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sohonos

Sohonos (Palovarotene) is a retinoid used to treat Heterotopic Ossification.

Palovarotene · by Ipsen

Not yet rated· sourced from the FDA label
Rated against independent regulatory sources·Last updated June 7, 2026·How we rate
Verified againstopenFDANIH DailyMedRxClass

Key facts

Active ingredient
Palovarotene
Drug class
Retinoid
Form
Capsule
Strength
Palovarotene 1.5MG · Palovarotene 10MG · Palovarotene 1MG · Palovarotene 2.5MG · Palovarotene 5MG
Type
Prescription (Rx)
Brand or generic
Brand-name
Manufacturer
Ipsen
FDA application
NDA215559

What is Sohonos?

From the FDA label:Palovarotene is an orally bioavailable retinoid that acts as a retinoic acid receptor (RAR) agonist with particular selectivity at the gamma subtype of RAR. Palovarotene is chemically described as 4-[( E )-2-(5,5,8,8-tetramethyl-3-pyrazol-1-ylmethyl-5,6,7,8-tetrahydro-naphthalen-2-yl)-vinyl]-benzoic acid with an empirical formula of C 27 H 30 N 2 O 2 and has a molecular weight of 414.54 g/mol. The structural formula is represented below: SOHONOS capsules are supplied in 1 mg, 1.5 mg, 2.5 mg, 5 mg and 10 mg strengths. Each capsule contains palovarotene as the active ingredient and the following inactive ingredients: croscarmellose sodium, lactose monohydrate, magnesium stearate, microcrystalline cellulose, povidone, and sodium lauryl sulfate. The capsule consists of gelatin and titanium dioxide. The black printing ink consists of black iron oxide, potassium hydroxide, propylene glycol and Shellac. Chemical Structure

How to use

Obtain a negative pregnancy test in females of reproductive potential before initiation of SOHONOS ( 2.1 ) Recommended dosage includes a chronic daily dose, which can be increased for flare-up symptoms ( 2.2 ) For adults and pediatric patients 14 years and older: Recommended dosage is 5 mg once daily, with an increase in dose at the time of a flare-up to 20 mg once daily for 4 weeks, followed by 10 mg once daily for 8 weeks for a total of 12 weeks (20/10 mg flare-up treatment) ( 2.2 ) For pediatric patients under 14 years: Weight-adjusted for daily and flare-up dosing. Recommended daily dosage range from 2.5 to 5 mg. Refer to Table 1 in Full Prescribing Information for complete pediatric dosing ( 2.2 ) Take SOHONOS with food preferably at same time each day ( 2.3 ). Reduce the dose in the event of adverse reactions as appropriate ( 2.4 ) See Full Prescribing Information for complete dosing instructions ( 2 ) 2.1 Pregnancy Testing Prior to Treatment with SOHONOS For females of reproductive potential, obtain a negative pregnancy test within one week prior to initiating and periodically during SOHONOS therapy . If pregnancy occurs, stop SOHONOS treatment immediately and refer patient to an obstetrician/gynecologist experienced in reproductive toxicity. [see Warnings and Precautions (5.1) and Use in Specific Populations (8.1 , 8.3) ]. 2.2 Recommended Dosage and Duration Dosage…

Side effects

The following clinically significant adverse reactions are described elsewhere in the labeling: Premature Epiphyseal Closure in Growing Pediatric Patients [see Warnings and Precautions (5.2) ] Mucocutaneous Adverse Reactions [see Warnings and Precautions (5.3) ] Metabolic Bone Disorders [see Warnings and Precautions (5.4) ] Psychiatric Disorders [see Warnings and Precautions (5.5) ] Night Blindness [see Warnings and Precautions (5.6) ] Most common adverse reactions (incidence ≥10%) are dry skin, lip dry, arthralgia, pruritus, pain in extremity, rash, alopecia, erythema, headache, back pain, skin exfoliation, nausea, musculoskeletal pain, myalgia, dry eye, hypersensitivity, peripheral edema, and fatigue ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact IPSEN Biopharmaceuticals, Inc at 1-855-463-5127 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The safety of SOHONOS was evaluated in clinical studies that enrolled a total of 164 subjects with FOP, including 139 subjects in the indicated population of ages 8 years and above for females and 10 years and above for males (8/10 years…

FDA Boxed Warning (the FDA’s most serious warning)

Boxed (black-box) warning — from the FDA label

EMBRYO-FETAL TOXICITY and PREMATURE EPIPHYSEAL CLOSURE IN GROWING PEDIATRIC PATIENTS WARNING: EMBRYO-FETAL TOXICITY and PREMATURE EPIPHYSEAL CLOSURE IN GROWING PEDIATRIC PATIENTS See full prescribing information for complete boxed warning. SOHONOS is contraindicated in pregnancy ( 5.1 , 8.1 ) Because of the risk of teratogenicity and to minimize fetal exposure, SOHONOS is to be administered only if conditions for pregnancy prevention are met ( 5.1 , 8.1 ) SOHONOS causes premature epiphyseal closure in growing pediatric patients with FOP, close monitoring is recommended ( 5.2 , 8.4 ) Embryo-Fetal Toxicity SOHONOS is contraindicated in pregnancy. SOHONOS may cause fetal harm. Because of the risk of teratogenicity and to minimize fetal exposure, SOHONOS is to be administered only if conditions for pregnancy prevention are met [see Warnings and Precautions (5.1) and Use in Specific Populations (8.1) ]. Premature Epiphyseal Closure Premature epiphyseal closure occurs in growing pediatric patients treated with SOHONOS, close monitoring is recommended [see Warnings and Precautions (5.2) and Use in Specific Populations (8.4) ] .

Warnings

Important safety information

Premature Epiphyseal Closure: Premature epiphyseal closure occurred with SOHONOS. Assess baseline skeletal maturity before SOHONOS therapy and monitor linear growth in growing pediatric patients ( 5.2 ) Mucocutaneous Adverse Reactions: Dry skin, lip dry, pruritus, rash, alopecia, erythema, skin exfoliation, and dry eye occurred with SOHONOS. Prevent or treat with skin emollients, sunscreen, artificial tears. Dosage reduction may be required in some patients ( 2.4 , 5.3 ) Metabolic Bone Disorders: Decreased vertebral bone mineral content and bone density may occur. Assess for spinal fracture periodically using radiologic method ( 5.4 ) Psychiatric Disorders: Depression, anxiety, mood alterations and suicidal thoughts and behaviors occurred with SOHONOS. Contact healthcare provider if new or worsening symptoms develop in patients treated with SOHONOS ( 5.5 ) Night Blindness: May occur and make driving at night hazardous ( 5.6 ) 5.1 Embryo-Fetal Toxicity SOHONOS can cause fetal harm and is contraindicated during pregnancy. SOHONOS is a member of the retinoid class of drugs which is associated with birth defects in humans. In animal reproduction studies, palovarotene administered orally to pregnant rats during organogenesis was teratogenic and caused fetal malformations typical of retinoids including cleft palate, misshapen skull bones, and shortening of the long bones at clinically relevant exposures. For females of reproductive potential, verify that the patient is not pregnant prior to initiating treatment, periodically during the course of therapy and one month after treatment discontinuation. Advise females of reproductive potential to use an effective method of contraception at least one month prior to treatment, during treatment with SOHONOS and for 1 month after the last dose [see Use in Specific Populations (8.1 , 8.3) and Clinical Pharmacology (12.3) ]. If a pregnancy occurs during SOHONOS treatment, discontinue treatment immediately and refer the patient to an obstetrician/gynecologist experienced in reproductive toxicity for further evaluation and counseling. Patients should be informed not to donate blood during SOHONOS therapy and for 1 week following discontinuation because the blood might be given to a pregnant patient whose fetus must not be exposed to palovarotene. 5.2 Premature Epiphyseal Closure in Growing Pediatric Patients SOHONOS can cause irreversible premature epiphyseal closure and potential adverse effects on growth. In clinical studies, premature epiphyseal closure occurred with SOHONOS treatment in growing pediatric patients with FOP [see Adverse Reactions (6.1) and Use in Specific Populations (8.4) ] . Monitoring of linear growth is recommended in growing pediatric patients [see Use in Specific Populations (8.4) ] . Prior to starting treatment with SOHONOS, all growing pediatric patients should undergo baseline assessment of skeletal maturity via hand/wrist and knee x-rays, standard growth curves and pubertal staging. Continued monitoring is recommended every 6 to 12 months until patients reach skeletal maturity or final adult height. If a patient exhibits signs of premature epiphyseal closure or adverse effects on growth based on clinical or radiologic evaluations, further evaluation may be required, including an assessment of the benefits and risks of continued treatment, or temporary or permanent discontinuation of SOHONOS until the patient achieves epiphyseal closure and skeletal maturity. 5.3 Mucocutaneous Adverse Reactions Mucocutaneous adverse reactions including dry skin, lip dry, pruritus, rash, alopecia, erythema, skin exfoliation [skin peeling], and dry eye occurred in most (98%) patients treated with SOHONOS. SOHONOS may contribute to an increased risk of skin and soft tissue infections, particularly paronychia and decubitus ulcer, due to a decreased skin barrier from adverse reactions such as dry and peeling skin [see Adverse Reactions (6.1) ] . Some of these mucocutaneous adverse reactions led to dose reductions which occurred more frequently during flare-up dosing suggesting a dose response relationship. Prophylactic measures to minimize risk and/or treat the mucocutaneous adverse reactions are recommended (e.g., skin emollients, sunscreen, lip moisturizers, or artificial tears). Some patients may require dose reduction or drug discontinuation [see Dosage and Administration (2.4) ] . Photosensitivity Photosensitivity reactions, such as exaggerated sunburn reactions (e.g., burning, erythema, blistering) involving areas exposed to the sun have been associated with the use of retinoids and may occur with SOHONOS. Precautionary measures for phototoxicity are recommended. Excessive exposure to sun or artificial ultraviolet light should be avoided, and protection from sunlight should be used when exposure cannot be avoided (use of sunscreens, protective clothing, and use of sunglasses). 5.4 Metabolic Bone Disorders Bone mineral density and fracture Retinoids are associated with bone toxicity, including reductions in bone mass and spontaneous reports of osteoporosis and fracture. In FOP clinical trials, SOHONOS resulted in decreased vertebral bone mineral content and bone density, and an increased risk of radiologically observed vertebral (T4 to L4) fractures in treated adult and pediatric patients compared to untreated patients. Periodic radiological assessment of the spine is recommended. [see Adverse Reactions (6.1) ] . Hyperostosis Retinoids have been associated with hyperostotic changes (bone spurs) and calcification of tendons or ligaments and may occur with SOHONOS. These effects generally occur with long-term use, especially at high doses. 5.5 Psychiatric Disorders New or worsening psychiatric events were reported with SOHONOS use. These include depression, anxiety, mood alterations and suicidal thoughts and behaviors. There is a relatively high background prevalence of psychiatric disorders in untreated patients with FOP. Monitor for development of new or worsening psychiatric symptoms during treatment with SOHONOS [see Adverse Reactions (6.1) ]. Individuals with a history of psychiatric illness may be more susceptible to these adverse effects. Patients and/or caregivers should contact their healthcare provider if new or worsening psychiatric symptoms develop during treatment with SOHONOS. 5.6 Night Blindness Night blindness has been associated with systemic retinoids, including SOHONOS. This may be dose-dependent, making driving a vehicle at night potentially hazardous during treatment. Night blindness is generally reversible after cessation of treatment but can also persist in some cases. Advise patients to be cautious when driving or operating any vehicle at night and to seek medical attention in the event of vision impairment.

Who should not take Sohonos

SOHONOS is contraindicated in the following patients: During Pregnancy [see Warnings and Precautions (5.1) and Use in Specific Populations (8.1) ] . A history of allergy or hypersensitivity to retinoids, or to any component of SOHONOS. Anaphylaxis and other allergic reactions have occurred with other retinoids. [see Description (11) ]. Pregnancy ( 4 , 5.1 , 8.1 ) Hypersensitivity to retinoids or any component of SOHONOS ( 4 , 11 )

Overdose — what happens if you take too much

No clinical experience with an overdose of SOHONOS has been reported. SOHONOS is a derivative of vitamin A. In case of accidental overdose, signs of hypervitaminosis A could appear, including severe headache, nausea or vomiting, drowsiness, irritability and pruritus. Any overdose should be treated with supportive care according to the signs and symptoms exhibited by the patient.

U.S. Poison Control: call or text 1-800-222-1222 (free, 24/7). In an emergency call 911. From the FDA label; not medical advice.

Interactions

CYP3A4 Inhibitors: May increase SOHONOS exposure. Avoid concomitant use of strong/moderate CYP3A4 inhibitors. If concomitant use of moderate CYP3A4 inhibitors is unavoidable, reduce the dose of SOHONOS by half ( 2.5 , 7.1 ) CYP3A4 Inducers: May decrease SOHONOS exposure. Avoid concomitant use of strong/moderate CYP3A4 inducers ( 7.1 ) Vitamin A: May cause additive effects ( 7.2 ) Tetracyclines: Avoid concomitant use with SOHONOS ( 7.3 ) Systemic Corticosteroids: No clinically significant drug interaction is expected with concomitant use of SOHONOS ( 7.4 ) 7.1 Effect of Other Drugs on SOHONOS Clinically significant drug interactions affecting the exposure of SOHONOS are listed in Table 6. Table 6. Drugs that affect exposure of SOHONOS. Strong CYP3A Inhibitors Clinical Impact Co-administration of SOHONOS with strong CYP3A4 inhibitors increased the exposures of palovarotene [see Clinical Pharmacology (12.3) ] , which may increase the risk of SOHONOS adverse reactions. Prevention or Management Avoid concomitant use of a strong CYP3A4 inhibitor during SOHONOS treatment [see Dosage and Administration (2.5) ] . Moderate CYP3A Inhibitors Clinical Impact Co-administration of SOHONOS with moderate CYP3A4 inhibitors may increase the exposure of palovarotene [see Clinical Pharmacology (12.3) ] , which may increase the risk of SOHONOS adverse reactions. Prevention or Management Avoid concomitant use of a moderate CYP3A4 inhibitor with SOHONOS, if possible. If co-administration will occur, reduce the SOHONOS dose by half when co-administered with moderate CYP3A inhibitors [see Dosage and Administration (2.5) ] . Strong CYP3A Inducers Clinical Impact Co-administration of SOHONOS with strong CYP3A4 inducers decreased the exposure of palovarotene [see Clinical Pharmacology (12.3) ] , which may reduce the effectiveness of SOHONOS. Prevention or Management Avoid concomitant use of strong CYP3A4 inducers with SOHONOS. [see Dosage and Administration (2.5) ] . Moderate CYP3A Inducers Clinical Impact Co-administration of moderate CYP3A4 inducers with palovarotene may decrease palovarotene exposure [see Clinical Pharmacology (12.3) ], which may reduce the effectiveness of SOHONOS. Prevention or Management Avoid concomitant use of moderate CYP3A4 inducers with SOHONOS. 7.2 Vitamin A Palovarotene belongs to the same pharmacological class as vitamin A. Therefore, the use of both vitamin A and SOHONOS at the same time may lead to additive effects. Concomitant administration of vitamin A in doses higher than the recommended daily allowance (RDA) and/or other oral retinoids with SOHONOS must be avoided because of the risk of hypervitaminosis A. 7.3 Tetracyclines Systemic retinoid use has been associated with cases of benign intracranial hypertension (also called pseudotumor cerebri), some of which involved the concomitant use of tetracyclines. Avoid coadministration of SOHONOS with tetracycline derivatives [see Adverse Reactions (6.1) ] . 7.4 Systemic Corticosteroids No clinically significant drug-drug interaction is expected when SOHONOS is co-administered with prednisone [see Clinical Pharmacology (12.3) ] .

Storing Sohonos, and how long it keeps

Quoted from this product’s own FDA label. Storage belongs to the product and its device, not to the drug in general — a pen and a tablet of the same medicine are kept completely differently.

  • SOHONOS must be kept in the original carton to protect from light.

Drug class

How this class works, per Tretinoin - StatPearls - NCBI Bookshelf.

May treat (source: NIH RxClass)

Dosage forms

Capsule

The forms currently marketed in the U.S., per the FDA National Drug Code Directory.

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Frequently asked questions

What does Sohonos treat?
Sohonos (Palovarotene) may be used to treat heterotopic ossification, based on NIH RxClass drug-classification data (conditions a drug may treat — not a verbatim copy of the FDA-approved label). This is general reference, not medical advice.
How does Sohonos work?
Sohonos is a retinoid. Retinoids are vitamin A derivatives that enter skin cells and switch on retinoic acid receptors in the nucleus, which changes how genes are read. This normalizes how skin cells grow and shed, unclogs pores, calms inflammation, and over time boosts collagen production.
Is there a coupon or discount for Sohonos?
pharmaranks is an independent ratings site, not a pharmacy — we don't issue coupons or sell Sohonos. To pay less, ask your prescriber or pharmacist whether a generic equivalent exists, check the manufacturer's copay/savings card and patient-assistance program, and compare a pharmacy discount card against your insurance copay. Prices vary by pharmacy, insurance, and location, so always confirm at the counter. This is general reference, not medical or financial advice.
Who makes Sohonos?
Sohonos is marketed by Ipsen. You can see Ipsen's full profile, rating, and other products on pharmaranks.
Is Sohonos a brand-name or generic drug?
Sohonos is a brand-name product with the active ingredient Palovarotene.
Is Sohonos available over the counter?
No. Sohonos is a prescription (Rx) medication in the US — you need a prescription from a licensed clinician (in person or via telehealth); it isn't sold over the counter. For some conditions there are OTC alternatives — ask your pharmacist.
What forms does Sohonos come in?
Sohonos is currently marketed as capsule, per the FDA's National Drug Code Directory.
What class of drug is Sohonos?
Sohonos is classified as retinoid, per the FDA's Established Pharmacologic Class.
Is Sohonos FDA-registered?
Sohonos is on record with the U.S. FDA under application number NDA215559. You can verify this on its official FDA label.
Is Sohonos safe?
There's no single safe-or-not verdict, and we don't yet have a composite recall-safety score for Sohonos. Review its FDA-label side effects and warnings below, and always consult a licensed professional.
What are the side effects of Sohonos?
Sohonos's side effects are taken directly from its FDA label. From the label: The following clinically significant adverse reactions are described elsewhere in the labeling: Premature Epiphyseal Closure in Growing Pediatric Patients [see Warnings and Precautions (5.2) ] Mucocutaneous Adverse Reactions [see Warnings and Precautions (5.3) ] Metabolic Bone Disorders [see Warning… Both common and serious reactions are documented in full on this page. This is general reference from the FDA, not medical advice — always consult a professional.

Clinical content sourced from the FDA label via openFDA (U.S. FDA). View the FDA label on DailyMed → Provided for general reference only — not medical advice. Always consult a licensed professional and the current prescribing information.

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