Navigation

Veterinary Drug Handbook

METHOD OF PREPARATION

1. Calculate the required quantity of each ingredient for the total amount to be prepared.

2. Accurately weigh and/or measure each ingredient.

3. Warm 86 g of white petrolatum until it is liquid.

4. Incorporate the pine tar and mix well.

5. Remove from heat and add the benzocaine, lanolin, vitamin A and vitamin E acetate and mix well while cooling.

6. Package and label.

PACKAGING

Package in tight, light-resistant containers.1

LABELING

Keep out of reach of children. Use only as directed. For veterinary use only.

STABILITY

A beyond-use date of up to 6 months is appropriate for this preparation.1

USE

This dressing has been used in the treatment of superficial wounds in animals, especially horses.

QUALITY CONTROL

Quality-control assessment can include theoretical weight compared to actual weight, specific gravity, active drug assay, color, texture-surface, texture-spatula spread, appearance, feel, rheological properties and physical observations.2

DISCUSSION

A number of products for treating wounds in animals are on the market. This formulation can easily be altered as necessary for specific animals.

Pine tar (tar) is the product obtained by the destructive distillation of the wood of Pinus palustris Miller, or of other species of Pinus Linne (Farn pinaceae). Its composition is a complex mixture of phenolic bodies that are insoluble in water. It is a very viscid, blackish-brown liquid that is translucent in thin layers. It has an empyreumatic, terebinthinate odor and a sharper and empyreumatic taste. It is miscible with alcohol, glacial acetic acid or fixed and volatile oils. It is a mild irritant and local antibacterial agent.3

Benzocaine (C^sub 9^H^sub 11^NO^sub 2^, MW 165.19, ethyl aminobenzoate) occurs as small, white crystals or as a white, crystalline odorless powder. It is very slightly soluble in water (1:2500) and freely soluble in alcohol (1:5-8) and ether (1:4).1

Lanolin, or wool fat, is a yellow, tenacious, unctuous mass, having a slight, characteristic odor. It is insoluble in water but mixes without separation with about twice its weight of water. It is sparingly soluble in cold ethanol (95%).1,4

Vitamin A contains a suitable form of retinol (C^sub 20^H^sub 30^O, vitamin A alcohol). Vitamin A in liquid form occurs as a light yellow-to-red oil that may solidify upon refrigeration. When in a solid form it may take on the appearance of any diluent that has been added. Vitamin A may be practically odorless or may have a mild fishy odor but has no rancid odor or taste. It is unstable to air and light. In liquid form it is insoluble in water and in glycerin but soluble in absolute alcohol and in vegetable oils. Solid forms may be dispersible in water.1

Vitamin E is a form of alpha tocopherol (C^sub 29^H^sub 50^O^sub 2^) and has numerous forms, including the acetate. It should be preserved in tight containers, protected from light. Some forms should be blanketed with a layer of inert gas. It should be labeled to indicate the chemical form and to indicate whether it is the d- or dl-form. The vitamin E activity may be expressed in terms of the equivalent amount of d-alpha tocopherol, in mg per g.1 Vitamin E occurs as a practically odorless and tasteless clear, yellow or greenish-yellow, viscous oil. The acetate may solidify in the cold. Vitamin E acetate is insoluble in water, soluble in alcohol, and miscible with acetone and vegetable oils.

White petrolatum (white petroleum jelly, white soft paraffin) is a white-colored, translucent, soft unctuous mass that is inert, odorless and tasteless. It has a specific gravity of about 0.815 to 0.880 and melts in a range between 38 and 60°C. It is practically insoluble in ethanol, glycerin and water, but is soluble in chloroform and most fixed and volatile oils.5

REFERENCES

1. US Pharmacopeial Convention, Inc. United States Pharmacopeia 27-National Formulary22. Rockville, MD: US Pharmacopeial Convention, Inc.; 2004: 1065-1067, 1944, 2345-2349, 2367, 2768, 2787-2788.

2. Alien LV Jr. Standard operating procedure for performing physical quality assessment of ointments/creams/gels. IJPC 1998; 2(4): 308-309.

3. Harvey SC. Topical drugs. In: Gennaro AR, ed. Remington's Pharmaceutical Sciences. 18th ed. Easton, PA: Mack Publishing Co.; 1990: 765.

4. Winfield AJ. Lanolin. In: Rowe RC, Sheskey PJ, Weller PJ, eds. Handbook of Pharmaceutical Excipients. 4th ed. Washington, DC: American Pharmaceutical Association; 2003: 333-335.

5. Weller PJ. Petrolatum. In: Rowe RC, Sheskey PJ, Weller PJ, eds. Handbook of Pharmaceutical Excipients. 4th ed. London: Pharmaceutical Press; 2003: 421-423.

Copyright International Journal of Pharmaceutical Compounding Jul/Aug 2004
Provided by ProQuest Information and Learning Company. All rights Reserved