HIV Protease Inhibitor (Boosted) — Antiretroviral Therapy Pregnancy: Used in pregnancy for PMTCT (prevention of mother-to-child transmission) — specialist guidance required; pharmacokinetics altered in pregnancy; dose adjustment may be needed

Lopinavir / Ritonavir

Brand names: Kaletra

Adult dose

Dose: 400 mg/100 mg (lopinavir/ritonavir) twice daily; or 800 mg/200 mg once daily (treatment-naive, no resistance)

Route: Oral (tablets or solution)

Frequency: Twice daily (standard); once daily (naive only)

Max: 800 mg/200 mg/day

Ritonavir acts as pharmacokinetic booster — inhibits CYP3A4, dramatically increasing lopinavir plasma levels. Tablets can be taken with or without food; solution must be taken with food. Major CYP3A4 inhibitor — extensive drug interactions. Increasingly replaced by integrase inhibitor-based regimens (dolutegravir) in UK for first-line HIV treatment but still used in resource-limited settings and in paediatrics.

Paediatric dose

Dose: 300 mg/m² lopinavir twice daily (BSA-based) or 12 mg/kg lopinavir BD (weight-based, under 40 kg) mg/kg

Route: Oral solution (80 mg/20 mg per mL) or tablets

Frequency: Twice daily

Max: 400 mg/100 mg per dose

BNFc: solution preferred in young children — flexible dosing; important in paediatric HIV treatment globally; PMTCT (prevention of mother-to-child transmission) — specialist guidance (or mg/m²)

Dose adjustments

Renal

No dose adjustment required

Hepatic

Use with caution in hepatic impairment — both drugs hepatically metabolised; avoid in decompensated liver disease; ritonavir can worsen hepatitis

Paediatric weight-based calculator

Patient weight (kg)

BNFc: solution preferred in young children — flexible dosing; important in paediatric HIV treatment globally; PMTCT (prevention of mother-to-child transmission) — specialist guidance (or mg/m²)

Clinical pearls

Ritonavir pharmacokinetic boosting: at 100 mg, ritonavir inhibits CYP3A4 without significant antiretroviral activity itself — 'shields' lopinavir from first-pass metabolism, increasing its half-life and trough levels; same principle used with cobicistat in modern regimens
Diarrhoeais the main tolerability issue — often limits adherence; loperamide can be used; once-daily dosing (800/200 mg) preferred by some patients but not suitable with resistance mutations
TB co-treatment: cannot use lopinavir/ritonavir with rifampicin — use rifabutin (adjusted dose) or super-boosting with ritonavir (complex — specialist HIV/TB team required)
COVID-19: RECOVERY and WHO Solidarity trials: lopinavir/ritonavir showed no benefit — do not use

Contraindications

Concurrent rifampicin (reduces lopinavir to sub-therapeutic levels)
Concurrent ergotamine, simvastatin, lovastatin
Concurrent amiodarone, flecainide, propafenone (cardiac arrhythmia risk)
Severe hepatic impairment

Side effects

GI disturbance (diarrhoea, nausea — very common)
Dyslipidaemia (elevated triglycerides, cholesterol)
Hyperglycaemia / insulin resistance
Lipodystrophy (body fat redistribution)
QTc prolongation (PR and QT interval effects)
Hepatotoxicity
Pancreatitis

Interactions

Rifampicin — contraindicated (lopinavir levels reduced to zero)
Rifabutin — use rifabutin 150 mg every other day (lopinavir doubles rifabutin exposure)
Statins (simvastatin/lovastatin) — contraindicated (rhabdomyolysis)
Atorvastatin — max 20 mg/day
Warfarin — unpredictable INR changes
Midazolam IV — increased sedation (reduce dose)
Oral contraceptives — reduced efficacy (use barrier method)

Monitoring

HIV viral load (every 3–6 months when stable)
CD4 count (every 6–12 months)
Fasting lipids and glucose (metabolic complications)
LFTs
ECG if cardiac risk factors
Drug interactions review at every visit

Reference: BNFc; BNF 90; BHIVA HIV Treatment Guidelines 2019; WHO Consolidated HIV Guidelines 2021; PENTA Paediatric HIV Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways