Biological Assay of Diphtheria Antitoxin

Biological Assay of Diphtheria Antitoxin

The potency of diphtheria antitoxin is determined by comparing the dose necessary to
protect guinea-pigs or rabbits against the  erythrogenic effects of a fixed dose of the
Standard Preparation of diphtheria antitoxin necessary to give the same protection. For
this purpose, a suitable preparation of diphtheria toxin is required to be used as a test
toxin. The test dose of the toxin is determined in relation to the Standard Preparation. The
potency of the preparation being examined is then determined in relation to the Standard
Preparation using the test toxin.

Biological Assay of Oxytocin

Biological Assay of Oxytocin

Principle: The potency of oxytocin is determined by comparing its activity with that of
the Standard Preparation of oxytocin under the conditions of a suitable method of assay.
Standard Preparation: The Standard Preparation is the 4th International Standard for
Oxytocin, established in 1978, consisting of freeze-dried synthetic oxytocin peptide with
human albumin and citric acid (supplied in ampoules containing 12.5 Units), or another
suitable preparation the potency of which has been determined in relation to the

Biological Assay of Heparin Sodium

Biological Assay of Heparin Sodium

Principle: The potency of heparin sodium is determined by comparing the concentration
necessary to prevent the clotting of sheep or goat or human plasma with the concentration
of the Standard Preparation of heparin sodium necessary to give the same effect under the
conditions of the following method of assay.

Bioassay of insulin

Bioassay of insulin

Standard preparation and unit: It is pure, dry and crystalline insulin. One unit contains
0.04082 mg. This unit is specified by Ministry  of Health, Government of India and is
equivalent to international unit.

Bioassay of digitalis

Bioassay of digitalis
Principle: Potency of the test sample is compared with that of the standard preparation by
determining the action on the cardiac muscle. Any other equivalent method, which gives
results similar to those obtained by this method as also valid.

Bioassay of D-Tubocurarine

Bioassay of D-Tubocurarine

1. Rabbit Head-drop Method : Principle: d-Tubocararine hydrochloride is injected into
the marginal vein of a rabbit’s ear till the rabbit’s neck muscles are relaxed such that the
animal cannot hold its head up. The total amount of test sample required to produce the
endpoint is compared with the total amount of the standard sample required to produce
similar endpoint.

Bioassay of acetylcholine

Bioassay of acetylcholine
Principle: Potency of the test sample is compared with that of the standard preparation.
There are several biological methods for its assay.

1. Rectus Abdominis Muscle of Frog: Dissect the rectus muscle and arrange the
assembly as per assay of d-tubocurarine. Plot log dose-response curve and find out the
potency of the sample of acetylcholine.

Principles and Methods of Bioassay

Bioassay is defined as the estimation of the potency of an active principle in a unit
quantity of preparation or detection and  measurement of the concentration of the
substance in a preparation using biological methods (i.e. observation of pharmacological
effects on living tissues, microorganisms or  immune cells or animal). Hence micro