I think that while drug companies may be trying to make a profit out of treating an illness, it is just business. I do not see anything unethical about them charging people for their services. Sure, there may be a lot of ill people who cannot afford the drugs, but that's how capitalism works.
Yes, drug companies are ethical, because the supply and demand of the market motivates them to be ethical. A drug companies knows that it has to provide a good drug that is effective and safe if it wants people to buy the drug. To that end, the reputation of the drug company is very important.
Drug companies are in the business to make a profit, which leads to a company being unethical. Having a policy not to release a name brand drug for production as a generic for a 5 years is a prime example. Many people could benefit from this drug but cannot afford to buy it. While a company makes a profit, people will suffer.
I do not believe drug companies are ethical. I think there is plenty of proof of this within the United States. Drug companies over charge for several drugs in this country and access is denied to those who can not afford it. In effect, these companies would rather let people die, then lose their profit.