Section 522.1085 - Guaifenesin powder for injection(a)Specifications. The product is a sterile powder containing guaifenesin. A solution is prepared by dissolving the drug in sterile water for injection to make a solution containing 50 milligrams of guaifenesin per milliliter of solution.(b)Sponsors. See Nos. 037990 and 054771 in § 510.600(c) of this chapter.(c)Conditions of use in horses -(1)Amount. Administer 1 milliliter of prepared solution per pound of body weight by rapid intravenous infusion.(2)Indications for use. For use as a muscle relaxant.(3)Limitations. Do not use in horses intended for human consumption. Federal law restricts this drug to use by or on the order of a licensed veterinarian. 79 FR 16189 , Mar. 25, 2014