Tocilizumab - Uses, Mechanism of Action, Precautions, and Side Effects

Overview:

Tocilizumab functions as a blocker against interleukin-6 receptors to treat different autoimmune diseases. The Food and Drug Association authorized Tocilizumab for market release on January 8th, 2010. Tocilizumab received European Commission approval in December 2021 before Health Canada authorized its use in October 2022 to treat COVID-19 in patients receiving systemic corticosteroids and ventilation therapy.

How Does Tocilizumab Work?

Tocilizumab binds to the soluble and membrane-bound interleukin-6 (IL-6) receptors. It inhibits sIL-6R and mIL-6R-mediated signaling. IL-6 is a pro-inflammatory cytokine produced by T and B cells, monocytes, and fibroblasts. IL-6 is involved in the pathogenesis of inflammatory diseases, osteoporosis, and neoplasia.

Uses of Tocilizumab:

• Rheumatoid arthritis.

• Giant cell arteritis.

• Polyarticular juvenile idiopathic arthritis.

• Systemic juvenile idiopathic arthritis.

• Cytokine release syndrome.

Dosage Restrictions:

1. Route of Administration

Intravenous infusion or subcutaneous injection.

2. Dosage Strengths

Intravenous Infusion: 80 mg/4 mL, 200 mg/10 mL, 400 mg/20 mL.

Subcutaneous Injection: 162 mg/0.9 mL.

3. Dosage Forms

Tocilizumab is a sterile, clear, colorless to pale yellow solution in 20 mg/mL single-dose vials.

Special Considerations:

• Pregnancy-Through placental transfer, Tocilizumab affects the immune response of infants. IL-6 signaling inhibition disrupts cervical dilatation functions and myometrial contractile activities which causes delays in the process of birth. The pregnancy exposure registry monitors health results for female patients who take Tocilizumab during their pregnancy.

• Fetal or Neonatal- During pregnancy, the placenta transports monoclonal antibodies to the fetus and reaches its highest concentration in the last trimester.

• Breastfeeding -Current research does not show if Tocilizumab appears in breast milk. The choice between breastfeeding and Tocilizumab administration should consider both maternal drug benefits and infant feeding advantages.

• Renal Impairment -A minor degree of kidney damage fails to modify the drug absorption patterns of Tocilizumab. Tocilizumab treatment does not require dosage adjustments for people having mild to moderate renal impairment.

• Pediatric -Doctors have not established the safety level of Tocilizumab for children younger than two years old.

• Elderly -Since the elderly do not need dosing adjustment beyond age 65 they can use the standard prescription.

Warnings and Contraindications:

Tocilizumab is contraindicated in patients with hypersensitivity to the medication.

Warnings and Precautions:

1. Infections

Fatal infections such as bacterial, mycobacterial, fungal, viral, protozoal, or other pathogens have been found in individuals treated with Tocilizumab. The typical serious infections caused by the drug include pneumonia, urinary tract infections, cellulitis, herpes zoster, gastroenteritis, diverticulitis, sepsis, and bacterial arthritis. In addition, opportunistic infections include tuberculosis, cryptococcus, aspergillosis, candidiasis, and pneumocytosis.

2. Gastrointestinal Perforations

In individuals treated with Tocilizumab, gastrointestinal perforations have been reported in certain clinical trials.

3. Neutropenia

Tocilizumab has been associated with increased neutropenia during treatment.

4. Thrombocytopenia

Tocilizumab has been associated with a decrease in the platelet count.

5. Elevated Liver Enzymes

Treatment with Tocilizumab has been associated with increased levels of transaminase, a liver enzyme.

6. Immunosuppression

Tocilizumab has been found to suppress immunity, which might increase the risk of developing certain malignancies.

7. Demyelinating Disorders

The impact of treatment with Tocilizumab on demyelinating disorders is not known, but cases of multiple sclerosis and chronic inflammatory demyelinating polyneuropathy were rarely reported.

8. Active Hepatic Disease and Hepatic Impairment

Treatment with Tocilizumab is not recommended in patients with active hepatic disease or hepatic impairment.

9. Vaccinations

Live vaccines should be avoided concurrently with Tocilizumab as no clinical safety has been established. Data on the effectiveness of vaccination in patients receiving Tocilizumab is not available. It is recommended that all patients, particularly children or the elderly, should be brought with all immunizations in agreement with current immunization guidelines before initiating Tocilizumab therapy.

For Patients:

Why Is Tocilizumab Prescribed?

• Tocilizumab treats autoimmune rheumatoid arthritis by stopping the body from attacking joint tissue which leads to pain along with swelling and functional impairment. Treatment with Tocilizumab injection helps manage inflammation of rheumatoid arthritis patients to enhance their symptoms.

• Giant Cell Arteritis develops as a disease that primarily affects blood vessel swelling across the scalp and head tissue in adults. The therapeutic use of Tocilizumab injection occurs when it decreases inflammation levels in blood vessels to treat this medical condition effectively.

• Systemic Sclerosis-associated Interstitial Lung Disease refers to the lung condition that results in lung scarring also known as scleroderma-associated interstitial lung disease. Healthcare providers sometimes give Tocilizumab administration as a treatment method for controlling lung inflammation.

• Polyarticular Juvenile Idiopathic Arthritis develops when five or more joints become inflamed and swollen among children who are at least two years old leading to the loss of function and experiencing pain in each joint. The medical establishment approved Tocilizumab injection treatment for juvenile patients experiencing inflammatory conditions and disabilities of their joints.

• Systemic Juvenile Idiopathic Arthritis causes broad body area inflammation along with fever and joint inflammation and swelling and growth delay in children older than two years. Patients use Tocilizumab injection to control symptoms and decrease inflammatory response.

• The medication Tocilizumab creates a danger to patients' lives by inducing Cytokine Release Syndrome among adults as well as children older than two who receive immunotherapy. Tocilizumab injection serves as a treatment for cytokine release syndrome by decreasing elevated levels of cytokines.

How Should One Take Tocilizumab?

• Tocilizumab comes as a sterile solution for intravenous or subcutaneous injection. It works by inhibiting interleukin-6 (IL-6) receptors, which are involved in the inflammatory process, reducing inflammation associated with various autoimmune conditions. This action is known as the Tocilizumab mechanism of action.

• For rheumatoid arthritis, it is given intravenously once every four weeks or subcutaneously once every week or alternate weeks.

• For polyarticular juvenile idiopathic arthritis, it is given intravenously once every four weeks or subcutaneously once every two to three weeks.

• To treat giant cell arteritis, it is usually given subcutaneously once every four weeks.

• It is given subcutaneously once a week for systemic sclerosis-associated interstitial lung disease.

• To treat systemic juvenile idiopathic arthritis, it is given intravenously once every two weeks or subcutaneously weekly once.

• The first dose of subcutaneous injection is received at the doctor's clinic.

• The injection needs to be brought to room temperature before injecting.

• The drug can be injected in the front of the thighs or stomach except for the naval area two inches around it.

• Do not inject the medication into the skin with bruises, scars, pain, scars, moles, or injury.

• Do not reuse the prefilled syringes, and do not recap the syringes after use.

What Should One Discuss With the Doctor Before Beginning Tocilizumab?

• The doctor needs to be notified about any allergic reactions to Tocilizumab and other medications, along with injection ingredients.

• Tocilizumab treatment requires notification to the doctor about all medications including prescribed and buy-over-the-counter drugs and vitamins and nutritional supplements and herbal products.

• Providing information to the doctor regarding cancer as well as diverticulitis, stomach or intestinal ulcers, high cholesterol, or any nervous system conditions, especially multiple sclerosis, chronic inflammatory demyelinating polyneuropathy, or liver disease, is essential.

• A person should notify their doctor about pregnancy status, future pregnancy plans and current breastfeeding status.

• A person should notify their doctor about receiving Tocilizumab intravenous injection before performing any surgical procedure, including tooth-related procedures.

• Prior to the administration of Tocilizumab treatment, the doctor needs to determine safe vaccination eligibility.

Is Tocilizumab Safe?

Tocilizumab might increase the risk of getting certain cancers or infections. Therefore, a proper discussion should be done with the doctor before starting the therapy.

Is Tocilizumab Effective?

Tocilizumab injection might control the symptoms but will not cure them. Therefore, the doctor will monitor the drug's efficacy by adjusting the dosage.

Can One Stop Taking Tocilizumab Without the Doctor's Approval?

Do not stop taking the injection without the doctor's approval.

Are There Any Dietary Restrictions to Consider When Taking Tocilizumab?

Continue with the regular diet unless the doctor recommends otherwise.

How Should One Store Tocilizumab?

The medication should be stored away from light, closed tightly, and out of children's reach. The injection should be stored in the refrigerator. The prefilled syringes should be kept dry.

How Should One Dispose of Tocilizumab?

• The unused medications should be disposed of so that pets, kids, and others cannot take them.

• The injection should not be flushed down the toilet.

• The medicine take-back program should be utilized to dispose of the vials.

What To Do in Case of Overdose?

In case of an overdose, the poison control team or emergency services should be contacted if the person collapses, has a seizure, or has trouble waking up.

For Doctors:

Indications

Tocilizumab is indicated in the following:

• Rheumatoid arthritis.

• Giant cell arteritis.

• Polyarticular juvenile idiopathic arthritis.

• Systemic juvenile idiopathic arthritis.

• Cytokine release syndrome.

What Is the Pharmacology of Tocilizumab?

Description

Tocilizumab exists as a recombinant anti-human interleukin 6 (IL-6) receptor monoclonal antibody that belongs to the immunoglobulin IgG1k (gamma 1, kappa) subclass with typical H2L2 polypeptide structure. All chains of light and heavy class lengths amount to 214 and 448 amino acids. The four polypeptide chains establish both inter and intra-chain bonding connections.

Before intravenous infusion, the intravenous Tocilizumab solution requires preparation to achieve a concentration of 20 mg/mL. It comes as a sterile preservative-free solution. Tocilizumab appears as a yellowish liquid that is clear and colorless at a pH level of 6.5.

Each prefilled subcutaneous Tocilizumab injection syringe contains 6.0 pH neutralized, clear, yellowish, and colorless preservative-free liquid solution. The intravenous Tocilizumab injection comes in 1 mL solution packed in a single-use prefilled syringe (PFS) with a connected needle safety device. The intravenous delivery of Tocilizumab comes in single-use vials with three available quantities consisting of 80 mg/ 4 mL, 200 mg/ 10 mL, or 400 mg/ 20 mL.

Components

1. Active Ingredients

• Tocilizumab.

2. Inactive Ingredients

Intravenous Injection:

• Sucrose.

• Polysorbate 80.

• Disodium phosphate dodecahydrate.

• Sodium dihydrogen phosphate dihydrate.

Subcutaneous Injection:

• L-arginine.

• L-arginine hydrochloride.

• L-methionine.

• L-histidine.

• L-histidine hydrochloride monohydrate.

Clinical Pharmacology:

Mechanism of Action

The medication Tocilizumab adheres to IL-6 (interleukin 6) receptors (sIL-6R and mIL-6R), which are soluble and membrane-bound, preventing IL-6-mediated signaling through these receptors. Different cell types, including T- and B-cells, lymphocytes, monocytes, and fibroblasts, generate the pleiotropic pro-inflammatory cytokine known as interleukin 6. IL-6 performs essential physiological roles, which include T-cell activation as well as immunoglobulin secretion stimulation and hepatic acute phase protein production, and promotes both hematopoietic precursor cell proliferation and differentiation. There is IL-6 production by synovial and endothelial cells, which generates IL-6 release within the joints of rheumatoid arthritis patients.

Pharmacodynamics

Pharmacodynamic changes such as a decrease in rheumatoid factor, erythrocyte sedimentation rate (ESR), serum amyloid A, and an increase in hemoglobin have been observed with doses of 4 mg per kg and 8 mg per kg IV doses or 162 mg weekly dosage.

Pharmacodynamic changes also occurred after Tocilizumab administration, leading to a decrease in CRP, ESR, and hemoglobin levels. In healthy individuals, administering 2 to 28 mg per kg intravenously and 81 to 162 mg subcutaneously, the neutrophil counts decreased in 3 to 5 days, but the neutrophils recovered towards the baseline. The relationship between these pharmacodynamic findings and clinical efficiencies has yet to be discovered.

Pharmacokinetics

• Mean Cmax - For 4 mg of Tocilizumab per kg, given every four weeks, the Cmax was 88+_41.4 mcg per mL.

• Median Tmax - 2.8 days after Tocilizumab was administered every week and 4.7 days after Tocilizumab was administered every other week.

[Cmax- Maximum concentration achieved by a drug in the blood, cerebrospinal fluid, or target organ after administration of a dose]

[Tmax- Time taken for a drug to reach maximum concentration after administration of a dose]

• Pharmacokinetic Changes

The pharmacokinetic parameters of Tocilizumab did not change with time. However, a dose-proportional increase in the AUC (area under the curve) and Cmin were observed for 4 and 8 mg/kg doses every four weeks.

A. Distribution:

• Steady-state Plasma Levels - 6.4 liters.

• Time to Approach Steady-state Levels - 10 to 12 weeks.

B. Metabolism

Tocilizumab is metabolized to smaller proteins and amino acids by proteolytic enzymes.

C. Elimination

Tocilizumab, after intravenous administration, gets removed from the circulation in two ways, one through a linear clearance and the other through a concentration-dependent clearance. In rheumatoid arthritis patients, the linear clearance is 9.5 mL/h. At high Tocilizumab concentration, the non-linear clearance pathway is saturated. Therefore, clearance is mainly determined by linear clearance. In rheumatoid arthritis patients, the half-life of Tocilizumab is concentration-dependent. At a steady state following a dose of 8 mg/kg every four weeks, the half-life decreased with decreasing concentrations with dose intervals from 18 days to 6 days.

Special Considerations:

• Research about Tocilizumab's impact on people with hepatic impairment failed to take place.

• The drug concentration of Tocilizumab remains unaffected by mild renal impairment in patients. People who have mild to moderate renal impairment do not need dosage adjustment of Tocilizumab.

• The placenta transports Tocilizumab monoclonal antibodies and other similar drugs into the third trimester of pregnancy, leading to possible changes in infant immune responses. The blockade of IL-6 signaling routes into delayed parturition because it affects both cervical dilatation and myometrial contractility. The pregnancy exposure registry tracks the health results generated from Tocilizumab exposure during pregnancy.

• The largest quantity of placenta-transported monoclonal antibodies occurs during the third trimester of pregnancy, followed by the time period from delivery through birth.

• Medical research has not determined if Tocilizumab appears in breast milk. When using Tocilizumab therapy mothers need to weigh whether the medicine benefits her more than the value of breastfeeding their child to decide if they should breastfeed or keep taking the drug.

Drug Interactions:

• Acetaminophen - The metabolism of Acetaminophen is increased when combined with Tocilizumab.

• Acyclovir - The metabolism of Acyclovir can be expanded when combined with Tocilizumab.

• Alprazolam - The metabolism of Alprazolam is increased in combination with Tocilizumab.

What Have Clinical Trials Shown Concerning Tocilizumab?

The efficacy and safety of intravenous administration of Tocilizumab in rheumatoid administration were obtained in five randomized, double-blind, multicenter studies in adult patients. Patients had at least eight tender and six swollen joints at baseline. Tocilizumab was given intravenously every four weeks as monotherapy (study I), in combination with methotrexate (studies II and III) or other disease-modifying anti-rheumatic drugs (study IV) in patients with an inadequate response to such drugs, or together with Methotrexate in individuals with an insufficient response to TNF (tumor necrosis factor) antagonists (study V).

Study I assessed patients with moderate to severe rheumatoid arthritis not treated with methotrexate within 24 weeks before randomization or who continued with previous methotrexate treatment due to clinically significant toxic effects or lack of response. The people received 8 mg per kg monotherapy or methotrexate alone. In this study, 67 % of patients were methotrexate-naive, and over 40 % had rheumatoid arthritis in less than two years.

Primary Endpoint - The proportion of Tocilizumab patients who achieved an ACR 20 response in the 24th week.

Study II was a 104-week study with an optional 156-week extension phase that accessed patients with moderate to severely active rheumatoid arthritis who had an inadequate response to methotrexate. Patients received Tocilizumab 8 mg per kg, 4 mg per kg, or placebo every four weeks, combined with methotrexate (10 to 25 mg weekly). Upon completion of 52 weeks, patients received open-label treatment with Tocilizumab 8 mg per kg through 104 weeks or could continue their double-blind treatment if there was an improvement more significant than 70 % in swollen or tender joints. Two pre-specified analyses at week 24 and week 52 were conducted.

Primary Endpoint - It was achieved in the 24th week and was the proportion of patients who achieved an ACR 20 response. At the 52nd and 104th weeks, the primary endpoints were changed from the baseline in the modified total Sharp-Genant score and the area under the curve of the change from the baseline in the HAQ-DI score.

Results

Patients treated with Tocilizumab reported an improvement in all the patient-reported outcomes.

Patient Counseling Information:

• The patient should be advised to read the FDA (Food and Drug Administration)-approved patient labeling.

• The patient and guardians of minors with PJIA, SJIA, or CRS should be warned of Tocilizumab's potential benefits and risks.

• The patients should be informed that Tocilizumab may lower their resistance to infections.

• The patient should contact their doctor immediately when infection symptoms appear to get a rapid evaluation and prompt treatment.

• The patients should be informed that some treatments with Tocilizumab have had complication effects on the stomach and intestines. Therefore, patients should be advised to contact their physician immediately to get appropriate treatment when severe, persistent abdominal pain symptoms appear.

• The patient should be informed of developing serious allergic reactions, including anaphylaxis, with Tocilizumab administration. They should get immediate medical help when they experience serious allergic reactions.

Administration Instructions:

1. Tocilizumab is available as a sterile solution for intravenous or subcutaneous injection.

2. Injection Technique

• The first injection should be given under the supervision of a qualified healthcare administrator. If a patient or caregiver is to give subcutaneous Tocilizumab, instruct them about the injection techniques and evaluate their ability to inject the drug subcutaneously to ensure proper administration.

• The patients or caregivers should be thoroughly instructed about the technique, proper syringe and needle disposal, and cautioned against reusing such items. Before use, the prefilled syringe should be removed from the refrigerator and allowed to come at room temperature for 30 minutes, out of the reach of children. A puncture-resistant container for needles and syringes disposal should be used and kept out of the reach of children.

Complications or Side Effects

Tocilizumab side-effects include the following:

• Injection site reactions.

• Upper respiratory tract infections.

• Nasopharyngitis.

• Constipation.

• Headache.

• Bronchitis.

• Rashes.

• Dizziness.

• Ulcers in the mouth.

• Pain in the upper abdominal area.

• Gastritis.

• Stomatitis.

• Increase in weight.

• Increase in the total bilirubin.

• Leukopenia.

• Edema in the peripheries.

• Cough.

• Dyspnea.

• Conjunctivitis.

• Anaphylaxis.

• Stevens-Johnson syndrome.

• Pancreatitis.

• Hepatitis or jaundice.