Hello guiness,
As you can see below, 2% is fine. The link where I have extracted what follows is at:
http://www.medicinenet.com/anal_fissure/page3.htmIf I were you, I would give the 2% a go.
Calcium channel blocking drugs. As is the case with nitroglycerin, ointments containing calcium channel blocking drugs (for example, nifedipine [Adalat] or diltiazem [Cardizem]) relax the muscles of the internal sphincter. They also expand the blood vessels of the anoderm and increase the flow of blood.
Nifedipine ointment (2%) is applied in a manner similar to nitroglycerin ointment, but seems to produce fewer side effects. Although healing of chronic fissures has been reported in up to 67% of patients treated with calcium channel blockers, they are most effective with acute fissures.