QUIBRON-T Drug Patent Profile

Which patents cover Quibron-t, and when can generic versions of Quibron-t launch?

Quibron-t is a drug marketed by Monarch Pharms and is included in two NDAs.

The generic ingredient in QUIBRON-T is theophylline. There is one drug master file entry for this compound. Twenty-six suppliers are listed for this compound. Additional details are available on the theophylline profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Quibron-t

A generic version of QUIBRON-T was approved as theophylline by RHODES PHARMS on September 1^st, 1982.

Summary for QUIBRON-T

US Patents:	0
Applicants:	1
NDAs:	2
Raw Ingredient (Bulk) Api Vendors:	142
Patent Applications:	3,330
DailyMed Link:	QUIBRON-T at DailyMed

US Patents and Regulatory Information for QUIBRON-T

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Monarch Pharms	QUIBRON-T	theophylline	TABLET;ORAL	088656-001	Aug 22, 1985		DISCN	No	No
Monarch Pharms	QUIBRON-T/SR	theophylline	TABLET, EXTENDED RELEASE;ORAL	087563-001	Jun 21, 1983		DISCN	No	No

Quibron-T Market Dynamics, Patent Status, and Financial Trajectory

Last updated: September 19, 2026

Quibron-T is an extended-release theophylline product that has lost commercial relevance as asthma and chronic obstructive pulmonary disease treatment shifted toward inhaled corticosteroids, long-acting bronchodilators, and combination inhalers. Its market is now primarily generic, price-sensitive, and fragmented. Public sources do not report standalone Quibron-T revenue, and the product does not have a meaningful current branded revenue stream.

What is Quibron-T and who manufactured it?

Quibron-T is an oral, extended-release formulation of theophylline, a methylxanthine bronchodilator. The product was marketed in multiple tablet strengths, including 200 mg, 300 mg, and 400 mg formulations. Purdue Pharma was identified as the labeler for Quibron-T in U.S. product information.[1]

The product was intended to provide sustained theophylline exposure and reduce dosing frequency compared with immediate-release formulations. Theophylline has historically been used for asthma, chronic bronchitis, and emphysema, but its narrow therapeutic range and substantial drug-interaction profile have reduced its role in modern respiratory treatment.[1]

Attribute	Quibron-T
Active ingredient	Theophylline
Drug class	Methylxanthine bronchodilator
Dosage form	Extended-release oral tablet
Historical strengths	200 mg, 300 mg, 400 mg
Primary indications	Asthma and chronic obstructive respiratory disease
U.S. sponsor or labeler	Purdue Pharma, based on historical prescribing information
Regulatory category	Prescription drug
Current commercial position	Legacy product with generic substitution and limited brand visibility
Biologic status	Not a biologic; biosimilar competition is not applicable

What is the FDA regulatory status of Quibron-T?

Quibron-T is a legacy FDA-approved prescription product, but its commercial availability has declined substantially. The FDA’s drug-discontinuation framework distinguishes a product that is no longer marketed from a product withdrawn for safety or effectiveness reasons.[2]

Available labeling identifies Quibron-T as an extended-release theophylline product. The commercial status of particular strengths, package sizes, and National Drug Code entries can change independently, and older NDC listings may remain in reference databases after active distribution has ended.

The FDA’s current therapeutic approach does not give theophylline a preferred position in routine asthma management. The Global Initiative for Asthma places inhaled therapies at the center of treatment and limits reliance on oral methylxanthines because of their lower efficacy and safety concerns.[3]

FDA regulatory factors affecting commercial demand

Theophylline demand has been constrained by:

• A narrow therapeutic index.
• Variable metabolism between patients.
• Significant interactions with smoking, macrolide antibiotics, fluoroquinolones, anticonvulsants, and other drugs.
• Need for serum concentration monitoring in higher-risk patients.
• Inferior convenience compared with inhaled maintenance therapies.
• Better-established alternatives for asthma and COPD.

These factors raise prescribing friction even where generic theophylline remains technically available.

When did Quibron-T lose exclusivity?

Quibron-T is not understood to have a current period of meaningful market exclusivity. Its active ingredient, theophylline, has been used for decades, and the relevant extended-release oral dosage form has long been subject to generic competition.

The commercial loss of exclusivity occurred through the normal lifecycle of an older small-molecule medicine rather than through a single recent patent cliff. Generic extended-release theophylline products have been available from multiple manufacturers, limiting the ability of a branded product to maintain premium pricing.

Exclusivity category	Quibron-T assessment
New chemical entity exclusivity	Expired or not commercially relevant
Orphan-drug exclusivity	Not applicable
Pediatric exclusivity	No current commercial significance identified
Biologic exclusivity	Not applicable
Active branded formulation exclusivity	No material current barrier identified
Generic substitution	Established
Current patent cliff	Historical rather than upcoming

What patents protect Quibron-T?

No active patent estate appears to provide Quibron-T with a material current commercial moat. Theophylline is an old active ingredient, and extended-release oral formulations have been developed and marketed by multiple companies.

The relevant intellectual-property categories would have included:

1. Composition patents covering theophylline.
2. Extended-release formulation patents.
3. Manufacturing-process patents.
4. Packaging or dosage-regimen claims.
5. Method-of-use claims for respiratory disease.

For a legacy product such as Quibron-T, any original composition protection would have expired long ago. Formulation patents, if previously asserted, would also be expected to have expired or to have become commercially irrelevant because multiple generic products entered the market.

The absence of a current patent barrier does not eliminate formulation risk. Extended-release theophylline products can differ in release characteristics and may not be therapeutically interchangeable across all products without regulatory evaluation. That issue affects substitution and physician confidence, but it is not equivalent to enforceable patent exclusivity.

What formulations are protected by Quibron-T?

Quibron-T’s principal technical value was its extended-release tablet formulation. The formulation was designed to release theophylline over an extended period and support less frequent dosing.

The commercial distinction between Quibron-T and generic products historically depended on:

• Release profile.
• Tablet strength.
• Dosing interval.
• Manufacturing consistency.
• Patient tolerance.
• Pharmacy substitution rules.
• Product availability.

The extended-release segment has faced a structural problem: formulation differentiation is difficult to monetize when the active ingredient is old, the clinical need is well understood, and generic manufacturers can offer comparable dosage forms at lower prices.

How strong is the Quibron-T patent estate?

The patent estate is weak from a present-day commercial perspective.

Patent-strength factor	Assessment
Active ingredient protection	None of current commercial significance
Remaining patent term	No material term identified
Formulation differentiation	Historically relevant, currently weak
Method-of-use protection	No meaningful current barrier identified
Orange Book leverage	Limited or absent
Generic blocking power	Low
Litigation value	Low
Licensing value	Low

Quibron-T also lacks the characteristics that support a strong lifecycle-management strategy. The product is not a biologic, does not require a complex delivery device, and does not depend on a proprietary manufacturing platform that would create a durable barrier to entry.

What is the Orange Book status of Quibron-T?

The Orange Book is relevant to Quibron-T only as a historical reference point. Any active Orange Book listing would need to be checked against the current FDA edition and the relevant product number because legacy products may be discontinued, delisted, or absent from current commercial listings.[4]

There is no apparent current Orange Book patent position that would prevent approval of a generic extended-release theophylline product. Generic applicants for an established product would generally rely on an abbreviated new drug application pathway, subject to the applicable reference-product and bioequivalence requirements.

Paragraph IV challenges

No current, commercially significant Paragraph IV campaign against Quibron-T is apparent. That outcome is consistent with the product’s age and the lack of a valuable remaining patent estate.

Historical generic entry would have involved abbreviated applications and, where applicable, patent certifications. Today, the economic value of a new Paragraph IV challenge would be limited because the market is mature, the active ingredient is inexpensive, and brand demand is small.

Which companies are challenging Quibron-T?

The current competitive challenge is not centered on named litigation opponents. It comes from generic theophylline manufacturers and therapeutic substitution.

Generic competition includes manufacturers that have marketed extended-release theophylline tablets or capsules under their own labels. The competitive field can change by strength, package size, manufacturing site, and supply status.

The more important challengers are alternative respiratory therapies:

• Inhaled corticosteroids.
• Long-acting beta agonists.
• Long-acting muscarinic antagonists.
• Inhaled corticosteroid and long-acting bronchodilator combinations.
• Biologic therapies for severe asthma.
• Short-acting rescue inhalers.

These products compete with theophylline for prescribing volume even when they do not contain the same active ingredient.

What patent litigation affects Quibron-T?

No material current patent litigation involving Quibron-T is apparent. The product’s age, generic availability, and limited revenue base reduce the incentive for branded patent litigation.

A meaningful litigation strategy would require a patent with enough remaining term and market value to justify litigation expense. Quibron-T does not appear to meet that threshold. Any dispute involving theophylline today would more likely concern:

• Product quality.
• Manufacturing compliance.
• Shortages.
• Bioequivalence.
• Labeling.
• Distribution rights.
• Contract or supply obligations.

These are regulatory or commercial issues rather than classic branded patent litigation.

What is the financial trajectory for Quibron-T?

Quibron-T’s financial trajectory is consistent with late-stage generic erosion:

1. Initial branded sales were supported by a prescription market for oral theophylline.
2. Revenue pressure increased as inhaled respiratory therapies became standard.
3. Generic entry reduced price and pharmacy-level brand retention.
4. Prescribing declined because of safety monitoring and interaction concerns.
5. Brand economics weakened further as distribution narrowed.
6. The product moved toward residual or discontinued commercial status.

No public filing appears to provide a standalone Quibron-T revenue line. Purdue Pharma historically reported portfolios rather than product-level revenue for many mature prescription products. Any precise revenue estimate would therefore lack reliable public support.

Financial driver	Direction of impact
Generic substitution	Strongly negative
Inhaled therapy adoption	Strongly negative
Theophylline price erosion	Negative
Low manufacturing complexity	Negative for brand pricing power
Narrow therapeutic index	Negative for prescribing
Residual low-cost demand	Modestly positive
Supply shortages of alternatives	Potentially positive but episodic
Patent protection	No current support
Licensing potential	Minimal

Does Quibron-T have biosimilar risk?

No. Biosimilar competition applies to biologic products. Quibron-T is a conventional small-molecule drug, so the relevant competitive threat is generic substitution, not biosimilar entry.

Generic manufacturers may compete through abbreviated new drug applications, product pricing, pharmacy contracts, wholesaler access, and supply reliability. The key regulatory issue is bioequivalence for the extended-release dosage form.

What generic launch scenarios exist for Quibron-T?

Three commercial scenarios are plausible for the remaining market.

Continued low-volume generic supply

Manufacturers continue supplying selected strengths to patients who remain stable on oral theophylline. Pricing stays low, and brand demand remains limited.

Intermittent shortage-driven demand

A manufacturer interruption or wholesaler shortage temporarily increases demand for another extended-release theophylline product. Such demand would likely be temporary and would not restore durable brand value.

Further market contraction

Prescribers continue switching patients to inhaled therapies, leaving theophylline for selected patients with cost, access, or clinical factors that limit alternatives. The market becomes smaller and more dependent on a few suppliers.

The third scenario is the most consistent with the long-term treatment trend documented in modern asthma and COPD guidelines.[3,5]

What geographic markets matter for Quibron-T?

The United States is unlikely to offer meaningful branded growth. The product’s commercial value is constrained by generic penetration, payer price controls, and declining use of oral theophylline.

International markets may retain pockets of demand where inhaled therapies are less affordable or less accessible. The commercial opportunity is still limited because:

• Theophylline is broadly off-patent.
• Local generic competition is established.
• Regulatory registrations differ by country.
• Pricing is typically low.
• Distribution depends on local manufacturing and tender systems.

Geographic expansion would therefore be a volume strategy, not a premium-pricing strategy.

What manufacturing and intellectual-property barriers remain?

Manufacturing barriers are moderate but not proprietary. Extended-release theophylline requires consistent control of dissolution and drug release. Manufacturers must manage:

• Content uniformity.
• Dissolution specifications.
• Stability.
• Batch-to-batch release performance.
• Packaging and moisture control.
• Bioequivalence requirements.

These requirements can cause supply problems for small manufacturers, but they do not create a durable patent moat. The main barriers are regulatory execution, quality systems, and commercial scale.

How does Quibron-T compare with modern respiratory drugs?

Factor	Quibron-T	Modern inhaled therapies
Administration	Oral	Inhaled
Monitoring	May require serum-level monitoring	Usually no serum monitoring
Therapeutic window	Narrow	Generally wider for routine use
Drug interactions	Significant	Product-specific, often more manageable
Clinical positioning	Limited or alternative therapy	Standard maintenance or rescue treatment
Patent potential	Minimal	May include composition, device, formulation, or method patents
Pricing power	Low	Higher for branded combinations and biologics
Generic exposure	High	Varies by molecule and device
Commercial growth	Declining or flat at best	Depends on product class and indication

Key Takeaways

• Quibron-T is an extended-release theophylline product with limited current commercial relevance.
• The product has no meaningful current patent moat or exclusivity period.
• Generic substitution and therapeutic replacement by inhaled drugs drove the long-term decline.
• No material current Paragraph IV campaign or patent litigation is apparent.
• Biosimilar competition does not apply because theophylline is a small molecule.
• Public sources do not provide standalone Quibron-T revenue, and the brand should be treated as a residual or discontinued commercial asset.
• Remaining value lies in low-cost generic supply, not branded pricing, licensing, or patent enforcement.
• The main barriers are manufacturing consistency, regulatory compliance, and distribution reliability.

FAQs

Is Quibron-T still available in the United States?

Availability can vary by strength, manufacturer, wholesaler, and pharmacy inventory. Historical Quibron-T labeling exists, but current supply should not be equated with active branded commercialization.

Is Quibron-T the same as generic theophylline?

Quibron-T contains theophylline in an extended-release formulation. Generic theophylline products may use different release technologies, strengths, manufacturers, and dosing instructions.

Is Quibron-T protected by patents?

No current patent protection appears to provide commercially meaningful exclusivity. Any historical patents covering the active ingredient or extended-release technology would be expected to have expired.

Why did doctors stop using Quibron-T?

Theophylline has a narrow therapeutic range, significant drug interactions, variable metabolism, and monitoring requirements. Inhaled therapies generally provide more targeted respiratory treatment and have become standard for many patients.[3,5]

Could Quibron-T regain commercial value during a respiratory-drug shortage?

A shortage of inhaled or alternative respiratory medicines could produce temporary demand for theophylline. That scenario would not create durable patent value or restore the product’s historical branded economics.

References

1. Purdue Pharma L.P. (n.d.). Quibron-T: Theophylline extended-release tablets prescribing information. U.S. Food and Drug Administration labeling archive. https://www.accessdata.fda.gov/

2. U.S. Food and Drug Administration. (n.d.). Drug products discontinued from marketing. https://www.fda.gov/drugs/drug-approvals-and-databases/drug-products-discontinued-marketing

3. Global Initiative for Asthma. (2024). Global strategy for asthma management and prevention. https://ginasthma.org/

4. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, 44th edition. https://www.fda.gov/drugs/drug-approvals-and-databases/orange-book-data-files

5. Global Initiative for Chronic Obstructive Lung Disease. (2024). Global strategy for prevention, diagnosis and management of COPD. https://goldcopd.org/