1. ID DB06273
TOCILIZUMAB

2. DESCRIPTION
Tocilizumab is a recombinant, humanized, anti-human interleukin 6 (IL-6) receptor monoclonal antibody that achieves a significant therapeutic response rate. The light chain is made up of 214 amino acids. The heavy chain is made up of 448 amino acids. The four polypeptide chains are linked intra- and inter-molecularly by disulfide bonds. FDA approved on January 8, 2010.
INDICATION
Indicated for the treatment of adult patients with moderately to severely active rheumatoid arthritis (RA) who have had an inadequate response to one or more Disease-Modifying Anti-Rheumatic Drugs (DMARDs). It is also indicated for the treatment of active polyarticular juvenile idiopathic arthritis (PJIA) and active systemic juvenile idiopathic arthritis (SJIA) in patients 2 years of age and older.
TOXICITY
Most common adverse reactions (incidence of at least 5%): upper respiratory tract infections, nasopharyngitis, headache, hypertension, increased ALT.

3. PHARMACODYNAMICS
A decrease in C-reactive protein (CRP) was noted as early as week 2. Changes in pharmacodynamic parameters were observed (i.e., decreases in rheumatoid factor, erythrocyte sedimentation rate (ESR), serum amyloid A and increases in hemoglobin) with both doses, however the greatest improvements were observed with 8 mg per kg tocilizumab. Similar pharmacodynamic changes were also observed in active polyarticular juvenile idiopathic arthritis and active systemic juvenile idiopathic arthritis patients.
MECHANISM OF ACTION
Interleukin (IL)-6 plays essential roles not only in the immune response, but also in haematopoiesis and the central nervous system. Deregulated production of IL-6 has been found in chronic inflammatory autoimmune diseases, such as rheumatoid arthritis (RA), systemic onset juvenile idiopathic arthritis (soJIA), Crohn's disease (CD) and systemic lupus erythematosus (SLE). Furthermore, IL-6 activities can explain many symptoms of these diseases. More importantly, serum levels of IL-6 are correlated with disease activity. Tocilizumab binds specifically to both soluble and membrane-bound IL-6 receptors (sIL-6R and mIL-6R), and has been shown to inhibit IL-6-mediated signaling through these receptors.

4. ABSORPTION
When 4 mg/kg of tocilizumab was given every 4 weeks to RA patients, the pharmacokinetic parameters at steady state are as follows: AUC = ± 5800 mcg∙h/mL; Cmax = 88.3 ± 41.4 mcg/mL. Tocilizumab accumulates following repeated doses. Furthermore, an increased body weight may increase plasma levels of tocilizumab. When a dose of 8 mg/kg of tocilizumab is given to PJIA patients, the pharmacokinetic parameters are as follows: AUC = ± 8660 mcg∙h/mL; Cmax = 182 ± 37 mcg/mL. When a dose of 8 mg/kg of tocilizumab is given to SJIA patients, the pharmacokinetic parameters are as follows: AUC = ± 9960 mcg∙h/mL; Cmax = 245 ± 57.2 mcg/mL.
HALF-LIFE
The half-life of tocilizumab is concentration-dependent. The concentration-dependent apparent half-life is up to 11 days for 4 mg/kg and up to 13 days for 8 mg/kg every 4 weeks in patients with RA at steady-state. The half-life in children with PJIA is up to 16 days. The half-life in pediatric patients with SJIA is up to 23 days.
ROUTE OF ELIMINATION
Following intravenous dosing, tocilizumab undergoes biphasic elimination from the circulation.

5. VOLUME OF DISTRIBUTION = In rheumatoid arthritis patients the central volume of distribution was 3.5 L and the peripheral volume of distribution was 2.9 L, resulting in a volume of distribution at steady state of 6.4 L.In pediatric patients with PJIA, the central volume of distribution was 1.98 L, the peripheral volume of distribution was 2.1 L, resulting in a volume of distribution at steady state of 4.08 L.In pediatric patients with SJIA, the central volume of distribution was 0.94 L, the peripheral volume of distribution was 1.60 L resulting in a volume of distribution at steady state of 2.54 L.
CLEARANCE = The clearance of tocilizumab decreases with increasing dose. At the 10 mg/kg single dose in RA patients, mean clearance was 0.29 ± 0.10 mL/hr/kg. The total clearance of tocilizumab is concentration-dependent and is the sum of the linear clearance and the nonlinear clearance. At low concentrations, concentration-dependent nonlinear clearance is dominant. At high concentrations, linear clearance dominates. The estimated linear clearances for specific patient populations are as follows:RA = 12.5 mL/h;PJIA, pediatric patients = 5.8 mL/h;SJIA, pediatric patients = 7.1 mL/h.
PATENT
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6. Interleukin-6 receptor subunit alpha
DRUG INTERACTION
<drugbank-id>DB00514</drugbank-id> <name>Dextromethorphan</name> <description>Dextromethorphan is a CYP2D6 and CYP3A4 substrate. Exposure of dextromethorphan decreases following administration of tocilizumab.</description> <drugbank-id>DB06674</drugbank-id> <name>golimumab</name> <description>Avoid combination due to the enhanced immunosuppression by TNF blockers. </description> <drugbank-id>DB00338</drugbank-id> <name>Omeprazole</name> <description>Omeprazole is a CYP2C19 and CYP3A4 substrate. Exposure of omeprazole decreases following administration of tocilizumab.. </description> <drugbank-id>DB06372</drugbank-id> <name>Rilonacept</name> <description>results in increased immunosuppressive effects; increases the risk of infection. </description> <drugbank-id>DB00641</drugbank-id> <name>Simvastatin</name> <description>Simvastatin is a CYP3A4 and OATP1B1 substrate. Exposure of simvastatin decreases following administration of tocilizumab. </description> <drugbank-id>DB08895</drugbank-id> <name>Tofacitinib</name> <description>Avoid combination due to the potential increase in tofacitinib related adverse effects.</description>
TARGETS
Interleukin-6 receptor subunit alpha

7. Tocilizumab AKA Actemra
IV and SC
ACTEMRA (tocilizumab) is a recombinant humanized anti-human interleukin 6 (IL-6) receptor monoclonal antibody of the immunoglobulin IgG1κ (gamma 1, kappa) subclass with a typical H2L2 polypeptide structure. Each light chain and heavy chain consists of 214 and 448 amino acids, respectively. The four polypeptide chains are linked intra- and inter-molecularly by disulfide bonds. ACTEMRA has a molecular weight of approximately 148 kDa.
DOSAGE:
Recommended IV Dosage Regimen:
Starting dose: 4 mg/kg given once every 4 weeks as a 60-minute single intravenous drip infusion, followed by an increase to 8 mg/kg based on clinical response
Doses exceeding 800 mg per infusion are not recommended.
Recommended Subcutaneous Dosage Regimen:
Patients less than 100 kg: 162 mg subcutaneously every other week, followed by an increase to every week based on clinical response.
Patients 100 kg or greater: 162 mg administered subcutaneously every week.

8. VIAL:
ACTEMRA is supplied as a sterile, preservative-free solution for intravenous (IV) infusion at a concentration of 20 mg per mL. ACTEMRA is a colorless to pale yellow liquid, with a pH of about 6.5. Single-use vials are available for intravenous administration containing 80 mg per 4 mL, 200 mg per 10 mL, or 400 mg per 20 mL of ACTEMRA. Injectable solutions of ACTEMRA are formulated in an aqueous solution containing disodium phosphate dodecahydrate and sodium dihydrogen phosphate dehydrate (as a 15 mmol per L phosphate buffer), polysorbate 80 (0.5 mg per mL), and sucrose (50 mg per mL).
HALF-LIFE: 151 ± 59 hours (6.3 days)
CLEARANCE: 0.29 ± 0.10 mL per hr per kg

9. ADVERSE REACTION:
Fever, flu symptoms, mouth and throat ulcers, weight loss, feeling very tired;
sores in your mouth and throat or on your skin;
easy bruising, unusual bleeding (nose, mouth, vagina, or rectum);
purple or red pinpoint spots under your skin;
cough with yellow or green mucus, stabbing chest pain, feeling short of breath;
pain or burning when you urinate.
DRUG INTERACTION:
Live Vaccines and CYP450 Substrates