All you need to know about Ritonavir

Ritonavir (Norvir): Norvir was the first representative of a new class called protease inhibitors for the treatment of HIV-infected patients.

Ritonavir is basically indicated in combination with another antiretroviral nucleoside analogue (s) for treating the HIV-1 infected patients with advanced or progressive immunodeficiency”.

Some clinical studies shows that, ritonavir mainly used as a pharmacokinetic enhancer (low doses) in order to boost the plasma concentrations of other PIs (protease inhibitors) in Human Immunodeficiency Virus (HIV)-infected patients has become available. According to the review of CHMP of data on quality, efficacy, and safety, the CHMP (Committee for Medicinal Products for Human Use) considered by consensus that the benefit or risk profile of Ritonavir (Norvir) was quite favourable when it combines with other antiretroviral agents for the treatment of such patients who are HIV-1 infected (adults and children of 2 year age and older).

Ritonavir with Lopinavir:

The class of Lopinavir/ritonavir is an HIV protease inhibitor. The combination of Lopinavir ritonavir has antiviral activity against HIV-1.

Mechanism of Action: Lopinavir/ritonavir inhibits the HIV protease enzyme by forming an inhibitor-enzyme complex thereby preventing cleavage of the gag-pol polyproteins. Non-infectious viral particles (Immature) are subsequently produced.

Mechanism of Resistance: Greater levels of PIs (protease inhibitor) resistance result from the accumulation of multiple protease inhibitor-resistance mutations. There are several mechanisms of resistance. These include

• Effects on dimer stability.
• Alterations in enzyme catalysis. 
• Alterations in inhibitor binding kinetics. 
• Re-shaping of the active site.
• Reduced binding affinity between the protease enzyme and inhibitors.

Adverse Effects: Some side effects of this combined medication are as follows:

• Diarrhea
• Nausea
• Asthenia
• Abdominal pain
• Vomiting
• Headache
• Rash
• Hyperglycemia
• Uremia
• Hyperbilirubinemia
• Elevated AST or ALT
• Hypercholesterolemia
• Hypertriglyceridemia
• Elevated amylase
• Hypophosphatemia and Neutropenia

Dosage:

For adult patients the recommended dose of lopinavir and ritonavir tablets is 400/100mg (3 capsules or 5.0mL) twice daily, should be administered with food.

Contraindications Or Warnings: Lopinavir/ritonavir is contraindicated with the following medications:
astemizole, terfenadine, dihydroergotamine, ergonovine, ergotamine, methylergonovine,
cisapride, pimozide, midazolam, and triazolam.

Drug Interactions: In vitro, Lopinavir/ritonavir has been shown to be a substrate for, and inhibitor of, CYP3A. In vivo, this combined drug has shown induction and autoinduction of other drugs mainly metabolized by the CYP450 enzymes. The drug is generally metabolized through the enzyme named CYP450 which may interact with lopinavir/ritonavir.

Ritonavir with Atazanavir:

Atazanavir/ritonavir is a combination medication used in the treatment of HIV/AIDS. It combines atazanavir ritonavir. This combination can be preferred instead of the lopinavir/ritonavir.
Where Atazanavir works as Protease inhibitor and Ritonavir works as Protease inhibitor (pharmacokinetic booster).

Side Effects: Side effects with these combined medications are generally minimal.
They may include as follows:

• Abdominal pain
• Diarrhea
• Yellowish skin
• Muscle pains
• Headache.

Greater care is recommended in people with underlying liver problems.

Dosage: The recommended dose of Atazanavir Ritonavir tablets should be based on the prescription of your healthcare provider.

Ritonavir with Darunavir:

Combination of Darunavir Ritonavir:
This combination is also quite effective.
The combination often combines Darunavir and Ritonavir.  This antiretroviral medication is generally used in the treatment and prevention of HIV/AIDS.

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