Expt 3 Bracketing bioassay
- 1. EXPERIMENT NO: 03 AIM : To estimate unknown concentration of acetylcholine solution by bracketing bioassays using hen’s ileum. Presented by: Prof. Mirza Anwar Baig Dept of Pharmcaology AIKTC, School of Pharmacy, New Panvel
- 2. REQUIREMENTS: 1. Basal tension – 0.5 gm 2. Extra load- 1 gm 3. Animal – Hen’s ileum tissue 4. Drug – Acetylcholine stock solution (10 μg/ml) & test solution. 5. Physiological solution – Tyrode solution 6. Contact time – 90sec 7. Magnification – 5-7 times.
- 3. PRINCIPLE:- o Matching & bracketing method is very useful if the amount of material is small and if the sensitivity of the tissue is not steady. o The results of the assay do not depend on the actual measurement of response. o It is decided whether a particular concentration of test solution is greater or smaller than that produced by the dose of the standard
- 4. Bioassay by Bracketing Method Performed by selecting two standard doses, which will give a close bracket on either side of the response produced by the unknown. The working dose of standard is first determined in the sensitive part of dose-response curve, that is, a dose that will approximately produce 50% of the maximal concentration. The dose of the standard drug is kept constant throughout the experiment, in order to have some idea about the change in the sensitivity of tissue with time. The standard drug is added at fixed intervals but alternating with the test so that each response produced by a dose of test substance is bracketed by responses produced by the dose of standard. Close bracketing gives more accurate results.
- 5. Observation on kymograph paper:
- 6. Formula to calculate concentration of unknown drug:
- 8. Result:
- 9. References: 1. Kulkarni S. K. Handbook of Experimental Pharmacology, Vallabh Prakashan, New Delhi. 2. Ghosh M.N. Fundamentals of Experimental Pharmacology Hilton & Company, Kolkata
- 10. Thank You