Patisiran (Monograph)

Brand name: Onpattro
Drug class: Other Miscellaneous Therapeutic Agents
- Small Interfering Ribonucleic Acids (siRNAs)
- Small Interfering RNAs (siRNAs)
Chemical name: RNA (A-U-G-G-A-A-Um-A-C-U-C-U-U-G-G-U-Um-A-C-dT-dT), complex with RNA (G-Um-A-A-Cm-Cm-A-A-G-A-G-Um-A-Um-Um-Cm-Cm-A-Um-dT-dT) (1:1)
Molecular formula: C₄₁₂H₄₈₀N₁₄₈Na₄₀O₂₉₀P₄₀
CAS number: 1420706-45-1

Medically reviewed by Drugs.com on Jul 15, 2024. Written by ASHP.

Introduction

Small interfering RNA (siRNA) that targets transthyretin mRNA; a transthyretin (TTR) silencer.

Uses for Patisiran

Hereditary Transthyretin-mediated Amyloidosis

Treatment of polyneuropathy in patients with hereditary transthyretin-mediated amyloidosis (designated an orphan drug by FDA for this use).

Transthyretin-mediated amyloidosis (ATTR) can be inherited as an autosomal dominant trait caused by pathogenic variants/mutations in the TTR gene (ATTRv) or by deposition of wild-type TTR protein (ATTRwt). Selection of an appropriate disease-modifying therapy in patients with ATTR is based on the presence of cardiomyopathy and polyneuropathy and the distinction between ATTRv and ATTRwt amyloidosis.

The American Heart Association (AHA) states that TTR silencing therapy with patisiran or inotersen may be considered in patients with ATTRv and polyneuropathy; these drugs are currently not indicated for ATTRv-cardiomyopathy without polyneuropathy or in patients with ATTRwt-cardiomyopathy. In patients with ATTRv-cardiomyopathy with polyneuropathy, the choice between inotersen and patisiran is based on availability and adverse effect profiles.

Patisiran Dosage and Administration

General

Patient Monitoring

Monitor patients during patisiran infusion and, if clinically indicated, after the infusion, for signs and symptoms of infusion-related reactions.

Premedication and Prophylaxis

To reduce the risk of infusion-related reactions, the manufacturer recommends a premedication regimen consisting of an IV corticosteroid (e.g., dexamethasone phosphate 10 mg or equivalent), oral acetaminophen (500 mg), an IV histamine H₁-receptor antagonist (diphenhydramine hydrochloride 50 mg or equivalent), and an IV H₂-receptor antagonist (e.g., ranitidine 50 mg or equivalent).
Administer premedications at least 60 minutes prior to the start of infusion.
Some patients may require additional or higher doses of one or more of the premedications in order to reduce the risk of infusion-related reactions.
If IV preparations are unavailable or not tolerated, equivalent oral doses may be used.
For patients who are tolerating the patisiran infusion, but are experiencing adverse effects related to corticosteroid premedication, dosage of the corticosteroid may be reduced by 2.5-mg increments to a minimum IV dexamethasone phosphate dose of 5 mg or equivalent.

Dispensing and Administration Precautions

Patisiran sodium lipid complex should be prepared and administered by a healthcare professional.

Administration

IV Administration

For solution and drug compatibility information, see Compatibility under Stability.

Administer by IV infusion using an ambulatory infusion pump.

Do not mix or dilute with other IV drugs.

Infuse only through a free-flowing dedicated IV line with an infusion set containing an inline polyethersulfone filter (pore size of 1.2 µm). The IV line and infusion set should be free of diethylhexylphthalate (DEHP).

Flush IV line with 0.9% sodium chloride injection after infusion.

Dilution

Must filter and dilute commercially available patisiran sodium lipid complex injection concentrate prior to IV infusion.

Determine number of vials needed based on patient's body weight and recommended dosage. Remove vial(s) from the refrigerator and allow to reach room temperature. Do not shake or vortex vials.

The injection concentrate should be a white to off-white homogenous solution; do not use if discoloration or particulate matter is observed. A white to off-white coating that may be visible at inner surface of vial should not impact quality of the drug.

Withdraw entire contents of vial(s) into a single syringe. Remove needle and replace with a 0.45-µm polyethersulfone syringe filter. Inject contents of syringe into a sterile container using filter needle. To prepare final diluted solution for infusion, transfer appropriate volume of filtered solution from the sterile container into a DEHP-free infusion bag and dilute with 0.9% sodium chloride injection to a total volume of 200 mL. Gently invert infusion bag to mix.

Vials contain no preservatives; for single use only. Discard any unused portions.

Administer immediately after dilution; if immediate use not possible, may store infusion bag at room temperature (≤30°C) for up to 16 hours (including infusion time). Do not freeze.

Rate of Administration

Infuse over approximately 80 minutes at an initial rate of approximately 1 mL/minute for the first 15 minutes, followed by approximately 3 mL/minute for remainder of infusion.

If infusion-related reaction occurs, consider slowing or interrupting infusion depending on severity. If infusion has been interrupted, may consider resuming infusion at a slower rate when symptoms resolve.

Dosage

Dosage of patisiran sodium expressed in terms of patisiran.

Adults

Hereditary Transthyretin-mediated Amyloidosis

Polyneuropathy

Dosage is based on actual body weight.

Patients weighing <100 kg: 0.3 mg/kg by IV infusion once every 3 weeks.

Patients weighing ≥100 kg: 30 mg by IV infusion once every 3 weeks.

If a dose is missed, administer missed dose as soon as possible within 3 days and give next dose at regularly scheduled time (i.e., 3 weeks from the day of the missed dose). If missed dose is not administered within 3 days, adjust administration schedule to maintain the recommended 3-week dosing interval.

Special Populations

Hepatic Impairment

No dosage adjustment necessary in patients with mild hepatic impairment (AST >ULN with normal bilirubin concentrations, or bilirubin concentrations >1–1.5 times the ULN).

Not studied in patients with moderate or severe hepatic impairment or in patients who have received a prior liver transplant.

Renal Impairment

No dosage adjustment necessary in patients with mild or moderate renal impairment (estimated GFR 30 to <90 mL/minute per 1.73 m²).

Not studied in patients with severe renal impairment or end-stage renal disease.

Geriatric Patients

No dosage adjustment necessary in geriatric patients ≥65 years of age.

Cautions for Patisiran

Contraindications

Manufacturer states none.

Warnings/Precautions

Infusion-related Reactions

Infusion-related reactions (e.g., flushing, back pain, nausea, abdominal pain, dyspnea, headache) reported.

Premedicate patients at least 60 minutes prior to start of infusion.

Monitor patients during infusion for signs and symptoms of infusion-related reactions. If an infusion-related reaction occurs, consider slowing or interrupting infusion and provide appropriate medical treatment (e.g., corticosteroids) as clinically indicated. If infusion has been interrupted, consider resuming infusion at a slower rate when symptoms resolve. Discontinue infusion permanently if a serious or life-threatening reaction occurs.

Reduced Vitamin A Concentrations

Treatment with patisiran may reduce serum vitamin A concentrations.

Patients receiving patisiran should receive supplementation with the recommended daily allowance (RDA) of vitamin A. Manufacturer states that dosages exceeding the RDA should not be administered in an attempt to achieve normal serum vitamin A concentrations since serum concentrations are not reflective of total vitamin A in the body.

Refer patients who develop ocular symptoms suggestive of vitamin A deficiency (e.g., night blindness) to an ophthalmologist.

Immunogenicity

Anti-patisiran antibodies detected (by measuring antibodies specific to a lipid component of the drug formulation). Antibodies do not appear to affect efficacy, safety, pharmacokinetics, or pharmacodynamics of patisiran; however, insufficient data to make definitive conclusions.

Specific Populations

Pregnancy

No data regarding use of patisiran in pregnant women.

Developmental toxicity (e.g., embryofetal mortality, reduced fetal body weights) and maternal toxicity observed in animal studies.

A pregnancy registry has been established; encourage patients to enroll by calling 1-877-256-9526 or contacting alnylampregnancyprogram@iqvia.com.

Lactation

Not known whether distributed into human milk. Drug not detected in milk of lactating rats; however, some lipid components of the formulation were present. Effects of the drug on nursing infants or on milk production not known.

Consider benefits of breast-feeding and importance of drug to the woman; also consider potential adverse effects on the breast-fed infant from the drug or underlying maternal condition.

Pediatric Use

Safety and efficacy not established in pediatric patients.

Geriatric Use

No overall differences in safety or efficacy relative to younger adults, but increased sensitivity cannot be ruled out.

Hepatic Impairment

Not studied in patients with moderate or severe hepatic impairment. Mild hepatic impairment is not expected to affect patisiran exposure.

Renal Impairment

Not studied in patients with severe renal impairment or end-stage renal disease. Mild or moderate renal impairment is not expected to affect patisiran exposure.

Common Adverse Effects

Upper respiratory tract infections, infusion-related reactions, dyspepsia, dyspnea, muscle spasms, arthralgia, erythema, bronchitis, vertigo.

Drug Interactions

No formal drug interaction studies to date. Not a substrate, inhibitor, or inducer of CYP isoenzymes or transporters.

Drugs Affecting Hepatic Microsomal Enzymes

In a population pharmacokinetic analysis, concomitant use of potent or moderate CYP3A inducers or inhibitors did not affect patisiran pharmacokinetics.

Not expected to be affected by inhibitors or inducers of CYP isoenzymes.

Patisiran Pharmacokinetics

Age, race, gender, and antibody development did not affect steady-state pharmacokinetics of patisiran.

Absorption

Bioavailability

Steady state attained by 24 weeks at recommended dosage.

Onset

Mean serum transthyretin concentrations reduced by approximately 80% within 10–14 days after single dose of 0.3 mg/kg.

Duration

Reductions in serum transthyretin concentrations sustained throughout 3-week dosing interval.

Plasma Concentrations

Following IV administration of a single dose, peak plasma concentrations and systemic exposure increase in a linear and dose-proportional manner over dose range of 0.01–0.5 mg/kg.

Special Populations

Mild hepatic impairment (AST >ULN with normal bilirubin, or bilirubin >1–1.5 times ULN): No effect on systemic exposure.

Mild or moderate renal impairment (estimated GFR ≥30 to <90 mL/minute per 1.73 m²): No effect on systemic exposure.

Distribution

Extent

Distributed principally to liver; small fraction distributed to other organs with fenestrated epithelium (e.g., spleen). Does not distribute into CNS or eye.

Not known whether distributed into human milk.

Plasma Protein Binding

Low (≤2.1% binding to serum albumin and human α₁-acid glycoprotein).

Elimination

Metabolism

Metabolized by nucleases to nucleotides of various lengths.

Elimination Route

Clearance principally through metabolism.

<1% excreted unchanged in urine.

Half-life

3.2 days.

Stability

Storage

Parenteral

Injection Concentrate

2–8°C. Do not freeze; discard vial if frozen.

Administer immediately after dilution; alternatively, may store at room temperature (<30°C) for up to 16 hours (including infusion time). Do not freeze.

Compatibility

Parenteral

Solution Compatibility1

Compatible
Sodium chloride 0.9%

Drug Compatibility

Do not mix or dilute with other drugs.

Actions

Double-stranded siRNA that targets and causes degradation of a genetically conserved sequence of both wild-type and mutant variants of transthyretin mRNA; reduces transthyretin (disease-causing protein) in patients with hereditary transthyretin-mediated amyloidosis through this RNA interference mechanism.
Produces high level of transthyretin “knockdown” (suppression of gene expression) and reduces serum concentrations of transthyretin by approximately 80–88%.
Commercially available as a lipid complex consisting of the siRNA molecule encapsulated in lipid nanoparticles; the lipid-based delivery system is essential for targeted delivery of the drug to liver where transthyretin is principally produced.

Advice to Patients

Risk of infusion-related reactions. Advise patients to notify their clinician immediately if signs and/or symptoms of infusion-related reactions (e.g., flushing, dyspnea, chest pain, syncope, rash, increased heart rate, facial edema) occur.
Importance of advising patients to take the RDA of vitamin A. Advise patients to notify their clinician if they experience ocular symptoms suggestive of vitamin A deficiency (e.g., night blindness), and refer patients who develop such symptoms to an ophthalmologist.
Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed. Encourage patients to enroll in the pregnancy registry if they become pregnant while receiving the drug.
Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs and dietary or herbal supplements, as well as any concomitant illnesses (e.g., renal disease, hepatic disease).
Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.