THE POSITIVELY AWARE 20th ANNUAL HIV DRUG GUIDE
Prezcobix PI
STANDARD DOSE
One tablet (800 mg darunavir/150 mg cobicistat) once daily with food, in patients with no darunavir drug resistance. When coadministered with drugs containing tenofovir disoproxil fumarate (Viread, Truvada) the kidney function should be above 70 mL/min. Take a missed dose as soon as possible, unless it is closer to the time of your next dose. Do not double up on your next dose. Cobicistat should be used in pregnancy only if the benefits justify the risks. There is only animal data in pregnancy. Cobicistat has not been studied in individuals under 18 years of age, thus Prezcobix should not be used in pediatric patients. Do not use in people with severe liver impairment.
manufacturer
Janssen Therapeutics prezcobix.com (800) JANSSEN (526-7736)
AWP
$1,862.13 / month
34
M A R C H + A P RIL 2 016
darunavir/cobicistat, or DRV/COBI
PROTEASE INHIBITOR/PHARMACOKINETIC ENHANCER (BOOSTER) | FIXED-DOSE COMBINATION
Potential side effects and toxicit y
See the pages for the individual drugs contained in this medication—Prezista and Tybost. Prezcobix was FDA approved based on bioequivalency data (similar drug levels in blood when compared to its FDA approved equivalent). In clinical trials with Prezista/Norvir, the most common side effects seen of at least moderate intensity in 5% or more of participants taking it were diarrhea, nausea, rash, headache, abdominal pain, and vomiting. There may be a small increase in serum creatinine (SCr) and decrease in estimated creatinine clearance (CrCl), but this does not affect actual kidney function. However, patients experiencing a confirmed increase in serum creatinine of greater than 0.4 mg/dL from baseline should be closely monitored for renal safety. Serum phosphorus in patients with or at risk for kidney impairment should also be monitored. Kidney impairment, including cases of acute kidney failure and Fanconi syndrome, have been reported in patients taking both cobicistat and Viread (tenofovir DF or TDF, also found in Truvada). When used with TDF, a baseline CrCl, urine glucose, and urine protein is needed; CrCl, urine glucose, and urine protein should be monitored regularly while taking Tybost-containing regimens. As darunavir (contained in Prezcobix) contains a sulfa component, patients with a known sulfonamide allergy should be monitored for rash after starting it.
Potential drug interactions
See the pages for the individual drugs contained in this medication—Prezista and Tybost. Tell your provider or pharmacist about all medications, herbals, and supplements that
Doctor’s comments
The combination of darunavir and cobicistat was approved based upon data showing bioequivalence with darunavir and ritonavir. Because fewer data are available to support this regimen, and because this small bioequivalence study found darunavir levels at the end of a dosing period to be higher with ritonavir than with cobicistat, this compound was ranked as alternative by the DHHS guidelines panel. The advantages are consolidation of two pills into one, and a single drug co-pay. But the drug may be on a high formulary tier requiring higher cost sharing on the part of the patient. Do the math! For those who are eligible, co-pay cards can alleviate this burden. —MELANIE THOMPSON, MD
DHHS ALTERNATIVE
you’re taking or thinking of taking, prescribed or not, before starting on a regimen that contains Prezcobix. Do not take with Evotaz, Genvoya, Kaletra, Norvir, Prezista, Stribild, or Tybost; all or part of these medications are already in Prezcobix or contain equivalent medication. Use with other protease inhibitors or Intelence, Sustiva, or Viramune is not recommended. Do not take with ergot derivatives, triazolam, oral midazolam, lurasidone, pimozide, Revatio, simvastatin, lovastatin, St. John’s wort, alfuzosin, ranolazine, rifampin, or dronedarone. Do not take with colchicine if there is kidney or liver impairment. Can be used with Daklinza. Based on the mechanism, drug interactions with other hepatitis C medications are probably similar to the interactions with Prezista/Norvir, but we are not certain. See the page for Prezista for those interactions.
More information
Prezcobix is an alternative PI for first-time therapy in Department of Health and Human Services (DHHS) HIV treatment guidelines, and is one of two PIs that is co-formulated with a booster (the other is Evotaz). Since Prezista must be used with a PK enhancer like cobicistat (Tybost) or ritonavir (Norvir), this formulation makes for greater convenience, one less pill, and one less co-pay. Tybost is not an HIV medication; like ritonavir (which is an HIV medication), it is used to boost blood levels of other drugs. The two PK enhancers have a long list of drug interactions. See package insert for more complete information on potential side effects and interactions.
Activist’s comments
Prezcobix is the brand name of the single-tablet coformulation of the PI darunavir (Prezista) and the drug booster cobicistat. As with Evotaz and other coformulated fixed-dose combinations, it is important to be aware of the particular side effects and drug-drug interactions of each of the drugs. Atazanavir/cobicistat brings the same advantages in Evotaz: fewer pills and co-pays. This co-formulation is not inferior to boosting with ritonavir. —Moisés Agosto-Rosario
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