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Ritonavir information from DrugsUpdate  

See Available Brands of Ritonavir in India

P - Caution when used during pregnancy
L - Contraindicated in lactation
FI - Food *

Ritonavir, with trade name Norvir (Abbott Laboratories), is an antiretroviral drug from the protease inhibitor class used to treat HIV infection and AIDS.

Ritonavir is frequently prescribed with HAART, not for its antiviral action, but as it inhibits the same host enzyme that metabolizes other protease inhibitors. This inhibition leads to higher plasma concentrations of these latter drugs, allowing the clinician to lower their dose and frequency and improving their clinical efficacy.

Pharmacodynamics

Pharmacokinetics

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.

Absorption

Peak plasma concentrations occur about 2-4 hours after oral admin.

Distribution
Protein binding: about 98%.

Metabolism

Extensively metabolised in the liver by CYP450 isoenzymes.

Excretion

Mainly excreted in the faeces. Half-life: 3-5 hours.

Ritonavir Indications / Ritonavir Uses

Information Not Available

Ritonavir Adverse Reactions / Ritonavir Side Effects

Syncope, orthostatic hypotension; dry mouth, mouth ulcers, throat irritation, cough; dyspepsia, nausea, vomiting, diarrhoea, taste disturbance, seizures, anxiety, sweating, fever, asthenia, fatigue, headache, dizziness, paraesthesia, myalgia, skin rashes, pruritus, renal insufficiency, anaemia, raised WBC, raised prothrombin time, lipodystrophy, pancreatitis, electrolyte imbalance.

Potentially Fatal: Hypersensitivity, anaphylaxis and Stevens-Johnson syndrome.

Precautions

Warnings
Drug interactions with certain nonsedating antihistamines, sedative hypnotics, antiarrhythmic agents, or ergot derivatives may result in serious and/or life-threatening adverse reactions.

Monitor
Because ritonavir can increase total triglycerides and cholesterol concentrations, measure triglycerides and cholesterol levels prior to initiating therapy and periodically during therapy. Monitor AST, ALT, gamma-glutamyltransferase, and glucose levels before initiating therapy and periodically thereafter.

Overdosage

Treatment includes general supportive measures such as vital sign monitoring and observation of clinical status of the patient.

Special 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.

Other Drug 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.

Other Interactions

Food Interaction
Co-admin with St. John's wort may lead to a substantial decrease in the plasma levels of ritonavir.

Dosage

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.
Child: Combined with other antiretrovirals: >2 years: 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.
Hepatic impairment: Dosage reduction may be required.

Oral

As a pharmacokinetic enhancer
Adult: To enhance the efficacy of other protease inhibitors: 100-200 mg once or twice daily.

Food(before/after)

Should be taken with food

List of Contraindications

Ritonavir and Pregnancy

Caution when used during pregnancy

Category B: Either animal-reproduction studies have not demonstrated a foetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the 1st trimester (and there is no evidence of a risk in later trimesters).

Ritonavir and Lactation

Contraindicated in lactation

Ritonavir and Children

Not recommended for children younger than 1 month of age

Ritonavir and Geriatic

Information Not Available

Ritonavir and Other Contraindications

Hypersensitivity; lactation; severe hepatic impairment

Storage

Store soft gelatin capsules in the refrigerator at 36° to 46°F until dispensed. Refrigeration of soft gelatin capsules by the patient is recommended but not required if used within 30 days and stored below 77°F. Protect from light. Avoid exposure to excessive heat. Store oral solution at 68° to 77°F. Do not refrigerate. Shake well before each use. Store and dispense in original container. Avoid exposure to excessive heat. Keep cap tightly closed.

Lab interference

Store soft gelatin capsules in the refrigerator at 36° to 46°F until dispensed. Refrigeration of soft gelatin capsules by the patient is recommended but not required if used within 30 days and stored below 77°F. Protect from light. Avoid exposure to excessive heat. Store oral solution at 68° to 77°F. Do not refrigerate. Shake well before each use. Store and dispense in original container. Avoid exposure to excessive heat. Keep cap tightly closed.

Ritonavir brands in India:

Empetus Ritomax Ritovir Synthivan

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