Formulary
Ritonavir: Indications, Dosing, Side Effects and Interactions
Ritonavir clinical drug profile including indications, dosing, side effects, cautions and interactions.
MedNext Academy | 4 min read
Ritonavir: Indications, Dosing, Side Effects and Interactions
Ritonavir clinical drug profile including indications, dosing, side effects, cautions and interactions.
Indications and dose
**HIV infection in combination with other antiretroviral drugs (high-dose ritonavir)**
- **Adult** (By Mouth): Initially 300 mg every 12 hours for 3 days, increased in steps of 100 mg every 12 hours over not longer than 14 days; increased to 600 mg every 12 hours.
**Low-dose booster to increase effect of other protease inhibitors**
- **Adult** (By Mouth): 100-200 mg 1-2 times a day.
**HIV infection in combination with other antiretroviral drugs (high-dose ritonavir) for ritonavir**
- **Child 2-17 years** (By mouth): Initially 250 mg/m2 twice daily, increased in steps of 50 mg/m2 every 2-3 days; increased to 350 mg/m2 twice daily (max. per dose 600 mg twice daily), tolerability of this regimen is poor.
**Low-dose ritonavir to increase the effect of atazanavir for ritonavir**
- **Child 6-17 years (body-weight 15 kg and above)** (By mouth): 100 mg once daily.
**Low-dose ritonavir to increase the effect of darunavir for ritonavir**
- **Child 3-17 years (body-weight 15-29 kg)** (By mouth): 50 mg twice daily.
- **Child 3-17 years (body-weight 30-39 kg)** (By mouth): 60 mg twice daily.
- **Child 3-17 years (body-weight 40 kg and above)** (By mouth): 100 mg twice daily.
- **Child 12-17 years (body-weight 40 kg and above)** (By mouth): 100 mg once daily for use in patients taking darunavir once daily.
**Low-dose ritonavir to increase the effect of fosamprenavir for ritonavir**
- **Child 6-17 years (body-weight 25-32 kg)** (By mouth): 3 mg/kg twice daily.
- **Child 6-17 years (body-weight 33 kg and above)** (By mouth): 100 mg twice daily.
Cautions
For all protease inhibitors Haemophilia (increased risk of bleeding) Cautions For ritonavir Cardiac conduction disorders; pancreatitis; structural heart disease
Contraindications
For all protease inhibitors Acute porphyrias
Side effects
For all protease inhibitors Common or very common Angioedema; anxiety; appetite abnormal; arthralgia; asthenia; diabetes mellitus; diarrhoea; dizziness; dyslipidaemia; fever; gastrointestinal discomfort; gastrointestinal disorders; headache; hepatic disorders; hypersensitivity; hypertension; myalgia; nausea; oral ulceration; pancreatitis; peripheral neuropathy; seizure; skin reactions; sleep disorders; syncope; taste altered; urinary frequency increased; vomiting Uncommon Alopecia; dry mouth; immune reconstitution inflammatory syndrome; myocardial infarction; osteonecrosis; weight increased Rare or very rare Stevens-Johnson syndrome Side-effects For ritonavir Common or very common Back pain; concentration impaired; confusion; cough; dehydration; feeling hot; flushing; gastrointestinal haemorrhage; gout; hypotension; menorrhagia; myopathy; oedema; oral paraesthesia; oropharyngeal pain; paraesthesia; peripheral coldness; pharyngitis; renal impairment; thrombocytopenia; vision blurred Rare or very rare Hyperglycaemia; toxic epidermal necrolysis Side-effects, further information Signs and symptoms suggestive of pancreatitis (including raised serum lipase) should be evaluated - discontinue if pancreatitis diagnosed.
Interactions
**Severe interactions:**
- Fosamprenavir/ ritonavir (700/100 mg BID) (Lopinavir/ritonavir 400/100 mg BID) or Fosamprenavir (1400 mg BID) (Lopinavir/ritonavir 533/133 mg BID) Fosamprenavir: Amprenavir concentrations are...
- Particular caution should be used when prescribing Kaletra in patients taking digoxin as the acute inhibitory effect of ritonavir on P-gp is expected to significantly increase digoxin levels.
- In addition, co-administration of apalutamide and Kaletra may lead to serious adverse events including seizure due to higher apalutamide levels.
- Co-administration of Kaletra with rifampicin is not recommended as the decrease in lopinavir concentrations may in turn significantly decrease the lopinavir therapeutic effect.
- Other medicinal products Based on known metabolic profiles, clinically significant interactions are not expected between Kaletra and dapsone, trimethoprim/sulfamethoxazole, azithromycin or...
**Other interactions (121):**
- Kaletra contains lopinavir and ritonavir, both of which are inhibitors of the P450 isoform CYP3A in vitro .
- Co-administered drug by therapeutic area Effects on drug levels Geometric Mean Change (%) in AUC, C max , C min Mechanism of interaction Clinical recommendation concerning co-administration with...
- Abacavir, Zidovudine Abacavir, Zidovudine: Concentrations may be reduced due to increased glucuronidation by lopinavir/ritonavir.
- The clinical significance of reduced abacavir and zidovudine concentrations is unknown.
- Non-nucleoside reverse transcriptase inhibitors (NNRTIs) Efavirenz, 600 mg QD Lopinavir: AUC: 20% C max : 13% C min : 42% The Kaletra tablets dosage should be increased to 500/125 mg twice...
- Efavirenz, 600 mg QD (Lopinavir/ritonavir 500/125 mg BID) Lopinavir: (Relative to 400/100 mg BID administered alone) Nevirapine, 200 mg BID Lopinavir: AUC: 27% C max : 19% C min : 51% The...
Pregnancy
Only use low-dose booster to increase the effect of other protease inhibitors.
Hepatic impairment
For all protease inhibitors In general, manufacturers advise use with caution in patients with chronic hepatitis B or C (increased risk of hepatic side-effects). Hepatic impairment For ritonavir When used as a low-dose booster , manufacturer advises caution in severe impairment; avoid in decompensated liver disease. When used in high-doses , manufacturer advises avoid in severe impairment. Dose adjustments Manufacturer advises consult product literature of co-administered protease inhibitor.
Medicinal forms
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
Inside MedNext for this topic
- 411 MedNext-authored chapters
- 80,000+ MCQ bank
- 15 study modes
- Growing visual cheat sheets
Study modes
- Notes
- MCQ
- Audio
- Video
- Visual
- 3D Anatomy
- Trace
- Flashcards
- Mnemonics
- Image Bank
- Clinical
- Microscopy
- Audio QBank
- Cadaver
- Book Match
Continue reading
Subject HubPharmacology Hub
All pharmacology resources in one place.
Drug SchedulesIndian Drug Schedules
Schedule H, H1, X and G classifications.
FormularyBrowse all drugs
Search 1,850+ drug profiles.
Study Ritonavir in the MedNext app
Challenge yourself with targeted pharmacology MCQs on this drug class. Every explanation links back to the chapter that teaches the concept.
Start drug challengeExplore the full formulary

