1. Routes of drug administration:

From the alimentary tract:
(i) Buccal cavity: e.g. nitrates
(ii) Stomach: e.g. aspirin, alcohol
(iii) Intestine: e.g. most of non ionized and ionized drugs.
(iv) Rectum: e.g. rectal suppositories, bisacodyl laxatives.
Advantages of oral route: This route is safe, convenient and economical.
Disadvantages of oral route: Onset of drug action is slow, irritant drugs cannot be
administered and it is not useful in vomiting and severe diarrhea, gastric acid and digestive
enzymes may destroy some drugs, and water soluble drugs are absorbed poorly.
b) From the parenteral route:
(i) Intradermal: This is given into the layers of the skin e.g. B.C.G. vaccine
(ii) Subcutaneous: Non-irritant substances are given into subcutaneous tissue
e.g. insulin
(iii) Intramuscular: Soluble substances, mild irritants, suspensions and colloids can be
injected by this route. These injections can be given to deltoid or gluteal muscle. This
route is one of the more common routes e.g. multivitamins, streptomycin, etc.

Advantages: rate of absorption is uniform, onset of action is faster than oral and
it can be given in diarrhoea or vomiting.
Disadvantages: Pain at local site of injection, the volume of injection should not
exceed 10 ml.
(iv) Intravenous: Drugs directly given into a vein, produce rapid action, no need of
absorption as they enter directly into blood, can be given as bolus e.g. furosemide,
morphine, dopamine or as continous infusion e.g. fluids during shock or
dehydration.
Advantages: It can be given in large volumes, production of desired blood
concentration can be obtained with a well designed dose.
Disadvantages: Drug effect cannot be halted if once the drug is injected,
expertise is needed to give injection.
(v) Intrathecal: Injected into subarachnoid space of spinal cord e.g. spinal anaesthetics.
(vi) Intraperitonial: Injections given into the abdominal cavity e.g. infant saline, glucose.
(vii) Intra–articular: Injected directly into a joint e.g. hydrocortisone.