Tybost
For adults and children weighing at least 77 pounds (if taken with atazanavir, brand name Reyataz) or at least 88 pounds (if taken with darunavir, brand name Prezista or in the single-tablet regimen Symtuza; anyone taking darunavir must be at least three years old). Tybost is not an HIV drug--it is a pharmacokinetic enhancer or a “booster” used to increase the levels of Prezista 800 mg once daily, Reyataz 300 mg once daily or elvitegravir 150 mg in Stribild and Genvoya. Tybost is not interchangeable with Norvir when used to increase the levels of other HIV medications.
Take missed dose as soon as possible (at the same time as any separate medication prescribed) as long as it is at least 12 hours before your next dose. Tybost is not recommended for people with CrCl less than 70 mL/min when co-administered with a regimen containing TDF or for people with severe liver problems.
- See package insert for more complete information on potential side effects and interactions.
gilead.com; tybost.com
(800) GILEAD-5 (445–3235)
JO-ANN JOSE, MD, MPH:
Cobicistat is not always interchangeable with the other PK booster drug, ritonavir. It has a lot of the drug interactions as ritonavir, but they are not all the same. Tybost should not be used with twice-daily darunavir 600 mg. Managing drug interactions is tricky with Tybost, so talk with your doctor about all the medications, drugs and over-the-counter supplements you take or plan to take. The University of Liverpool maintains an online HIV drug interactions checker; GO TO hiv-druginteractions.org/checker. Close monitoring of blood creatinine is needed to make sure it improves or doesn’t get worse.
Tybost interacts with many drugs; see the package insert. Tybost is not interchangeable with Norvir. Do not take with alfuzosin, amiodarone, avanafil, cisapride, clopidogrel, dapagliflozin/saxagliptin, dihydroergotamine, dofetilide, dronedarone, eplerenone, ergotamine or ergot derivatives, flibanserin, irinotecan, ivabradine, simvastatin, lomitapide, lovastatin, lumateperone, lurasidone, methylergonovine, midazolam, ranolazine, rifabutin, rifampin, rifapentine, rivaroxaban, pimozide, ticagrelor, triazolam, oral midazolam, Revatio, silodosin, suvorexant, triazolam, vorapaxar or St. John’s wort. Carefully weigh benefits of co-administering tamsulosin and monitor for possible side effects or adjust dose if indicated. Tybost may increase levels of nasal or inhaled fluticasone (Flonase, Advair, Breo Ellipta, Arnuity Ellipta and Flovent). Use an alternative corticosteroid and monitor for signs of Cushing’s syndrome (increased abdominal fat, fatty hump between the shoulders, rounded face, red/purple stretch marks, increased appetite, bone loss, possible high blood pressure and sometimes diabetes). No significant interactions with beclomethasone. Tybost may increase levels of certain calcium channel blockers, beta blockers, HMG-CoA reductase inhibitors (statins or cholesterol medicines), anticoagulants, antiplatelets, antiarrhythmics, antidepressants, sedative-hypnotics, rifabutin, bosentan, erectile dysfunction agents, inhaled corticosteroids and norgestimate. Caution should be taken, with possible dose adjustments of these medications, when used with Tybost. Itraconazole (antifungal) and clarithromycin (antibiotic) may increase Tybost concentrations. Tybost may also increase Biaxin levels. Tybost should not be given with clarithromycin in people with CrCl less than 50mL/min. Rifabutin and some anti-seizure medications, such as carbamazepine (Tegretol), eslicarbazepine, oxcarbazepine, phenobarbital and phenytoin (Dilantin) may decrease Tybost drug levels and should not be co-administered. If co-administering with colchicine, a lower dose may be required as well as extra monitoring. Do not co-administer with colchicine in patients with hepatic or renal impairment. Start metformin at lowest dose and titrate based on tolerability and clinical effect. Do not take with Olysio, Viekira Pak or Zepatier. Avoid Harvoni if tenofovir disoproxil fumarate (TDF) is part of the HIV regimen. Tybost has drug interactions similar to Norvir, but they are not interchangeable, and there may be some drug interactions with Tybost that are not observed with Norvir. Tybost may increase levels of methamphetamines. Tell your care provider or pharmacist about all medications, herbals and supplements you are taking or thinking of taking, prescribed or not, as there are other drug interactions which are not listed here.
Side effects observed in clinical studies (greater than 2% of people) include rash, jaundice and yellowing of the eyes. However, it was studied with Reyataz (no longer recommended or used) so the jaundice and yellowing of eyes were most likely due to the Reyataz component. Before taking Tybost, kidney function testing should be conducted, including serum creatinine (SCr), serum phosphorus, urine glucose and urine protein. These measurements should continue to be monitored while taking Tybost. Cobicistat can cause a small, reversible increase in serum creatinine within the first few weeks of treatment without affecting actual kidney function. While cobicistat does not affect actual kidney function, its effect on SCr can make monitoring of impaired kidney function more difficult or less accurate.
Tybost is not an HIV medication. It is used to boost blood levels of Prezista and is available in fixed-dose tablets with that medication (see Prezcobix and the single-tablet regimen Symtuza). These medications are recommended in the HHS treatment guidelines for use in certain clinical situations and for rapid ART for people who took Apretude (CAB-LA) for PrEP. The COVID-19 treatment Paxlovid includes the booster ritonavir; it can be taken in addition to a cobicistat-containing regimen, but watch out for potential side effects and drug interactions. see Norvir page. Tybost shares some of the same side effects, such as increased cholesterol and increased triglycerides, as Norvir; however, in clinical trials they were less pronounced. Tybost co-administered with elvitegravir, darunavir or atazanavir should not be initiated in pregnant individuals and is not recommended during pregnancy. Inadequate levels of ART (antiretroviral therapy) in second and third trimesters as well as viral breakthroughs have been reported. Tybost is not recommended during pregnancy because of lower drug levels. Pregnant individuals can voluntarily enroll in the Antiretroviral Pregnancy Registry through their provider;
GO TO apregistry.com.
JUAN MICHAEL PORTER II:
Tybost (cobicistat) is another booster with more problems than pros—including jaundice as a side effect among some people! There are better options out there.