Drug targets are key molecules involved in a particular metabolic or signalling pathway that is specific to a disease condition or pathology.

Important drug targets:

1. Enzymes - proteins that act as the bodys catalysts.

2. Receptors - proteins that are crucial for the bodys communication process.

3. Carrier proteins - transport important polar molecules across the cell wall.

4. Structural proteins - include tubulin in humans, cellulose in plants and collagen in animals.

5. Nucleic acids - targets for several important drugs, including various antimicrobial and anticancer agents.

6. Lipids - cell membranes consist of a phospholipids bilayer, which acts as a hydrophobic barrier.

7. Carbohydrates - cell surface carbohydrates are promising drug targets.

Routes of drug administration:

A drugs route of administration affects the rate and extent of absorption of the drug. Routes of drug administration are as follows:

1. Enteral Route

a. Taken by mouth (orally); eg. Acetaminophen

b. Placed under the tongue (sublingually); eg. Nitroglycerin

c. Through the rectum (rectally) or vagina (vaginally); eg. progestin

2. Parenteral Route

a. Into a vein (intravenously)

b. Into a muscle (intramuscularly)

c. Beneath the skin (subcutaneously); eg. heparin

d. Into the space around the spinal cord (intrathecally); eg: Some anesthetics and analgesics (such as baclofen)

3. Topical Route

a. Instilled in the eye (by ocular route); eg. betaxolol

b. Sprayed into the nose and absorbed through nasal membranes (nasally) eg. calcitonin

c. Inhaled into the lungs, usually through the mouth

d. Applied to the skin (cutaneously) for a local or bodywide effect; eg. phenytoin

e. Delivered through the skin by a patch (transdermally) for a systemic effect; eg. fentanyl