Pharmacotherapy Newsletter

Volume 1, Issue 10, 03/23/2009

Question

Part 2: How does the antibiotic minocycline (Minocin®, Dynacin®, Solodyn™) cause staining or discoloration of the teeth, how is it different from tetracycline and who is at risk?

Answer

This is part 2 of a 3 part series (please see part 1 for background information).  As mentioned in the last newsletter, minocycline (Minocin®, Dynacin®, Solodyn^TM) was derived from tetracycline.   Minocycline has the same basic ring structure as tetracycline, but lacks a functional group at C6 and has a substitution of a dimethylamino group at C7.¹  These small modifications increase both the lipophilicity (increased lipid solubility) and the half-life of minocycline.   Unfortunately, like tetracycline, minocycline can stain the teeth; however, it is through a process that is different from that of tetracycline.  Because of the differences in mechanism of this effect, minocycline has the potential to cause this adverse effect in all patients exposed to the drug, not just those 8 years old or younger.^1,2  This is important given the likelihood of longer courses of therapy with minocycline (in particular Solodyn^TM) for the treatment of acne.  Staining of the teeth in this population may compound the negative psychological impact of their condition.^1,3  So, how does minocycline cause teeth discoloration and how is it different from tetracycline (as presented in part 1 of this series)?