PHARAMACOLOGY

 INTRAMUSCULAR::

It is the commonest and choicest route of administering injectable drugs The muscle has rich lymphatic supply and hence the absorption is very rapid Irritant drugs and suspensions can be injected by this route Drugs like iron dextran (imferon) and procaine penicillin are injected intramuscularly 

Care for intramuscular injection ::

(1) Intramuscular injections must be given at safe sites e.g. the lower part of the deltoid region (shoulder ) or upper and outer quadrant of buttocks 

(2) The site of injection should be away from nerves and joints otherwise there is a risk of nerve damage and /or disturbances in movements 

(3) Ordinary injections should be given in superficial part of the muscle whereas irritating and painful ones are to be given into deeper part of the muscle e.g. injection of quinine 

(4) Aspiration in the syringe before injection is essential if injection goes into the vein it may prove fatal 

(5) Volume of fluid given should not be more than 10 ml 

    one may think that intramuscular route is always better for bioavailability however there are some exceptions Intramuscular injection of phenytoin results in about half plasma concentration as produced by equal dose given orally This is because of the precipitation of phenytoin at the site of injection 

Intravenous ::

This is the quickest route for fastest action of a drug it goes directly into blood circulation hence desired blood concentrations can be achieved irritant Substances can also be given by this route 

Care ::

For intravenous injection a superficial vein is selected area sterilized and injection is administered with aseptic technique after aspirating blood and ensuring that the needle is in the vein only the necessary quantity is administered and the speed of administration is regulated Airbubble should not find entry into the vein Air embolus is often fatal