martes, 5 de abril de 2016

HIV/AIDS Update - Approval of Descovy (emtricitabine (FTC) and tenofovir alafenamide (TAF) fixed-dose combination)

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On April 4, 2016 FDA approved DESCOVY, a two-drug fixed dose combination tablet containing 2 HIV nucleoside analog reverse transcriptase inhibitors (NRTIs), emtricitabine (FTC) and tenofovir alafenamide (TAF). Each DESCOVY tablet contains 200 mg of FTC and 25 mg of TAF (equivalent to 28 mg of tenofovir alafenamide fumarate).
DESCOVY is not a complete regimen for the treatment of HIV-1 infection and must be combined with other antiretroviral agents to form a complete regimen.
The approval is based on a relative bioavailability trial demonstrating FTC and TAF exposures were similar between DESCOVY and GENVOYA (elvitegravir/cobicistat/FTC/TAF). A clinical trial to evaluate the efficacy and safety of DESCOVY was not required because the safety and efficacy of FTC and TAF was established previously in clinical trials with GENVOYA.
TAF 25 mg provides for TAF exposures that match or exceed those observed in patients receiving GENVOYA, ensuring adequate antiviral effect. With respect to safety, TAF exposures for FTC/TAF 200 mg/25 mg when used with some boosted protease inhibitors will be higher than that of GENVOYA. However, exposures of the metabolite, tenofovir, will remain substantially lower than that observed with previously approved tenofovir disoproxil fumarate (TDF) formulations such as, Viread (TDF), Truvada (FTC/TDF) and Stribild (Elvitegravir, COBI, FTC, TDF). Thus, the safety of DESCOVY is supported by formulations with substantially higher tenofovir exposures.
Below are more specific details included in the DESCOVY package insert.
INDICATIONS AND USAGE
DESCOVY is indicated, in combination with other antiretroviral agents, for the treatment of HIV-1 infection in adults and pediatric patients 12 years of age and older.
Limitations of Use:
DESCOVY is not indicated for use as pre-exposure prophylaxis (PrEP) to reduce the risk of sexually acquired HIV-1 in adults at high risk.
DOSAGE AND ADMINISTRATION
Testing Prior to Initiation of DESCOVY
Prior to initiation of DESCOVY, patients should be tested for hepatitis B virus infection
Estimated creatinine clearance, urine glucose, and urine protein should be assessed before initiating DESCOVY therapy and should be monitored during therapy in all patients
Recommended Dosage
The recommended dosage of DESCOVY is one tablet taken orally once daily with or without food in adults and pediatric patients 12 years of age and older with body weight at least 35 kg and creatinine clearance greater than or equal to 30 mL per minute
Not Recommended in Patients with Severe Renal Impairment
DESCOVY is not recommended in patients with estimated creatinine clearance below 30 mL per minute
The product labeling contains the following WARNINGS and PRECAUTIONS
WARNINGS AND PRECAUTIONS
  • Lactic Acidosis/Severe Hepatomegaly with Steatosis
  • Severe Acute Exacerbation of Hepatitis B in Patients Coinfected with HIV-1 and HBV
  • Fat Redistribution
  • Immune Reconstitution Syndrome
  • New Onset or Worsening Renal Impairment
  • Bone Loss and Mineralization Defects
Additionally, the DESCOVY label includes a boxed warning for lactic acidosis/severe hepatomegaly with steatosis and post treatment acute exacerbation of Hepatitis B.
DRUG INTERACTIONS
Potential for Other Drugs to Affect One or More Components of DESCOVY
TAF, a component of DESCOVY, is a substrate of P-gp, BCRP, OATP1B1, and OATP1B3. Drugs that strongly affect P-gp activity may lead to changes in TAF absorption (see Table 1). Drugs that induce P-gp activity are expected to decrease the absorption of TAF, resulting in decreased plasma concentration of TAF, which may lead to loss of therapeutic effect of DESCOVY and development of resistance. Coadministration of DESCOVY with other drugs that inhibit P-gp may increase the absorption and plasma concentration of TAF. TAF is not an inhibitor of CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, or UGT1A1. TAF is a weak inhibitor of CYP3A in vitro. TAF is not an inhibitor or inducer of CYP3A in vivo.
Drugs Affecting Renal Function
Because FTC and tenofovir are primarily excreted by the kidneys by a combination of glomerular filtration and active tubular secretion, coadministration of DESCOVY with drugs that reduce renal function or compete for active tubular secretion may increase concentrations of FTC, tenofovir, and other renally eliminated drugs and this may increase the risk of adverse reactions. Some examples of drugs that are eliminated by active tubular secretion include, but are not limited to, acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides (e.g., gentamicin), and high-dose or multiple NSAIDs
Established and Other Potentially Significant Interactions
Table 1 provides a listing of established or potentially clinically significant drug interactions with recommended steps to prevent or manage the drug interaction (the table is not all inclusive). The drug interactions described are based on studies conducted with either DESCOVY, the components of DESCOVY (emtricitabine and tenofovir alafenamide) as individual agents, or are predicted drug interactions that may occur with DESCOVY.
Table 1  Established and Other Potentially Significanta Drug Interactions
Concomitant Drug Class: Drug NameEffect on ConcentrationbClinical Comment
Antiretroviral Agents: Protease Inhibitors (PI)
tipranavir/ritonavirTAFCoadministration with DESCOVY is not recommended.
Other Agents
Anticonvulsants:
carbamazepine
oxcarbazepine
phenobarbital
phenytoin
↓TAF



Consider alternative anticonvulsant.
Antimycobacterials:
rifabutin
rifampin
rifapentine
↓TAF
Coadministration of DESCOVY with rifabutin, rifampin, or rifapentine is not recommended.
Herbal Products:
St. John’s wort (Hypericum perforatum)
↓TAFCoadministration of DESCOVY with St. John’s wort is not recommended.
     a This table is not all inclusive.
    ↓=Decrease
Drugs without Clinically Significant Interactions with DESCOVY
Based on drug interaction studies conducted with the components of DESCOVY, no clinically significant drug interactions have been either observed or are expected when DESCOVY is combined with the following antiretroviral agents: atazanavir with ritonavir or cobicistat, darunavir with ritonavir or cobicistat, dolutegravir, efavirenz, ledipasvir, lopinavir/ritonavir, maraviroc, nevirapine, raltegravir, rilpivirine, and sofosbuvir. No clinically significant drug interactions have been either observed or are expected when DESCOVY is combined with the following drugs: buprenorphine, itraconazole, ketoconazole, lorazepam, methadone, midazolam, naloxone, norbuprenorphine, norgestimate/ethinyl estradiol, and sertraline.
Drug Interaction Studies
The effects of coadministered drugs on the exposure of TAF are shown in Table 5 and the effects of DESCOVY or its components on the exposure of coadministered drugs are shown in Table 6 [these studies were conducted with DESCOVY or the components of DESCOVY (FTC or TAF) administered alone].
Table 5  Drug Interactions: Changes in TAF Pharmacokinetic Parameters in the Presence of Coadministered Drug(s)a
Coadministered DrugCoadministered Drug(s) Dosage (once daily)
(mg)
Tenofovir Alafenamide Dosage
(once daily)
(mg)
NMean Ratio of TAF PK Parameters (90% CI);
No effect = 1.00
CmaxAUCCmin
Atazanavir300 (+100 ritonavir)10101.77
(1.28, 2.44)
1.91
(1.55, 2.35)
NC
Cobicistat1508122.83
(2.20, 3.65)
2.65
(2.29, 3.07)
NC
Darunavir800 (+150 cobicistat)25b110.93
(0.72, 1.21)
0.98
(0.80, 1.19)
NC
Darunavir800 (+100 ritonavir)  10101.42
(0.96, 2.09)
1.06
(0.84, 1.35)
NC
Dolutegravir5010101.24
(0.88, 1.74)
1.19
(0.96, 1.48)
NC
Efavirenz60040b110.78
(0.58,1.05)
0.86
(0.72, 1.02)
NC

Lopinavir
800 (+200 ritonavir)10102.19
(1.72, 2.79)
1.47
(1.17, 1.85)
NC
Rilpivirine2525171.01
(0.84, 1.22)
1.01
(0.94, 1.09)
NC
Sertraline50 (dosed as a single dose)10c191.00
(0.86, 1.16)
0.96 (0.89,1.03)NC
NC=Not Calculated
All interaction studies conducted in healthy volunteers.
Study conducted with DESCOVY (FTC/TAF).
c Study conducted with FTC+TAF with EVG+COBI.
Table 6 Drug Interactions: Changes in PK Parameters for Coadministered Drug in the Presence of DESCOVY or the Individual Componentsa
Coadministered DrugCoadministered Drug Dosage (once daily)
(mg)
Tenofovir Alafenamide Dosage
(once daily)
(mg)
NMean Ratio of Coadministered Drug PK Parameters (90% CI);    
No effect = 1.00
CmaxAUCCmin
Atazanavir300 +100 ritonavir10100.98
(0.89, 1.07)
0.99
(0.96, 1.01)
1.00
(0.96, 1.04)
Cobicistat1508141.06
(1.00, 1.12)
1.09
(1.03, 1.15)
1.11
(0.98, 1.25)
Darunavir800 +150 cobicistat25b111.02
(0.96, 1.09)
0.99
(0.92, 1.07)
0.97
(0.82, 1.15)
Darunavir800 +100 ritonavir10100.99
(0.91, 1.08)
1.01
(0.96, 1.06)
1.13
(0.95, 1.34)
Dolutegravir50 mg10101.15
(1.04, 1.27)
1.02
(0.97, 1.08)
1.05
(0.97, 1.13)
Lopinavir800 +200 ritonavir10101.00
(0.95, 1.06)
1.00
(0.92, 1.09)
0.98
(0.85, 1.12)
Midazolamc2.5 (orally)25
18
1.02
(0.92, 1.13)
1.12
(1.03, 1.22)
NC
1 (intravenous)0.99
(0.89, 1.11)
1.08
(1.04, 1.14)
NC
Rilpivirine2525160.93
(0.87, 0.99)
1.01
(0.96, 1.06)
1.13
(1.04, 1.23)
Sertraline50 (dosed as a single dose)10d191.14
(0.94, 1.38)
0.93
(0.77, 1.13)
NC
NC=Not Calculated
All interaction studies conducted in healthy volunteers.
Study conducted with DESCOVY (FTC/TAF).
A sensitive CYP3A4 substrate.
Study conducted with FTC+TAF with EVG+COBI.
The product labeling for DESCOVY will be made available through Drugs@FDA and DailyMed.
DESCOVY is a product of Gilead Sciences.
Richard Klein
Office of Health and Constituent Affairs
Food and Drug Administration
Kimberly Struble
Division of Antiviral Products
Food and Drug Administration
Steve Morin
Office of Health and Constituent Affairs
Food and Drug Administration
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