GLASGOW, Scotland, November 14 /PRNewswire/ --
-- Data Presented at HIV 8 Conference -
New studies on the use of PREZISTA(TM), an investigational anti-HIV medication, suggest that it can be co-administered with many common medications taken by people with HIV, including other antiretrovirals, proton pump inhibitors, H2 blockers and selective serotonin reuptake inhibitors. According to current HIV treatment guidelines, potential drug interactions between HIV antiretrovirals and other necessary drugs can be dangerous and require special monitoring(i).
Three studies, including one oral poster, on the co-administration of PREZISTA, were presented at the Eighth Annual International Congress on Drug Therapy in HIV Infection (HIV 8) taking place in Glasgow, Scotland from 12 - 16 November.
PREZISTA (darunavir, also known by the investigational compound number TMC114), co-administered with 100 mg ritonavir (darunavir/rtv), is being studied for the treatment of human immunodeficiency virus (HIV) infection in antiretroviral treatment-experienced adult patients. It is currently approved in the United States, Canada and Russia. An application for marketing authorization was filed with the European Agency for the Evaluation of Medicinal Products in January 2006.
"With many HIV-infected people taking multiple medications, the increased potential for drug interactions poses a serious challenge in finding a safe and effective antiretroviral treatment regimen," said David J. Back, Ph.D., Professor, Department of Pharmacology, University of Liverpool. "These data are important because they provide information on the interactions between PREZISTA/rtv and other medications commonly used in patients with HIV."
Use of PREZISTA with common medications (Oral poster PL 5.1)
Location and time: Clyde Auditorium; Tuesday, November 14, 10:30 - 10:45 a.m. GMT
Dr. Back reported results in an oral presentation from clinical studies evaluating the pharmacokinetic interactions between darunavir/rtv and a variety of drugs including antiretrovirals such as atazanavir, indinavir, lopinavir/ritonavir, saquinavir/ritonavir, efavirenz, nevirapine, tenofovir disoproxil fumarate; antibiotics such as clarithromycin and ketoconazole; and other medications for various conditions including atorvastatin, omeprazole, ranitidine, sildenafil, sertraline, paroxetine and oral contraceptives. Results showed that darunavir/rtv may be combined with many drugs with no dose adjustments. Some co-administered drugs, such as indinavir, sildenafil and atorvastatin may require dose adjustments. In general, the study found that drug interactions between darunavir/rtv and drugs commonly used in patients with HIV are manageable.
Pharmacokinetic interaction between PREZISTA with SSRIs assessed (Poster # P295)
Location and time: Exhibition Hall 4; Monday, November 13 to Wednesday, November 15, 10:00 a.m. - 7:00 p.m. GMT
The pharmacokinetic interaction between darunavir/rtv and the selective serotonin reuptake inhibitors (SSRIs), paroxetine and sertraline, were assessed in a phase I, open-label, two-panel, randomised, crossover study in 36 HIV-negative, healthy volunteers presented by Vanitha Sekar, Ph.D. of Tibotec Pharmaceuticals. Safety and tolerability also were assessed. The study found that the pharmacokinetics of darunavir/rtv were not significantly affected in the presence of sertraline or paroxetine, and that darunavir/rtv was generally well tolerated. Paroxetine and sertraline total concentrations were decreased in the presence of darunavir/rtv. Clinical monitoring is recommended when co-administering darunavir/rtv with SSRIs, although studies have not shown a correlation between plasma concentration of SSRIs and antidepressant response.
Co-administration of PREZISTA with methadone (Poster # P294)
Location and time: Exhibition Hall 4; Monday, November 13 to Wednesday, November 15, 10:00 a.m. - 7:00 p.m. GMT
Dr. Sekar also conducted a trial assessing the effect of multiple doses of darunavir/rtv on plasma concentrations of methadone since administration of boosted protease inhibitors has been shown to decrease methadone plasma concentrations. Results of the open-label, add-on trial involving 16 patients found co-administration of the treatment with methadone did not adversely affect the blood plasma concentrations of methadone, methadone adjustment was not required when administered with darunavir/rtv, and withdrawal syndrome was uncommon, occurring in one patient (1/16 patients, 6 percent) during the co-administration period.
About PREZISTA
PREZISTA (darunavir) is an investigational protease inhibitor that is currently in Phase III comparative clinical trials versus lopinavir/ritonavir in treatment-naïve (ARTEMIS) and treatment-experienced patients (TITAN).
PREZISTA does not cure HIV infection or AIDS, and does not prevent passing HIV to others.
In studies, darunavir/rtv was generally well tolerated. The most common moderate to severe side effects associated with darunavir include headache (3.8 percent), diarrhoea (2.3 percent), abdominal pain (2.3 percent), constipation (2.3 percent), and vomiting (1.5 percent). Mild to moderate rash was seen in 7 percent of patients. Severe skin rash, including erythema multiforme and Stevens-Johnson Syndrome, has been reported in subjects receiving PREZISTA during the clinical development program. Four percent of patients discontinued treatment due to adverse events. People who are allergic to darunavir or any of its ingredients or ritonavir (Norvir) should not take darunavir. It should be used with caution in patients with known sulfonamide allergy.
There were few relevant drug-drug interactions with other medications commonly used in HIV patient populations, such as other antiretroviral medications, proton pump inhibitors, and H2 receptor antagonists. Patients should talk to their healthcare provider about all the medicines they are taking or plan to take, including prescription and nonprescription medicines, vitamins, and herbal supplements. Due to the need for co-administration of darunavir with 100mg ritonavir, please refer to ritonavir prescribing information for a description of ritonavir contraindications.
Before taking darunavir, patients should tell their healthcare provider if they have any medical conditions, including diabetes, liver problems, haemophilia, or allergy to sulfa medicines and should tell their doctor if they are pregnant or planning to become pregnant, or are nursing. Darunavir should be used with caution in patients with hepatic impairment.
High blood sugar, diabetes or worsening of diabetes, muscle pain, tenderness or weakness, and increased bleeding in people with haemophilia have been reported in patients taking protease inhibitor medicines like darunavir. Changes in body fat have been seen in some patients taking anti-HIV medicines, including loss of fat from legs, arms and face, increased fat in the abdomen and other internal organs, breast enlargement and fatty lumps on the back of the neck. The cause and long-term health effects of these conditions are not known at this time.
Clinical laboratory safety observed in the darunavir group was comparable to the control group.
PREZISTA was developed by Tibotec Pharmaceuticals Ltd. In the U.S., it is marketed by Tibotec Therapeutics, a division of Ortho Biotech Products, L.P. In Canada, it is marketed by Tibotec, a division of Janssen-Ortho Inc. Pending regulatory approval, Tibotec, a division of Janssen-Cilag, will commercialise PREZISTA in Europe and other countries.
For further information, please visit www.tibotec.com.
About Tibotec Pharmaceuticals Ltd.
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