DR. MOHD NAZAM ANSARI

 Analgesics:  Types of Analgesics & MOA  Opioid/Narcotic analgesics:  Non opioid/non-narcotic analgesics:  Difference between narcotic and non-narcotic analgesics Non-Narcotic AnalgesicsNarcotic Analgesics Act peripherallyAct centrally Do not cause addictionCause addiction Do not produce CNS depressionProduce CNS depression Produce gastric irritationDo not produce gastric irritation Has anti-inflammatory effectHas no anti-inflammatory effect

Membrane phospholipid Phospholipase A 2 Arachidonic Acid Cycloxygenase Cyclic endoperoxides PGG 2 PGH 2 Isomerase Thromboxane synthetase ProstaglandinTXA 2 (PGE 2, PGD 2, PGF 2 α ) TXB 2

COX enzymes COX-1 enzyme Responsible for protecting body’s stomach lining and kidneys COX-2 enzyme Responsible for causing pain and inflammation

NSAIDs Inhibit COX-1 enzyme Inhibit prostaglandin that Protect the stomach lining COX-2 enzyme Inhibit prostaglandin that causes pain and inflammation Gastric ulceration and colitis anti-inflammatory & analgesic action

 Chemical  Electrical  Thermal  Mechanical

 Most widely used 1.Eddy’s Hot Plate: Animal is placed on hot plate and time for jumping from plate is noted before and after administration of drug. Hind paw licking (4-6 sec) or jump response (2-3 sec) 2.Davies Test or Tail flick method: only for narcotic analgesics 3.Immersion of tail of rat in hot water

 The paws of rats are very sensitive to heat at temperature.  So the response are jumping, withdrawal of paws and licking of the paws.  The time until this response occur is prolonged after administration of centrally acting analgesics.

Wistar albino rats of either sex with weight of about g. The hot plate consist of electrically heated surface with controlled temperature 55±1°C. Animals are place on hot plate and time of flicking or jumping is recorded by stop watch, before drug administration. The latency time is recorded after 15,30,45,60 minutes following oral or subcutaneous administration of the test compound

Reaction time in second Minutes after drug administrationControlRat No

 Shows the prolongation of latency time by comparing value before and after administration of test compound.  Comparison done by statistical analysis using t-test.  The value which is exceed the value before administration for 50% or 100% can be regarded as positive response.  ED 50 value can be calculated.