Answer:
When there is an Ethical issue, there is no substitute for doing the right thing. To try avoiding potentially undesirous consequences as a result of doing correcting one's mistakes is more damaging in the long run.
First, it starts internally. When employee of such company find out that the management and stakeholders have compromised on the standards of the ethics of integrity, it creates an excuse for them to do likewise and may even become too difficult to manage as it may become a source of blackmail in the short or long run.
My advice to the company is to quickly put out a campaign against the drug which is killing people.
The primary reason why the company is in business in the first place is to save lives by creating drugs that help to do so. To keep quiet in the face of this mistake is to go against everything it stands for.
Yes, it is possible for legal charges to follow. However, as a multinational, it is expected that they have anticipated and made some preparations for this by way of instituting Insurances such as product liability and or errors and omissions which help to reduce the liability of the company in the event of this kind of issues as well as provide monies for compensating the affected individuals and families.
The company will, of course, have to notify it's insurers immediately.
History shows that a public apology has been shown to work in similar circumstances and can help to douse (though not eliminate completely) the onslaught against its reputation that would follow when it makes the announcement.
Legally, when an issue of tort such as this arises, the best bet is for the company to quickly settle out of court if possible.
Cheers!