A method of coacting a fluid with a media, such as granular particles. The present invention also relates to compositions containing compounds of formula I useful for the prevention and treatment of HIV-1 infections and the treatment of AIDS andor ARC. The demultiplexer includes first and second samplehold circuits for alternately sampling data currents and holding sampled data corresponding to the sampled data, and third and fourth samplehold circuits for respectively sampling the sampled data held by the first and second samplehold circuits and programming the current which correspond to the sampled data to the two signal lines.