EVALUATION OF OINTMENTS

Ointments are semisolid preparations applied to skin with or without friction.

SPECIFIED TESTS FOR EVALUATION OF OINTMENTS

The evaluation of a drug means to perform the tests for the maintenance of quality and quantity according to the specifications.

After the manufacturing of drug or during the production, the specific tests are done for that particular product to evaluate it.

Following tests are specified for the evaluation of ointments:

Weight variation test.

Consistency.

Identification of active contents.

Assay of active contents.

Melting point.

Solubility.

1). WEIGHT VARIATION TEST (USP)

Select the sample of 10 filled container and remove any labeling that might alter weight during removing of the contents from the containers.

Thoroughly clean and dry the outside of the container by a suitable means and weigh individually.

Remove the contents from each container by cutting opening and washing with a suitable solvent, taking care to retain the closures and any other parts of each container.

Dry and again weigh each empty container together with its corresponding parts.

The difference between weights is the net weight of the contents of each container.

The average net weight of contents of 10 containers is not less than the labeled amount and the net weight of contents of any single container is not less than 90% of the labeled amount, where the labeled amount is more than 60 grams but not more than 150 grams.

If the requirements are not met, determine the net weight of the contents of 20 additional containers.

The average weight of the contents of 30 containers is not less than the labeled amount and the net weight of contents of not more than one container of the 30 containers is not less than 90% of the labeled amount, where the labeled amount is 60 grams or less and not less than 95% of the labeled amount, where the labeled amount is more than 60 grams but not more than 150 grams.

2). CONSISTENCY

Should be smooth, no solid particles.

3). IDENTIFICATION OF ACTIVE CONTENTS

Warm a saturated solution in water with Silver Ammonium Nitrate solution in a test tube. Metallic Silver is deposited as a mirror on the sides of the tube.

4). ASSAY OF THE ACTIVE CONTENTS

For example: Salicylate ointment.

Dissolve 10 grams in a mixture of 20 ml of alcohol (95%) previous neutralized to phenol red solution and 20ml of ether and titrate with 0.1N NaOH using phenol red solution as indicator.

1ml of 0.1N NaOH=0.01381 grams of salicylic acid.

5). MELTING POINT

Not less than 11C.

6). SOLUBILITY

Should be soluble in 9 parts of water and 17 parts of boiling water, miscible with alcohol, with solvent such as ether, chloroform or with volatile oils.