Ritonavir
NORVIR
Pronunciation: ri-TOE-na-veer (NOR-veer)
“Write on a Nor virus”
InHibitor (H for High) and inDucer (D for Down)
What it isHIV protease inhibitor now used almost entirely as a pharmacokinetic booster; HIV regimens and nirmatrelvir.
Why this oneIts potent CYP3A4 inhibition is exploited deliberately to raise partner drug levels, allowing lower doses.
What limits itThat same inhibition causes the interactions — every co-prescription must be checked. It also induces some enzymes, which complicates prediction.
FDA-approved for
- HIV infection (1996)
- pharmacokinetic booster (1996)
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| HIV-1 infection (with other antiretrovirals) | Adults | 300 mg BID, titrate up by 100 mg BID q2-3 days | 600 mg BID | 600 mg BID |
| HIV-1 infection (with other antiretrovirals) | Pediatric >1 month | 250 mg/m2 BID, titrate up by 50 mg/m2 BID q2-3 days | 350-400 mg/m2 BID | 600 mg BID |
Titration Increase at 2-3 day intervals
Renal Undefined
Hepatic Mild-moderate (Child-Pugh A/B): no adjustment; severe (Child-Pugh C): not recommended
Instructions
- Take with meals
- Swallow tablets whole; do not chew, break, or crush
- Reduce ritonavir dose when used to boost other protease inhibitors (atazanavir, darunavir, fosamprenavir, saquinavir, tipranavir)
- Must be used in combination with other antiretroviral agents
Available strengths
- cap 100 mg
- tab 100 mg
- powder 100 mg/packet
Contraindications
- Drugs highly dependent on CYP3A for clearance with serious/life-threatening toxicity at elevated levels: alfuzosin; ranolazine; antiarrhythmics (amiodarone, dronedarone, flecainide, propafenone, quinidine); voriconazole; colchicine; lurasidone; pimozide; ergot derivatives (dihydroergotamine, ergotamine, methylergonovine); cisapride; lovastatin, simvastatin; lomitapide; suzetrigine; sildenafil (Revatio) for PAH; triazolam, oral midazolam
- Potent CYP3A inducers that markedly reduce ritonavir levels: apalutamide, St. John's Wort
Cautions
- Hepatotoxicity - fatalities have occurred; monitor liver function
- Pancreatitis - fatalities have occurred
- Allergic reactions/hypersensitivity (anaphylaxis, TEN, SJS, angioedema, bronchospasm)
- PR interval prolongation; second/third degree AV block
- Elevated total cholesterol and triglycerides
- New-onset or worsening diabetes/hyperglycemia
- Immune reconstitution syndrome
- Fat redistribution/accumulation
- Increased bleeding in patients with hemophilia
Adverse reactions
- Diarrhea
- Nausea
- Vomiting
- Abdominal pain
- Paresthesia (including oral)
- Dysgeusia
- Fatigue/asthenia
- Rash
Pregnancy Antiretroviral Pregnancy Registry data show no increased birth defect rate vs background; no evidence of teratogenicity in animals.
Lactation HIV-infected mothers should not breastfeed due to risk of HIV transmission.
Cost
| Strength | #/mo | generic $ | CostPlus | |
|---|---|---|---|---|
| 100 mg | tab | 60 BID | $36.40/mo | offered |
| 100 mg | cap | 60 BID | not offered | |
| 100 mg/packet | powder | per unit | not offered |
Available combined with: Lopinavir (in KALETRA) · lopinavir / ritonavir · nirmatrelvir / ritonavir
Generic entry2015
⚠ BOXED WARNING
- Drug interactions leading to potentially serious or life-threatening reactions
Classes and tags
Clinical profile
Legacy pregnancy categoryUnknown / historical label unavailable
Defining liabilityAgent-specific renal, hepatic, hematologic, metabolic and drug-interaction toxicity.
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