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Spanish Doctors Try Switching Therapy
from Month to Month

May 16, 2001


Highly active antiretroviral therapy (HAART) often has high adherence requirements and unpleasant side effects. Not surprisingly, some people with HIV/AIDS (PHAs) who use HAART consider taking drug holidays. However, during drug holidays, levels of the immune system's vital CD4+ cells often fall significantly. Moreover, it may take a minimum of one year of therapy before CD4+ counts rise to their pre-drug-holiday levels. Perhaps one way to help reduce drug side effects while also decreasing the risk of HIV becoming resistant to HAART is by cycling or alternating therapy. Under such a scheme, PHAs would take one combination of drugs for a month and a different combination the next month, switching between the two combinations from month to month. Researchers in Madrid, Spain, have been testing these alternating monthly cycles of therapy for one year and recently reported their results.

Study Details

Researchers enrolled 21 HIV positive subjects (gender unavailable), 17 of whom had previously experienced AIDS-related infections. Their profile was as follows:

All subjects had been previously exposed to many anti-HIV drugs for an average of about 3.5 years before entering this study. Researchers created treatment regimens that adapted to each person depending on his or her past experiences of side effects. Generally, the most commonly used combinations were as follows:

Before starting the study regimens, most subjects took a one-month drug holiday. Once they entered the study they took their combinations twice daily.


Six subjects had to stop taking their drugs before the end of the study because of severe side effects. In the remaining 15 subjects, 6 (40%) had their viral load fall below the 500 copy mark by the sixth month of the study. By the 12th month, 33% of subjects were able to maintain this level of viral suppression. The doctors noted that, in general, CD4+ counts increased by more than 50 extra cells in 67% of subjects. No one developed any life-threatening infections during the study.

The results of this study are interesting because finding effective combinations for PHAs who have been heavily pre-treated is not easy. However, cycling from month to month is not for everyone. Indeed, further research on these types of protocols needs to be done, comparing the results to other novel schedules.

AIDS Patient Care 2001;15(4):177-179.

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