That was good info Dawn! It helps answer the question of "in" or "out" with rectogesic, diltiazem and nifedipine.
"This author recommends that a small amount of ointment be applied to a cotton-tipped swab with the swab then inserted into the anus only for the depth of the cotton-tipped portion of the swab. Smearing ointment around the outside of the anus does not allow the ointment to reach the anoderm where its effects are important, yet the nitroglycerin will be absorbed and produce side effects. "
"Nifedipine ointment (2%) is applied in a manner similar to nitroglycerin ointment"
and even when...
"Nitroglycerin is more rapidly absorbed if blood flow in the anoderm is high. For this reason, it is recommended that nitroglycerin not be applied within 30 minutes of a bath since the warm water of the bath enlarges (dilates) the blood vessels in the skin and anoderm and increases their flow of blood."
(I guess they associate rapid absorption with increased side effects, and therefore not a good thing - at least that is how I interpret it)??

I think I will print this out and take it with me to my doctor. Seems up to date, too. Thanks!