Investigational drug shows promise
The first data from an ongoing Phase II study show an investigational protease inhibitor from Abbott Laboratories in Abbott Park, IL, reduces viral load in multiple protease inhibitor-experienced patients.
In this study, presented at the recent XIII International AIDS Conference in Durban, South Africa, ABT-378r inhibitor (lopinavir/ritonavir) was used in conjunction with the nonnucleoside reverse transcriptase inhibitor efavirenz and nucleoside transcriptase inhibitors.
Efavirenz is known to decrease the levels of some drugs in the blood. The study set out to evaluate the pharmacokinetics, efficacy, and safety of a regimen containing ABT-378r and efavirenz along with investigator-selected nucleoside reverse transcriptase inhibitors in multiple protease inhibitor-experienced patients, according to lead investigator Jurgen Rockstroh, MD, of the University of Bonn in Germany.
Researchers randomized 57 patients to receive either a dose of 400/100 mg of ABT-378r in three capsules twice daily or 533/133 mg in four capsules twice daily with a once-daily dose of efavirenz and investigator-selected nucleoside reverse transcriptase inhibitors.
Encouraging results
At week 24, 69% of patients taking the three-capsule dose and 82% of patients taking the four-capsule dose had viral load below 400 copies/ml. The average CD4 count increased 48 cells/mm3 in the three-capsule group and 41 cells/mm3 in the four-capsule group.
ABT-378r levels achieved with the three-capsule dose are reduced when co-dosed with efavirenz, report researchers. Blood levels of ABT-378r with the four-capsule dose in the presence of efavirenz were similar to the blood levels of ABT-378r achieved with the three-capsule dose without efavirenz.
"We are encouraged by these preliminary results from this ongoing study," says Rockstroh. "The ability to achieve viral suppression in patients previously treated with multiple protease inhibitors continues to be a significant challenge."
Through 24 weeks, three patients discontinued ABT-378r because of side effects. The most commonly reported side effects were diarrhea and general fatigue.
For more on ABT-378r, visit Abbott’s Web site at www.abbott.com.
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