Study: Triple-nucleoside combination works
Two studies comparing the triple-nucleoside regimen of abacavir sulfate plus lamivudine/ zidovudine with triple-drug regimens containing protease inhibitors as first-line antiretroviral therapy in therapy-naive patients found the triple-nucleoside regimen effective and patient tolerance and adherence high, researchers told colleagues at the recent XIII International AIDS Conference in Durban, South Africa.
In a study of 342 antiretroviral-naive patients, patients were randomized to receive either the triple-nucleoside regimen of abacavir sulfate plus lamivudine/zidovudine or indinavir plus lamivudine/zidovudine for 48 weeks. Patients on the first regimen took one abacavir sulfate and one lamivudine/zidovudine twice a day without dietary restrictions. Patients on the nucleoside plus protease inhibitor regimen took two indinavir tablets every eight hours and one lamivudine/zidovudine tablet twice daily. The patients taking indinavir were required to take the tablets one hour before or two hours after a meal and drink one and a half quarts of water a day.
Patients were stratified according to baseline plasma viral load, with 63% having a viral load greater than 5,000 copies/ml but less than 100,000 copies/ml, and 37% having a viral load greater than 100,000 copies/ml.
At 24 weeks, 68% of patients on abacavir sulfate plus lamivudine/zidovudine had a viral load of less than 400 copies/ml, compared with 57% on the indinavir plus lamivudine/zidovudine regimen. Of the 245 patients for whom data were available from the more sensitive <50 copies/ml assay, 79% of patients on the abacavir sulfate plus lamivudine/zidovudine regimen were below the threshold, compared with 73% on the indinavir plus lamivudine/zidovudine regimen.
Adherence findings
Other findings include:
• Among patients whose baseline viral load was less than 100,000 copies/ml at baseline, 87% of the abacavir sulfate plus lamivudine/zidovudine patients achieved a viral load of less than 50 copies/ml, compared with 81% of patients in the other group.
• In patients whose baseline viral load was above 100,000 copies/ml, 65% in the abacavir sulfate plus lamivudine/zidovudine group achieved a viral load of <50 copies/ml, compared with 63% in the other group.
Adherence was self-reported by patients using the Treatment Assessment and Satisfaction Questionnaire, a validated measure of adherence. Researchers found that 74% of patients on the abacavir sulfate plus lamivudine/zidovudine regimen reported taking all antiretroviral doses over the previous four weeks or missed less than one dose per week, compared with 45% of patients in the indinavir plus lamivudine/zidovudine group. Only 6% of patients in the abacavir sulfate plus lamivudine/zidovudine group reported that their regimen was difficult to take as scheduled, compared with 38% in the other group.
"These early data offer important information about this triple-nucleoside regimen," says Pedro Cahn, MD, director of Fundacion Huesped in Buenos Aires, Argentina, and principal investigator of the study.
In a second study by French researchers, 195 patients were randomized to receive either one abacavir sulfate tablet plus one lamivudine/ zidovudine tablet twice a day without dietary restrictions or three nelfinavir tablets every eight hours and one lamivudine/zidovudine tablet twice a day for 48 weeks. The median CD4 cell counts at baseline were 387 cells/ml in the first group and 449 cells/ml in the second group.
Findings include:
• 67% of patients in the abacavir sulfate plus lamivudine/zidovudine group had a viral load below 50 copies/ml and 72% had viral load below 400 copies/ml, compared with 66% below 50 copies/ml and 71% below 400 copies/ml in the other group.
• The median CD4 cell count increase was 91 cells/mm3 in the abacavir sulfate plus lamivudine/zidovudine group and 65 cells/mm3 in patients the other group.
• Ten patients on the abacavir sulfate plus lamivudine/zidovudine group experienced serious adverse events, including anemia, retinal detachment, and acute confusional psychosis.
• Four patients on the nelfinavir plus lamivudine/zidovudine group experienced serious adverse events, including depression, diarrhea, and hepatic cytolysis.
Abacavir sulfate is manufactured under the brand name Ziagen by Glaxo Wellcome in Research Triangle Park, NC. Lamivudine/zidovudine is also a Glaxo product manufactured under the brand name Combivir. For details on either drug, visit www.glaxowellcome.com or drug- specific sites at www.ziagen.com and www. combivir.com.
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