This is probably a worthwhile opportunity to rant about the war on drugs, because it is looking increasingly likely that it killed Philip Seymour Hoffman.
It is suspected that the heroin that killed Hoffman was laced with fentanyl, a painkiller that has
directly caused a large number of drug overdoses recently (this is just the most recent article I found; there are plenty more). Fentanyl is a much more potent painkiller than heroin and greatly increases the chance of death by overdose; as a result, fatal overdoses have spiked recently. Evidently it shows up because it "makes up" for poor-quality heroin. It is also so remarkably strong that it is extremely difficult to dilute it properly and safely, especially when it's being handled by clandestine makers, and can easily kill someone not habituated to a stronger dose. This mix is therefore much, much worse than pure heroin.
The fact that such a shoddy and dangerous mix can even be sold is a direct consequence of the war on drugs. The result of heroin being illegal is that the consistency and purity of the drug cannot be regulated, and people ingesting or injecting the drug really have no idea what they're taking. Keith Richards managed to avoid overdosing in twenty or more years of using the drug because he always, always used the same amount, but he also was fortunate enough to have a source that provided him with heroin of a consistent purity and potency. With the drug market not being regulated, the drug becomes vastly more harmful, since apart from its addictiveness, it is arguably less harmful to the body than alcohol when a consistent amount is consistently used. The difficulty is, of course, in using a consistent amount consistently when you don't actually know what you're getting.
Of course, we have to note that some people seek the heroin-fentanyl mixture out deliberately because of its potency, but even bearing that in mind, the illegality still affects drug users negatively because it is so difficult to dilute the mixture safely.
It's also worth noting that addicts frequently overdose when they resume using after stints in rehab (which Hoffman had recently visited) because they may go back to the dose they were using before they cleaned up, which they no longer have the tolerance for.
Anyway, people are inevitably going to use this to call for stricter policing of drugs and whatnot when it's in fact a direct consequence of the war on drugs that we even have so many overdoses, and it pisses me off. The whole idea that keeping the drug supply illegal will make people safer has been completely and utterly discredited; people who are addicted to potentially dangerous substances are not concerned with the legality of their drug of choice. Setting up safe injection sites where addicts can be assured a safe, untainted supply that is not likely to kill them (either through needle infection or through overdose) is far less harmful to society than trying to eliminate the supply of drugs. Even Richard Nixon understood this, which is why he set up methadone clinics. Unfortunately, modern politicians are completely clueless, and until there is a sea change in the way drugs are handled, many more people will continue to die unnecessarily.
But really, until the details are confirmed we can't be sure what happened. A huge tragedy, though. There were few actors in his calibre (Daniel Day-Lewis and Meryl Streep are the only two that come to mind) and I can't even imagine how awful his family must feel.