Oxytocin-bioassay

D.SUCHITRAD.SUCHITRA

M.PHARM (PA & QA)M.PHARM (PA & QA)

ROLL NO. 100809885016ROLL NO. 100809885016

BIOLOGICAL ASSAY OF BIOLOGICAL ASSAY OF OXYTOCINOXYTOCIN

INTRODUCTIONINTRODUCTION

Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-GlyNH2GlyNH2

Mol. Wt.1007.2Mol. Wt.1007.2Oxytocin is a nonapeptide hormone Oxytocin is a nonapeptide hormone

obtained by a process of obtained by a process of fractionation from the posterior lobe fractionation from the posterior lobe of the pituitary gland of healthy oxen of the pituitary gland of healthy oxen or other mammals.or other mammals.

It is released by stimuli – coitus, It is released by stimuli – coitus, parturition & suckling. parturition & suckling.

PHARMACOLOGICAL ACTIONSPHARMACOLOGICAL ACTIONS

1. UTERUS : Increases uterine 1. UTERUS : Increases uterine contractions – parturition.contractions – parturition.

Useful in induction of labour.Useful in induction of labour.2. MILK EJECTION REFLEX : Initiated 2. MILK EJECTION REFLEX : Initiated

by suckling.by suckling.

LACTATION : PRODUCINGLACTATION : PRODUCING & RELEASING MILK& RELEASING MILK

BIOASSAY OF OXYTOCIN BIOASSAY OF OXYTOCIN

The potency of oxytocin injection is The potency of oxytocin injection is determined by comparing its activity determined by comparing its activity with that of the standard preparation with that of the standard preparation of oxytocin under the conditions of of oxytocin under the conditions of the following method of assay. the following method of assay.

Standard Preparation and Standard Preparation and Unit:Unit:

          The standard preparation is a freeze The standard preparation is a freeze dried preparation of oxytocin with albumin dried preparation of oxytocin with albumin and citric acid or any other suitable and citric acid or any other suitable preparation, the potency of which had preparation, the potency of which had been determined in relation to the been determined in relation to the International standard.International standard.

          The Unit is the specific oxytocin activity The Unit is the specific oxytocin activity corresponding to that yielded by 0.0005 g corresponding to that yielded by 0.0005 g of the Standard preparation. of the Standard preparation. 

EXTRACT OF STANDARD EXTRACT OF STANDARD PREPARATION:PREPARATION:

METHOD: METHOD:

Test animals: Use female rats in Test animals: Use female rats in dioestrus, weighing between 120 and dioestrus, weighing between 120 and 200 g or nulliparous, anoestrus 200 g or nulliparous, anoestrus female guinea pigs weighing female guinea pigs weighing between 175 g and 350 g. between 175 g and 350 g.

Method of Comparison: Method of Comparison:

By contraction of the rat uterus By contraction of the rat uterus — — Inject 100 μg of Inject 100 μg of oestradiol benzoate oestradiol benzoate intramuscularlyintramuscularly

Kill the rat and suspend one horn of Kill the rat and suspend one horn of the uterus in a bath containing Locke the uterus in a bath containing Locke ringers solutionringers solution

Maintain the bath at a temperature Maintain the bath at a temperature of 32ºof 32º

Contd…..Contd…..

Oxygenate the solution.Oxygenate the solution. Record the contractions produced by Record the contractions produced by

the addition to the bath of two doses the addition to the bath of two doses of the Standard Preparation suitably of the Standard Preparation suitably diluted with the above solution.diluted with the above solution.

The doses should be such as to The doses should be such as to produce clearly discriminated, produce clearly discriminated, contractions.contractions.

Contd….Contd….

The required doses : between 10 and The required doses : between 10 and 50 micro Units per ml of bath liquid.50 micro Units per ml of bath liquid.

When maximal contraction has been When maximal contraction has been reached, replace the bath liquid by a reached, replace the bath liquid by a fresh solution.fresh solution.

The doses should be added at The doses should be added at regular intervals of 3 to 5 minutes regular intervals of 3 to 5 minutes

Contd…..Contd…..

Dilute the preparation under examination Dilute the preparation under examination so as to obtain responses on the addition so as to obtain responses on the addition of two doses similar to those obtained of two doses similar to those obtained with the Standard Preparation.with the Standard Preparation.

The ratio between the two doses of the The ratio between the two doses of the preparation under examination should be preparation under examination should be the same as that between the two doses the same as that between the two doses of the Standard Preparation and this ratio of the Standard Preparation and this ratio should be kept constant throughout the should be kept constant throughout the assay.assay.

Contd…….Contd…….

The two doses of Standard The two doses of Standard Preparation and the two doses of the Preparation and the two doses of the test should be given in a random test should be given in a random order and at least six responses to order and at least six responses to each should be recorded.each should be recorded.

Measure all the responses and Measure all the responses and calculate the result of the assay by calculate the result of the assay by standard statistical methods.standard statistical methods.

INDIAN PHARMACOPOEIA VOLUME 3

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