Yesterday I read in the paper that the manufacturer of Thalidomide finally apologized (after 50 years) for the harm it did. It might be a good first example of why we need to research drugs and get them approved. The FDA never approved Thalidomide in the US, which is why it was never a big problem here.
OK, here's another. While in Disney World in August, my kids took a Youth Education Series Class in Marine Careers. I chaperoned them (while my husband chaperoned our youngest in her Synergy in Science Class) One of the the people we spoke to --whose title I forget-- dealt with the water chemistry in all Disney's tanks. I bet you could somehow tie in that to the chemistry of backyard pools.
In fact, my husband came home with a staph infection-- we suspect he may have picked it up in one of the hot tubs there.
Something else you may want to look at is the problem of mixing caffeine and OTC drugs. I remember one night in 1980 I had a miserable cold, and took a Contact pill before going to work. While at work, I drank a Coke every chance I got because I was so thirsty. I ended up with a blinding headache, unable to drive myself home. I spent a good 12 hours in bed (listening to, but not really fully watching, the US team beat the Russians in hockey) before the effects started to lessen. Lesson learned: caffeine is a drug that interacts with other drugs.
How about allergies? You could do something with the whole idea of histimines and antihistimines, not exactly sure what...
How about blood sugar and diabetes?
Or about taking a look at what chemo actually is and how it works? As I understand it (fortunately, this is as an outsider looking in) the drugs they use target quickly growing cells, and that's what leads to the hair loss.
OK, here's another one that occurred to me (in mass, actually. I forget just what father said during the homily that sparked it.)
How about vaccinations? I'm not sure what you could do, but you could talk about the chemistry involved in vaccinations. Possibly have them research the supposed MMR-Autism link, take a side on the issue, and defend it.
Do you have access to video equipment? Creating public service announcements for lab safety, how to handle lab accidents and the health consequences of chemical exposure (why do waft vapor toward your nose instead of inhaling over a beaker? for example).
Another idea: research a chemical reaction. Search for or create a reaction of this type that can be shown as a demonstration for the class. Chemical reaction demo must meet with teacher approval.
Students can explain the chemistry involved in their reaction and then demonstrate it to their peers or a younger group of students.
If you are more concerned about the chemistry aspect of things you could have students research the various chemical interactions between types of drugs. It could lead to a focus on why certain drugs can't be prescribed with others.
There are some Pharmacology lessons adapted to chemistry you could download for free. Also you could have them research an element and make a mole model to go with the element. The chemistry teacher I work with does this. Then you could have a celebration of mole day. A hot air balloon or the chemistry of cosmetics or perfume might be good as well. Another idea is how to use Green Chemistry. Hope this helps.