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Questions and Answers
What is the main purpose of a digitalis bioassay?
What is the required amount of alcohol used in the extract preparation per gram of powder?
Which parameter is important when selecting guinea pigs for a digitalis bioassay?
What does 1 Unit of standard digitalis preparation contain in milligrams?
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What is the allowed limit of error in the potency estimation during the assay?
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What condition should be avoided in pigeons when preparing for the bioassay?
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What parameter determines when to stop the injection into the guinea pig?
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At what temperature should the extract be stored after preparation?
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What is the appropriate method for preparing the digitalis extract from the standard preparation?
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Which condition must be met when selecting guinea pigs for the bioassay?
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What should be done immediately after centrifuging the digitalis extract?
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What is the required mean body weight difference between the groups of guinea pigs used?
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What is the main purpose of injecting the extract into the guinea pig?
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Which temperature range is specified for storing the digitalis extract after preparation?
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What is the maximum allowed error percentage for estimating digitalis potency when using 6 guinea pigs per group?
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Why is it necessary to maintain the respiration of the guinea pig during the injection?
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Study Notes
Bioassay of Digitalis
- Purpose: To determine the activity of a digitalis sample by comparing it to a standard preparation.
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Standard Preparation:
- Supplied in ampoules or vials containing approximately 2.5g.
- 1 mg contains 76 Units of the standard preparation.
- 1 Unit contains 0.01316 mg.
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Preparation of Extracts:
- Transfer standard preparation to a weighing bottle, weigh and transfer to a glass-stoppered container.
- Add 10 ml of 80% alcohol for each gram of powder.
- Shake continuously for 24 hours at 20-30°C or 48 hours at 10-20°C.
- Centrifuge or filter through a sintered glass filter, avoiding evaporation.
- Transfer the liquid to a dry, hard glass bottle and store between 5°C and -5°C.
- Use the extract within one month.
- Prepare the test sample extract in the same manner.
Bioassay using Guinea Pigs
- Select 12 guinea pigs weighing 200-600g.
- The weight difference between the heaviest and lightest animal should not exceed 100g.
- Divide into two groups (test and standard preparation).
- The mean body weight of each group should not differ by more than 10%.
- Inject the extract slowly into the vein of an anaesthetized guinea pig.
- Maintain artificial respiration.
- The injection duration should be between 20-40 minutes.
- Continue injection until the heart is arrested (determined by electrical recording).
- Determine the lethal dose (volume of extract administered).
- Calculate the mean lethal dose (ml) per kg of body weight for each group.
Results
- Refer to the Pakistan Pharmacopeia 1973 to calculate the assay result.
- The allowed error limit is 80-125% of the estimated potency when 6 guinea pigs are used for each group.
Bioassay using Pigeons
- Select 12 or more pigeons randomly and divide into two groups.
- Pigeons should be healthy, free from disease, obesity, or emaciation.
Bioassay of Digitalis
- Digitalis activity is measured by comparing a sample's effect on guinea pig or pigeon heart muscle to a standard preparation.
- The standard preparation comes in ampoules or vials containing approximately 2.5 grams.
- One milligram of the standard preparation contains 76 Units.
- One Unit contains 0.01316 milligrams.
Preparation of Extracts
- Transfer the contents of a vial containing a suitable quantity of the standard preparation to a stoppered weighing bottle and weigh it.
- Transfer the contents of the weighing bottle to a hard glass, glass-stoppered container with a minimum capacity of 50 ml.
- Add 10 ml of 80% alcohol for each gram of powder.
- Shake the container continuously for 24 hours at 20°C-30°C, or for 48 hours at 10°C-20°C.
- Centrifuge or filter the mixture through a sintered glass filter, taking precautions to avoid solvent evaporation.
- Transfer the liquid to a dry, hard glass bottle, close tightly, and store at 5°C to -5°C.
- Use the extract within one month.
- Prepare an extract of the test sample in the same manner.
By Injection into Guinea Pigs
- Randomly select 12 guinea pigs weighing between 200-600 grams.
- The weight difference between the heaviest and lightest animal should not exceed 100 grams.
- Divide the guinea pigs into two groups, ensuring the mean body weight of each group does not differ by more than 10%.
- Designate one group for the test sample and the other for the standard preparation.
- Anesthetize the guinea pigs with urethane and artificially maintain their respiration.
- Inject the extract slowly into the vein until the heart is arrested.
- The injection duration should be between 20-40 minutes.
- Determine the lethal dose as the volume of the extract administered until cardiac arrest.
- Calculate the mean lethal dose (ml) per kg of body weight for each group.
Result
- Refer to the Pakistan Pharmacopeia 1973 to calculate the assay results.
- When using 6 guinea pigs for the standard preparation and 6 for the test sample, the allowed error margin is 80-125% of the estimated potency.
By Injection into Pigeons
- Randomly select 12 or more pigeons, free from disease, obesity, or emaciation.
- Divide the pigeons into two groups.
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Description
This quiz tests your knowledge of conducting a bioassay using digitalis samples and guinea pigs. It covers preparation methods, standard measurements, and extraction techniques. Navigate through different aspects of the experiment and enhance your understanding of pharmacology and bioassays.
