3a.Dosage forms & Routes of drug administration_28 Feb 2024 & 01 Mar 2024.ppt

Routes of administration

1. Routes of Drug Administration
And Dosage Forms
Dr.R.Rao Prethendhira singh.
BDS., Msc Medical Pharmacology; PG Dip. In Clinical Research
LECTURER
DEPT. OF PHARMACOLOGY

2. Dosage Forms
•Dosage forms applied locally to the skin are powders, paste,
lotions, ointments, creams, plasters and jellies.
•On the skin, drug is applied in the form of ointment, cream,
lotion, paste, plaster,powder etc.
•Topical application is also used on the mucous membranes
i.e. nose, throat, eye, ear, bronchi, rectum, urethra, vagina and
rectum.
•In case of mouth and pharynx, the drug is used in the form of
throat paints, lozenges, gargles or mouth washes
•In case of corneal application (in the form of ointments, drops)

3. •The nasal mucosa is treated with drug solution in the form of
spray or Irrigation.
•The bronchial mucosa and lungs are treated with inhalations,
aerosols (in the form of fine powder with the help of nebulizer)
e.g.salbutamol (ASTHALIN) inhaler.
•Drugs may also be administered locally in the form of bougies,
jellies for urethra, pessaries, vaginal tablets, creams and
douches for vagina and suppositories for rectal administration
•Administration of drug in the form of liquid into the rectum is
called enema, which may be soap water or glycerine
vegetable oil

11. Factors governing choice of route
1.Physical and chemical properties of the drug
2.Site of desired action
3.Rate and extent of absorption of the drug
4.Effect of digestive juices and first pass metabolism on
the drug
5.Rapidity with which the response is desired
6.Accuracy of dosage required
7.Condition of the patient

13. Types :
1. local route
2. Systemic route

14. LOCAL ROUTES
1. Topical
(a) skin
(b) mucous
membranes
2. Deeper tissues
3. Intra arterial
4. Intra thecal

15. 1. Topical :
(a) skin:
(b) mucous membranes: the dosage form
depends on the site-
•Mouth and Pharynx
•ENT
•GIT
•Bronchi and Lungs
•Urethra
•Vagina
•Anal canal

17. Contd..
2.Deeper tissues:
Intra articular
Retrobulbar
injection

18. Contd..
•Intra arterial:
• a drug is injected directly into an artery
to localize its effect in a particular
tissue /organ i.e liver tumors/head &
neck ca, limb malignancies.
•Reserved for experts
•The first pass and cleansing effects of the
lung are not available in this route.

19. Intrathecal :
• Drugs are injected directly
into the SUB ARACHNOID
SPACE. E.g. spinal
anesthesia, CNS infections.
•INTRA VENTRICULAR
drug administration – brain
tumors

20. SYSTEMIC ROUTES
1.Oral
2.Sublingual or buccal
3.Rectal
4.Cutaneous
5.Inhalation
6.Nasal
7.Parental – s.c, i.m, i.v,
intra dermal

21. Oral Route:
•Commonest mode of drug
administration
•Both solid dosage forms and
liquid dosage forms can be
given orally
•Advantages:
•cheaper
•Safer, more convenient
•Does not need assistance
•Non- invasive, painless
•Medicament need not be
sterile

22. Contd..
Limitations :
•Action is slower, not suitable for
emergencies
•Unpalatable drugs are difficult to
administer
•Cause nausea and vomiting
•Cannot be used for unco-operative /
unconscious / vomiting patients
•Certain drugs are not absorbed
•Drugs are destroyed by digestive juices or
in liver

23. SUBLINGUAL
•Drugs placed under the tongue or crushed in
the mouth and spread over the buccal mucosa
•Only Lipid soluble and non-irritating drugs
•Advantages :
•Rapid action
•Avoidance of first pass metabolism
•Examples:
•Nitroglycerine, isoprenaline,
Methyltestosterone, Clonidine

25. RECTAL ROUTE
•Irritant and unpleasant drugs can be given as
suppositories or retention enema.
•Can be used in pts with vomiting.
•Drugs absorbed into external haemorrhoidal
veins bypasses liver
Examples :
 Aminophylline,
 Indomethacin,
 Diazepam,
 Paraldehyde,ergotamine.

26. Limitations:
•It is inconvenient
and embarrassing.
•Absorption is slower,
irregular,
unpredictable.
•Rectal inflammation
may occur with
irritant drugs

27. CUTANEOUS ROUTE
•Highly lipid soluble drugs can be applied over the
skin for slow and prolonged action
•Liver is bypassed
•TRANSDERMAL THERAPEUTIC SYSTEMS:
•These are devices in the form of adhesive patches
which deliver the contained drug at a constant
rate into systemic circulation via stratum
corneum

28. Transdermal patch

29. CONTD..
•The drug is delivered at the skin surface
by diffusion for percutaneous absorption
into circulation
•Sites :
chest, abdomen, upper arm, lower
back, buttock, mastoid region
Examples:
Nitroglycerine, Fentanyl, Nicotine,
Estradiol

30. Transdermal patch

31. Contd..
•Advantages :
•Provide smooth plasma concentrations of
the drug without fluctuations
•Minimize inter individual variations, side
effects
•Better Patient compliance
•Limitations :
•Local irritation, erythema – mild
•Discontinuation is necessary in 2-7 % cases

32. INHALATION
•Volatile liquids and gases are given by inhalation for
systemic action
•Controlled administration is possible
•Absorption takes place from the vast surface of alveoli
•Action is very rapid
•Limitations:
•Irritant vapours cause inflammation of respiratory tract and
increase secretion
•Examples:
•General anaesthetics , amylnitrite

33. Inhalation

34. NASAL ROUTE:
•GnRH agonists and
desmopressin applied
as spray or nebulised
solution.
•Digestive juices and
liver are bypassed.

35. PARENTERAL
(Par – beyond, enteral – intestinal)
•Administration by injection which takes
the drug directly into the tissue fluid /
blood
•Advantages:
•Action is faster
•Valuable in emergencies
•Gastric irritation and vomiting - Absent
•Suitable in uncooperative, unconscious,
vomiting patients

36. Contd..
•No interference with food / digestive juices
•Liver is bypassed
•Disadvantages:
•Sterilization is needed
•Costly
•Invasive
•Painful
•Assistance is needed
•More risky

37. Parenteral routes:
•1. subcutaneous
•2. intramuscular
•3. intravenous
•4. intradermal

38. SUBCUTANEOUS ROUTE (S.C)
•The drug is deposited in the loose subcutaneous
tissue which has rich nerve supply and is less
vascular
•Self injection is possible (insulin injection)
•Advantages:
•Repository preparations can be injected for
prolonged action.
•Should avoid in the patients with SHOCK

39. S.C route

40. SPECIAL FORMS OF S.C ROUTE
•1. DERMOJET:
•Needle is not used.
•High velocity jet of drug solution is
projected from a micro fine orifice using a
gun like implement.
•2. PELLET IMPLANTATION:
•Solid pellet introduced with trochar and
cannula. E.g. testosterone

41. Contd..
•3. SIALISTIC (NONBIODEGRADABLE)
& DEGRADABLE IMPLANTS:
•Drugs packed in tubes and implanted under
the skin.
•Slow and uniform release of the drug occurs
over months providing constant blood
levels.
•E.g. NORPLANT

42. Dermojet
•Norplant implantation

43. Intramuscular (i.m)
•The drug is injected in large
skeletal muscles – deltoid,
triceps, gluteus maximus,
rectus femoris.
•Absorption is faster
•Irritants can be injected
•Less painful
•Depot preparations can be
injected.

46. INTRAVENOUS ROUTE
•I.V bolus injection (t PA in
acute MI)
•I.V infusion (antibiotics)
• Advantages:
•100% bioavailability
•Great value in
EMERGENCY
•Irritant solutions can be
given
•Titration of the dose with
the response is possible.
(e.g. BP, induction of
surgical anesthesia)

47. Limitations: :
•Most risky route
•Unfavorable reactions can occur
•Close monitoring of the patient’s response
•Should maintain the patency of the vein
(THROMBOPHLEITIS)
•Necrosis of the adjoining tissues if
extravasations occurs
•Drugs in an oily vehicle, those that precipitate blood
constituents/haemolyze erythrocytes must not be
given by this route

48. INTRA DERMAL
•The drug is injected into the skin raising a
bleb.
•This route is employed for specific
purposes only.
•Examples :
•BCG vaccination
•Sensitivity testing

50. Intradermal injection

62. THANK YOU