Algorithms Evaluated by IAPAC Norvir Advisory Committee
Alternative Therapeutic Strategies in Addressing Ritonavir Capsules Shortage
Stadtlanders was recently informed by Abbott Laboratories regarding manufacturing difficulties they are experiencing with the ritonavir (Norvir) capsule formulation, which will result in an indefinite shortage of Norvir capsules. At this time, it is uncertain whether patients initiated on Norvir capsules will be able to continue therapy. However, Abbott assured Stadtlanders that Norvir solution will continue to be available. The best suggestion at this time is to switch all patients on current Norvir capsules to Norvir solution preparation or change to an alternative therapeutic option (see attached algorithm). It is important that patients remain on all other current HIV/AIDS medications unless otherwise directed by their physicians (i.e., nucleoside reverse transcriptase inhibitors, etc.).
Alternative Therapeutic Strategies to Ritonavir Capsules
RTV Containing Regimens
RTV=Ritonavir, Norvir. IDV=Indinavir, Crexivan. FTV=Saquinavir SGC (Fortovase). NFV=Nelfinavir, Viracept. NNRTI=Non Nucleoside Reverse Transcription Inhibitor. NRTI=Nucleoside Reverse Transcription Inhibitor.
Common Dosages for Single PI Regimen
Comments from Joel Gallant, MD, Infectious Diseases, John Hopkins HospitalHere are my comments on the Stadtlanders algorithm:
Somewhere in this algorithm, it needs to be made clear that replacement of a single drug with another single drug is only appropriate if the viral load is undetectable at the time of the switch.
In the algorithm, if replacement with another PI is NOT possible, and use of an NNRTI is not possible, then you are advised to use a new PI and 2 new nukes. That doesn't make sense, since it's already been determined that a new PI is not an option. Such patients should remain on ritonavir liquid.
There is no reason to even discuss Invirase. Clearly the dose listed (600 tid) is not a substitute for any of the other PIs.
There are some problems in the dual regimen section:
I believe that the first dose combination of IDV/NFV listed was shown to produce inadequate dose levels of NFV.
The dose of NFV/FTV listed above is from a smaller, more preliminary study. The larger European study used 750 tid of NFV and 800 tid of FTV, and that's what should be recommended. "Standard doses of both" is therefore also incorrect.
Response to Comments from Joel Gallant from Eric Archibeque, MD, Medical Director, Stadtlanders Pharmacy HIV Program, and Assistant Clinical Professor of Medicine, University of California, San Francisco (9/17/98)Thank you for your thoughtful review and excellent comments of the algorithm that have put forward.
This project was developed to provide practicing clinicians with a common sense approach to deal effectively with the problem of Ritonavir capsule unavailability. Our hope was that this approach would be used as one of a number of tools that a clinician would utilize to make a decision should the patient be unable or unwilling to switch to the liquid formulation because of intolerance or viral escape.
We agree with your comment that a single PI substitution be made only with an undetectable viral load at the time of the switch and stress that the final decision be individualized to the patient's clinical, virologic and antiretroviral drug history. We have indicated in the paragraphs that precede the algorithm that it would be unwise to follow a flow chart such as this without individualizing therapy.
There appears to be some ambiguity on the right side of the algorithm under "No alternative PI as an option." The PI's listed under Q: Is there an NNRTI available for RTV substitution, refer to those patients who initially were on a dual PI regimen and have no additional PI with which to use.
We agree also with the appropriate doses of the dual PI drug regimens and have already corrected it in a prior revised copy.
Fortunately, at this time we are not aware of any patients who have needed to substitute RTV with an alternate PI. We conducted an informal telephone survey of 800 physicians who have prescribed ARV drugs through Stadtlanders Pharmacy. We are able to contact approximately 40% (320) MD's. All of the MD's surveyed stated that they have switched all of their patients who were on a RTV containing regimen to the liquid formulation. At this time, intolerance of the liquid formulation has not been a problem that has required changing to an alternative PI.
Update 9/18/98: Charles Farthing, MD, invited Eric Archibeque, MD, to be a member of the IAPAC Norvir Advisory Committee, and Dr. Archibeque accepted the invitation.
IAPAC's Request to Stadtlanders Pharmacy for Information Regarding the Stadtlanders Algorithm (September 14, 1998)A physician sent us an algorithm identified as developed by your organization, a copy of which is attached, that is being evaluated by the IAPAC Norvir Advisory Committee. Since the mission of the IAPAC Norvir Advisory Committee includes the evaluation of medical information from various sources applicable to the switch from Norvir capsules to the Norvir liquid formulation, it would be helpful for the committee to know the following:
We are planning to upload the attached algorithm and some of our committee members' comments on the algorithm on the IAPAC Norvir Advisory on September 18, 1998, and welcome posting your responses to these questions as part of the documentation.
Response to IAPAC's Request to Stadtlanders Pharmacy from Eric Archibeque, MD, Medical Director, Stadtlanders Pharmacy HIV Program, and Assistant Clinical Professor of Medicine, University of California, San Francisco (9/17/98)Stadtlanders has received your letter dated September 14, requesting information regarding our algorithm for addressing the Norvir capsule shortage. Our responses are included in this letter.
Please note that it is critical to understand the purpose for which this algorithm was intended In view of the possibility that we could have no capsule availability and a period of limited liquid availability, we attempted to inform prescribers of alternatives for consideration.. This was strictly to be a tool to be considered in a time of crisis and not a consensus document.
The algorithm is a dynamic document that is updated as needed. The current version of the algorithm is attached to this letter. Physicians and other healthcare providers may access the current version on our Internet web page (www.stadtlander.com).
Your questions and our responses are as follows:
Our goal, as always, is to provide our patients with the best care possible and to ensure that they receive optimal therapy. If your organization feels strongly that his algorithm is not in the best interest of patient care, we will gladly consider your comments. If needed, we will consider removing the algorithm from our Internet web page.
Comments from other Committee members will be added as they are received.
©2002, International Association of Physicians in AIDS Care