Resistance to Agenerase found to be low
Resistance to Agenerase found to be low
Two new studies have analyzed the resistance profile of Agenerase (amprenavir), a protease inhibitor manufactured by Glaxo Wellcome in Research Triangle Park, NC. (For additional information on Agenerase, visit the Web at www. agenerase.com.)
The first study by German researchers evaluated the cross-resistance to amprenavir among patients treated with other protease inhibitors, analyzing 155 samples from 132 patients. Treatment history was available for 127 patients. Of those, 16 were not protease inhibitor-experienced, and 111 were pretreated with from one to four protease inhibitors. Findings include:
• Phenotypic assay showed that 105 samples, or 68%, were sensitive to amprenavir.
• Twenty-five samples were intermediately resistant to amprenavir, and 25 were highly resistant to the drug.
• Of 62 samples with cross resistance to the other four protease inhibitors, 23 remained sensitive to amprenavir.
• Resistance to amprenavir was more often associated with previous treatment with indinavir or ritonavir than previous treatment with either saquinavir or nelfinavir.
The second study by researchers at Children’s Hospital in Los Angeles evaluated the safety and efficacy of two doses of amprenavir oral solution in protease inhibitor-naive and protease inhibitor-experienced children, ages 2 to 12 years. Subjects were randomized to receive 20 mg/kg twice daily or 15 mg/kg three times daily in combination with nucleoside reverse transcriptase inhibitors.
Researchers found that two of 23 protease inhibitor-naive patients, or 9%, and 11 of 15 protease-experienced patients, or 73% had baseline virus with protease inhibitor-resistant mutations.
Of the 40 subjects who were evaluated, 84% responded to amprenavir. Only one showed reduced susceptibility to amprenavir, compared with 11 who demonstrated phenotypic resistance to one or more of these protease inhibitors: ritonavir, saquinavir, nelfinavir, and indinavir.
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