Poster Session 22404: Pharmacokinetic Interaction Between Nevirapine and Indinavir and Correlation with Antiviral Activity

Nevirapine and indinavir are metabolized by the same enzyme 'pathway' in the liver -- called the "P450" enzyme -- and therefore have the potential of affecting each other's pharmacokinetics, or the amount, and thus the effect, of each drug in the body.

In this important study presented by The Body's own Robert Murphy, 24 patients who were either naïve or on stable nucleoside RTI treatment began taking the protease inhibitor indinavir (IDV), dosed at 800 mg every 8 hours. After 7 days, patients added the non-nucleoside RTI nevirapine (NVP), dosed at 200 mg once a day, for 14 days (i.e., until Day 21). After Day 21 the dose was raised to 200 mg twice-a-day. Therapy then continued for 58 weeks, with intensive pharmacokinetic (PK) tests performed at days 7 (baseline) and 36.

Dr. Murphy found that at Day 36, there was decrease in the amount of indinavir in the bloodstream as compared with baseline measurements; the decreases were most pronounced in patients who had a particularly high IDV level at day 7. Nonetheless, viral load decreases were still significant, and indinavir levels stayed above the minimum level required for effectiveness.