Nirmatrelvir + Ritonavir

Nirmatrelvir + Ritonavir Uses, Dosage, Side Effects, Food Interaction and all others data.

Each combipack contains- 4 Nirmatrelvir Tablets (each tablet contains Nirmatrelvir INN 150 mg) and 2 Ritonavir Tablets (each tablet contains Ritonavir USP 100 mg)

Nirmatrelvir + Ritonavir
Uses
Dosage
Side Effect
Precautions
Interactions
Uses during Pregnancy
Uses during Breastfeeding
Accute Overdose
Food Interaction
Half Life
Volume of Distribution
Clearance
Interaction With other Medicine
Contradiction
Storage

Trade Name	Nirmatrelvir + Ritonavir
Generic	Nirmatrelvir + Ritonavir
Type
Therapeutic Class
Manufacturer
Available Country	Bangladesh
Last Updated:	September 24, 2024 at 5:38 am

Uses

Indicated for mild-to-moderate COVID-19 positive adult and pediatric patients (12 years of age and older weighing at least 40 kg), who are at high risk for progression to severe COVID-19, including hospitalization or death.

Nirmatrelvir + Ritonavir is also used to associated treatment for these conditions: Human Immunodeficiency Virus (HIV) Infections

How Nirmatrelvir + Ritonavir works

Ritonavic inhibits the HIV viral proteinase enzyme that normally cleaves the structural and replicative proteins that arise from major HIV genes, such as gag and pol. Gag encodes proteins involved in the core and the nucleocapsid, while pol encodes the the HIV reverse transcriptase, ribonuclease H, integrase, and protease . The pol-encoded proteins are initially translated in the form of a larger precursoe polypeptide, gag-pol, and needs to be cleaved by HIV protease to form other complement proteins . Ritonavir prevents the cleavage of the gag-pol polyprotein, which results in noninfectious, immature viral particles. Ritonavir is a potent inhibitor of cytochrome P450 CYP3A4 isoenzyme present both in the intestinal tract and liver . It is a type II ligand that perfectly fits into the CYP3A4 active site cavity and irreversibly binds to the heme iron via the thiazole nitrogen, which decreases the redox potential of the protein and precludes its reduction with the redox partner, cytochrome P450 reductase . Ritonavir may also play a role in limiting cellular transport and efflux of other protease inhibitors via the P-glycoprotein and MRP efflux channels .

Dosage

Nirmatrelvir + Ritonavir dosage

Nirmatrelvir must be co-administered with Ritonavir. Initiate this treatment as soon as possible after diagnosis of COVID-19 and within 3-5 days of symptom onset. Administer orally with or without food.Dosage: 300 mg Nirmatrelvir (two 150 mg tablets) with 100 mg Ritonavir (one 100 mg tablet), with all three tablets taken together twice daily for 5 days.Missed Dose: If the patient misses a dose of this within 8 hours of the time it is usually taken, the patient should take it as soon as possible and resume the normal dosing schedule. If the patient misses a dose by more than 8 hours, the patient should not take the missed dose and instead take the next dose at the regularly scheduled time. The patient should not double the dose to make up for a missed dose.

Side Effects

Adverse events (incidence >1% and subject difference) were dysgeusia, diarrhea, hypertension, and myalgia.

Toxicity

Human experience of acute overdose with ritonavir is limited. One patient in clinical trials took ritonavir 1500 mg/day for two days. The patient reported paresthesias which resolved after the dose was decreased. A post-marketing case of renal failure with eosinophilia has been reported with ritonavir overdose. The approximate lethal dose was found to be greater than 20 times the related human dose in rats and 10 times the related human dose in mice. Oral LD value in rats is >2500 mg/kg. Adverse effects of ritonavir may arise from drug-drug interactions. Other effects include hepatotoxicity, pancreatitis, and allergic reactions/hypersensitivity.

Precaution

The concomitant use of this tablet and certain other drugs may result in potentially significant drug interactions. Consult the full prescribing information prior to and during treatment for potential drug interactions.Hepatotoxicity: Hepatic transaminase elevations, clinical hepatitis, and jaundice have occurred in patients receiving Ritonavir.HIV-1 Drug Resistance: This tablet use may lead to a risk of HIV-1 developing resistance to HIV protease inhibitors in individuals with uncontrolled or undiagnosed HIV-1 infection.

Interaction

Co-administration of this tablet with drugs highly dependent on CYP3A for clearance and for which elevated plasma concentrations are associated with serious and/or life-threatening events is contraindicated. Co-administration with other CYP3A substrates may require a dose adjustment or additional monitoring. Nirmatrelvir and Ritonavir are CYP3A substrates; therefore, drugs that induce CYP3A may decrease Nirmatrelvir and Ritonavir plasma concentrations and reduce this tablet therapeutic effect.

Volume of Distribution

The estimated volume of distribution of ritonavir is 0.41 ± 0.25 L/kg.

Elimination Route

The absolute bioavailability of ritonavir has not been determined. Following oral administration, peak concentrations are reached after approximately 2 hours and 4 hours (T_max) after dosing under fasting and non-fasting conditions, respectively. It should be noted that ritonavir capsules and tablets are not considered bioequivalent.

Half Life

The approximate half-life of ritonavir is 3-5 hours.

Clearance

The apparent oral clearance at steady-state is 8.8 ± 3.2 L/h. Renal clearance is minimal and estimated to be 7

Elimination Route

Ritonavir is primarily eliminated in the feces. Following oral administration of a single 600mg dose of radiolabeled ritonavir, approximately 11.3 ± 2.8% of the dose was excreted into the urine, of which 3.5 ± 1.8% was unchanged parent drug. The same study found that 86.4 ± 2.9% of the dose was excreted in the feces, of which 33.8 ± 10.8% was unchanged parent drug.

Pregnancy & Breastfeeding use

This is not recommended during pregnancy and in people who can become pregnant and who are not using contraception. Breastfeeding should be interrupted during treatment. These recommendations are because laboratory studies in animals suggest that high doses of this may impact the growth of the fetus. This drug should be used during pregnancy only if clearly needed and the benefit outweighs the risk to the fetus; use of oral solution is not recommended.

Contraindication

History of clinically significant hypersensitivity reactions to the active ingredients (Nirmatrelvir or Ritonavir) or any other components. Co-administration with drugs highly dependent on CYP3A for clearance and for which elevated concentrations are associated with serious and/or life-threatening reactions. Co-administration with potent CYP3A inducers where significantly reduced Nirmatrelvir or Ritonavir plasma concentrations may be associated with the potential for loss of virologic response and possible resistance.

Special Warning

Pediatric Use: This tablet is not authorized for use in pediatric patients younger than 12 years of age or weighing less than 40 kg. The safety and effectiveness of this tablet have not been established in pediatric patients.Geriatric Use: Clinical studies of this tablet include subjects 65 years of age and older and their data contributes to the overall assessment of safety and efficacy.Renal Impairment: No dosage adjustment is needed in patients with mild renal impairment. In patients with moderate renal impairment (eGFR >30 to <60 mL/min), reduce the dose of This tablet to 150 mg Nirmatrelvir and 100 mg Ritonavir twice daily for 5 days. This tablet is not recommended in patients with severe renal impairment (eGFR <30 mL/min).Hepatic Impairment: No dosage adjustment of this tablet is needed for patients with either mild (Child-Pugh Class A) or moderate (Child-Pugh Class B) hepatic impairment. This tablet is not recommended in patients with severe hepatic impairment (Child-Pugh Class C).

Acute Overdose

Treatment of an overdose of this tablet should consist of general supportive measures including monitoring of vital signs and observation of the clinical status of the patient. There is no specific antidote for overdose with this tablet.