Cobicistat
TYBOST
Pronunciation: koe-BIK-i-stat (TYE-bost)
“Cob-stat Tie booster”
Strong CYP3A4 inHibitor
OAT inhibitor
What it isPotent CYP3A inhibitor without antiviral activity; pharmacokinetic booster in HIV regimens.
Why this oneUnlike ritonavir, it was engineered solely as a booster, simplifying fixed-dose antiretroviral combinations.
What limits itEvery co-prescription needs interaction review. It raises creatinine by blocking tubular secretion without reducing true filtration.
FDA-approved for
- pharmacokinetic booster (HIV) (2014)
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| HIV-1: PK booster of atazanavir (with other antiretrovirals) | Adults & peds >=35 kg | 150 mg QD with food, at same time as atazanavir 300 mg QD | 150 mg QD | |
| HIV-1: PK booster of atazanavir | Peds 14 to <25 kg (with atazanavir 200 mg QD) | 90 mg QD with food | 90 mg QD | |
| HIV-1: PK booster of atazanavir | Peds 25 to <35 kg (with atazanavir 200 mg QD) | 150 mg QD with food | 150 mg QD | |
| HIV-1: PK booster of darunavir (no darunavir resistance substitutions) | Adults & peds >=40 kg | 150 mg QD with food, at same time as darunavir 800 mg QD | 150 mg QD | |
| HIV-1: PK booster of darunavir | Peds 15 to <25 kg (darunavir 600 mg): 90 mg; 25 to <30 kg (darunavir 600 mg): 150 mg; 30 to <40 kg (darunavir 675 mg): 150 mg | 90-150 mg QD with food per weight band | Per weight band |
Renal No adjustment needed (incl. severe impairment); however with tenofovir DF not recommended if estimated CrCl <70 mL/min; cobicistat lowers estimated CrCl without affecting true glomerular function
Hepatic Mild-moderate: no adjustment; severe: no data
Not an antiretroviral itself - CYP3A inhibitor used only to boost atazanavir or darunavir
Instructions
- Must be coadministered at the same time as atazanavir or darunavir, with food, plus other antiretrovirals
- Assess estimated CrCl before initiation; with tenofovir DF also urine glucose and protein at baseline (serum phosphorus if CKD)
- Not interchangeable with ritonavir for darunavir 600 mg BID, fosamprenavir, saquinavir, or tipranavir
- Do not use with regimens containing ritonavir or other cobicistat-containing products, or with more than one agent requiring PK enhancement
Available strengths
- tab 150, 90 mg
Contraindications
- Coadministration (with atazanavir or darunavir) with drugs whose altered levels cause serious/life-threatening events or loss of effect: alfuzosin, ranolazine, dronedarone, carbamazepine, phenobarbital, phenytoin, colchicine, rifampin, irinotecan (atazanavir only), lurasidone, pimozide, ergot derivatives (dihydroergotamine, ergotamine, methylergonovine), St. John's wort, drospirenone/ethinyl estradiol, lomitapide, lovastatin, simvastatin, nevirapine, sildenafil for PAH (Revatio), indinavir, triazolam, oral midazolam
Cautions
- Decreases estimated CrCl without affecting true GFR - assess CrCl at baseline; confirmed serum creatinine rise >0.4 mg/dL warrants close renal monitoring
- New-onset/worsening renal impairment incl. acute renal failure and Fanconi syndrome when used with tenofovir DF - monitor CrCl, urine glucose/protein; avoid with nephrotoxic agents
- Serious interactions via CYP3A inhibition - review all comedications before and during therapy
- Not recommended: with more than one PK-enhanced antiretroviral, protease inhibitors other than once-daily atazanavir or darunavir, ritonavir-containing regimens, darunavir+efavirenz/nevirapine/etravirine, atazanavir+etravirine
Adverse reactions
- With atazanavir: jaundice (6%)
- Rash (5%)
Pregnancy Not recommended during pregnancy (with darunavir or atazanavir) - substantially lower exposures in 2nd/3rd trimesters; do not initiate in pregnancy and switch to alternative regimen if pregnancy occurs; exposure registry available
Lactation No human milk data (present in rat milk); breastfeeding risks: HIV-1 transmission, viral resistance in HIV-positive infants, infant adverse reactions
Cost
| Strength | #/mo | generic $/mo | CostPlus | |
|---|---|---|---|---|
| 150 mg | tab | 30 qd | not offered | |
| 90 mg | tab | 30 qd | not offered |
Available combined with: elvitegravir / cobicistat / emtricitabine / tenofovir / alafenamide
Generic entry2024
NO BOXED WARNINGS
Principal riskEvery co-prescription must be checked for CYP3A4
Classes and tags
Clinical profile
Legacy pregnancy categoryUnknown / historical label unavailable
Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.
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