A TLR9 inhibitor includes a compound of general formula (I):




wherein the meanings of the variables are explained in the specification,
or a stereoisomeric form or a mixture of stereoisomeric forms, or pharmaceutically acceptable salts thereof. A pharmaceutical composition can include compounds of the invention, which can be used in a method for inhibiting TLR9 activity in vitro or in vivo. The method can be performed by administering the compound to a subject to inhibit TLR9 activity, which can be used to treat a disease or disorder associated with TLR9.