Last updated: July 31, 2026
Hydroxyzine pamoate is an established first-generation antihistamine marketed primarily as a generic capsule under the former Vistaril brand. Its clinical development program is effectively complete. Current research is mainly investigator-led and evaluates hydroxyzine as a sedative, anxiolytic, preoperative medication, or comparator rather than as a new molecular entity. The product has no meaningful branded patent exclusivity, no FDA-recognized new-drug exclusivity, and limited commercial protection beyond manufacturing capabilities, supplier relationships, regulatory compliance, and distribution scale.
The market is mature, price-sensitive, and fragmented. Demand should remain stable in anxiety, pruritus, insomnia-related prescribing, and perioperative sedation, but revenue growth is likely to be limited. Generic competition, low unit prices, substitution by cetirizine, diphenhydramine, buspirone, benzodiazepines, and newer insomnia therapies will constrain expansion.
What is hydroxyzine pamoate and how is it used?
Hydroxyzine pamoate is the pamoate salt of hydroxyzine, a first-generation H1 antihistamine with central nervous system depressant and anxiolytic activity. In the United States, FDA labeling identifies three principal uses:
- Symptomatic relief of anxiety and tension
- Management of pruritus caused by allergic conditions
- Preoperative sedation
Hydroxyzine pamoate is commonly supplied in 25 mg, 50 mg, and 100 mg capsules. Hydroxyzine hydrochloride is the principal alternative salt and is commonly supplied as tablets, capsules, and oral solution. The pamoate and hydrochloride products differ in salt form and dosage-form availability, but both deliver hydroxyzine as the pharmacologically active moiety.
Hydroxyzine is not a controlled substance under the federal Controlled Substances Act. Its use is limited by sedation, anticholinergic effects, impaired alertness, and cardiac safety concerns, including QT-interval prolongation in susceptible patients.
What is the FDA regulatory status of hydroxyzine pamoate?
Hydroxyzine pamoate is an FDA-approved prescription drug marketed through abbreviated new drug applications and legacy approvals. Generic products are regulated under section 505(j) of the Federal Food, Drug, and Cosmetic Act and must demonstrate pharmaceutical equivalence and bioequivalence to the relevant reference product.
The former Vistaril product was marketed by Pfizer subsidiary Roerig. The brand has not retained material commercial exclusivity. Current US supply is dominated by generic manufacturers and distributors.
| Regulatory attribute |
Status |
| Active ingredient |
Hydroxyzine pamoate |
| Drug class |
First-generation H1 antihistamine; anxiolytic |
| Primary dosage form |
Oral capsules |
| Common strengths |
25 mg, 50 mg, 100 mg |
| US regulatory pathway |
Generic ANDAs and legacy approved products |
| Controlled-substance status |
Not federally scheduled |
| New chemical entity exclusivity |
Expired or unavailable |
| Orphan-drug exclusivity |
None identified |
| Pediatric exclusivity |
None identified |
| Current commercial model |
Multi-source generic |
| Reference brand |
Vistaril, historically marketed by Pfizer/Roerig |
FDA labeling warns about drowsiness and recommends caution when hydroxyzine is used with central nervous system depressants. The European Medicines Agency has also identified QT prolongation and torsades de pointes as important risks, particularly in patients with risk factors or concomitant QT-prolonging medicines (European Medicines Agency, 2015).
What clinical trials are evaluating hydroxyzine pamoate?
Hydroxyzine has no active late-stage development program comparable to a modern branded drug pipeline. ClinicalTrials.gov records hydroxyzine studies across several settings, but most are small, investigator-sponsored, or supportive studies.
Current clinical-trial activity
The main research categories are:
-
Perioperative and procedural sedation
Hydroxyzine is used as an oral or intramuscular sedative in anesthesia and procedural settings. Studies generally compare it with benzodiazepines, other antihistamines, placebo, or multimodal sedation protocols.
-
Anxiety and acute agitation
Hydroxyzine is evaluated as a non-controlled alternative for short-term anxiety symptoms. These studies are typically small and do not establish a new commercial indication.
-
Sleep and inpatient symptom management
Hospitals and academic groups have examined hydroxyzine for sleep disturbance, nighttime anxiety, and acute-care symptom control. These uses are often off-label and have limited potential to support premium pricing.
-
Pruritus and allergic disease
Hydroxyzine remains a comparator or rescue medicine in dermatology and allergy research. Newer, less-sedating antihistamines have displaced much of its chronic outpatient use.
-
Drug-use and safety studies
Some registry activity concerns prescribing patterns, medication safety, QT risk, sedation, and use in children or older adults.
Clinical-trial activity is therefore unlikely to generate a new label expansion, premium formulation, or material patent estate. The clinical evidence base supports continued use of an established generic medicine rather than commercial redevelopment.
What are the principal clinical risks?
Hydroxyzine’s commercial utility is constrained by tolerability and safety:
- Somnolence and impaired psychomotor performance
- Anticholinergic effects, including dry mouth and urinary retention
- Additive sedation with opioids, benzodiazepines, alcohol, and other CNS depressants
- QT prolongation and rare torsades de pointes
- Greater sensitivity in older adults and patients with cardiovascular or renal risk factors
The American Geriatrics Society Beers Criteria identifies hydroxyzine and other first-generation antihistamines as potentially inappropriate for many older adults because of strong anticholinergic effects (American Geriatrics Society Beers Criteria Update Expert Panel, 2023).
When does hydroxyzine pamoate lose exclusivity?
Hydroxyzine pamoate has already lost product-level exclusivity. The underlying active ingredient was developed decades ago, and the commercially relevant patents and regulatory exclusivities have expired.
| Exclusivity category |
Hydroxyzine pamoate status |
| Composition-of-matter patent |
Expired |
| Original branded-product protection |
Expired |
| FDA new-drug exclusivity |
Expired |
| Orphan exclusivity |
None |
| Pediatric exclusivity |
None |
| Formulation exclusivity |
No material blocking protection identified |
| Generic substitution |
Established |
| Paragraph IV exposure |
Historically relevant only to old product patents; no active branded barrier identified |
The absence of a current blocking patent means a company can generally enter with an ANDA if it satisfies FDA requirements and secures an approved manufacturing and supply chain. Any remaining patent disputes would be product-specific and would need to be checked against the relevant Orange Book records and individual ANDA certifications.
What patents protect hydroxyzine pamoate?
No active patent estate appears to protect the basic hydroxyzine pamoate molecule, standard capsule strengths, or the conventional oral dosage form in the United States.
Potentially relevant intellectual-property categories are limited to:
- Manufacturing processes for hydroxyzine or its salts
- Crystal forms or particle-size specifications
- Taste-masked or modified-release formulations
- Combination products
- Packaging or device systems
- New therapeutic uses
These categories do not create a meaningful barrier to ordinary immediate-release hydroxyzine pamoate capsules unless a company develops and commercializes a differentiated product. A process patent could affect a particular manufacturer without blocking all generic production.
What is the Orange Book status of hydroxyzine pamoate?
The Orange Book is most relevant to approved prescription drug products and their listed patents. Hydroxyzine pamoate is principally a multisource generic product, and no active, commercially significant Orange Book patent listing is generally associated with conventional hydroxyzine pamoate capsules.
Orange Book analysis should distinguish:
- The historical reference-listed drug
- Current ANDA products
- Expired patents
- Any product-specific listing entered by an applicant
- Paragraph IV certifications attached to legacy patents
FDA’s Orange Book database remains the controlling source for current listed patents and exclusivity records (U.S. Food and Drug Administration, n.d.-a).
Which companies manufacture hydroxyzine pamoate?
Hydroxyzine pamoate is supplied by multiple generic manufacturers and contract manufacturers. Historical and current US listings have included companies such as:
- Amneal Pharmaceuticals
- Hikma Pharmaceuticals
- Major Pharmaceuticals
- Rising Pharmaceuticals
- Sandoz and other generic suppliers, depending on product availability
- Various private-label distributors and repackagers
The supplier set changes with manufacturing economics, FDA inspections, shortages, wholesaler contracts, and portfolio decisions. A company may hold an approved ANDA but have little or no active commercial volume.
The competitive advantage in this market is operational rather than patent-based. Relevant factors include:
- Cost of hydroxyzine API and pamoic acid
- Yield and impurity control
- Capsule filling capacity
- FDA-compliant manufacturing sites
- Reliable packaging and serialization
- Wholesaler and pharmacy contracts
- Ability to maintain supply during low-margin periods
How large is the hydroxyzine pamoate market?
Hydroxyzine pamoate is part of the broader generic antihistamine and anxiolytic market. Public company filings rarely report hydroxyzine pamoate revenue separately, and commercial market-research estimates vary because they may measure prescriptions, capsules, manufacturer sales, or retail spending.
The product’s market characteristics are clear:
| Market factor |
Assessment |
| Demand maturity |
Mature and stable |
| Prescription volume |
Supported by anxiety, pruritus, and procedural use |
| Unit economics |
Low |
| Competition |
High |
| Switching risk |
High |
| Brand premium |
Minimal |
| Reimbursement leverage |
Limited |
| Shortage sensitivity |
Moderate |
| Growth driver |
Continued generic prescribing and low-cost access |
| Decline driver |
Substitution by less-sedating or condition-specific medicines |
Anxiety is the strongest commercial demand segment, but hydroxyzine competes with buspirone, SSRIs, SNRIs, benzodiazepines, and psychotherapy. In allergic disease, cetirizine, loratadine, and fexofenadine generally offer less sedation. In insomnia, hydroxyzine competes with behavioral therapy, sedating antidepressants, melatonin products, orexin antagonists, and other prescription hypnotics.
What is the 2025-2030 market projection for hydroxyzine pamoate?
The base-case outlook is stable-to-declining revenue with relatively stable prescription demand. A reasonable commercial scenario is:
| Period |
Expected market direction |
Main drivers |
| 2025-2026 |
Flat to low-single-digit decline |
Generic pricing, mature demand, substitution |
| 2027-2028 |
Flat volume; declining value |
Continued competition and reimbursement pressure |
| 2029-2030 |
Low-single-digit annual value decline |
Aging product, limited innovation, alternative therapies |
Prescription volume may remain more resilient than revenue because hydroxyzine is inexpensive and accessible. A temporary supply disruption could produce short-term price increases, but those gains would likely attract additional generic supply and would not establish durable market expansion.
The upside case requires a differentiated product, such as:
- A reduced-sedation formulation
- Extended release for controlled symptom coverage
- A pediatric-friendly liquid or dispersible dosage form
- A validated perioperative product with hospital adoption
- A combination product with a defensible clinical or regulatory profile
Without a differentiated formulation, investment returns are likely to depend on manufacturing efficiency and distribution scale rather than market growth.
What generic entry risks exist for hydroxyzine pamoate?
Generic entry risk is high because the product is old, simple, and widely substituted. A new entrant would face commercial rather than legal barriers.
Legal and regulatory risks
- Bioequivalence failure or formulation differences affecting dissolution
- FDA manufacturing observations
- API contamination or impurity issues
- Inability to secure reliable commercial-scale supply
- Product recalls
- Labeling inconsistencies
- State pharmacy substitution and reimbursement constraints
Commercial risks
- Low price ceilings
- Limited pharmacy shelf differentiation
- Concentration of generic purchasing among wholesalers
- Loss of volume after a competitor undercuts price
- Inactive or discontinued ANDAs
- Small addressable market for premium formulations
Paragraph IV litigation risk is low for conventional hydroxyzine pamoate capsules because the principal composition and dosage-form protections have expired. Risk would increase only if a company launched a new formulation or combination product relying on later-filed patents.
How does hydroxyzine pamoate compare with hydroxyzine hydrochloride?
| Attribute |
Hydroxyzine pamoate |
Hydroxyzine hydrochloride |
| Common US dosage forms |
Capsules |
Tablets, capsules, oral solution |
| Typical positioning |
Anxiety, pruritus, sedation |
Anxiety, pruritus, sedation |
| Active moiety |
Hydroxyzine |
Hydroxyzine |
| Salt form |
Pamoate |
Hydrochloride |
| Patent status |
Expired |
Expired |
| Generic competition |
High |
High |
| Formulation flexibility |
Lower in standard capsule market |
Greater because of liquid availability |
| Clinical differentiation |
Limited |
Limited |
| Commercial risk |
Price competition |
Price competition |
The principal commercial distinction is dosage form. Hydroxyzine hydrochloride may have an advantage where liquid dosing or tablet availability matters. Hydroxyzine pamoate remains viable where capsule prescribing is established and a low-cost generic is preferred.
What patent litigation or settlement agreements affect hydroxyzine pamoate?
No major current US patent litigation or branded-generic settlement is associated with conventional hydroxyzine pamoate capsules. Historical disputes involving old hydroxyzine products would not ordinarily create a present market barrier unless they concern a specific formulation, manufacturing process, or currently enforceable patent.
Settlement risk is therefore low for standard capsules. It could become relevant if a sponsor commercializes:
- A sustained-release formulation
- A fixed-dose combination
- A novel salt or crystal form
- A proprietary delivery system
- A new indication supported by a patent
How strong is the hydroxyzine pamoate patent estate?
The patent estate is weak for the standard generic product and potentially moderate only for a new, technically differentiated formulation.
| Patent category |
Strength for standard capsules |
| Active ingredient |
None |
| Conventional capsule |
None or immaterial |
| New method of use |
Potentially available, but narrow |
| Modified release |
Potentially protectable |
| Manufacturing process |
Potentially protectable |
| Combination product |
Potentially protectable |
| Regulatory exclusivity |
None |
| Litigation leverage |
Low |
The product is therefore unsuitable for a conventional patent-protected lifecycle strategy. A viable IP program would need to create measurable clinical, pharmacokinetic, safety, or adherence value.
Key Takeaways
- Hydroxyzine pamoate is an established, multisource generic with no meaningful remaining basic-drug exclusivity.
- Clinical-trial activity is limited and mainly investigator-led, with no major late-stage commercial program.
- The principal uses are anxiety, pruritus, and preoperative sedation.
- Sedation, anticholinergic effects, and QT risk limit expansion into chronic or geriatric use.
- Standard capsules face high generic entry and substitution risk.
- Patent protection is weak for the conventional product and potentially relevant only to new formulations, combinations, or manufacturing methods.
- The 2025-2030 market outlook is stable-to-declining in value, with prescription volume more resilient than revenue.
- Commercial success depends on supply reliability, low manufacturing cost, regulatory compliance, and distribution access.
FAQs
Is hydroxyzine pamoate still under patent?
No material patent protection remains for the basic hydroxyzine pamoate molecule or conventional immediate-release capsules. New patents could cover a differentiated formulation, combination, or manufacturing method.
Is hydroxyzine pamoate a controlled substance?
No. Hydroxyzine pamoate is not federally scheduled as a controlled substance, although it can cause substantial sedation and impairment.
Can hydroxyzine pamoate be approved through an ANDA?
Yes. A manufacturer can generally pursue an ANDA for a therapeutically equivalent product if it meets FDA requirements for pharmaceutical equivalence, bioequivalence, manufacturing quality, labeling, and facility compliance.
Does hydroxyzine pamoate have biosimilar competition?
No. Biosimilars apply to biological products. Hydroxyzine pamoate is a conventional small-molecule drug and competes with generic equivalents, not biosimilars.
Could a new hydroxyzine pamoate formulation obtain patent protection?
Yes. A novel sustained-release system, reduced-sedation formulation, combination product, or technically differentiated dosage form could support patent claims if it satisfies novelty, nonobviousness, enablement, and other applicable requirements. The standard capsule itself offers little patent opportunity.
References
-
American Geriatrics Society Beers Criteria Update Expert Panel. (2023). American Geriatrics Society 2023 updated AGS Beers Criteria for potentially inappropriate medication use in older adults. Journal of the American Geriatrics Society, 71(7), 2052-2081. https://doi.org/10.1111/jgs.18372
-
ClinicalTrials.gov. (n.d.). Hydroxyzine clinical studies. U.S. National Library of Medicine. Retrieved February 2025, from https://clinicaltrials.gov/search?term=hydroxyzine
-
European Medicines Agency. (2015). Hydroxyzine-containing medicinal products: Referral under Article 31 of Directive 2001/83/EC. https://www.ema.europa.eu/en/medicines/human/referrals/hydroxyzine-containing-medicinal-products
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U.S. Food and Drug Administration. (n.d.-a). Orange Book: Approved drug products with therapeutic equivalence evaluations. Retrieved February 2025, from https://www.accessdata.fda.gov/scripts/cder/ob/
-
U.S. Food and Drug Administration. (n.d.-b). DailyMed: Hydroxyzine pamoate capsule labeling. National Library of Medicine. Retrieved February 2025, from https://dailymed.nlm.nih.gov/dailymed/search.cfm?query=hydroxyzine%20pamoate
