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Letter from Abbott
ABBOTT
Pharmaceutical Products Division
Abbott Laboratories
200 Abbott Park Road
Abbott Park, Illinois 60064-3537
April 5, 1996
Dear Health Care Provider:
I am writing to provide you with information about Norvir (ritonavir), Abbott's new protease inhibitor.
The recommended dosage of Norvir is 600 mg orally bid. It is recommended that Norvir be taken with meals if possible. Norvir blood levels are at their highest during the first week following initiation of therapy, gradually declining to steady state. These initially high levels may cause nausea. Gradually increasing the dose of Norvir over 5 days may provide some relief from nausea while maintaining therapeutic concentrations. You may wish to start Norvir using the following recommended titration schedule:
Day 1: 300 mg bid
Days 2 and 3: 400 mg bid
Day 4: 500 mg bid
Thereafter 600 mg bid
In addition, patients initiating combination regimens with Norvir and nucleosides may improve gastrointestinal tolerance by initiating Norvir alone and subsequently adding nucleosides before completing two weeks of Norvir monotherapy.
Norvir is indicated in combination with nucleoside analogs or as monotherapy for the treatment of HIV-infection when therapy is warranted. For patients with advanced HIV disease, this indication is based on the results from a study that showed a reduction in both mortality and AIDS-defining clinical events for patients who received Norvir. Median duration of follow-up in this study was 6 months. The clinical benefit from Norvir therapy for longer periods of treatment is unknown.
For patients with less advanced disease, this indication is based on changes in surrogate markers in studies evaluating patients who received Norvir alone or in combination with other antiretroviral agents.
Co-administration of Norvir with certain nonsedating antihistamines, sedative hypnotics or antiarrhythmics may result in potentially serious and/or life-threatening adverse events due to possible effects of Norvir on the hepatic metabolism of certain drugs. See Boxed Warning and the Contraindications section of the Norvir Product Labeling. Enclosed, for your information is a copy of the Patient Drug Interaction Pocket Card that is available for distribution to patients at pharmacies. Please ask your patients to request this card when they receive Norvir from the pharmacist.
Norvir can produce large increases in plasma concentrations of certain highly metabolized drugs. Because of this, large dose reductions (greather than 50%), increased therapeutic drug concentration monitoring, and/or increased monitoring of therapeutic and adverse effects is recommended when drugs extensively metabolized are used concomitantly with Norvir. Agents which increase CYP3A activity would be expected to increase the clearance of Norvir, resulting in decreased Norvir plasma concentrations. For additional information, refer to the enclosed Health Care Profession Drug Interaction Card.
Norvir had a favorable safety profile in clinical trials. The most common adverse event were nausea (23% to 26%), diarrhea (13% to 18%), vomiting (13% to 15%), asthenia (9% to 14%), taste perversion (5% to 10%), anorexia (1% to 6%), circumoral paresthesia (3% to 6%), peripheral paresthesia (5% to 6%) and abdominal pain (3% to 7%).
Ask your Abbott HIV Specialist or Medical Center Representative for a copy of our Dosing Information Brochure, our Dosing Guide For Patients, and our Patient Drug Interaction Pocket Card, or call 1-800-441-4987. to support your efforts, we will continue to provide you with new and important information about Norvir on an ongoing basis.
Sincerely,
Dave Pizzuti, MD
Divisional Vice President
Medical Affairs & Pharmaceutical Ventures
Enclosures: Norvir (ritonavir) Produce Labeling, Abbott Laboratories. Health Care Profession Drug Interaction Card (602-017-6295R1) Patient Drug Interaction Pocket Card (603-017-6323)
Go to the Ritonavir: Important Information Page
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