routes of drug administration

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Reach the site of action:

Reach the site of action When does a drug exert its pharmacological effect?

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Major routes Enteral Parenteral Topical Oral Sublingual Rectal Injections Inhalation Transdermal Conjunctival,Nasal,Auditory ,Mucosal Vaginal and Urethral Inunction and Dermal

Commonly Used Routes of Drug Administration:

Commonly Used Routes of Drug Administration


FACTORS GOVERNING CHOICE OF ROUTE Physical & chemical properties of drug Rate & extent of absorption from various routes Effect of digestive juices & first pass effect Site of desired action Rapidity of the desired response Accuracy of dosage Condition of the patient


Enteral Enteron -intestine Placement of drug into any part of GIT


ADVANTAGES Safe Convenient Economical Usually good absorption Can be self administered Painless DISADVANTAGES Slow absorption Slow action Irritable and unpalatable drugs Unco -operative and unconscious patients Some drugs destroyed First-pass effect ORAL=MOUTH

First pass effect::

First pass effect:


Examples Solid- Tablet,Capsule,Powder Liquid- Syrup,Elixir,Mixture

Sublingual and Buccal:

Sublingual and Buccal Sublingual :beneath the tongue Buccal : Crushed and spread over buccal mucosa


ADVANTAGES Economical Drug absorption is quick First-pass avoided Quick termination-Spit off Can be self administered DISADVANTAGES Unpalatable & bitter drugs Irritation of oral mucosa Large quantities not given HMW drugs not absorbed SUBLINGUAL ROUTE


Example Systemic use Isosorbide dinitrate Nitroglycerine Nifedipine Local Antispetic lozenge


ADVANTAGES Used in children Little or no first pass effect Used in vomiting/unconscious Higher concentrations rapidly achieved Can use gastric irritants DISADVANTAGES Embarrasing Inconvenient Absorption is slow and erratic Irritation or inflammation of rectal mucosa can occur RECTAL ROUTE-RECTUM

Prepackaged enema container:

Prepackaged enema container


Example Local Effects Dulcolax , Glycerine suppository ,enema, ointment Systemic Effects Aminophylline , Indomethacin suppositories

Gastric Tube Administration:

Gastric Tube Administration Gastric tubes provide access directly to the GI system.

Confirm proper tube placement.:

Confirm proper tube placement.

Withdraw the plunger while observing for the presence of gastric fluid or contents.:

Withdraw the plunger while observing for the presence of gastric fluid or contents.

Instill the medication into the gastric tube.:

Instill the medication into the gastric tube.

Gently inject the saline.:

Gently inject the saline.

Clamp off the distal tube.:

Clamp off the distal tube.

Parenteral Routes:

Parenteral Routes Routes other than enteral are called parenteral

Administration of drugs by the parenteral route:

Administration of drugs by the parenteral route


Intradermal Intradermal -outer layers Amount of drug small, slow absorption Tuberculin syringe Example: BCG vaccine, diagnostic tests, allergic sensation testing

Subcutaneous administration Site: Injection under skin :

Subcutaneous administration Site: Injection under skin Merits Smooth but slow absorption depot injections/implants Examples Local-local anaesthetic Systemic-Insulin Demerits small volume(1 ml) irritant drugs-sloughing and necrosis not suitable in shock

Intramuscular Injections:

Intramuscular Injections Site-Deltoid muscle, Gluteus, Vastus

Intramusular route:

ADVANTAGES Absorption reasonably uniform Rapid onset of action Mild irritants can be given First pass avoided Gastric factors can be avoided DISADVANTAGES Only upto 10ml drug given Local pain and abcess Expensive Infection Nerve damage Intramusular route

Intravenous Administration :

Intravenous Administration Merits Bypass first pass metabolism(100%) Quick onset of action In uncooperative and unconscious patients those with nausea and vomiting hypertonic solutions and irritants large volumes amount of drug can be controlled accurately Demerits Antiseptic conditions Depend on others Painful and risky-cant be recalled Embolism Suspensions/oily drugs/depots cant be given Venous thrombosis and phlebitis Necrosis due to extravasation


Examples IV infusion- Ringer,Dextrose 5%,DNS,Dopamine IV bolus- Diazepam,Adenosine,Insulin

Intraarterial :

Intraarterial Site: Lumen of artery Merits: Greater concentration of the drug can be delivered Demerits: Expertise and asepsis Examples: Radiopaque contrast for coronary angiography and cerebral angiography


Intraperitoneal Site-Peritoneal space Merits-Rapid absorption-large surface area Demerits- Painful,Risky,Adhesions,Peritonitis Example: Dialysing fluid-poisoning and renal failure In lab animals

Intrathecal (Intraspinal):

Intrathecal ( Intraspinal ) Site: Subarachanoid space Merits: Bypass blood brain barrier and blood CSF barrier-acts directly on meninges and spinal cord Demerits-Asepsis, Expertise, Painful,Risky Example: Radioopaque contrast media, Xylocaine injection


Epidural Through vertebral interspace between dura and lining of spinal canal Example: Xylocaine injection

Intramedullary :

Intramedullary Site:Tibial or Sternal bone marrow Merits: onset of action very fast Demerits: Strict aseptic conditions, expertise and skill required Painful and risky Examples: Bone Marrow transplantation


Intraarticular Site: Injection directly into the joint space Merit: High concentration in localised area Demerits: Asepsis, Joint damage, Pain Examples: Hydrocortisone, Gold chloride for rheumatoid arthritis

Intracardiac injection:

Intracardiac injection Left fourth intercostal space into heart muscle Eg Adrenaline injection-cardiac arrest


Inhalation Site: Inspiration nose/mouth Merits: fast, quick-large surface area, self Demerits: increased bronchial and salivary secretions Examples: Salbutamol ,Na cromoglycate –Metered dose inhalers


drugs directly into the nose. Desmopressin is administered intranasally in the treatment of diabetes insipidus Salmon calcitonin - osteoporosis GnRH aanalogues Intranasal


TOPICAL OR LOCAL ROUTE Mucous membrane of eye, ear, nose throat, mouth urinary bladder, vagina and rectum Ointments, creams ,lotions and powders used


Topical Conjunctival , Nasal ,Auditory Mucosal drops, sprays Vaginal and urethral Solutions, ointment ,emulsions, suppositories, pessary,pencil shaped bougie Inunction and dermal Rubbing into skin Dust/spray

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