Agonists of guanylate cyclase and their uses

1. A method of colonic cleansing, the method comprising administering to a subject in need thereof an effective amount of a composition comprising a phosphate salt laxative and a composition comprising an effective amount of a guanylate cyclase receptor agonist (GCRA) peptide consisting essentially of the sequence of SEQ ID NO: 9.

2. The method of claim 1 , further comprising administering to said subject an effective amount of an osmotic colonic evacuant.

3. The method of claim 2 , wherein said osmotic colonic evacuant is magnesium citrate.

4. The method of claim 1 , further comprising administering to said subject an effective amount of L-glucose, lubiprostone (Amitiza), prucalopride, an agent for treating chronic constipation, or any combination thereof.

5. The method of claim 4 , wherein said effective amount of L-glucose is a unit dose of 20 g-200 g.

6. The method of claim 1 , further comprising administering to said subject an effective amount of a cGMP-specific phosphodiesterase inhibitor.

7. The method of claim 6 , wherein said cGMP-specific phosphodiesterase inhibitor is selected from the group consisting of sulindac sulfone, zaprinast, motapizone, vardenafil, and sildenafil.

8. The method of claim 1 , wherein the effective amount of a GCRA peptide is a unit dose of 0.01 mg to 60 mg.