Pastes, Plasters and Glycerogelatins

March 07, 2016

Shahid FareedRoll No: 67-E-14

Pharm(D)Department of Pharmacy

Bahauddin Zakariya University

Multan 60700, Pakistan.E-mail:

shahidfareed21@gmail.com

Pastes

¨ Pastes are semisolid preparations intended for application to the skin;

¨ They generally contain a larger proportion of solid material than ointments and therefore are stiffer.

Pastes - Continued

Because of Stiffness of pastes, they remain in place after application and are effectively employed to absorb serous secretions.

Because of their stiffness and impenetrability, pastes are not suited for application to the hairy parts of the body.

Pastes - Examples

Lassar’s plain Zinc paste (which is prepared by mixing 25% each of zinc oxide and starch with white petrolatum).

Use: The product is very firm and is better able to protect the skin and absorb secretion than is zinc oxide ointment.

Preparation Methods of Paste

Incorporation Mix together (mortar & pestle, spatula & slab) roller mill "levigating" the powder (reduction of particle size

in suspending agent compatible with the paste base)

Fusion In porcelain dish all or some components of an

paste melted together and cooled with constant stirring until congealed, add non-melting substances as the paste is being cooled and stirred.

Plasters

Plasters are solid or semisolids adhesive masses spread on backing of paper, fabrics, moleskin or plastic.

The adhesive material is a rubber base or a synthetic resin.

Plasters are applied to skin to provide prolonged contact at the site.

Types of Plasters

Medicated Plasters Medicated plasters provide effects at the site of application. They may be cut to site to conform to the surface to be covered. Un-medicated Plasters Un-medicated plasters provide protection or mechanical support at the site of application.

Plasters - Examples

Among the few plasters in use today is

salicylic acid plaster used on toes for the

removal of corns.

The horny layers of skin are removed by the

kera-tolytic action of salicylic acid.

Concentration of salicylic acid used in

Commercial corn plasters ranges from 10% to

40%.

Difference b/w Pastes and Plasters

Paste: Have very solid

consistency and contain usually relatively large quantities of solids.

Contain a larger percentage of solid material than ointments (thicker and stiffer).

Will not soften and flow after application .

Ointment: Any greasy or oily

semi-solid preparation, usually medicated, that can be applied externally to the skin in order to heal, soothe or protect it.

It is a viscous semisolid preparation used topically on a variety of body surfaces.

Glycerogelatins

Glycerogelatins are plastic masses containing gelatin (15%) , glycerin (40%), water (35%) an added medicinal substance (10%) such as zinc oxide.

Glycerogelatins are applied to the skin for the long time they are melted before the application, cold to slightly above body temperature and applied to the affected area with a fine brush.

Following application, the Glycerogelatins hardens is usually covered with the bandage, and is allowed to remain in place for weeks.

Glycerogelatins Preparation

They are prepared by first softening the gelatin in the water for about 10 minutes, heating on a steam bath until the gelatin is dissolved.

Adding the medicinal substance mixed with glycerin.

Allowing the mixture to cool with stirring until congealed.

Most recent official Glycerogelatins was zinc gelatin used in the treatment of varicose ulcers. It was also known as zinc gelatin boot because of its ability to form a pressure bandage.

Thank you!!!