Anakinra

Introduction Overview

Generic Name

anakinra

Brand Name

Kineret

Dosage Form

Subcutaneous injection (pre-filled syringe 100 mg/0.67 mL)

Drug Class

Antirheumatics, Interleukin inhibitors

Pharmacokinetics

Absorption: Anakinra, administered via subcutaneous injection, exhibits rapid absorption with peak plasma concentrations typically reached within 3 to 7 hours post-dose. The bioavailability of anakinra following subcutaneous administration is estimated to be approximately 80-95%, reflecting efficient systemic availability from the injection site. Absorption kinetics are not significantly influenced by food intake, making dosing flexible regarding meals. Clinical implications include the need for consistent timing of daily subcutaneous administration to maintain therapeutic plasma levels.

Distribution: The volume of distribution of anakinra approximates the extracellular fluid volume, around 0.1 L/kg, consistent with limited penetration into intracellular compartments. Anakinra shows a moderate degree of plasma protein binding, which is generally low and not expected to cause significant displacement interactions with other highly protein-bound drugs. Due to its nature as a recombinant protein, anakinra does not readily cross the blood-brain barrier and is not extensively distributed into tissues beyond the extracellular compartment.

Metabolism: As a recombinant non-glycosylated form of the human interleukin-1 receptor antagonist, anakinra undergoes proteolytic degradation primarily via proteases to smaller peptides and amino acids. It is not metabolized by cytochrome P450 enzymes, which minimizes potential drug-drug interactions mediated by CYP pathways. The metabolic clearance pathways are systemic proteolysis and receptor-mediated endocytosis, with the latter potentially contributing to its elimination in target tissues.

Elimination: Anakinra is eliminated predominantly by the kidneys through glomerular filtration and subsequent proteolytic degradation in renal tubules. The elimination half-life in healthy adults averages 4 to 6 hours but may be prolonged in patients with moderate to severe renal impairment, necessitating dosage adjustments. Approximately 75% of the administered dose is recovered in urine mainly as metabolites. In patients with creatinine clearance below 30 mL/min, dosing frequency is reduced to every other day to avoid drug accumulation and toxicity. The pharmacokinetic profile supports once-daily subcutaneous dosing in most populations, with careful monitoring in renal impairment.

Dosage Forms

Available Dosage Forms:
Kineret is available as a sterile, preservative-free, clear and colorless solution in pre-filled glass syringes intended for subcutaneous injection. The commercial formulation contains 100 mg anakinra in 0.67 mL of solution per pre-filled syringe. This single-dose prefilled syringe facilitates ease of use and precise dosing.

Dosages for Adults and Adolescents:
- Rheumatoid Arthritis: The usual dose is 100 mg administered subcutaneously once daily, ideally at the same time each day. Injection site rotation is recommended to minimize local injection site reactions.
- Deficiency of Interleukin-1 Receptor Antagonist (DIRA): Initial dosing starts at 1 to 2 mg/kg subcutaneously daily with titration increments of 0.5 to 1 mg/kg, up to a maximum of 8 mg/kg daily based on clinical response.
- COVID-19 Emergency Use Authorization (EUA): 100 mg subcutaneously once daily for 10 days. For patients with severe renal impairment (creatinine clearance <30 mL/min), dosing is adjusted to 100 mg every other day for 5 doses over 10 days.

Specific Patient Populations:
- Pediatrics: For Cryopyrin-Associated Periodic Syndrome (CAPS), including Neonatal-Onset Multisystem Inflammatory Disease (NOMID), and pediatric DIRA patients aged 1 month and older, initial dosing parallels adults at 1 to 2 mg/kg subcutaneously daily, titrated by 0.5 to 1 mg/kg increments, with a maximum of 8 mg/kg daily. Twice daily dosing may be considered in particular clinical scenarios.
- Renal Impairment: Dose adjustment to every other day injection is recommended for patients with severe renal impairment or end-stage renal disease to reduce the risk of accumulation and adverse effects.
- Administration Instructions: Patients should be trained on subcutaneous injection techniques, including site selection (upper arm, abdomen excluding a 2-inch area around the navel, thighs, or buttocks) and site rotation for each injection to reduce injection site reactions.
- Storage: Kineret should be refrigerated (2°C to 8°C, 36°F to 46°F), protected from light, and not frozen. Prefilled syringes should not be shaken and any product exhibiting cloudiness, discoloration, or particulate matter should be discarded.

Mechanism Of Action

Kineret (anakinra) is a recombinant, non-glycosylated homolog of the human interleukin-1 receptor antagonist (IL-1Ra). It exerts its therapeutic effects by competitively binding to the interleukin-1 type I receptor (IL-1RI) without activating the receptor, thereby preventing interleukin-1 alpha (IL-1α) and interleukin-1 beta (IL-1β) from initiating their pro-inflammatory signaling cascades. This blockade interrupts the IL-1 mediated inflammatory response, which is central to the pathophysiology of various autoinflammatory and autoimmune diseases.

At the molecular level, IL-1 is a key cytokine involved in the activation of the nuclear factor kappa B (NF-κB) pathway and mitogen-activated protein kinases (MAPKs), leading to the transcription of multiple inflammatory mediators including cytokines, chemokines, and adhesion molecules. By inhibiting IL-1 receptor activation, anakinra attenuates these downstream signaling pathways, reducing the resultant inflammation, tissue degradation, and joint destruction observed in rheumatoid arthritis and related disorders.

Anakinra’s ability to dampen excessive IL-1 activity is particularly important in genetically mediated diseases such as Neonatal-Onset Multisystem Inflammatory Disease (NOMID) and Deficiency of Interleukin-1 Receptor Antagonist (DIRA), wherein mutations cause aberrant or unregulated IL-1 activity. By restoring the balance between IL-1 and IL-1Ra, Kineret mitigates systemic and organ-specific inflammation, improving clinical outcomes in these rare autoinflammatory syndromes.

Clinically, the blockade of IL-1 with anakinra leads to rapid suppression of fever, reduction in inflammatory markers such as C-reactive protein (CRP) and serum amyloid A (SAA), and improvement of patient-reported symptoms including pain and stiffness. Compared with other biologic agents that target tumor necrosis factor-alpha (TNF-alpha), anakinra provides a distinct mechanism targeting the IL-1 pathway, which may be particularly beneficial in patients refractory to TNF inhibitors. Clinical studies have shown that anakinra’s mechanism of action leads to decreased joint inflammation and structural damage progression in rheumatoid arthritis and control of disease flares in CAPS and DIRA.

Pharmacological Actions

Interleukin-1 receptor antagonist that competitively inhibits IL-1α and IL-1β binding to IL-1 type I receptor.
Suppresses IL-1 mediated pro-inflammatory signaling pathways including NF-κB and MAPK activation.
Reduces the production of inflammatory mediators such as prostaglandins, cytokines (IL-6, TNF-alpha), and chemokines.
Attenuates inflammation and immune-mediated tissue destruction in autoimmune and autoinflammatory diseases.
Modulates immune response by decreasing neutrophil and monocyte recruitment to inflammatory sites.
Slows down joint damage progression by inhibiting IL-1 induced cartilage degradation in rheumatoid arthritis.
Restores balance in dysregulated IL-1 signaling pathways seen in genetic autoinflammatory disorders like NOMID and DIRA.
Exhibits immunosuppressive properties that increase susceptibility to infections due to impaired cytokine signaling.
Has demonstrated clinical efficacy in reducing symptoms and biomarkers of systemic inflammation.
Distinct from TNF inhibitors, provides targeted blockade of IL-1 pathway.
May synergize with disease modifying antirheumatic drugs (DMARDs) for enhanced therapeutic effects.
Reduces fever and acute phase reactants by antagonizing systemic IL-1 activity.
Impacts both innate and adaptive immune system components by altering cytokine milieu.
Decreases fatigue, pain, and stiffness associated with IL-1 driven inflammatory conditions.
Used off-label with emergency use authorization in severe COVID-19 to mitigate cytokine storm-related lung injury.

Therapeutic Or Clinical Uses

Treatment of moderately to severely active rheumatoid arthritis in adults unresponsive to one or more DMARDs.
Management of Neonatal-Onset Multisystem Inflammatory Disease (NOMID), a severe form of cryopyrin-associated periodic syndromes (CAPS).
Treatment of Deficiency of Interleukin-1 Receptor Antagonist (DIRA) in both pediatric and adult patients.
Emergency use authorization for hospitalized adult patients with COVID-19-associated pneumonia at risk for severe respiratory failure.
Reduction of systemic inflammation by blocking IL-1 in rare autoinflammatory and genetic disorders.
Used to slow progression of structural joint damage in rheumatoid arthritis.
Symptom control in patients with refractory rheumatoid arthritis not adequately responding to TNF inhibitors.
Management of inflammatory symptoms such as fever, rash, joint pain, and headache in CAPS.
Off-label use in other autoinflammatory or autoimmune conditions characterized by IL-1 driven inflammation.
Adjuvant therapy with conventional DMARDs to improve patient outcomes in chronic inflammatory arthritis.
Treatment of systemic juvenile idiopathic arthritis in selected clinical scenarios.
Potential investigational use in controlling cytokine release syndrome or hyperinflammatory states.
Alleviation of chronic inflammation-associated organ dysfunction in rare genetic diseases.
Used as part of a comprehensive management plan including immunosuppressants and biologics for autoimmune disorders.
Control of refractory autoinflammatory disease flares and prevention of further tissue injury.

Side Or Adverse Effects

Injection site reactions including redness, bruising, itching, swelling, and stinging.
Increased risk of infections including upper respiratory tract infections, cellulitis, and pneumonia due to immunosuppression.
Common flu-like symptoms such as headache, fever, malaise, and fatigue.
Gastrointestinal disturbances including nausea, vomiting, diarrhea, and abdominal pain.
Rash and other hypersensitivity skin reactions.
Potential for allergic reactions, including anaphylaxis, especially within the first weeks of treatment.
Elevated liver function tests indicating possible hepatotoxicity.
Worsening or flare of arthritis symptoms in some patients.
Low white blood cell counts (neutropenia), increasing infection risk.
Signs and symptoms of tuberculosis activation or reactivation including fever, night sweats, weight loss, and cough.
Rare reports of dizziness and cardiovascular effects such as tachycardia.
Potential development of autoantibodies with long-term use.
Injection site pain or discomfort that may limit patient adherence.
Possible exacerbation of pre-existing infections or delayed infection resolution.
Uncommon but serious hypersensitivity manifested by swelling of face, lips, tongue, or throat requiring immediate medical attention.

Precautions

Assess patient history for active or chronic infections before initiation.
Avoid use in patients with known hypersensitivity to E. coli derived proteins or anakinra.
Monitor white blood cell counts regularly to detect neutropenia early.
Screen for latent tuberculosis before starting treatment due to increased risk of reactivation.
Use cautiously in patients with renal impairment; adjust dose accordingly.
Advise patients to avoid exposure to infectious agents and report signs of infection promptly.
Vaccinations: live vaccines are contraindicated during therapy; schedule vaccinations appropriately.
Pregnancy: benefits versus risks should be carefully assessed due to limited safety data.
Breastfeeding: risk of immunosuppression in nursing infants; consult with healthcare providers.
Avoid concomitant use with other immunosuppressants unless closely monitored.
Consider risk of allergic reactions, especially during the first several weeks of therapy.
Advise patients on proper injection technique and site rotation to minimize local reactions.
Discontinue therapy if serious infections or hypersensitivity reactions occur.
Regular hepatic function monitoring advised due to potential elevated liver enzymes.
Avoid sudden discontinuation; tapering may be necessary in some clinical contexts.

Warnings

Not to be used in patients with active infections or known hypersensitivity to anakinra or E. coli derived proteins.
May increase susceptibility to severe infections including sepsis, bacterial pneumonia, and opportunistic infections.
Patients should be monitored for signs and symptoms of infection during and after treatment.
Immunosuppressive effects may lead to reactivation of latent infections such as tuberculosis.
Use in conjunction with other immunosuppressive agents increases risk of infections significantly.
Do not administer live vaccines during therapy due to risk of vaccine-induced infection.
Careful monitoring required during COVID-19 treatment under EUA to assess for respiratory deterioration.
Adequate laboratory monitoring is essential to detect hematologic abnormalities and liver toxicity.
Potential for severe allergic reactions including anaphylaxis necessitates readiness for emergency treatment.
Not approved for use in children under 18 years with rheumatoid arthritis due to limited safety data.
Discontinue if severe hypersensitivity or serious infections develop.
Injection site reactions are common but generally mild and manageable.
Avoid use in patients with known latex allergy if latex is present in materials used for injection devices.
Pregnancy: potential risks to fetus unknown, but untreated disease may also pose risks; benefits should outweigh risks.
Breastfeeding risk unknown; weigh benefit versus potential for immune suppression in infant.

Contraindication

Known hypersensitivity or allergy to anakinra or any component of the formulation.
Allergy to medicines containing Escherichia coli (E. coli) derived proteins.
Presence of active infection including localized or systemic bacterial, viral, or fungal infections.
Patients receiving live vaccines concurrently.
Use in pediatric patients under 18 years old for rheumatoid arthritis due to lack of approval and safety data.
Severe immunodeficiency states where further immunosuppression is contraindicated.
Known latent or active tuberculosis without adequate treatment.
Sepsis or signs of systemic infection.
History of serious hypersensitivity reactions to biologic agents in the IL-1 antagonist class.
Severe uncontrolled infections such as abscesses or extensive tissue infections.
Pregnancy unless clearly necessary and benefits outweigh potential risks.
Use in combination with other biologic immunomodulators targeting IL-1 pathways unless under specialist supervision.
Cannot be used in patients with known latex allergy if latex is present in needles or syringe components.
Known hypersensitivity to bacterial endotoxins contamination should also contraindicate usage.
Inability to self-administer or lack of support for proper subcutaneous injection technique.

Drug Interactions

Enhanced immunosuppression and increased infection risk when used concomitantly with TNF inhibitors such as adalimumab, etanercept, infliximab, certolizumab, and golimumab.
Caution when combining with systemic corticosteroids due to additive immunosuppressive effects.
Possible interaction with cancer chemotherapy agents that compromise immune function, increasing infection susceptibility.
Concurrent use with other biologic immunomodulators targeting cytokines should be monitored carefully.
No significant cytochrome P450-mediated interactions observed given protein nature and proteolytic metabolism of anakinra.
Potential increased risk of adverse reactions when combined with live vaccines; live vaccines are contraindicated.
No major interactions with common DMARDs such as methotrexate, hydroxychloroquine, or sulfasalazine, but close clinical monitoring advised.
No documented interactions with over-the-counter vitamins or herbal supplements; however, patients should disclose all products taken.
Drugs impacting renal function may alter pharmacokinetics of anakinra in renally impaired patients requiring dose adjustment.
Concomitant use of immunosuppressive drugs requires vigilant infection monitoring and possible dose modifications.
No direct interactions with anticoagulants have been documented, but overall infection risk warrants caution.
Potential pharmacodynamic interactions with agents that modulate inflammatory pathways requiring individualized assessment.
No interactions reported with commonly used analgesics or antipyretics such as acetaminophen or NSAIDs.
Monitoring is advised when switching from other biologics to anakinra due to overlapping immunosuppressive effects.
Certain patient conditions treated with multiple immunosuppressants may increase risk of hematologic toxicity.

Preparations Of The Drug

Kineret is supplied as a sterile, preservative-free solution in a single-use, prefilled glass syringe containing 100 mg anakinra in 0.67 mL volume for subcutaneous injection.
The product is formulated to be clear, colorless, and free of visible particles.
It is recommended to store Kineret refrigerated at 2°C to 8°C (36°F to 46°F) in the original package to protect from light.
The solution must not be shaken to avoid protein denaturation and loss of efficacy.
Once removed from refrigeration, Kineret can be kept at room temperature (up to 25°C) for a limited period (usually up to 8 hours), but should then be discarded if not used.
Discard any unused portions after single use; syringes are intended for one-time administration only.
Syringes are designed with safety features compatible with subcutaneous injection and are accompanied by detailed instructions for use.
No preservatives are present, thus the product must be used immediately after opening to maintain sterility.
Preparation for administration includes visual inspection for discoloration or particulate matter; product should not be used if abnormalities are noted.
Safety disposal guidelines for needles and syringes must be followed, including use of puncture-resistant sharps containers.
Handling instructions recommend avoidance of freezing and exposure to direct heat sources.
Available in cartons with multiple syringes for patient convenience and consistent dosing.
Formulation includes excipients such as sodium citrate, sodium chloride, and polysorbate 80 to stabilize the protein solution.
Each syringe is labeled with dose, lot number, and expiration date for quality assurance.
The formulation is free of latex in the syringe plunger but caution advised if patients have latex allergy due to potential other components.