According to David Dryer (the film's Effects Supervisor), the pill she is swallowing is in fact a birth control pill:
Scott's intentions with this imagery, as related by special effects supervisor, David Dryer, are revealing; "What happened... was that Ridley and I had a meeting where he told me,'I want a bunch of phony oriental commercials where geisha girls are doing unhealthy things. Smoking, taking drugs or whatever. To kind of continue with the oppressive feeling throughout the landscape". Dryer also reveals the idea he had for the type of pills the geisha is seen to be swallowing, namely, birth control pills: "This was strictly my idea - it seemed to make sense that birth control would be heavily advertised in such an overpopulated future". Berliner Chic
IMDb also identifies the line that is playing:
In the strange Japanese advertisement shown on the side of a blimp, in which a Geisha-like woman is swallowing a pill, the loud speakers play a line from a Japanese Noh play, saying "Iri Hi Katamuku," literally "the setting sun sinks down."
For completeness, I'd like to mention that the advert itself is considered to be a parody of an existing Japanese product; Strong Wakamoto. A yeast-based pill that supposedly keeps you (ahem) regular.
