Pentothal rhymes with:
laventhol, agarwal, aircal, algol, berdahl, bergdahl, bergendahl, biocontrol, castrol, caterwaul, clairol, consol, ebersol, engdahl, erdahl, ethyol, ewbal, felbatol, filtrol, firewall, jaspal, jordahl, kcal, kufahl, laventhol, liljedahl, lubrizol, malval, naral, nordahl, o'driscoll, odriscoll, offerdahl, oftedahl, opsahl, phenol, photocall, pofahl, pufahl, ransall, repsol, ringdahl, sandall, scurdall, snowfall, stordahl, stovall, sturdhal, topol, tricentrol, vertol, vorpahl
Pentothal sounds like:
panhandle, pantaleo, pantel, pantle, pendell, pendley, pendola, pendyala, pimental, pimentel, pindell, pointedly, pontillo, ponytail