Determine LD50 value
- 1. TO DETERMINE THE LD50 VALUE OF A GIVEN DRUG. BINAL PATEL SHREE NARANJIBHAI LALBHAI PATEL COLLEGE OF PHARMACY, UMARAKH.
- 2. REQUIREMENTS Animal- Mice (20-25g) Drug- Procaine hydrochloride BINAL PATEL, DEPARTMENT OF PHARMACOLOGY, SNLPCP, UMARAKH. 2
- 3. PRINCIPLE The determination of ED50 (the dose effective in producing certain expected response in 50% of the animal group) values helps in ascertaining the potency of a drug in terms of a reference standard. The calculation of ED50 value is done when a drug is showing graded response. BINAL PATEL, DEPARTMENT OF PHARMACOLOGY, SNLPCP, UMARAKH. 3
- 4. But, when the response is quantal or all or none, the ED50 value becomes LD50 (the dose lethal to 50% of the animal group). Both these values i.e., ED50 and LD50 are important for knowing the safety of a drug. The ratio between LD50 and ED50 (LD50/ED50) represents therapeutic index. Greater the therapeutic, safer is the drug. BINAL PATEL, DEPARTMENT OF PHARMACOLOGY, SNLPCP, UMARAKH. 4
- 5. METHODS 1. Graphical method 2. Arithmetical method and 3. Statistical approach. For research purpose, the most widely used method is that of Litchfield and Wilcoxon. BINAL PATEL, DEPARTMENT OF PHARMACOLOGY, SNLPCP, UMARAKH. 5
- 6. For calculating LD50 by either method, find out the least tolerated dose and most tolerated dose by hit and trail method. Once these two doses are determined, select at least 5 doses in between the least tolerated and most tolerated doses and observe the mortality due to these doses. Generally, mice are used for this purpose and each dose group should consist of 10 animals. One can determine the LD50 value by different routes of administration. The LD50 value of a new drug is determined by oral as well as by one of the parenteral routes of administration. BINAL PATEL, DEPARTMENT OF PHARMACOLOGY, SNLPCP, UMARAKH. 6
- 7. PROCEDURE: 1. Use overnight fasted mice. Each dose group should consist of 10 mice. 2. Mice are divided into 6-8 group of 10 mice each. The drug under study is injected by intraperitoneal route (or Oral route) in different doses to different groups. 3. The animals are then observed for signs of toxicity and the mortality for 2 hours and then at 24 hours. 4. At the end of 24 hours number of animals dead are counted in each group percent death is then calculated and is transferred to probits using probit table. 5. Probits are then plotted (y-axis) against log dose of the drug. BINAL PATEL, DEPARTMENT OF PHARMACOLOGY, SNLPCP, UMARAKH. 7
- 8. Procaine Hydrochloride Toxicity Data in Mice OBSERVATIONS: BINAL PATEL, DEPARTMENT OF PHARMACOLOGY, SNLPCP, UMARAKH. 8
- 9. TRANSFORMATION OF PERCENTAGES TO PROBITS BINAL PATEL, DEPARTMENT OF PHARMACOLOGY, SNLPCP, UMARAKH. 10
- 10. OBSERVATIONS: Procaine Hydrochloride Toxicity Data in Mice Group Dose mg/kg, ip Log dose Dead/Total % Dead Corrected % Probit 1 68 1.83 0/10 0 2.5* 3.04 2 75 1.87 1/10 10 10 3.72 3 91 1.96 2/10 20 20 4.16 4 110 2.04 6/10 60 60 5.25 5 146 2.16 9/10 90 90 6.28 6 161 2.21 10/10 100 97.5* 6.96 BINAL PATEL, DEPARTMENT OF PHARMACOLOGY, SNLPCP, UMARAKH. 11
- 11. 0 1 2 3 4 5 6 7 8 0 20 40 60 80 100 120 140 160 180 PROBIT DOSE 105.9 MG/KG BINAL PATEL, DEPARTMENT OF PHARMACOLOGY, SNLPCP, UMARAKH. 12
- 12. RESULT THE LD50 VALUE OF PROCAINE HYDROCHLORIDE WAS FOUND TO BE 105.9 mg/kg, ip. BINAL PATEL, DEPARTMENT OF PHARMACOLOGY, SNLPCP, UMARAKH. 13
- 13. EXERCISE Pentobarbital sodium Toxicity Data in Mice Group Dose mg/kg, ip Log dose Dead/Total % Dead Corrected % Probit 1 30 2 45 3 50 4 65 5 75 BINAL PATEL, DEPARTMENT OF PHARMACOLOGY, SNLPCP, UMARAKH. 14