Routes of administration

Routes of administration


General Pharmacology

       Routes of administration

       Advantages and disadvantages of various routes of administration

       Differentiate between oral and parental route

Intended Learning Outcomes

At the end of this lecture, student will be able to

       Classify various routes of administration

       Explain the advantages and disadvantages of various routes of administration

       Differentiate between oral and parenteral route of administration

Routes of administration

Parenteral Route


      Unconscious, unco-operative patient

      Patients with vomitting and diarrhoea

      Drugs irritating stomach

      Avoid FPM, drug modification by GIT juices or liver enzymes

      Rapid action

      Accuracy of dose



      No self-medication

      Liable to cause infection

      Injury to arteries/ nerves


Parenteral Route – Injections 


       BCG vaccine

       Given to the layers of skin, Painful

       Small quantity can be administered

       Employed for testing drug sensitivity


       Commonest – insulin

       s.c. drug implants depot therapy - Sex hormone implants

       Only non-irritant substances

       Absorption slower than i.m.

       Unreliable in shock


       Soluble substances, mild irritants, suspensions, colloids

       Rate of absorption – Reasonably uniform, rapid onset

       Volume should not exceed 10 ml

       Diazepam, hydrocortisone, phenytoin, digoxin

       May cause local pain or necrosis - Quinine, paraldehyde

       Care to avoid nerve damage

       Child – to the lateral thigh


       Directly into the vein and rapid action

       Desired blood conc obtained rapidly with well-defined dose


      Needle position should be ensured

      Irritating solutions – Piggybacking into a running i.v. drip


      Local irritation can lead to phlebitis

      No Self medication

      Extravasation – severe irritation, sloughing

       Drug may be injected:

      As a bolus (Furosemide)

      Over 5-10 min (Aminophylline in 10-20 ml of isotonic glucose/ saline

      In an infusion 50-100 ml

      Infusion is employed:

      To slow the administration of drug to avoid toxicity – Morphine

      To maintain a constant plasma level – insulin/ dopamine

      To administer larger volume– Fluid in shock / dehydration

Intra-arterial route

      Into artery

      Used in diagnostic studies – Angiogram, embolization therapy

      Antimalignancy compounds – localised malignancies

Intraperitoneal route

      Large surface area for absorption

      Infants – giving fluids

      Peritoneal dialysis


      Into sub-arachnoid spaces

      Drugs act directly on CNS

      Strict asceptic precautions


      Antimalignancy compounds

Epidural/ Extradural

      Over the dura mater



      Into bone marrow of iliac crest or tibia

      Rapid absorption

      Adrenaline in severe shock with sudden cardiac arrest

Intra articular

      Directly into a joint

      Hydrocortisone acetate in RA

      High local conc of drug

II. Transcutaneous


      Galvanic current allows the penetration of drugs applied into the skin into the deeper tissues

      Anode Iontophoresis: for +ve compounds

      Catode Iontophoresis: for –ve compounds

      Eg. salicylates


      Rubbed into the skin

      NG ointment in Angina Pectoris

       Jet injection

      High velocity jet produced through a micro fine orifice

      No needle


       Adhesive unit

      Deliver the drug slowly

      Scopolamine for motion sickness

III. Transmucosal


      NG in angina pectoris

      Buprenorphine as analgesic


      GnRH, calcitonin


      Indomethacin in RA

      Diazepam in SE


      Adrenaline, atropine, diazepam, lignocaine

IV. Inhalation Route

       Produce rapid effects

       Drugs directly to the left side of the heart

       May produce cardiac toxicity

       By pressurised metered aerosols – Salbutamol, beclomethasone in bronchial asthma

       Dry powders from inhalers – Salbutamol

       Oxygen or compressed air driven nebulised solution

       Gases-  General anaesthetics


       Routes of administration: Oral and Parenteral

       Parenteral includes intravenous, intramuscular, intrathecal, intradermal, subcutaneous

       Parenteral routes are useful in unconscious, unco-operative patient, patients with vomitting and diarrhea, drugs irritating stomach

       Inhalational routes produce rapid effects, drugs directly enter  into left side of the heart and may produce cardiac toxicity

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