A pharmaceutical composition for oral use is disclosed. It includes, as active principle, a drug liable to undergo a strong first intestinal passage effect and a carrier which is self-micro-emulsifying on contact with an aqueous phase. The carrier includes: a therapeutically effective amount of the active principle; a lipophilic phase, which is a mixture of glycerol mono-, di- and triesters and of PEG mono- and diesters with at least one fatty acid chosen from the group comprising C.sub.8 -C.sub.18 fatty acids; a surfactant phase which is a mixture of glycerol mono-, di- and triesters and of PEG mono- and diesters with caprylic acid (C.sub.8) and capric acid (C.sub.10); a co-surfactant phase which is an ester of a polyvalent alcohol with at least one fatty acid chosen from the group comprising caprylic esters of propylene glycol, lauric esters of propylene glycol and oleic esters of polyglycerol. A method of decreasing the effect of intestinal metabolism on a drug using the composition is also disclosed.