Abstract: A stable and lyophilized formulation of prostaglandin E-1 made by the process comprising a) dissolving PGE-1 in a solution of lactose and tertiary butyl alcohol wherein said tertiary butyl alcohol is present in an amount of from about 15% to about 33% volume/volume and the ratio of said lactose to PGE-1 is from about 40,000 to 1 to about 10,000 to 1 weight/weight whereby a formulation of PGE-1 dispersed in lactose is formed; b) adjusting and maintaining the pH of said formulation from about 3.5 to about 6 with an organic acid buffer, c) freezing said formulation to about -50.degree. C.; and d) drying said formulation to obtain a moisture content of less than 1% by dry weight and a tertiary butyl alcohol content of less than 3% by dry weight. Preferably, step c) includes after freezing said formulation to about -50.degree. C., warming to about -25.degree. C. for about 2 hours then refreezing to about -50.degree. C.

Abstract: A stable and lyophilized formulation of prostaglandin E-1 made by the process comprising a) dissolving PGE-1 in a solution of lactose and tertiary butyl alcohol wherein said tertiary butyl alcohol is present in an amount of from about 15% to about 33% volume/volume and the ratio of said lactose to PGE-1 is from about 40,000 to 1 to about 10,000 to 1 weight/weight whereby a formulation of PGE-1dispersed in lactose is formed; b) adjusting and maintaining the pH of said formulation from about 3.5 to about 6 with an organic acid buffer; c) freezing said formulation to about -50.degree. C.; and d) drying said formulation to obtain a moisture content of less than 1% by dry weight and a tertiary butyl alcohol content of less than 3% by dry weight. Preferably, step c) includes after freezing said formulation to about -50.degree. C., warming to about -25.degree. C. for about 2 hours then refreezing to about 50.degree. C.