pH sensitive carrier and preparation method thereof, and pH sensitive drug and pH sensitive drug composition each containing the carrier, and method for treating or preventing diseases using the same

A method for treating tumor or inflammation in a patient in need thereof which comprises:

• administering a pH sensitive drug which comprises a pH sensitive carrier which comprises at least one amphipathic substance, and a physiologically active substance supported in the pH sensitive carrier to induce the pH sensitive carrier to develop a membrane disruptive function and to deliver the physiologically active substance to the site,
• said pH sensitive carrier including at least one pH sensitive compound selected from the group consisting of deoxycholic acid, cholic acid, ursodeoxycholic acid, chenodeoxycholic acid, hyodeoxycholic acid, C27 bile acid, glycodeoxycholic acid, glycyrrhizic acid, glycyrrhetinic acid and salts thereof, and said at least one amphipathic substance being at least one selected from the group consisting of a phosphatidylcholine having 10 to 12 carbon atoms, a polyoxyethylene sorbitan monofatty acid ester having 12 to 18 carbon atoms, a sorbitan fatty acid ester having 16 to 18 carbon atoms, glycerol monooleate, glycerol dilaurate, glycerol distearate, glycerol dioleate, polyoxyethylene castor oil and α-tocopherol, and is capable of developing a membrane disruptive function promoting effect, and
• the pH sensitive compound being present in an amount not less than 10 moles per 100 moles of the amphipathic substance.