Another combination of protease inhibitors (PIs) that is useful for some PHAs is ritonavir (Norvir) and saquinavir (Fortovase). Some doctors prescribe a combination of 400 mg of ritonavir and 400 mg of saquinavir to be taken twice daily; this is sometimes called "400-400." This combination is used because ritonavir acts as a "booster," raising levels of saquinavir in the blood far higher than if saquinavir alone were taken.
Although the 400-400 dose combination is clearly effective against HIV, this high daily dose of ritonavir is not always easy to tolerate. Researchers are therefore testing lower doses of ritonavir with higher doses of saquinavir, in the hope of finding a more tolerable combination with greater anti-HIV activity.
Researchers in the U.S. recruited 66 healthy, HIV negative adult subjects (9 females, 57 males) for their study. Subjects were confined to a hospital for the two weeks that this study lasted. Different subjects received the following drugs taken 15 minutes after a meal, twice daily:
Although subjects in this study were HIV negative, the results may be useful for physicians who prescribe combinations of ritonavir and saquinavir for their patients.
Analysis of blood samples from subjects showed that in all cases where combinations of ritonavir and saquinavir were used, saquinavir levels were much higher than if saquinavir alone were used. While ritonavir boosted saquinavir levels, saquinavir did not increase (or decrease) ritonavir levels.
The researchers described most of the side effects as being "mild" in their severity. Common side effects seen were as follows:
Those subjects who received no ritonavir or who received ritonavir 200 mg together with saquinavir 800 mg, both twice daily, reported few side effects.
Two subjects left the study, one because of a severe rash and the other because of nausea and vomiting.
On average, ritonavir-saquinavir 200-800 mg twice daily resulted in a greater increase in saquinavir levels in the blood than when the 400-400 mg combination or saquinavir 1,200 mg three times daily (without ritonavir) was used (according to data from previous experiments). Further testing on HIV positive people to note and compare the effectiveness of ritonavir-saquinavir 200-800 mg twice daily against that of other PI combinations needs to be done.
REFERENCE
1. Buss N, Snell P, Bock J, et al. Saquinavir and ritonavir pharmacokinetics follwing combined ritonavir and saquinavir (soft gelatin capsules) administration. British Journal of Clinical Pharmacology 2001;52:255-264.
20010910
CATE12105
Copyright © 2001 - TreatmentUpdate. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Editor, The Canadian AIDS Treatment Information Exchange, 555 Richmond St. West, Suite 505, Box 1104, Toronto, ON, M5V 3B1 • Phone: 416-203-7122 • Toll Free: 1-800-263-1638 • Fax: 416-203-8284 http://www.catie.ca.
AEGiS is made possible through unrestricted grants from Boehringer Ingelheim, Elton John AIDS Foundation, iMetrikus, Inc., the National Library of Medicine, and donations from users like you. Always watch for outdated information. This article first appeared in 2001. This material is designed to support, not replace, the relationship that exists between you and your doctor.
AEGiS presents published material, reprinted with permission and neither endorses nor opposes any material. All information contained on this website, including information relating to health conditions, products, and treatments, is for informational purposes only. It is often presented in summary or aggregate form. It is not meant to be a substitute for the advice provided by your own physician or other medical professionals. Always discuss treatment options with a doctor who specializes in treating HIV.
