It depends on what you reconstitute it with.

I've been told that peptides mixed with acidic solutions have a longer life before degradation than with plain bac water, but also it is dependent on the peptide/ph balance needed for the specific peptide (which I don't know for trip.)

If I remember right, I think it is usually good for about 4 weeks before it will begin to degrade as long as you refrigerate it.

Just the substance before reconstitution will stay good for a long time though.