PHARMACOLOGY

 ROUTES OF PARENTERAL INJECTIONS ::

(A) INTRADERMAL ::

Here the drug is given within the skin layers (dermis) This route is used for testing sensitivity to drugs e.g. penicillin antitetanus serum (ATS) etc Highly diluted and a small quantity of the drug is administed Even this is painful Absorption is through the lymphatics Intradermal sensitivity test gives a clue as to whether the drug (to be injected) would be safe or allergic in nature for the concerned patient 

Inoculation ::

Small pox vaccine is administered by superficial puncturing or scaring of the epidermis The vaccine drop is slowly absorbed by lymphatics Administration of vaccine by intradermal route is known as inoculation 

(B) SUBCUTANEOUS ::

Drugs are injected under the skin Their absorption is slow hence the action is prolonged Sometimes very potent drugs are given by this route so that their effect is slow and sustained e.g. adrenaline There are three different methods for subcutaneous route of drug administration 

1.Hypodermoclysis ::

        It is a special process of infusing large amount of drugs like glucose and saline through loose subcutaneous tissues of the body The breasts buttocks and thighs are good sites for continuous drips of this type 

2.Hypospray :: 

    This is a new needleless technique for introducing drugs in the subcutaneous tissue Drug is introduced under high pressure in the form of a fine jet This hypospray method is painless it is not much used in practice 

3.Implants :: 

        This is a new technique of implanting a tablet or porous capsule into the loose tissues by incision of the skin which is then stiched up The tablet or porous capsule so introduced slowly liberates the drug and the action continues for weeks or even months Certain hormonal drugs are implanted in this way