Pre-treatment with isradipine, a calcium channel antagonist, produced significant reductions in positive subjective effects of d-methamphetamine in 18 healthy volunteers. Studies in methamphetamine users are underway (Johnson, Roache, Bordnick & Ait-Daoud, 1999). An unpublished controlled study of another calcium channel blocker, amlodipine, found that 5-10 mg/day in 77 methamphetamine users resulted in no difference in treatment retention or in any other outcome measures including amphetamine use and cravings (Batki, Moon, Delucchi & Bradley, 2001).