Ritonavir
Indications
Ritonavir is used for:
HIV infection, AIDS
Adult Dose
Oral
HIV infection
Adult: Combined with other antiretrovirals: Initially, 300 mg bid for 1 day. May increase dose gradually by 100 mg bid over a period of up to 14 days to 600 mg bid.
Hepatic impairment: Dosage reduction may be required.
As a pharmacokinetic enhancer
Adult: To enhance the efficacy of other protease inhibitors: 100-200 mg once or twice daily.
Hepatic Impairment
Monitor therapy carefully with moderate and severe hepatic impairment
Child Dose
Oral
HIV infection
Child: Combined with other antiretrovirals: >2 yr: 250 mg/m2 bid. Increase dose by 50 mg/m2 bid at 2-3 day intervals up to 400 mg/m2 bid.
Max: 600 mg bid.
Renal Dose
Administration
Should be taken with food.
Contra Indications
Hypersensitivity; lactation; severe hepatic impairment.
Precautions
Pregnancy; child; hepatic impairment; DM; haemophilia; pancreatitis. Monitor glucose, lipid, uric acid and blood counts. Ensure adequate hydration to reduce risk of nephrolithiasis. Discontinue treatment if patient develops haemolytic anaemia.
Lactation: HIV+ women shouldn't breastfeed
Pregnancy-Lactation
Pregnancy
Advise pregnant women not to use oral solution during pregnancy owing to its alcohol content
Follow current CDC/WHO recommendations for HIV treatment during pregnancy
Lactation
Excreted in human milk
The CDC recommends that HIV-1-infected mothers in the United States not breastfeed their infants to avoid risking postnatal transmission of HIV-1 infection, risk of developing viral resistance (in HIV-positive infants), and risk of serious adverse reactions
Interactions
Decreased plasma conc with phenobarbital, carbamazepine, dexamethasone, phenytoin, rifabutin and rifampicn. Increased plasma conc of certain drugs highly metabolized by CYP3A. May increase serum levels of sildenafil.
Potentially Fatal: Avoid concurrent admin of oral solution (contains alcohol) with disulfiram or metronidazole. Increased risk of myopathy when used with simvastatin or lovastatin. Concurrent use with alfuzosin may lead to serious hypotension. Increased risk of cardiac arrhythmias when used with amiodarone, cisapride, propafenone, quinidine, flecainide and pimozide. Risk of acute ergot toxicity when used with ergot derivatives. Increased risk of serious adverse reactions when used with midazolam or triazolam.
Side Effects
Side effects of Ritonavir :
>10%
Increased triglycerides (17-34%), Diarrhea (15-23%), Nausea (26-30%), Taste perversion (7-11%), Vomiting (14-17%), Weakness (10-15%), Increased GGT (5-20%), Increased creatinine phosphokinase (9-12%)
1-10%
Abdominal pain (6%), Anorexia (2-8%), Dizziness (3-4%), Dyspepsia (6%), Eosinophilia, Fever (1-2%), Flatulence (1-2%), Headache (6-7%), Insomnia (2-3%), Increased uric acid (4%), Increased LFTs (6-10%), Local throat irritation (2-3%), Malaise (1-2%), Myalgia (2%), Diaphoresis (2-3%), Paresthesia (3-7), Pharyngitis (1-3%), Rash (<4%), Somnolence (2-3%), Pharyngitis (1-3%)
<1%
Adrenal suppression, Cerebral ischemia, Dementia, Edema, Leukopenia, Tachycardia, Ulcerative colitis
Potentially Fatal: Hypersensitivity, anaphylaxis and Stevens-Johnson syndrome.
Mode of Action
Ritonavir, a selectively competitive reversible inhibitor of HIV protease, interferes with the formation of essential proteins and enzymes. Afterwhich, the formation of immature and non-infectious viruses follows. It also interferes with the production of infectious HIV and limits further infectious spread of the virus.