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

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.

Adverse 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.

Mechanism 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.