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Liver Warning with Prezista

Posted Dec 18 2008 7:28pm
Tibotec Dear Healthcare Professional:

IMPORTANT DRUG WARNING

March 2008
Dear Healthcare Professional:

Tibotec Therapeutics, in cooperation with the U.S. Food and Drug Administration, would like to inform you of an important update to the prescribing information for PREZISTA TM (darunavir) tablets regarding addition of a Warning on Hepatotoxicity.

In clinical trials and postmarketing experience, drug-induced hepatitis (e.g., acute hepatitis, cytolytic hepatitis) has been reported in patients receiving combination therapy with PREZISTA/rtv. Given the clinical relevance of this adverse reaction, the following information on hepatotoxicity has been added to the WARNINGS section of the PREZISTA Prescribing Information:

WARNINGS:

Hepatotoxicity

Drug-induced hepatitis (e.g., acute hepatitis, cytolytic hepatitis) has been reported with PREZISTA/rtv. During the clinical development program (N=3063), hepatitis has been reported in 0.5% of patients receiving combination therapy with PREZISTA/rtv. Patients with preexisting liver dysfunction, including chronic active hepatitis B or C, have an increased risk for liver function abnormalities including severe hepatic adverse events.

Post-marketing cases of liver injury, including some fatalities, have been reported. These have generally occurred in patients with advanced HIV-1 disease taking multiple concomitant medications, having comorbidities including hepatitis B or C coinfection, and/or developing immune reconstitution syndrome.
A causal relationship with PREZISTA/rtv therapy has not been established.

Appropriate laboratory testing should be conducted prior to initiating therapy with PREZISTA/rtv and patients should be monitored during treatment. Increased AST/ALT monitoring should be considered in patients with underlying chronic hepatitis, cirrhosis, or in patients who have pretreatment elevations of transaminases, especially during the first several months of PREZISTA/rtv treatment.

If there is evidence of new or worsening liver dysfunction (including clinically significant elevation of liver enzymes and/or symptoms such as fatigue, anorexia, nausea, jaundice, dark urine, liver tenderness, hepatomegaly) in patients on PREZISTA/rtv, interruption or discontinuation of treatment must be considered.


In addition, the Adverse Reaction section of the PREZISTA Prescribing Information and the Patient Package Insert have been updated to include this new information.

Enclosed, please find the updated Prescribing Information as well as the Patient Package Insert.

Please see PREZISTA Indication and additional Important Safety Information included on page 3 and page 4 of this letter.

Tibotec Therapeutics is committed to ensuring that PREZISTA is used safely and effectively and providing you with the most current information for our products.

Should you have any questions, require further information on product safety, or wish to report adverse patient experiences, please contact Tibotec Therapeutics Medical Information at 1-877REACH TT (1-877-732-2488).

Alternatively, adverse events may be reported to FDA's MedWatch reporting system
o By phone (1800FDA1088), by facsimile (1800FDA0178),
o Online (https://www.accessdata.fda.gov/scripts/medwatch/) or
o Mailed, using the MedWatch for FDA 3500 postage paid form, to the FDA Medical Products Reporting Program, 5600 Fishers Lane, Rockville, MD 208529787

Sincerely,

Alan Tennenberg, MD, MPH
Vice President, Clinical Affairs


FDA Issues New Prezista (Darunavir) Label Changes

Label attached; A Dear Doctor Letter from Tibotec follows below.

Updates have been made to Prezista (darunavir) tablets labeling to reflect significant new risk information. Changes have been made to the CLINICAL PHARMACOLOGY section to include data from 6 pharmacokinetic, drug interaction Phase 1 trials, and to the WARNINGS, PRECAUTIONS AND ADVERSE REACTIONS sections of the package insert to include hepatotoxicity information. Other updates include those made to PRECAUTIONS, updates to DOSAGE AND ADMINISTRATION, and changes to Table 11 to include information regarding a potential drug-drug interaction with rosuvastatin.

In the WARNINGS section, the following has been added:

"Hepatotoxicity
Drug-induced hepatitis (e.g., acute hepatitis, cytolytic hepatitis) has been reported with PREZISTA/rtv. During the clinical development program (N=3063), hepatitis has been reported in 0.5% of patients receiving combination therapy with PREZISTA/rtv. Patients with preexisting liver dysfunction, including chronic active hepatitis B or C, have an increased risk for liver function abnormalities including severe hepatic adverse events.

Post-marketing cases of liver injury, including some fatalities, have been reported. These have generally occurred in patients with advanced HIV-1 disease taking multiple concomitant medications, having co-morbidities including hepatitis B or C co-infection, and/or developing immune reconstitution syndrome. A causal relationship with PREZISTA/rtv therapy has not been established.

Appropriate laboratory testing should be conducted prior to initiating therapy with PREZISTA/rtv and patients should be monitored during treatment. Increased AST/ALT monitoring should be considered in patients with underlying chronic hepatitis, cirrhosis, or in patients who have pre-treatment elevations of transaminases, especially during the first several months of PREZISTA/rtv treatment.

If there is evidence of new or worsening liver dysfunction (including clinically significant elevation of liver enzymes and/or symptoms such as fatigue, anorexia, nausea, jaundice, dark urine, liver tenderness, hepatomegaly) in patients on PREZISTA/rtv, interruption or discontinuation of treatment must be considered."

The PRECAUTIONS section has been changed to read as follows:

"Patients with co-existing conditions
Hepatic Impairment: No dose adjustment of PREZISTA/rtv is necessary for patients with either mild or moderate hepatic impairment. There are no pharmacokinetic or safety data available for subjects with severe hepatic impairment, therefore, PREZISTA/rtv is not recommended for use in patients with severe hepatic impairment (see CLINICAL PHARMACOLOGY, Pharmacokinetics in Adults, Special Populations, Hepatic Impairment and DOSAGE AND ADMINISTRATION)."

Table 11, Established and Other Potentially Significant Drug Interactions, has been modified, under HMG-CoA Reductase Inhibitors, to include rosuvastatin, indicating increased concentration of rosuvastatin, with the following clinical comment: "Use the lowest possible dose of atorvastatin, pravastatin or rosuvastatin with careful monitoring, or consider other HMG-CoA reductase inhibitors such as fluvastatin in combination with PREZISTA/rtv."

The following sentence has been added to the CLINICAL PHARMACOLOGY section, under Absorption and Bioavailabilty: "In vivo data suggests that darunavir/ritonavir is an inhibitor of the p-glycoprotein (p-gp) transporters."

The following has been added under: Special Populations
"Hepatic Impairment: Darunavir is primarily metabolized by the liver. The steady-state pharmacokinetic parameters of darunavir were similar after multiple dose co-administration of PREZISTA/rtv 600/100 mg b.i.d. to subjects with normal hepatic function (n=16), mild hepatic impairment (Child-Pugh Class A, n=8), and moderate hepatic impairment (Child-Pugh Class B, n=8). The effect of severe hepatic impairment on the pharmacokinetics of darunavir has not been evaluated (see PRECAUTIONS, Patients with co-existing conditions, Hepatic Impairment and DOSAGE AND ADMINISTRATION)."

In addition, there are updates to Table 4: Drug Interactions Pharmacokinetic Parameters for Darunavir in the Presence of Co-administered Drugs, and Table 5: Drug Interactions: Pharmacokinetic Parameters for Co-administered Drugs in the Presence of Darunavir/Ritonavir.

The last paragraph of the ADVERSE REACTIONS section now reads: "Patients co-infected with hepatitis B and/or hepatitis C virus: In subjects co-infected with hepatitis B or C virus receiving PREZISTA/rtv, the incidence of adverse events and clinical chemistry abnormalities was not higher than in subjects receiving PREZISTA/rtv who were not co-infected, except for increased hepatic enzymes (see WARNINGS, Hepatotoxicity). The pharmacokinetic exposure in co-infected subjects was comparable to that in subjects without co-infection."

In addition, the following has been added:

"Additional adverse reactions identified in clinical studies, occurring in less than 1% of the patients, are listed below by body system:

Hepatobiliary System: acute hepatitis, cytolytic hepatitis, hepatotoxicity, hyperbilirubinemia

Skin and Appendages: erythema multiforme, Stevens-Johnson Syndrome
[this duplicate information was deleted from the Skin and Appendages section under the treatment-emergent adverse events occurring in less than 2% of de novo subjects]"

Changes were also made to DOSAGE AND ADMINISTRATION, to include the following: "Hepatic Impairment: No dose adjustment is required in patients with mild or moderate hepatic impairment. There are no data regarding the use of PREZISTA/rtv when co-administered to subjects with severe hepatic impairment; therefore, PREZISTA/rtv is not recommended for use in patients with severe hepatic impairment (see CLINICAL PHARMACOLOGY, Pharmacokinetics in Adults, Special Populations, Hepatic Impairment and PRECAUTIONS, Patients with co-existing conditions, Hepatic Impairment)."

The new label will be posted soon at DailyMed to replace the 08/2007 version.

Richard Klein
Office of Special Health Issues
Food and Drug Administration

Kimberly Struble
Division of Antiviral Drug Products
Food and Drug Administration
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