This invention concerns the use of a compound for the manufacture of a medicament for the prevention of HIV infection via sexual intercourse and related intimate contact between partners, wherein the compound is a compound of formula (I) a N-oxide, a pharmaceutically acceptable addition salt, a quaternary amine and a stereochemically isomeric form thereof, wherein the ring containing -a<;SUP>;1<;/SUP>;=a<;SUP>;2<;/SUP>;-a<;SUP>;3<;/SUP>;=a<;SUP>;4<;/SUP>;- and -b<;SUP>;1<;/SUP>;=b<;SUP>;2<;/SUP>;-b<;SUP>;3<;/SUP>;=b<;SUP>;4<;/SUP>;- represents phenyl, pyridyl, pyrimidinyl, pirazinyl, pyridazinyl; and pharmaceutical compositions comprising them.