In PI experienced patients receiving Agenerase capsules 600 mg twice daily and low dose ritonavir, 100 mg twice daily, the nature and frequency of adverse events (grade 2-4) and Grade 3/ 4 laboratory abnormalities were similar to those observed with Agenerase alone, with the exception of elevated triglyceride levels, and elevated CPK levels which were very common in patients receiving Agenerase and low dose ritonavir.