Postural hypotension may occur with higher doses of sildenafil,
tadalafil or vardenafil given at the same time as doxazosin or
terazosin. It seems likely that this effect will
occur with most alpha blockers, although it is seen less frequently with modified-
release
alfuzosin and tamsulosin.
Patients should be stable on an alpha blocker before a
phosphodiesterase type-5 inhibitor is started, and the lowest starting dose (e.g. sildenafil 25 mg) should be
considered. The risk may also be minimised if
administration is separated so that
the peak levels of the two drugs do not coincide. Patients should be advised what
to do if they develop postural hypotension (i.e. lay down, raise the legs and, when
recovered, get up slowly).