PHARMACOLOGY

 

ENTERAL OR ORAL ROUTE ::

This is the most ancient convenient and commonly used route of administration of drugs Drugs administered by oral route can have 

(a) Local Action ::

kaolin as a local adsorbent streptomycin for local antibiotic action in intestine glycerine tannic acid for astringent action on gums Such an action is also called topical action 

(b) Reflex Action :: 

Gentian as bitter reflex sialogogue ammonium chloride as reflex expectorant and as a reflex emetic in large does 

(c) Systemic Action :: 

Drugs like aspirin as analgesic and antipyretic barbiturates as hypnotics  anthracene group of drugs as purgative and other innumerable drugs can be listed since most drugs are administered orally for their systemic action i.e. after absorption through the body fluids 

Advantages of oral route ::

(1) It is safe (2) It is convenient (3) It is economical (4) Self medication is possible (5) Absorption is selective as per need 

Disadvantages of oral route ::

1.The absorption may be uneven and hence their blood levels can not be predicted many a times this is inconsistent and erratic 

2.The onset of action is slow 

3.Drugs are either destroyed or altered after absorption in the gastro-intestinal tract and also in the liver (biotransformation) this is known as the first pass effect 

4.Irritant and unpalatable drugs cannot be administered since they will be vomited out 

5. A person who has severe diarrhoea or vomiting or is unconscious convulsive or non -co-operative cannot be given drugs safely by this route 

6.Larger dose of drugs are required Phenytoin is an exception where oral route requires smaller dose as compared to parenteral route 

7.Acid resistant drugs cannot be given 

8.Some drugs may form complexes with food e.g. tetracycline 

9. Some drugs destroyed by acid or enzymes in the gut cannot be given e.g. insulin benzyl penicillin 

Sublingual ::

The drug in the form of a tablet is put under the tongue only lipid soluble and non -irritating drugs can be administered by this route The drug is thus absorbed straight into systemic circulation through the sublingual route without passing through the liver Hence it does not undergo reduction in its potency Another advantage is that if it is found toxic it can be spit out to safely The drug most commonly used by this route is glyceryl trinitrite in angina pectoris and isoprenaline in asthma if the drug is to be used in large amount and frequently then this route becomes inconvenient