Phenylbutazone may be the most common prescription drug routinely used in horses as it is an anti-inflammatory and pain medication. Although phenylbutazone is available as an injection, tablets, and paste, the powder form may be the most commonly used form, especially in horses on long-term therapy with chronic disease. As it is less expensive and easy to use, there are FDA-approved bute powders on the market but there are also compounded bute powdered products. Many people request flavored compounded products as they may be less expensive than the FDA-approved products.
However, there is a concern with using any compounded product especially when an FDA-approved product is available. First of all, it is illegal for a pharmacy to compound a product that is available commercially so any pharmacy that does illegal compounding should be a concern. Secondly, a few years ago a study was performed on 15 compounded bute products from different pharmacies and results were a little concerning. Some products had 12% less active ingredient that the label claimed while other had 37% more product. With a product like bute that can cause many side effects if the dosage is not correct, using a compounded product with questionable quality can be dangerous for your horse.
Another item to consider with any powdered product is the manner in filling a scoop as this was shown in a study to make a difference; shaking a full scoop until it is level is the most accurate method of judging the dosage. Filling the scoop to overflow and then scraping against the edge of the container caused 22% more product to be in the scoop and this could be a dangerous overdose with some drugs