1. This route is used for injection of small volume parenterals.
2. The preparation is administered beneath the skin, especially in the loose interstitial tissue of the outer upper arm, anterior thigh or lower abdomen.
3. The site of injection is usually changed when frequent injections are required.
4. The skin at the injection site should be thoroughly cleaned before drug administration.
5. The maximum amount of medication that can be injected subcutaneously is about 2 ml because amounts greater than this can cause pain. Syringes of 3 ml capacities and 24 gauge needles are used.
6. Irritating drugs and drugs in thick suspension form may cause abscess or pain.

Intradermal Route

1. Drug substances are effectively injected into the cornium layer, beneath the epidermis. This route is preferred for diagnostic determinations or for desensitization or immunization procedures.
2. The site for intradermal injection is the anterior forearm.
3. For drug administration, a short and a narrow needle is normally employed. The needle is inserted horizontally into the skin with the bevel facing up. The maximum amount of medication that can be injected by this route is about 0.2 ml.

lntra-arterial Route

1. This route is used for inducing rapid drug action in the peripheral area.
2. Injection is made into an artery targeting a particular area.
3. The danger associated with this route is that it may cause gangrene and arterial spasm.

Intrathecal Route

1. Drug substances are injected into the subarachnoid space that surrounds the spinal cord.
2. This route of administration is difficult and causes severe pain to the patients.