes for drug administration.

5.  When doesadrug exert its pharmacological
effect?
Reach the site of
action
The drug must come in contact with the tissues of organs
and cells of tissues.

6. The way that drug comes in contact or is madeaccessible to the
tissue fluids, tissue cells, ECF &ICF
Route of administration
Local action Systemicaction
Local routes Systemicroutes

7. Factors for the choice of Drugs:-
Physical and Chemical properties
Site of action
Rate and extent ofabsorption
Effectof digestive juicesand HFPM(hepatic first pass
metabolism)
Rapidity of response
Accuracy of dosage
Condition of thepatient

8. LOCAL ROUTES:-
Used only for localized lesions ataccessible sites.
Systemic absorption is minimal or absent.
High concentrations attained at desired site.
Systemic toxicity is absentor minimal.
Ex: Dusting powder, Paste, Lotion, Drops, Ointment, Plaster,
Pessaryetc.

10. Topical : external application of thedrug
Skin Mucous membrane
Advantages:-
 Local therapeuticeffects
 Lower risk of sideeffects
 Moreconvenientand encouraging to the patient
Disadvantages:-
 Notwell absorbed into the deeper tissue

11. o Skin : drug is applied asointment, cream, lotion, paste, powder,
dressing, sprayetc.
o Mucous membrane:
• Mouth and Pharynx: paints, lozenges, mouth washes,gargles.
• Eyes, Ear and Nose: drops, ointments, nasalspray.
• GIT: non-absorbable drug(Magnesium hydroxide, sucralfate)
• Bronchi and Lungs: inhalations, aerosols.
• Urethra: jellys.
• Vagina: pesseries, vaginal tablets.
• Anal canal: suppositories.

13. Inhalation route:-
 Volatile liquids andgases
 Ex: general anaesthetics, amylnitrite, albuterol,and
corticosteroids such asfluticasone
 This route is particularlyeffectiveand convenient for patients
with respiratory complaints (such as asthma, or chronic
obstructive pulmonarydisease)

14.  Because thedrug is delivered directly to the siteof action and
systemicsideeffectsare minimized
 Inhalation provides the rapid delivery of a drug across thelarge
surface area of the mucous membranes of the respiratory tract and
pulmonary epithelium
 Produces an effect almost as rapidly as with IV injection.

15. Advantages
Rapid absorption (large surfacearea)
 Provide local action
Minor systemiceffects
Lesser sideeffects
No first passeffect
Disadvantages
Only fewdrugs can beused

16. Nasal :-
 This route involves administration of drugs directly
into the nose
Ex: nasal decongestants, Desmopressin is administered
intranasally in the treatment of diabetes insipidus,
salmon calcitonin a peptide hormone used in the
treatment of osteoporosis, is also available as a nasal
spray.
• The abused drug, cocaine, is generally taken by intranasal
sniffing
• Digestive juice and liver by passed

17. Deeper tissue:- using syringe and needle
• But systemic absorption of drug isslow.
o Intra-articular injection/Joint injection: procedure used in
thetreatment of inflammatory joint conditions

18. o Intrathecal injection: into the spinal canal, or into the
subarachnoid space so that it reaches the cerebrospinal fluid
(CSF) and is useful in spinal anaesthesia, chemotherapy, or
pain managementapplications.

19. o Retrobulbar injection: the area located behind the globe of
the eye.
• This injection provides akinesia of the extraocular muscles
by blocking cranial nerves II, III, and VI, thereby
preventing movement of the globe.
• This block is most commonly employed for cataract surgery

20. Arterial supply:- ex:Anti-cancer drugs, inAngiography.
Disadvantage: need expertise

21. Systemic route: drug administered is intended to be
absorbed into blood and distributed all over, includingsite of
action
Oral route: (Enteron)
 The most commonest and oldest mode of drug
administration
 Drug is given through oralcavity
 Dosage forms Capsules, powders, Tablets, spansules,
Syrup, emulsion, Suspension, elixirs

23. ADVANTAGES
 Safe
 Convenient- self-administered
 pain free, non-invasive and easy to take
Economical- compared to other parenteral routes (No need for
sterilization)
Usually good absorption- takes place along the whole length
of the GItract

24. Disadvantages:-
 Slowabsorption,slowaction -can notused inemergency
 Irritable and unpalatable drugs- nausea andvomiting
 Cannotbe used nonco-operative,vomitingand
unconsciouspatients
 Somedrugsdestroyed
 First-pass effect- DuetoBiotransformation
 Food–Drug interactions and Drug-Drug interactions

25. Sublingual route :- where the dosage form is placed under
the tongue
 Rapidly absorbed by Sublingual mucosa
 Action can be produced in minutes

26. Advantages
 Economical
 Quick termination (can spit the drug once getting desired
action)
 First-pass metabolism avoided
 Drug absorption isquick
Disadvantages
 Unpalatable & bitterdrugs
 Irritation of oral mucosa
 Large quantities notgiven
 Few drugs areabsorbed

27.  Buccal route:-
 Buccal administration where the dosage form is
placed between gums and inner lining of the cheek
(buccal pouch)
 Drug is absorbed by buccal mucosa

29.  ADVANTAGES
 Avoid first passeffect
 Rapid absorption
 Drug stability
 DISADVANTAGES
 Inconvenience
 advantages lost if swallowed
 Small doselimit

30. Rectal route:-
 Drugs thatareadministered rectallyas a suppository
 In this form, a drug is mixed with a waxysubstancethat
dissolvesor liquefies after it is inserted into the rectum
 ex- Diazepam, indomethacin, paraldehyde,
ergotamine

31. Advantages:-
 Used inchildren
 Littleor no first passeffect
 Used in vomiting or unconscious
 Higherconcentrations rapidly achieved
Disadvantages:-
 Inconvenientandembarrassing
 Absorption is slowand
 Erratic (unpredictable/irregular)
 Irritation or inflammationof rectal mucosa canoccur

32.  Parenteral ( beyond enteral):-
 Administration of the drug byinjection
 Wheredrug directly reaches into the tissue fluid or blood
 Without having to cross the intestinal mucosa (by passesthe
alimentarycanal)

33. Advantages:-
 action is faster & surer (valuable in emergency)
Gastric irritation and vomiting are notprovoked
Can be employed even in unconscious, uncooperativeor
vomiting condition
Nochancesof interference by food ordigestive juice
Bypasses the liver
Disadvantages:-
Costlier (sterile preparation)
Painful
Assistance of another personneeded
Chances of local injury and is morerisky

34. A)Intradermal –
injection into skin
B)Subcutaneous -
Absorption of drugs
from thesubcutaneous
tissues
C) Intramuscular
(IM)
drug injected into
skeletal muscle
D)Intravascular (IV)-
placing adrug directly into
the blood stream

35. Into the dermalregion

36. Sub-cutaneous:-
 Drug is administered into the loose subcutaneoustissue
 Which is richly supplied by nerves but is less vascular
 Absorption isslower
 Dermojet: highvelocity jet produced through a micro-fineorifice,
no needle isreqired
 Pellet implantation
 Sialistic

38. Advantages:-
 Good route of administration
 Safer than i.m. and i.v.
 Absorption is slower (prolonged effectcan be achieved)
Disadvantages:-
 Irritantdrugscannot be used

39. Intramuscular:- drug is injected in one of the large skeletal
muscles like deltoid, triceps, gluteus maximus, rectus femoris etc
 Muscles are less richly supplied with sensory nerves (mild irritants
can be injected )
 As it is more vascular
(absorption is faster)
 Self injection is not possible

40. Intravenous:-
 Drugsgiven directly intoavein
 Produces rapid action
 Sincedrugs getdiluted with blood,highly irritantdrugs can also be
given through i.v.
 100% Bioavailability
Disadvantages:-
 Thrombophlebitis, necrosis
 Action cannot behalted
 Self administration is notpossible
 Sterile andcostlier

41. Novel drug delivery system(NDDS):-
 Transdermal system:- recently developed in the form of adhesive
patches of various shapes and sizeswhich deliversdrug ata
constant rate intosystemiccirculation
 Ex: nitroglycerine, verapamil, digoxin, insulinetc

42.  Transcutaneous:-
 Iontophoresis: a technique of introducing ionic medicinal
compounds into the body through the skin byapplying a local
electric current.
 galvanic current allows the penetration of drugs applied to the
skin into deepertissues
 Force of repulsion b/w likechargesdrives thedrug ion into the
deepertissue

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