(Mode of Action of Drugs)

ChapterChapter

2.4

Non-Narcotic

Analgesics

(NSAID’s)(NSAID’s)(NSAID’s)(NSAID’s)(NSAID’s)

Non-steroidal antiinflammatory drugs
(NSAIDs) are also known as nonopioid an-
algesics. They relieve pain without interact-
ing with opioid receptors and do not depress
CNS and have no drug dependence or drug
abuse property and possess antipyretic ac-
tivity also. They act primarily on peripheral
pain mechanisms and also in CNS to raise
pain threshold.

They can be classified as in table 2.4.1.
NSAIDs exert analgesic, antipyretic,
anti-inflammatory and related effects. Dur-
ing pain, fever and inflammation the arachi-
donic acid is liberated from the phospho-
lipid fraction of the cell membrane which is
then converted to prostaglandins (PGs) via
cyclooxygenase pathway (both COX-1 &
COX-2). COX-1 is present in kidney, stom-
ach and blood vessels and COX-2 is present
in activated leukocytes and other inflamma-
tory cells.

SALICYLATES

Salicylates are esters or salts of salicylic acid.
Acetyl salicylic acid (aspirin) is rapidly con-

Non-Narcotic

Analgesics

verted in the body to salicylic acid and pro-

duce the pharmacological actions.

Analgesic action: Salicylates relieve

pain by both central and peripheral action.

The site of action of central analgesia seems

to be the hypothalamus. It does not have

cortical action on the reaction component of

the pain but raises the threshold to pain per-

ception. Unlike morphine, they do not pro-

duce sedation and there is no drug tolerance

or dependence and are not effective against

visceral pain.

The peripheral component of their an-

algesic action is due to the inhibition of

prostaglandin synthetase and thereby in-

hibiting the synthesis of prostaglandins

(PGs) which sensitise the pain receptors to

mechanical and chemical stimuli. Aspirin

inhibits prostaglandin synthesis and blocks

the sensitization of pain mechanism.

They are useful in relieving all dull

itching, throbbing pain of muscles and

joints, dysmenorrhoea, toothache, head-

ache etc. The NSAID’s are the mainstay for

the management of acute dental pain.