Aqueous prolonged release formulation

This invention relates to novel compositions useful for the sustained-release of bioactive proteins. More particularly, the present invention provides a superior aqueous sustained release injectable formulation of bovine growth hormone releasing factor. Also provided are methods of using these novel compositions for the sustained or prolonged release of bovine growth hormone releasing factor. Prolonged parenteral release into the circulatory system of a cow of a bioactive growth hormone releasing factor at desirably effective levels can be achieved using novel compositions in which the growth hormone releasing factor is present in an aqueous liquid at a dose of at least about 50 mg and at a concentration of at least about 20 mg/ml. Preferably, the growth hormone releasing factor is present in an aqueous liquid at a dose of about 200 mg and at a concentration of about 180 mg/ml. The aqueous bovine growth hormone releasing factor formulation provides for the sustained release of bovine somatotropin into the circulatory system of the animal for greater than seven (7) days.