1. Analgesics
 Drugs which relive pain by acting on the central nervous system
and reduce without loss of consciousness
 They are of two types:
 *Narcotic Analgesics
 *Non-narcotic Analgesics.
 Non-narcotic Analgesics: Don’t produce significant depression of
the central nervous system. e.g.salicylates and related compounds
 Narcotic Analgesics: Produce depression of the central nervous
system.
 Classified into
 *Natural Analgesics e.g.morphine,codeine etc
 *Synthetic Analgesics e.g. pethidine,methadone etc

2. NARCOTIC ANALGESICS
Naturally Occurring:
Morphine
 opium alkaloid obtained from papaver somniferum
 morphine is generally used as sulphate and hydrochloride
 structure of morphine-isoquinoline alkaloid
 solutions of morphine are sterilized at 98-100 for 30 min with
bactericide.

3. Analgesic action
 powerful analgesic
 relief from pain without altering the functions of the central nervous system.
 does not lead to abnormal behavior.
 large doses can relive all types of pain.
 increases the threshold of the pain
 does not remove pain completely but helps to tolerate the pain.
 induces analgesia by acting on the receptors situated both in the higher
centers and spinal cord.
 produces depression of respiration and miosis.
Uses
 analgesic for reliving the pain
 used to reduce pain in acute myocardial infraction, burns, fractures of bones,
pleurisy etc.
 administered intravenously
 used to reduce post operative pain.
 it shows sedative effect
 used as a premedication for surgery.

4. .
Disadvantage
 invaluable in the treatment of pulmonary-edema
 drug of addiction due to euphoriant effect
 over dose causes poisoning
 causes dryness of mouth, mental clouding, dysphoria, vomiting,
headache, fatigue, constipation etc.

5. Codeine
 White crystalline powder
 sparingly soluble in water
 bitter in taste
 less potent analgesic than morphine
 better absorbed when administered orally

6. SYNTHETIC ANALGESICS
 Some important synthetic morphine substitutes are:
 1. Pethidine.
 2. Methadone.
Pethidine
• White crystalline substance.
• Bitter taste.
• Forms salts with acid.
• Action is similar to Morphine.
• Powerful analgesic in short duration of action
• Used in respiratory depressant like morphine.
• For treatment of shock.
• Used in place of morphine as an analgesic in
myocardial infarction.

7. Methadone
 Synthetic compound.
 Slightly potent than morphine.
 Available as Methadone Hydrochloride tablet doses 5 to 10mg.
 Also available in ampoules in injection form.
 Is a racemic mixture.
 Used as a substitute for Morphine and Pethidine.
 Gives relief from visceral pain.
 As respiratory depressant.

8. Morphinan
.
 syntheticanalgesics
 example of morphinan compound is levorphanol
 potent than morphine
 well absorbed when administered orally
Benzomorphan
 Potent than morphine
 synthetic agent
 used intramuscularly in the dose 2 to 3 mg

9. .
Salicyclic acid
The derivative of Salicyclic acid is analgesic and has antipyretic action.
The most important drugs are Aspirin, Sodium salicylate, salicin, etc.

10. .
Asprin
It’s also known as Acetyl salicyclic acid.
• Obtained by acetylation of Salicyclic acid.
• White crystalline, odorless powder.
• Sparingly soluble in water.
• Slight acid taste.
• In the presence of moisture, it gets hydrolyzed to
acetic acid & salicyclic acid.
• Stored in airtight containers.
• Stable in dry conditions.
• Used as analgesic in case of mild pain.
• Has antipyretic action.
• Used in headaches, cold, arthritis, toothache, etc.
• Used as anti-inflammatory agent.
• Reduces edema, tissue swelling, etc.
• Used as antirheumatic drug.
• Reliefs from signs and symptoms of inflammation.
• Has shown beneficial effect in radiation diarrhea.

11. Methyl salicylate
.
(Oil of winter green)
• Chemically it is O-hydroxy benzoate.
• Colourless pale yellow liquid.
• Slightly soluble in water.
• Has sweet taste and aromatic odor.
• Used for topical application.
• Methyl salicylate ointment is made in
white bees wax and hydrous wool fat.
• Flavoring agent.
• Used as analgesic in sciatica, rheumatic,
etc.

12. .
Sodium salicylate
Colourless small crystals or crystalline powder.
• Unpleasant taste
• Soluble in water.
• Taken in a mixture form with alkali.
• Used for integumental pain and acute rheumatic fever.

13. Salicin
• Obtained from bark of willows.
• Synthesized by the action of acetobromo-glucose and
Salicylaldehyde.
• Used in rheumatic pain and fever.

14. .
Diethylamine Salicylate
• It is a diethyl amine salt of salicylic acid.
• White crystalline substance.
• Topically used.
• Available as creams.
• Used in rheumatic and muscular pain.

15. .
The Para-aminophenol derivatives
 Analgesic and antipyretic effects.
 Not useful anti-inflammatory drugs.
 Commonly used drugs are Phenacetin and para-acetamol.
Para acetamol
• Chemically it is 4-hydroxy Actanilide.
• White crystalline powder.
• Is odourless ans highly soluble in water.
• Daily dosage should not exceed 2.5% in adults.
• More potent antipyretic than Phenacetin.
• Used for relief of pain and fever.
• Shows adverse effect are sweating, nausea, vomiting, etc.

16. .
Phenacetin
• White odourless, crystalline powder.
• Sparingly bitter in taste.
• Prepared from p-nitrophenol.
• Used with aspirin for relief of integumental pain.
• Phenacetin is hydrolyzed to paracetamol and this is the cause for
antipyretic-analgesic action.

17. .
Indolyl and aryl acetic acid derivatives
Important drugs are Indomethacin and Sulindae
Indomethacin
• Chemically it is named as 1-(4-chlorobenzoyl)-5-methoxy-2-methyl-3
indolylacetic acid.
• It is an indole acetic acid derivative.
• Brownish yellow crystalline powder.
• Insoluble in water.
• Soluble in organic solvents.
• Available as 25 mg capsules.
• Has an inflammatory, analgesic and antipyretic action.
• Effective in rheumatic disorders.
• Useful in treatment of gout.
• Some adverse effects are nausea, vomiting, skin rashes, diarrhea, etc.

18. Sulindae
• Chemically it is named as [5-fluoro-2 methyl-1 (4-methyl
sulphinyl-benzylidene) inden-3 yl] acetic acid.
• It is a fluorinated derivative of indomethacin.
• Yellow crystalline powder.
• Insoluble in water.
• Has longer duration of action than indomethacin.
• Used in the treatment of rheumatic and musculo-skeletal
disorders.