Last updated: July 31, 2026
Daranide is the former brand name for dichlorphenamide, an oral carbonic anhydrase inhibitor. The original Daranide product is no longer an active commercial growth asset in the United States. Its active ingredient was later developed as Keveyis for primary periodic paralysis, a rare neuromuscular disorder. No active clinical-development program is associated with the Daranide brand itself. Current commercial analysis therefore centers on dichlorphenamide and Keveyis rather than on Daranide as a standalone product.
What is Daranide and how does dichlorphenamide work?
Daranide contained dichlorphenamide, a sulfonamide carbonic anhydrase inhibitor. The drug reduces renal bicarbonate reabsorption and alters electrolyte handling. Its historic uses included glaucoma and certain neurologic or metabolic indications.
Dichlorphenamide is also used to reduce attacks of primary periodic paralysis, including hypokalemic and hyperkalemic forms. The modern U.S. product is Keveyis, marketed by Xeris Pharmaceuticals after Xeris acquired Strongbridge Biopharma. The FDA approved Keveyis in 2015 for the treatment of primary hyperkalemic periodic paralysis, primary hypokalemic periodic paralysis, and related variants in adults and adolescents age 12 years and older. [1]
| Attribute |
Daranide |
Keveyis |
| Active ingredient |
Dichlorphenamide |
Dichlorphenamide |
| Drug class |
Carbonic anhydrase inhibitor |
Carbonic anhydrase inhibitor |
| Historic brand status |
Legacy product |
Current U.S. specialty product |
| Primary modern indication |
No active Daranide development program |
Primary periodic paralysis |
| Dosage form |
Oral tablets |
Oral tablets |
| FDA status |
Legacy/discontinued brand |
FDA-approved product |
| Commercial owner |
Historical manufacturers |
Xeris Pharmaceuticals |
| Market category |
Historical generic-like drug |
Rare-disease specialty medicine |
Are there active Daranide clinical trials?
No active clinical-trial program is associated with the Daranide brand. The relevant modern clinical evidence comes from studies of dichlorphenamide conducted for Keveyis.
The pivotal program evaluated dichlorphenamide in patients with primary periodic paralysis. Periodic paralysis is rare, and the clinical program used a small-patient-population design that included randomized withdrawal and attack-frequency endpoints rather than conventional large-scale registration trials.
What did the pivotal dichlorphenamide trials show?
The FDA review identified two principal controlled studies. One study enrolled patients with hypokalemic periodic paralysis, while the other included patients with hyperkalemic periodic paralysis or related phenotypes. Patients were randomized to dichlorphenamide or placebo after dose stabilization, and efficacy was assessed through the frequency of paralytic attacks.
The studies supported a reduction in attack frequency for selected patients with primary periodic paralysis. The treatment effect was clinically relevant but variable, consistent with the heterogeneous genetic and phenotypic nature of the disease. Common adverse reactions included paresthesia, cognitive effects, fatigue, gastrointestinal symptoms, and laboratory abnormalities associated with carbonic anhydrase inhibition. [1]
| Clinical element |
Dichlorphenamide evidence |
| Development population |
Primary periodic paralysis |
| Main subtypes |
Hypokalemic and hyperkalemic periodic paralysis |
| Trial design |
Randomized, placebo-controlled withdrawal studies |
| Primary efficacy concept |
Reduction in paralytic attack frequency |
| Key safety issues |
Paresthesia, cognitive effects, fatigue, metabolic acidosis, electrolyte changes, renal complications |
| Regulatory outcome |
U.S. approval as Keveyis in 2015 |
Because the product has been used for decades, much of the broader evidence base consists of older case reports, observational studies, clinical experience, and small investigator-led studies rather than large contemporary trials.
What is the FDA regulatory status of Daranide?
Daranide is not the current FDA-marketed brand for dichlorphenamide. Keveyis is the relevant FDA-approved product in the United States.
The regulatory distinction matters for market analysis:
- Daranide does not represent a current branded revenue stream.
- Dichlorphenamide remains an FDA-approved active ingredient through Keveyis.
- Historical Daranide approvals and labeling do not establish current commercial rights for the original brand.
- Current prescribing, safety information, and approved indications should be evaluated through the Keveyis label and FDA approval record. [1][2]
Keveyis was approved under NDA 204902. The approval was based on clinical studies in primary periodic paralysis and included dosing, contraindications, warnings, and monitoring requirements specific to dichlorphenamide.
When did Daranide lose exclusivity?
Daranide's original composition-of-matter protection expired decades ago, if it was protected by a patent in the relevant jurisdiction. Dichlorphenamide is an old small-molecule active ingredient and is not protected today by meaningful original-molecule exclusivity.
The commercial protection for Keveyis has instead depended on:
- Orphan-drug exclusivity;
- Product-specific patents;
- Regulatory exclusivity associated with the approved indication;
- Formulation, dosing, and method-of-use rights;
- Manufacturing and supply controls;
- The small size of the periodic-paralysis patient population.
Keveyis received orphan-drug designation for primary periodic paralysis. Orphan-drug exclusivity generally lasts seven years in the United States from approval, subject to statutory exceptions and the scope of the protected indication. That exclusivity period does not create permanent protection for the active ingredient.
What patents protect Keveyis and dichlorphenamide?
The relevant patent estate is narrower than the estate for a newly discovered chemical entity. The active ingredient itself is old. Potential protection has focused on the use of dichlorphenamide in periodic paralysis, dosing regimens, patient selection, and commercial product presentation.
Publicly available FDA and patent records should be reviewed for the current Orange Book listing and expiration status of each Keveyis patent. The original Daranide product does not provide a current patent barrier comparable to a new molecular entity. Patent risk for a competing product would therefore depend on the exact proposed indication, labeling, dosage regimen, formulation, and regulatory pathway.
| Protection category |
Relevance to Daranide/Keveyis |
| Original active-ingredient patent |
Expired or commercially obsolete |
| Periodic-paralysis method patents |
Potentially relevant to labeled-use claims |
| Formulation patents |
Potentially relevant if a competing product uses a protected formulation |
| Orphan exclusivity |
Historically important for the approved rare-disease indication |
| Manufacturing patents |
Possible process protection, but less likely to block a conventional generic route |
| Trademark rights |
Daranide and Keveyis branding rights do not prevent sale of a non-infringing generic |
What is the Orange Book status of Daranide and Keveyis?
Daranide should not be treated as a current Orange Book commercial reference product. Keveyis is the relevant listed FDA product for dichlorphenamide in the United States.
An Orange Book assessment should examine:
- The active Keveyis NDA;
- Listed patents and their expiration dates;
- Any pediatric exclusivity;
- Whether patents are method-of-use patents;
- Whether a generic applicant can carve out protected indications;
- Whether the reference product has current commercial availability.
A Paragraph IV applicant would need to challenge any listed patent it believes is invalid, unenforceable, or not infringed. A filing could also use a section viii statement to omit a patented method of use, provided the proposed labeling does not actively encourage the protected indication.
Which companies are challenging Daranide or Keveyis?
There is no material public litigation profile involving the original Daranide brand. The relevant competitive question is whether generic manufacturers will challenge or enter against Keveyis.
A generic entrant would face several practical constraints:
- The patient population is small.
- Demand is concentrated among specialist neurologists.
- Diagnosis is often delayed or genetically unresolved.
- The market may support only limited commercial scale.
- The branded product has established specialty distribution and reimbursement infrastructure.
- Method-of-use patents could create labeling and litigation issues.
- The generic applicant must demonstrate pharmaceutical equivalence and adequate quality controls.
No broad-based generic challenge should be inferred solely from the age of dichlorphenamide. An old active ingredient can still support a commercially protected specialty product when regulatory exclusivity, orphan economics, and specialized distribution reduce entry incentives.
What generic entry risks exist for dichlorphenamide?
Generic entry risk is moderate from a chemistry perspective and more limited from a commercial perspective.
Dichlorphenamide is a small molecule with a long history of use. That makes synthesis and analytical characterization comparatively straightforward. A conventional immediate-release tablet may not present the technical barriers associated with complex biologics, depot injectables, or advanced delivery systems.
The principal barriers are commercial and regulatory:
| Risk factor |
Impact on generic entry |
| Old active ingredient |
Lowers technical development risk |
| Rare-disease population |
Limits expected sales volume |
| Specialist prescribing |
Raises market-access costs |
| Orphan indication |
Can delay competitive entry during exclusivity |
| Method-of-use patents |
May require Paragraph IV or section viii strategy |
| Reimbursement |
Can favor the established product |
| Limited competitors |
May preserve attractive pricing for the brand |
| Manufacturing |
Requires compliant tablet production and validated controls |
A generic could launch under a carve-out label if it excludes protected periodic-paralysis use and still has a legally supportable indication. That strategy would be commercially weak if most demand is tied to the protected rare-disease use.
How strong is the patent estate for Daranide?
The Daranide patent estate is weak as a standalone asset because the brand and active ingredient are old. The Keveyis estate is stronger in regulatory and commercial terms than in basic chemistry.
Patent-strength assessment
| Estate component |
Relative strength |
| Active ingredient |
Weak |
| Historic Daranide brand |
Weak |
| New chemical entity protection |
None of current commercial significance |
| Periodic-paralysis use claims |
Moderate, depending on claim scope and expiration |
| Formulation protection |
Product-specific and potentially limited |
| Orphan exclusivity |
Historically strong but time-limited |
| Supply-chain and specialty distribution |
Moderate commercial barrier |
| Manufacturing know-how |
Potentially useful but unlikely to block all generic production |
The highest litigation risk would arise from a generic application that directly seeks approval for primary periodic paralysis while listed method-of-use patents remain enforceable. The lowest risk would arise from a product with a legally permissible label that excludes protected uses and does not induce infringement.
What is the market size and revenue exposure for Keveyis?
Daranide has no meaningful current standalone market forecast. The addressable market is the commercial market for dichlorphenamide in primary periodic paralysis, primarily through Keveyis in the United States.
Primary periodic paralysis is an ultra-rare condition. Prevalence estimates vary by subtype, geography, diagnostic criteria, and genetic ascertainment. The treated population is much smaller than the total number of potentially affected individuals because diagnosis is frequently delayed and treatment is concentrated among specialized centers.
Revenue depends on:
- Number of diagnosed patients;
- Number of treated patients;
- Net annual price;
- Payer coverage;
- Persistence and dose;
- Patient-assistance programs;
- Competition from generic dichlorphenamide;
- Use of alternative carbonic anhydrase inhibitors such as acetazolamide.
Xeris reports product-level commercial performance in its public filings, although reporting categories and net revenue disclosure can change over time. Keveyis is part of Xeris's commercial specialty portfolio, and revenue should be analyzed from company filings rather than inferred from prescription volume alone. [3]
Commercial scenario framework
| Scenario |
Market development |
Likely effect |
| Base case |
Stable specialty use with gradual diagnosis growth |
Modest revenue growth or stability |
| Upside case |
Greater genetic testing, specialist awareness, and treatment penetration |
Higher patient count and durable pricing |
| Downside case |
Generic entry, payer restrictions, or substitution with older therapy |
Material price and share erosion |
| Litigation-delay case |
Patent challenge delays approved generic launch |
Continued branded revenue protection |
| Generic-entry case |
One or more approved generics enter the periodic-paralysis market |
Rapid price compression, with uncertain patient switching |
A conventional blockbuster forecast is inappropriate. The asset is an orphan specialty product with a narrow patient pool, potentially high annual treatment revenue per patient, and substantial sensitivity to generic entry.
How does Daranide compare with acetazolamide and other treatments?
Dichlorphenamide competes with acetazolamide and other carbonic anhydrase inhibitors in periodic paralysis. Acetazolamide is older, widely available, and generally less commercially protected. Dichlorphenamide may be selected when clinicians seek an alternative or when response to acetazolamide is inadequate.
| Drug |
Role in periodic paralysis |
Commercial profile |
| Dichlorphenamide |
FDA-approved Keveyis indication for primary periodic paralysis |
Branded rare-disease product |
| Acetazolamide |
Common off-label or established alternative |
Low-cost generic |
| Potassium supplementation |
Used in selected hypokalemic patients |
Commodity therapy |
| Trigger avoidance |
Supportive management |
No drug revenue |
| Other carbonic anhydrase inhibitors |
Case-specific alternatives |
Limited commercial differentiation |
The competitive threat from acetazolamide is significant because it is inexpensive and familiar. The commercial value of Keveyis depends on treatment response, physician preference, payer acceptance, and the ability to maintain a differentiated approved product despite generic availability of the active ingredient.
What manufacturing and intellectual-property barriers affect generic launch?
Manufacturing barriers are relatively low compared with biologic drugs. Dichlorphenamide is a small molecule administered as an oral tablet, with no biosimilar pathway or complex delivery system.
A manufacturer would still need to address:
- Active pharmaceutical ingredient sourcing;
- Impurity specifications;
- Tablet formulation and dissolution;
- Stability data;
- Bioequivalence;
- Quality-system compliance;
- Labeling strategy;
- Patent certification;
- Pharmacovigilance.
Biosimilar risk is not applicable. Dichlorphenamide is not a biologic, peptide, or cell-based therapy. The relevant competitive pathway is an abbreviated new drug application for a chemically equivalent product, subject to FDA requirements.
What is the outlook for Daranide and dichlorphenamide?
The original Daranide brand has little forward commercial value. Dichlorphenamide retains clinical relevance through Keveyis, but its opportunity is limited to a rare disease with a small treated population.
The most important variables through the next several years are:
- The enforceability and expiration of any Keveyis-listed patents.
- The timing of an ANDA filing and any Paragraph IV litigation.
- Generic manufacturers' willingness to pursue a small specialty market.
- Xeris's ability to maintain reimbursement and specialist access.
- Diagnosis expansion through genetic testing and neuromuscular referral.
- Substitution by acetazolamide and other low-cost therapies.
- Net price erosion after generic entry.
The likely market pattern is stable specialty revenue before credible generic entry, followed by substantial price pressure if a generic obtains approval for the core periodic-paralysis market. The absence of active clinical trials for Daranide limits the likelihood of a new indication or formulation materially expanding the legacy brand's value.
Key Takeaways
- Daranide is the legacy brand for dichlorphenamide and is not the current U.S. commercial growth product.
- Keveyis is the FDA-approved modern product containing dichlorphenamide for primary periodic paralysis.
- No active clinical-development program is associated with Daranide itself.
- The modern evidence base consists of small controlled studies supporting reduced attack frequency in primary periodic paralysis.
- Original active-ingredient protection is no longer commercially meaningful.
- Relevant protection is based on indication-specific patents, orphan exclusivity, regulatory status, and commercial execution.
- Generic entry is technically feasible but may be delayed by limited market size, patent issues, and specialized distribution.
- Biosimilar competition is irrelevant because dichlorphenamide is a small-molecule drug.
- Acetazolamide is the principal low-cost therapeutic competitor.
- Daranide has no meaningful standalone revenue forecast; commercial exposure should be assessed through Keveyis and Xeris filings.
FAQs
Is Daranide still available in the United States?
The original Daranide brand is not the current U.S. commercial product. Dichlorphenamide is marketed in the United States as Keveyis for primary periodic paralysis.
Is dichlorphenamide a generic drug?
Dichlorphenamide is an old small-molecule active ingredient, but branded Keveyis has been marketed as an orphan specialty product for primary periodic paralysis. Generic availability depends on FDA approvals, patent status, and labeling.
Does Daranide have biosimilar risk?
No. Biosimilar competition applies to biologic products. Dichlorphenamide is a chemically synthesized small molecule, so any competition would come through generic drug pathways.
Can acetazolamide replace dichlorphenamide?
Acetazolamide is used as an alternative in periodic paralysis, but clinical response varies by patient and disease subtype. Treatment selection depends on physician assessment, attack pattern, electrolyte status, adverse effects, and payer access.
What would cause Keveyis revenue to decline?
The main risks are generic entry, patent invalidation or expiration, payer restrictions, substitution by acetazolamide, reduced net pricing, and limited growth in the diagnosed and treated patient population.
References
- U.S. Food and Drug Administration. (2015). Keveyis (dichlorphenamide) prescribing information. FDA.
- U.S. Food and Drug Administration. (n.d.). Drugs@FDA: Keveyis NDA 204902. FDA.
- Xeris Biopharma Holdings, Inc. (2024). Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934. U.S. Securities and Exchange Commission.
