antibioticsbooks

228 PART 5 Antiviral Drugs
• NNRTIs have a much broader drug interaction
profile than the NRTIs (remember, one N
makes a lot of difference!). Generally, nevirapine
is an inducer of drug metabolism, delavirdine
is an inhibitor, efavirenz and etravirine
show mixed inducing and inhibitory properties,
and rilpivirine does not as yet appear to
have significant effects on metabolism of other
drugs. Concentrations of the NNRTIs can
themselves be affected by inhibitors or inducers
of drug-metabolizing enzymes. Thus, careful
screening of these drugs against all other
agents in a patient’s regimen is warranted.
What They’re Good For
A combination regimen of efavirenz with the NRTIs
tenofovir and emtricitabine is one of the preferred
regimens for treatment-naïve patients with HIV.
Co-formulated as Atripla, this regimen represents
the long-sought one-pill, once-daily antiretroviral
regimen. Of course, this does not mean it is necessarily
the best choice for any individual patient.
The other NNRTIs tend to be used as second-line
therapy in treatment-experienced patients.
Don’t Forget!
When initiating an NNRTI, the first few weeks are
key. Patients must be counseled carefully about recognizing
adverse effects, especially skin reactions
and symptoms of hepatotoxicity. The need for strict
adherence to prevent resistance, the dose titration
schedule for nevirapine, and the CNS effects of efavirenz
must be fully explained to patients. There’s
really only one shot to get it right with these very
valuable drugs!