I've never heard of using PicoLax in an enema. I don't think it'll do much
Here's why: PicoLax is chemically similar to Bisocodyl (Dulcolax) but the med has been modified so as not to be active, and stimulate the GI tract, until it has been digested (or chemically modified) in the large bowel. When that modification happens, the chemical forms that stimulates peristalsis and the cramping and urge to poo starts.
This is similar to Dulcolax, in which the laxative chemical is protected by the enteric coating until the pills travel through your GI tract and dissolve in your large bowel, releasing the laxative chemical.
I suspect, but do not know, how long the chemical reaction to convert the Picolax to the active form takes, but I doubt it's instant. But that reaction must happen for the Picolax to have any poo making effect.
Here is my guess as to what happen in 4 cases:
If Dulcolax is given in a large volume enema, within a few minutes you'll get a STRONG urge to poo.
If Picolax is given in a large volume enema, the enema water my simply make you poo before the Picolax has much effect
If Dulcolax is given in a small volume enema (60ml), up high, you will likely poo within a half hour.
If Picolax is given in a small volume enema (60ml), up high, you will likely poo within an hour or so.
Frankly, I don't think there is much point in giving Picolax in an enema Dulcolax is easy to get and prepare for enema use. The Magic Bullet suppositories are water soluble and each contain 10mg bisacodyl. Dissolve two or three in a bag of warm water and let it run in as rapidly as you can take it, then just wait, retaining the solution. You probably won't be able to wait very long.
A further thought on Picolax… here really doesn't seem to be much point in the med. Really, the only difference between it and Dulcolax pills is the recipient doesn't have to swallow the pills whole… useful if the person can't or won't swallow the pills. A full dose can be put in a cup of juice or coffee (about 20 drops) and not be noticed until the laxation starts. I've had it that way and it is completely tasteless.