Evaluation of Analgesics

(Screening of Narcotic Analgesic)

Points to be discussed

1. Classification of analgesics

2. Morphine; MOA, Pharmacological effects, Uses, Side effects

3. Morphine antagonists

4. Methods of screening of narcotic analgesic

Lab work

Material:

Drugs:

• Morphine 0.5 mg/ml

• Unknown

Instruments:

• Cages.

• Stop watches.

• 1 ml syringes.

• Thermostatically controlled hot plate.

• Thermometer.

Animals: 30 mice.

Method:

1. The animals are weighed to the nearest gm. Then the mice will be divided into two groups (each group had 6 mice), the groups are labeled I, II.

2. The sensitivity of all animals is tested on the hot plate (55°C) before the administration of any drug by measuring their reaction time (licking of their leg or jumping out of beaker), it should not exceed 10 seconds.

3. To group I, morphine group, morphine (0.5 mg/ml) is given in a dose of 0.2ml/10 gm wt intraperitoneally. Then the sensitivity of each mouse is tested every 10 min. following the injection till recovery.

4. To group II, unknown group, unknown is given in a dose of 0.2ml/10 gm wt intraperitoneally. Then the sensitivity of each mouse is tested every 10 min. following the injection till recovery.

5. The results are recorded in tables.

6. Draw the curve of results.

(Screening of Non-narcotic Analgesic)

Points to be discussed

1. Classification of analgesics

2. NSAID: Examples, MOA, SE.

3. Methods of screening of Non-narcotic analgesic

Lab work

Writhing method:

Material:

1- Animal: Mice

2- Painful stimulus: Chemicals e.g. acetic acid (0.6%) solution in a dose of 1 ml/100 gm IP.

3- Drug used: NSAID e.g. Na salicylate (2%); dose1= 100 mg/kg, dose2= 200 mg/kg IP.

Method:

- Weigh three mice (one mouse is control i.e. given acetic acid only; the other two mice are treated with 100mg/kg Na salicylate and 200mg/kg Na salicylate, respectively)

- Calculate the dose of acetic acid for each animal and the doses of Na salicylate for the two treated mice

- Inject the calculated doses of Na salicylate IP to the animals and inject the control with acetic acid IP. 5min. later inject the calculated doses of acetic acid to the animal pretreated with Na salicylate IP.

- The mice then are observed and the time needed by the animal to writhe is recorded. The number of writhings in 10 minutes for each animal is recorded in the table.

Category: Pharmacology Notes