triamcinolone acetonide extended-release injectable suspension (Rx)

Brand and Other Names:Zilretta
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Dosing & Uses


Dosage Forms & Strengths

injectable, powder for reconstitution

  • 32mg/single-dose vial
  • When reconstituted, forms an extended-release suspension


Indicated for management of osteoarthritis knee pain

32 mg as a single intra-articular injection in the knee

Also see Administration

Dosing Considerations

Not interchangeable with other formulations of injectable triamcinolone acetonide

Not suitable for use in small joints (eg, hand)

Limitations of use: Efficacy and safety of repeat administration have not been demonstrated

Safety and efficacy not established



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            Adverse Effects


            Joint swelling (3%)

            Contusion (2%)

            Sinusitis (2%)

            Cough (2%)

            Contusions (2%)






            Triamcinolone acetonide extended-release injectable suspension is for intra-articular use only, not for IV, IM, SC, intraocular, epidural, intraocular, or intrathecal (IT) use

            Rare instances of anaphylaxis have been reported in individuals receiving triamcinolone acetonide injection, regardless of the route of administration (see Contraindications)

            Intra-articular injection of corticosteroid may be complicated by joint infection; avoid injection into an infected site; intra-articular infection may result in damage to joint tissues

            Intra-articularly injected corticosteroids are systemically absorbed; patients taking corticosteroids are more susceptible to infections than are healthy individuals

            Corticosteroids can produce reversible hypothalamic-pituitary-adrenal axis suppression, potential for adrenal sufficiency after withdrawal of treatment, which may persist for months; institute corticosteroid replacement therapy in situations of stress (eg, stress) during that period

            Corticosteroids may increase blood pressure, salt and water retention, and potassium and calcium excretion; monitor for signs or symptoms (eg, edema, weight gain, and imbalance in serum electrolytes) in congestive heart failure or hypertensive patients

            Corticosteroid may be associated with development or exacerbation of increased intraocular pressure; monitor patients with elevated intraocular pressure for potential treatment adjustment

            Increased risk of gastrointestinal perforation with certain GI disorders (eg, active or latent peptic ulcers, diverticulosis, diverticulitis, ulcerative colitis, fresh intestinal anastomoses)

            Corticosteroids decrease bone formation and increase bone resorption through their effect on calcium regulation and inhibition of osteoblast function

            Risk of behavioral and mood disturbances may be associated with corticosteroid use; advise patients and/or caregivers to immediately report any new or worsening behavior or mood disturbances

            Serious neurologic adverse events with epidural or IT injection

            • Serious neurologic events, some resulting in death, have been reported with epidural or IT injection
            • Specific events reported include, but are not limited to, spinal cord infarction, paraplegia, quadriplegia, cortical blindness, and stroke
            • These serious neurologic events have been reported with and without use of fluoroscopy
            • Safety and effectiveness of epidural administration of corticosteroids have not been established, and corticosteroids are not approved for this use

            Drug interaction overview

            • Aminoglutethimide may lead to a loss of corticosteroid-induced adrenal suppression
            • Concomitant with potassium-depleting agents (ie, amphotericin B, diuretics), observe for development of hypokalemia
            • Cases reported in which concomitant use of amphotericin B and hydrocortisone was followed by cardiac enlargement and congestive heart failure
            • Macrolide antibiotics have been reported to cause a significant decrease in corticosteroid clearance
            • Concomitant use of anticholinesterase agents and corticosteroids may produce severe weakness in patients with myasthenia gravis; if possible, withdraw anticholinesterase agents at least 24 hours before initiating corticosteroid therapy
            • Coadministration of corticosteroids and warfarin usually results in inhibition of response to warfarin; monitor INR
            • Corticosteroids may increase blood glucose concentrations, dosage adjustments of antidiabetic agents may be required
            • Corticosteroids may decrease isoniazid serum concentrations
            • Cholestyramine may increase corticosteroid clearance
            • Increased activity of both cyclosporine and corticosteroids may occur when the 2 are used concurrently; convulsions have been reported with this concurrent use
            • Estrogens may decrease the hepatic metabolism of certain corticosteroids, thereby increasing their effect
            • Patients on digitalis glycosides may be at increased risk of arrhythmias due to hypokalemia
            • Corticosteroids may suppress reactions to allergy related skin tests
            • Aspirin and NSAIDs
              • Coadministration of aspirin (or other NSAIDs) and corticosteroids increases risk of gastrointestinal side effects Use this combination cautiously in hypoprothrombinemia
              • Salicylate clearance may be increased if coadministered with corticosteroids
            • CYP3A4 inducers/inhibitors
              • Concomitant use with CYP3A4 inducers may enhance the metabolism of corticosteroids and may require an increase in the corticosteroid dose
              • Ketoconazole, a strong CYP3A4 inhibitor, has been reported to decrease the metabolism of certain corticosteroids by up to 60% leading to an increased risk of corticosteroid side effects


            • Prolonged corticosteroid therapy may cause a diminished response to toxoids, live, or inactivated vaccines due to inhibition of antibody response; possibly potentiate the replication of some organisms contained in live attenuated vaccines
            • If possible, defer routine administration of vaccines or toxoids until corticosteroid therapy is discontinued

            Pregnancy & Lactation


            There are no data regarding the use in pregnant women to inform a drug associated risk of adverse developmental outcomes

            In animal reproductive studies from published literature, pregnant mice, rats, rabbits, or primates administered triamcinolone acetonide during organogenesis period at doses that produced exposures less than the maximum recommended human dose (MRHD) caused resorptions, decreased fetal body weight, craniofacial and/or other abnormalities such as omphalocele

            Corticosteroids may result in menstrual pattern irregularities (eg, deviations in timing, duration of menses, increased/decreased blood loss)


            There are no available data on the presence of triamcinolone acetonide in either human or animal milk, the effects on the breastfed infant, or the effects on milk production

            Corticosteroids have been detected in human milk and may suppress milk production

            Caution should be exercised when corticosteroids are administered to breastfeeding women

            Pregnancy Categories

            A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA: Information not available.



            Mechanism of Action

            Corticosteroid with anti-inflammatory and immunomodulating properties; it binds to and activates the glucocorticoid receptor, leading to activation of anti-inflammatory transcription factors (eg, lipocortins); it also inhibits inflammatory transduction pathways by blocking arachidonic acid release and preventing prostaglandin and leukotriene synthesis


            Peak plasma time: 7 hr

            Peak plasma concentration: 1143.7 pg/mL

            AUC: 21,219.2 pg·h/mL (0-24 hr); 842,149.2 pg·h/mL (0-inf hr)


            Half-life: 633.9 hr



            Intra-articular Preparation

            Tap vial firmly on a padded surface to loosen up powder

            Visually inspect vial to ensure powder is properly dislodged

            Gently push vial adapter down onto powder vial until the adapter will snap into place

            Withdraw 5 mL of supplied diluent with syringe and needle

            Remove plastic holder from vial; remove needle from syringe containing diluent

            Attach syringe onto vial adapter by pushing down and turning clockwise

            Slowly and completely push down the plunger; slowly pull back on plunder to the 5 mL mark

            Mix diluent and powder; tap bottom edge of the vial repeatedly and firmly

            Swirl gently every five or six taps; tap for at least 1 minute until all powder is completely dispersed

            Avoid vigorous shaking of the vial to minimize foaming

            Inspect vial to ensure a uniform suspension has been achieved; properly mixed suspensions appear milky white, contain no clumps, and move freely down the vial wall

            Intra-articular Administration

            Intra-articular use only

            Administered via a single dose device

            Swirl the vial gently for at least 10 seconds to ensure the powder is fully suspended

            Promptly inject after preparation to avoid settling of the suspension

            If needed, the suspension can be stored in the vial for up to 4 hr at ambient conditions; gently swirl the vial to resuspend any of the settled microspheres prior to preparing the syringe for injection

            Withdraw the full contents from vial into the syringe

            Do not reuse

            Discard any excess suspension in the vial immediately after the injection


            Unopened kit

            • Store refrigerated 36-46°F (2-8°C)
            • Do not freeze
            • If refrigeration is unavailable, may store at temperatures not exceeding 77°F (25°C) for up to 6 weeks and then discard
            • Do not expose the single-dose kits to temperatures above 77°F (25°C)

            Diluted suspension

            • If needed, may store in the vial for up to 4 hr at ambient conditions




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            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.