Dapivirine, a non-nucleoside reverse-transcriptase inhibitor (NNRTI), is a substituted diamino- pyrimidine (DAPY) derivative with potent antiviral activity against HIV-1. Dapivirine is chemically described as 4-[[4-[(2,4,6-trimethylphenyl)amino]-2- pyrimidinyl]amino]benzonitrile.6 The dapivirine matrix VR is a flexible ring containing 25 mg of drug substance dispersed in a platinum-catalyzed-cured silicone matrix. Dapivirine is known to be well-suited for delivery via VR, as evidenced by favorable safety and pharmacokinetic data to date described below.