21.   A study is now being conducted to determine how the two drugs work together.

22.   According to a Pfizer spokesman, men who called the number frequently had to be reminded that the drug would not work without sexual stimulation.

23.   After his leukemia accelerated and other drugs no longer worked, Barnes moved into the most advanced blast crisis stage within a month.

24.   All three drugs work by changing the levels of brain chemicals that influence appetite and cravings.

25.   All three forms are caused by the same microbe, Bacillus anthracis, and scientists say they believe that all the drugs could work equally well.

26.   But drugs work only when taken, and many states failed to build a promised network of clinics to monitor patients.

27.   But first the drug must work in her.

28.   But if weight gain is a concern, a different drug might work better.

29.   But if the drug works well, a major setback could be in store for an American company pushing its own remedy to the flu bug.

30.   But many chemotherapy drugs work against cancer by capitalizing on free radicals and turning their destructive force against tumors.