Several cases describe large reductions in
ciclosporin levels in patients given
phenobarbital. In one case the
ciclosporin dose had to be increased 3-fold to keep the levels within the therapeutic range. As
primidone is metabolised to
phenobarbital it seems likely that it will interact similarly.
Ciclosporin levels and effects (e.g. on
renal function) should be monitored as a matter of routine, but it may be prudent to increase monitoring if these drugs are stopped, started, or the dose altered.