Determination of LD50 of Phenobarbital

on 12.1.09 with 0 comments



Points to be discussed

  • Phenobarbital: MOA, SE

  • LD50

  • Determination of phenobarbital LD50

Lab work

Material:

Drugs:

  • Phenobarbital (2%)

Animals: 48 mice.

Method:

  1. The animals are weighed to the nearest gm. Then the mice are divided according to the animals weight into 6 groups (each group had 8 mice with equal weight distribution), the groups were labeled 1, 2,3,4,5, and 6.

  2. Phenobarbital is injected intraperitoneally in different doses (according to the animal wt.) to the animals. Each group is given a certain dose per animal wt. (see table 1.).

  3. After 24 hr. the number of dead animals in each group is counted and recorded in table 1.

  4. LD50 of phenobarbital is calculated by arithmetic and graphic methods


Table 1

Group

Dose (mg/kg)

Log dose

Dead

Dead %

Corrected %

Probit

1

330






2

300






3

280






4

250






5

220






6

120






*Correction formulas: for the 0% dead, 100(0.25/n). For the 100% dead, 100 [(n-0.25)/n], where n= number of animals in each group.

Table2. Phenobarbital toxicity in mice, computed by Karber method

Group

Dose (mg/kg)

Dose difference (mg/kg) = a

Dead

Mean b

Product a*b

1

330

-

8

-


2

300

30

7

7.5


3

280

20

5

6


4

250

30

3

4


5

220

30

1

2


6

120

100

0

0.5



T=

- LD50 = 330 – (T/8) = mg/kg


Category: Pharmacology Notes

POST COMMENT

0 comments:

Post a Comment