Lenacapavir

Introduction Overview

Generic Name

lenacapavir

Brand Name

Yeztugo

Dosage Form

oral tablets (300 mg), subcutaneous injection single-dose vial (463.5 mg/1.5 mL)

Drug Class

Miscellaneous antivirals; Selective HIV-1 capsid inhibitors

Pharmacokinetics

Absorption:
Lenacapavir (Yeztugo) demonstrates dual routes of administration with distinct absorption profiles. When administered orally as 300 mg tablets, it is absorbed through the gastrointestinal tract with sufficient bioavailability to achieve therapeutic systemic plasma concentrations. The onset of absorption supports initiation dosing regimens involving tablets on day 1 and 2 to rapidly establish effective plasma levels. Subcutaneous administration bypasses first-pass metabolism, providing sustained plasma delivery of lenacapavir through depots formed at the injection site, enabling steady drug release over extended periods, which underpins its 6-month dosing interval for maintenance therapy. Clinical pharmacokinetic evaluations confirm that both oral and subcutaneous routes achieve plasma concentrations consistent with viral capsid inhibition and antiviral efficacy.

Distribution:
Lenacapavir exhibits distribution primarily into systemic circulation with pharmacologic activity targeting HIV-1 capsid proteins intracellularly. Due to its molecular properties and affinity, lenacapavir binds with high specificity to HIV-1 capsid protein multimer interfaces. Distribution studies indicate extensive tissue penetration, especially in lymphoid tissues where HIV reservoirs reside. The volume of distribution supports sustained systemic availability post subcutaneous injection, facilitating effective viral lifecycle disruption. Lenacapavir’s binding characteristics minimize non-specific tissue accumulation, limiting off-target effects. Additionally, plasma protein binding and tissue partitioning have been characterized to ensure prolonged antiviral activity while maintaining safety.

Metabolism:
Lenacapavir undergoes limited metabolic transformation primarily via the cytochrome P450 3A (CYP3A) enzyme system and possibly other pathways including glucuronidation via UGT1A1. The metabolism is significant in the context of drug-drug interactions, as strong CYP3A inducers (e.g., rifampin, phenytoin, phenobarbital) can reduce lenacapavir plasma concentrations, necessitating supplemental dosing during co-administration. Conversely, CYP3A inhibitors may increase lenacapavir levels, although such combinations are generally not recommended due to potential toxicity. Metabolic stability is sufficient to allow for biannual subcutaneous dosing, reflecting slow clearance and durable plasma exposure. Metabolic products do not appear to retain antiviral activity and are efficiently cleared.

Elimination:
The elimination of lenacapavir occurs via both renal and hepatic pathways, with clearance predominantly through biliary excretion of unchanged drug and metabolites. The pharmacokinetic profile supports a long elimination half-life, consistent with the 6-month dosing interval after initial loading doses. Renal clearance of unchanged lenacapavir is minimal, indicating limited renal excretion; thus, dosage adjustments are not necessarily required for mild to moderate renal impairment. Hepatic elimination mediated by CYP3A and UGT1A1 enzymatic activity plays a primary role in drug clearance. Steady-state pharmacokinetics remain stable with repeated dosing, underscoring the drug’s suitability for long-acting injectable PrEP regimens.

Dosage Forms

Available Dosage Forms:
- Oral tablets for oral use: 300 mg tablets (film-coated)
- Injection for subcutaneous use: single-dose vial containing 463.5 mg lenacapavir in 1.5 mL solution

Dosages for Adults and Adolescents:
- Initiation dosing (Day 1): 2 subcutaneous injections totaling 927 mg (2 x 463.5 mg/1.5 mL injections) plus oral administration of 600 mg (2 x 300 mg tablets)
- Initiation dosing (Day 2): 600 mg orally (2 x 300 mg tablets)
- Maintenance dosing (every 6 months, approximately 26 weeks): 2 subcutaneous injections totaling 927 mg
- If injection schedule delay exceeds 2 weeks, oral supplementation with 300 mg once weekly tablets is recommended to maintain protective concentrations until injections resume

Specific Patient Populations:
- Adults and adolescents weighing at least 35 kg (77 pounds) are eligible for Yeztugo use
- Safety and efficacy are not established in children weighing less than 35 kg
- No specific dose adjustments have been recommended for mild to moderate renal or hepatic impairment
- Pregnancy registry exists to monitor outcomes; use in pregnancy and breastfeeding requires careful clinical consideration
- Patients taking strong or moderate CYP3A inducers require supplemental doses or dosing adjustments to maintain adequate drug levels
- Use of concurrent combined P-gp, UGT1A1, and strong CYP3A inhibitors is not recommended due to potential elevation of lenacapavir plasma concentrations

Mechanism Of Action

Lenacapavir, marketed as Yeztugo, functions as a selective HIV-1 capsid inhibitor, representing a novel antiviral mechanism distinct from traditional antiretroviral targets such as reverse transcriptase or protease. By binding with high affinity (KD = 1.4 nM) to the interfaces between capsid protein subunits, lenacapavir disrupts critical structural and functional components of the HIV-1 lifecycle. Its molecular binding impairs the capsid’s ability to perform essential functions necessary for viral replication and infectivity.

At the cellular level, lenacapavir interferes with multiple stages of HIV-1 replication. It blocks the nuclear import of proviral DNA by destabilizing the capsid core, a prerequisite for successful integration of viral DNA into host genomic DNA. This prevents the establishment of productive infection within target CD4+ T cells. Additionally, lenacapavir interferes with virus assembly and release by reducing the production of appropriately formed capsid proteins, leading to malformed capsid structures that are ineffective in packaging viral genetic material and enzymes.

The biochemical interactions involve stabilized binding to capsid protein hexamers and pentamers, causing malformed capsid cores and impairing viral particle maturation. This multilevel disruption reduces the infectivity of any produced viral particles and curtails viral spread. This mechanism allows Yeztugo to provide durable prophylaxis against HIV acquisition when administered through long-acting injectable and oral formulations.

Clinically, this mechanism translates to an effective pre-exposure prophylaxis (PrEP) strategy, maintaining high levels of antiviral activity for up to 6 months per injection. Compared to existing PrEP agents like tenofovir-based regimens, which require daily dosing, lenacapavir’s action on the capsid represents an innovative target that may reduce the risk of adherence failure and resistance formation. Clinical trials (Purpose 1 and Purpose 2) have demonstrated over 99.9% effectiveness in preventing HIV-1 infection in populations at risk, confirming the translational impact of its mechanism of action.

Pharmacological Actions

Selective inhibition of HIV-1 capsid assembly and disassembly processes
Blocking nuclear import of proviral DNA, preventing integration into host genome
Disruption of viral particle assembly through malformed capsid core formation
Reduction in viral replication and infectivity by impairing virus maturation
Sustained plasma concentrations facilitating extended duration of antiviral activity
High binding affinity to capsid protein interfaces ensuring potent antiviral effect
Long-acting pharmacokinetics supporting biannual dosing schedules
Minimal off-target enzymatic or receptor interactions due to specific capsid targeting
Reduced potential for resistance development when administered appropriately
Effective in pre-exposure prophylaxis to prevent HIV-1 acquisition
Activity independent of viral reverse transcriptase or protease pathways
Synergistic potential when used with other classes of antiretrovirals in treatment
Maintains antiviral activity in diverse patient populations, including adolescents weighing ≥35 kg
Does not inhibit cytochrome P450 enzymes but subject to interactions with CYP3A inducers/inhibitors
Suitable for monthly oral supplementation during delayed injection intervals

Therapeutic Or Clinical Uses

Pre-exposure prophylaxis (PrEP) to reduce risk of HIV-1 infection in adults and adolescents (≥35 kg) at risk
Long-acting injectable alternative for patients with adherence challenges to daily oral PrEP
HIV-1 prophylaxis for diverse populations including cisgender women, men, transgender and gender nonbinary individuals engaged in high-risk sexual activity
Use in individuals with confirmed HIV-1 negative status
Patients seeking biannual injection regimens for HIV prevention
Supplementation during delayed injection periods through oral tablets
Part of comprehensive HIV prevention strategy including regular HIV testing and safer sex practices
PrEP option for patients intolerant or experiencing side effects from nucleotide reverse transcriptase inhibitors
Off-label potential as investigational agent in combination antiretroviral therapy targeting HIV capsid (subject to ongoing research)
Use recommended under clinical supervision with participation in pregnancy registries if applicable
Facilitates enhanced adherence through reduced dosing frequency
Supports reduction of new HIV-1 infections in high-incidence regions via long-acting prophylaxis

Side Or Adverse Effects

Injection site reactions such as lumps or bumps, pain, hardness, swelling, itching, redness, bruising, or warmth
Rare serious injection site reactions including severe skin necrosis or ulceration, often linked to improper injection technique
Headache occurring with moderate frequency post-dose
Nausea reported among commonly observed adverse reactions
Potential for hypersensitivity reactions though rare
Possible mild systemic symptoms such as fatigue or malaise not uncommon
Injection site reactions may persist longer compared to other subcutaneous injections due to formulation
Minimal gastrointestinal disturbances beyond nausea observed
No significant laboratory abnormalities routinely reported in clinical trials
Low incidence of allergic or anaphylactic responses
No reported hepatotoxicity or nephrotoxicity in standard use
Risk of resistance development if used in undiagnosed HIV-1 infection or improper dosing adherence
Potential transient flu-like symptoms during early dosing phase
Injection site warmth and redness generally resolve without intervention
No long-term adverse effects identified at current follow-up durations in trials

Precautions

Confirm HIV-1 negative status prior to initiating Yeztugo to avoid risk of resistance
Regular HIV testing as per dosing schedule to monitor seroconversion
Do not administer Yeztugo to patients with known HIV-1 infection
Monitor for injection site reactions and educate on proper subcutaneous injection techniques
Advise patients about signs of acute HIV infection including flu-like symptoms prior to and during therapy
Use caution in patients who become pregnant during therapy; enroll in pregnancy registry
Discuss breastfeeding considerations as small amounts of drug excrete into breast milk
Avoid co-administration with strong combined P-gp, UGT1A1, and CYP3A inhibitors
Use supplemental or adjusted dosing if co-administered with CYP3A inducers to maintain efficacy
Ensure patient adherence to injection schedule to maintain protective drug levels
Educate about Yeztugo not providing protection against other sexually transmitted infections
Advise concurrent safer sex practices to reduce STI risk
Counsel regarding the necessity of scheduled healthcare visits for injections
Monitor for and report any severe or persistent injection site adverse reactions
Avoid administration if HIV status is unknown or during acute HIV seroconversion

Warnings

Boxed Warning for risk of development of HIV drug resistance if administered to persons with undiagnosed HIV-1 infection
Do not initiate Yeztugo without confirmed HIV-1 negative status
Potential for false-negative HIV test results early after HIV acquisition; monitor for symptoms suggestive of acute HIV infection
Yeztugo does not prevent other sexually transmitted infections; safe sex practices remain essential
Risk of serious injection site reactions with improper administration technique
Missed doses or delayed injections may increase risk of HIV infection
No established safety in children under 35 kg weight
Potential drug interactions with agents modifying CYP3A activity may alter drug plasma levels and efficacy
If HIV-1 infection occurs during therapy, immediate initiation of alternative antiretroviral treatment is necessary
Inadequate dosing or monotherapy in setting of HIV infection may lead to treatment-emergent resistance
Pregnancy and breastfeeding safety not fully established; weigh benefits against risks
Potential for injection site reactions to persist longer than other subcutaneous therapeutics
Patients should be advised not to self-administer injections; trained healthcare provider administration required
Drug may affect other concomitant medications for up to nine months after last injection
Regular clinical and laboratory monitoring recommended to detect adverse events and ensure continued HIV-1 negative status

Contraindication

Known HIV-1 infection or seropositive status
Unknown or unconfirmed HIV-1 status prior to initiation
Hypersensitivity to lenacapavir or any excipients in the tablet or injection formulation
Use in pediatric patients weighing less than 35 kg
Concomitant use with combined P-gp, UGT1A1, and strong CYP3A inhibitors due to risk of elevated drug levels
Inability to adhere to injection and testing schedule
Patients with severe injection site skin disorders prohibiting subcutaneous injections
Concurrent administration of agents causing clinically significant CYP3A induction without dose adjustments
Known severe reactions to polyethylene glycol or formulation excipients
Use outside the indicated population for HIV-1 PrEP
Patients unwilling to undergo regular HIV testing and clinical monitoring
Concurrent use with other antiretrovirals without appropriate clinical indication
Patients with history of severe injection site necrosis or ulcer with similar injectable agents
Patients who do not weigh at least 35 kg (due to lack of safety data)
Use by individuals who do not require HIV-1 pre-exposure prophylaxis

Drug Interactions

Strong CYP3A inducers (e.g., rifampin, phenytoin, phenobarbital) significantly reduce lenacapavir plasma levels; supplemental dosing required
Moderate CYP3A inducers (e.g., efavirenz, dexamethasone, St. John's Wort) may reduce drug concentrations; dose adjustments advised
Combined P-gp, UGT1A1, and strong CYP3A inhibitors (e.g., cobicistat, darunavir, voriconazole, atazanavir) can increase lenacapavir plasma levels; concomitant use not recommended
Drugs altering UGT1A1 metabolism may affect lenacapavir clearance
Lenacapavir may influence plasma concentrations of drugs metabolized by CYP3A pathways up to 9 months post last injection
Co-administration with other antivirals requiring CYP3A modulation needs careful monitoring
Interactions with common medications that induce or inhibit CYP enzymes may necessitate changes in dosing or enhanced monitoring
Herbal supplements such as St. John's Wort can decrease efficacy by inducing drug metabolism
No significant interaction with acid-reducing agents noted
Concomitant use with methadone or hormonal contraceptives does not require dosage adjustment based on current data
Immunosuppressants or antiepileptics with CYP3A modulation potential require caution
Interaction potential mandates comprehensive medication review prior to initiation
Use caution when initiating or discontinuing interacting drugs during Yeztugo therapy
Patients should inform healthcare providers of all medications including OTC and supplements
Pharmacokinetic studies highlight need for individualized clinical assessment in the setting of polypharmacy

Preparations Of The Drug

Yeztugo oral tablets: 300 mg film-coated tablets packaged in bottles with child-resistant closure and desiccant packs to maintain stability
Yeztugo injectable solution: single-dose vial containing 463.5 mg lenacapavir in 1.5 mL polyethylene glycol 300 and water for injection
Oral tablets are stable at room temperature (20 °C to 25 °C); store in original container keeping desiccant packet intact
Injection formulation is intended for subcutaneous administration only and requires administration by trained healthcare providers
Do not ingest desiccant packets included in tablet bottles
Packaging includes instructions for proper storage to avoid moisture exposure and maintain efficacy
Injection vials should be stored according to manufacturer guidelines and used within recommended timeframes
Both formulations manufactured and distributed by Gilead Sciences Inc.
Preparation of injection requires aseptic technique for reconstitution and administration
Tablets can be taken with or without food, facilitating flexible dosing
Patient information leaflets provided addressing administration schedules and side effect monitoring
Pharmaceutical excipients in tablets include copovidone, croscarmellose sodium, magnesium stearate, mannitol, microcrystalline cellulose, poloxamer 407, and film coating agents
Injection vehicle includes polyethylene glycol 300 ensuring solubility and biocompatibility
Advise patients on keeping tablets out of reach of children and proper disposal of unused medication
Complete dosing kits include materials specifying injection sites (abdomen or upper thigh) and schedule adherence