HIV and ID Observations

From the FDA Advisory:

There have been postmarketing reports of cases of Stevens-Johnson syndrome, toxic epidermal necrolysis and erythema multiforme, as well as hypersensitivity reactions characterized by rash, constitutional findings, and sometimes organ dysfunction, including hepatic failure. Intelence therapy should be immediately discontinued when signs and symptoms of severe skin or hypersensitivity reactions develop.

These rare — but potentially life-threatening — reactions have been reported with all the NNRTIs.  From my extremely unsophisticated perspective (the less said about my biochemistry performance in med school the better), the molecular structure of these drugs look quite different.

So what is it with this drug class?