Coadministration has not been studied but based on metabolism and clearance, a pharmacokinetic interaction is unlikely. Tizanidine is metabolised by CYP1A2, which is not inhibited or induced by cabotegravir or rilpivirine. However, rilpivirine has been associated with prolongation of the QTc interval at supra-therapeutic doses but these are unlikely to occur when coadministered with tizanidine. However, the product label indicates that rilpivirine should be used with caution in combination with drugs with a known risk of Torsade de Pointes. Tizanidine has a possible risk of QT prolongation and/or TdP on the CredibleMeds.org website.