Glecaprevir And Pibrentasvir

Introduction Overview

Generic Name

glecaprevir and pibrentasvir

Brand Name

Mavyret

Dosage Form

oral tablets, oral pellets

Drug Class

Antiviral combinations

Pharmacokinetics

Absorption:
Glecaprevir and pibrentasvir, the two active components of Mavyret, exhibit optimal oral bioavailability when taken with food. Food intake enhances absorption significantly, improving systemic exposure. The presence of food can increase the absorption of glecaprevir and pibrentasvir, and thus, it is clinically recommended that Mavyret be administered with meals or snacks to ensure adequate plasma concentrations and improved antiviral efficacy. Peak plasma concentrations (Cmax) for both agents are typically achieved within 5 hours of dosing. The bioavailability of the fixed-dose combination is also influenced by the formulation; the oral pellets for pediatric use retain similar absorption profiles when administered correctly mixed with specific foods, ensuring adequate drug delivery in children.

Distribution:
Following absorption, glecaprevir and pibrentasvir are highly protein-bound (>97%), primarily to albumin, which facilitates prolonged systemic circulation and effective delivery to hepatocytes, the primary site of HCV infection. The volume of distribution is moderate, consistent with extensive distribution into hepatic tissue. Both agents achieve effective concentrations in hepatic cells due to targeted hepatic uptake mechanisms. The binding affinity and distribution profile contribute to the potent antiviral activity by maintaining therapeutic levels in the liver. No significant penetration into cerebrospinal fluid has been reported.

Metabolism:
Glecaprevir undergoes primary metabolism via oxidative pathways largely mediated by the cytochrome P450 enzyme CYP3A, whereas pibrentasvir exhibits minimal metabolism and is primarily excreted unchanged. The involvement of CYP3A underscores potential interaction risks with strong inducers or inhibitors of this enzyme. However, metabolism is limited compared to many drugs, reducing variability in pharmacokinetics. Both agents demonstrate minimal active metabolites, with the parent drugs responsible for the antiviral effects. Clinical studies indicate low potential for accumulation, supporting once-daily dosing.

Elimination:
Glecaprevir and pibrentasvir are eliminated primarily via biliary excretion into feces, with minimal renal excretion (<1% renal clearance). The elimination half-life of glecaprevir ranges around 6 hours, whereas pibrentasvir has a half-life of approximately 13 hours, supporting once-daily dosing regimens. Hepatic impairment, particularly moderate to severe forms, can significantly affect clearance, and thus, Mavyret is contraindicated in patients with Child-Pugh B or C liver disease. Renal impairment has minimal effect on elimination, allowing for use in patients with varying degrees of kidney function without dose adjustment. Overall, the elimination profile favors high safety and efficacy in patients with impaired renal clearance but necessitates caution in advanced liver disease.

Dosage Forms

Available Dosage Forms:
- Oral tablets: Each tablet contains glecaprevir 100 mg and pibrentasvir 40 mg.
- Oral pellets: Designed for pediatric use, each packet contains 50 mg glecaprevir and 20 mg pibrentasvir.

Dosages for Adults and Adolescents:
- Adults and children aged 12 years and older (weighing at least 99 pounds/45 kg) are prescribed 3 tablets once daily (total daily dose: glecaprevir 300 mg, pibrentasvir 120 mg).
- Treatment duration commonly spans 8 weeks for treatment-naïve patients without cirrhosis or with compensated cirrhosis (Child-Pugh A).
- Extended treatment durations of 12 or 16 weeks may be required for treatment-experienced patients or those with specific genotypes or liver conditions.

Specific Patient Populations:
- Children aged 3 to less than 12 years: Dosing is weight-based using oral pellets; administered once daily mixed with small amounts of specific foods.
- Patients with renal impairment require no dose adjustment; Mavyret is safe across all stages of kidney dysfunction, including hemodialysis.
- Not recommended for patients with moderate/severe hepatic impairment (Child-Pugh B or C).

Administration Instructions for Pellets:
- Pellets should be mixed immediately before administration with recommended foods such as peanut butter, yogurt, or hazelnut spread and consumed without chewing to avoid bitterness and loss of effectiveness.
- The mixture must be ingested within 5 minutes to avoid a bitter taste and within 15 minutes to maintain efficacy.
- Leftover mixtures should be discarded and not saved for later use.

Mechanism Of Action

Mavyret's antiviral efficacy is derived from the combined action of its two molecular constituents, glecaprevir and pibrentasvir, which target distinct and essential viral proteins involved in hepatitis C virus replication.

Glecaprevir functions as a potent NS3/4A protease inhibitor; it binds reversibly to the active site of the NS3/4A serine protease enzyme essential for cleavage of the HCV polyprotein into mature, functional viral proteins. Inhibition of this enzyme halts the processing of viral proteins required for viral assembly and replication, thereby suppressing viral propagation. This disruption effectively prevents maturation of viral particles and reduces the viral load.

Pibrentasvir targets the NS5A protein, a multifunctional viral phosphoprotein pivotal in RNA replication complex formation and viral assembly. By binding to NS5A, pibrentasvir disrupts its ability to orchestrate replication complex assembly and inhibits the synthesis of the viral RNA genome. This blockade leads to a rapid decline in viral RNA levels. Furthermore, NS5A inhibitors also impact virion assembly and release.

The complementary mechanisms targeting two separate and essential HCV proteins provide a high barrier to resistance and broaden the antiviral activity across all major HCV genotypes (1 through 6). This dual inhibition prevents the development of resistant viral strains frequently observed with monotherapies.

Clinical studies demonstrate that this combination achieves rapid and sustained virologic response (SVR) rates typically exceeding 95%, confirming its potent antiviral activity. The mechanistic synergy of glecaprevir and pibrentasvir underpins Mavyret’s role as a pan-genotypic direct-acting antiviral agent effective against acute and chronic HCV infections, including difficult-to-treat populations such as those with prior treatment failure or compensated cirrhosis.

Pharmacological Actions

Inhibition of hepatitis C virus (HCV) NS3/4A protease, preventing viral polyprotein cleavage.
Inhibition of HCV NS5A protein, disrupting viral RNA replication and virion assembly.
Pan-genotypic antiviral activity effective against HCV genotypes 1 through 6.
Rapid reduction in viral RNA load leading to sustained virologic response (SVR).
High barrier to viral resistance due to dual mechanism of action.
Orally bioavailable fixed-dose combination targeting multiple viral lifecycle steps.
Effective in both acute and chronic HCV infections.
Activity maintained in patients with compensated cirrhosis (Child-Pugh A).
No significant immunomodulatory effects; antiviral action is direct.
Minimal metabolism of pibrentasvir reduces potential drug interactions and variability.
Efficacious in patients with renal impairment without dosage adjustments.
Improvement in liver function parameters following viral clearance.
Clinical efficacy supported by large-scale randomized controlled trials.
Compatibility with HIV antiretroviral regimens in HIV/HCV co-infected patients.

Therapeutic Or Clinical Uses

Treatment of chronic hepatitis C virus infection across genotypes 1, 2, 3, 4, 5, and 6.
Treatment of acute (recently acquired) hepatitis C infection in adults and children aged 3 years and above.
Use in patients with compensated cirrhosis (Child-Pugh A) for HCV infection.
Therapy for treatment-experienced patients, including those previously treated with NS5A or NS3/4A protease inhibitors (but not both).
Indicated for pediatric patients aged 3 to less than 12 years using oral pellet formulation.
Use in adult and adolescent patients weighing at least 45 kg via oral tablet formulation.
Treatment option for HCV patients with renal impairment, including those on dialysis.
Approved for HCV-infected patients co-infected with HIV-1 under certain conditions.
A shorter treatment course (8 weeks) applicable for treatment-naïve patients without cirrhosis.
Alternative therapy for patients ineligible or intolerant to interferon and ribavirin.
Facilitates high cure rates with good tolerability and safety profile.
Reduces progression to liver fibrosis, cirrhosis, and hepatocellular carcinoma by eradicating HCV.
Included in guidelines as a first-line direct-acting antiviral treatment for HCV.

Side Or Adverse Effects

Common: headache affecting approximately 10% or more patients.
Common: fatigue or tiredness reported frequently during treatment.
Rare but serious: potential for hepatitis B virus reactivation in co-infected patients.
Hepatic adverse effects including possible worsening of liver function in patients with advanced liver disease.
Gastrointestinal symptoms such as nausea, diarrhea, or abdominal discomfort.
Elevations in liver enzymes (ALT/AST) during therapy requiring monitoring.
Hypersensitivity reactions are uncommon but possible.
Rare reports of anemia or changes in blood counts.
Increased bleeding risk is uncommon but requires caution in patients with coagulopathies.
Potential for mild rash or skin irritation.
No significant reports of hair loss associated with treatment.
Drug-induced liver injury has been reported in rare cases, particularly in patients with pre-existing liver impairment.
Fatigue and headache generally resolve after completion of therapy.
No significant impact on renal function observed during therapy.
Serious side effects generally occur in patients with contraindications or severe hepatic dysfunction.

Precautions

Perform baseline screening for hepatitis B virus infection before initiating therapy due to risk of reactivation.
Monitor liver function tests during treatment, especially in patients with pre-existing liver disease.
Avoid use in patients with moderate to severe hepatic impairment (Child-Pugh B or C).
Caution in patients with prior liver decompensation; assess risks and benefits carefully.
Use with caution in patients co-infected with HIV; monitor for possible drug-drug interactions.
Advise patients to take Mavyret with food to enhance absorption and reduce gastrointestinal side effects.
Pregnancy safety has not been established; use only if clearly needed and benefits outweigh risks.
Breastfeeding safety unknown; counsel patients on breastfeeding decisions during treatment.
Discourage alcohol consumption during treatment due to potential for accelerated liver damage.
Counsel patients on adherence to full treatment course to avoid development of resistance.
Monitoring required when administering concomitant medications metabolized by liver enzymes.
Advise patients to report signs of liver dysfunction such as jaundice, dark urine, or unusual bleeding.
Consider dose modifications or discontinuation if severe adverse effects or intolerance develops.
Avoid co-administration with contraindicated drugs that reduce Mavyret efficacy or increase toxicity.
Adjust administration methods appropriately in pediatric patients using oral pellet formulation.

Warnings

Contraindicated in patients with moderate to severe liver disease (Child-Pugh B or C) or history of liver decompensation.
Concomitant use with atazanavir or rifampin is contraindicated due to significant drug interactions and toxicity.
Serious risk of hepatitis B virus reactivation during or after treatment in patients with history of hepatitis B infection.
Rare cases of worsening liver function including liver failure and death have been reported in patients with advanced liver disease.
Patients should be monitored promptly for signs and symptoms of hepatic decompensation including jaundice, confusion, or bleeding.
Mavyret safety and efficacy have not been established in children under 3 years of age.
Not for use in patients with severe renal impairment requiring dose adjustment, although generally safe in renal dysfunction.
Potential for clinically significant drug interactions requiring careful medication reconciliation prior to therapy.
Avoid starting new medications during therapy without consulting healthcare providers to prevent interactions.
Patients should be advised to seek immediate medical attention if symptoms of liver impairment occur.
Use cautiously in pregnant women and nursing mothers due to limited safety data.
Avoid abrupt discontinuation without medical advice to prevent viral relapse or resistance.
Monitor for possible allergic reactions or hypersensitivity symptoms during treatment.
Potential interaction with warfarin and other anticoagulants requires monitoring of coagulation parameters.
Discontinue therapy if severe adverse reactions or life-threatening events occur.

Contraindication

Moderate to severe hepatic impairment (Child-Pugh class B or C).
History of hepatic decompensation (ascites, hepatic encephalopathy, variceal hemorrhage).
Concomitant use with atazanavir due to risk of significant drug interaction and toxicity.
Concomitant use with rifampin due to strong induction of drug metabolism reducing Mavyret efficacy.
Known hypersensitivity to glecaprevir, pibrentasvir, or any component of the formulation.
Use in children below 3 years of age due to insufficient safety and efficacy data.
Concomitant use with strong inducers of CYP3A enzyme that significantly reduce drug levels.
Severe renal impairment requiring dialysis is not a contraindication but requires clinical monitoring.
Use with caution in patients with active hepatitis B without appropriate monitoring and management.
Concomitant use with other antiviral regimens containing similar NS5A or protease inhibitors without clinical indication.

Drug Interactions

Carbamazepine: strong CYP3A inducer reducing plasma levels of glecaprevir and pibrentasvir.
Dabigatran: co-administration may require careful monitoring due to altered drug exposure.
Digoxin: potential for drug interactions necessitating monitoring of digoxin levels.
Ethinylestradiol-containing medications (e.g., combined oral contraceptives): potential interaction requiring counseling.
HIV antivirals such as atazanavir, darunavir, efavirenz, lopinavir, or ritonavir may interact and affect Mavyret levels.
Immunosuppressants like cyclosporine increase glecaprevir exposure significantly; contraindicated or require monitoring.
Rifampin: potent CYP3A inducer contraindicated with Mavyret due to decreased efficacy.
St. John’s wort: induces metabolism enzymes reducing Mavyret plasma concentration leading to treatment failure.
Statins (atorvastatin, fluvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin, simvastatin) may increase risk of statin-associated adverse effects.
Warfarin and other medications metabolized by liver enzymes may have altered efficacy during Mavyret therapy.
Buprenorphine/naloxone and methadone: no dosage adjustment required when coadministered.
Naltrexone interaction unknown; caution advised.
Potential interactions with other hepatically metabolized drugs require clinical monitoring.
New medications started during Mavyret therapy should be assessed for interaction potential.
Close monitoring recommended when coadministering with drugs affecting CYP3A or P-glycoprotein.

Preparations Of The Drug

Mavyret tablets contain active ingredients glecaprevir 100 mg and pibrentasvir 40 mg per tablet.
In addition to active ingredients, tablets contain inactive excipients such as colloidal silicon dioxide, copovidone, croscarmellose sodium, hypromellose, iron oxides (red), lactose monohydrate, polyethylene glycol 3350, propylene glycol monocaprylate, sodium stearyl fumarate, titanium dioxide, and vitamin E polyethylene glycol succinate.
Mavyret tablets are gluten-free.
Mavyret oral pellets, intended for pediatric patients, contain glecaprevir 50 mg and pibrentasvir 20 mg per packet.
Oral pellets include similar excipients with added iron oxide yellow for pellet color.
Inactive ingredients of the oral pellets also include colloidal silicon dioxide, copovidone, croscarmellose sodium, hypromellose, lactose monohydrate, polyethylene glycol/macrogol 3350, propylene glycol monocaprylate, sodium stearyl fumarate, titanium dioxide, and vitamin E polyethylene glycol succinate.
Pellets are gluten-free and designed for ease of swallowing in pediatric populations.
Available preparations are manufactured by AbbVie Inc., ensuring consistent pharmaceutical quality.
Tablets are administered as three tablets once daily with food for adult and adolescent patients.
Pellets are mixed with specific foods immediately before administration and are taken once daily for pediatric use.
Both formulations are stored at controlled room temperature (below 30°C/86°F) in original packaging.
No modifications or crushing of tablets are recommended to preserve pharmacokinetic properties.
Pellets must not be crushed or dissolved in soft food due to bitterness and reduced efficacy.
Discard any unused oral pellet/food mixture promptly to avoid degradation.
Mavyret's formulations utilize advanced excipient matrices to enhance stability and bioavailability.