CALAN Drug Patent Profile

Which patents cover Calan, and what generic alternatives are available?

Calan is a drug marketed by Gd Searle Llc and Pfizer and is included in three NDAs.

The generic ingredient in CALAN is verapamil hydrochloride. There is one drug master file entry for this compound. Forty-six suppliers are listed for this compound. Additional details are available on the verapamil hydrochloride profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Calan

A generic version of CALAN was approved as verapamil hydrochloride by EXELA PHARMA on March 30^th, 1984.

Summary for CALAN

US Patents:	0
Applicants:	2
NDAs:	3
Raw Ingredient (Bulk) Api Vendors:	1
Patent Applications:	3,378
Drug Prices:	Drug price information for CALAN
DailyMed Link:	CALAN at DailyMed

See drug prices for CALAN

US Patents and Regulatory Information for CALAN

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Gd Searle Llc	CALAN	verapamil hydrochloride	INJECTABLE;INJECTION	019038-001	Mar 30, 1984		DISCN	No	No
Pfizer	CALAN SR	verapamil hydrochloride	TABLET, EXTENDED RELEASE;ORAL	019152-002	Dec 15, 1989		DISCN	Yes	No
Pfizer	CALAN	verapamil hydrochloride	TABLET;ORAL	018817-002	Sep 10, 1984		DISCN	Yes	No
Pfizer	CALAN SR	verapamil hydrochloride	TABLET, EXTENDED RELEASE;ORAL	019152-001	Dec 16, 1986		DISCN	Yes	No
Pfizer	CALAN	verapamil hydrochloride	TABLET;ORAL	018817-003	Feb 23, 1988		DISCN	No	No
Pfizer	CALAN	verapamil hydrochloride	TABLET;ORAL	018817-001	Sep 10, 1984		DISCN	Yes	No

Calan (Verapamil) Market Dynamics, Patent Status, and Financial Trajectory

Last updated: September 19, 2026

Calan is the legacy brand for verapamil hydrochloride, a calcium-channel blocker used for hypertension, angina, and supraventricular tachycardia. Its commercial value is now driven by generic verapamil rather than brand sales. Core composition-of-matter and regulatory exclusivity periods expired long ago, no meaningful biosimilar issue exists, and public company filings do not report material standalone Calan revenue.

The commercial outlook is mature and low-growth. Value is concentrated in generic supply, hospital and outpatient formulary access, manufacturing reliability, and extended-release formulations rather than in brand pricing or patent protection.

What is Calan and how is it used?

Calan is an oral formulation of verapamil hydrochloride. Calan SR is the sustained-release version. Verapamil reduces calcium influx in cardiac and vascular smooth muscle and is used in several cardiovascular indications.

Product	Active ingredient	Typical dosage form	Principal uses
Calan	Verapamil hydrochloride	Immediate-release tablets	Hypertension, angina, arrhythmias
Calan SR	Verapamil hydrochloride	Sustained-release tablets	Hypertension, angina, rate control
Generic verapamil	Verapamil hydrochloride	Immediate- and extended-release tablets, capsules, and other formulations	Same broad therapeutic categories

FDA labeling identifies important pharmacokinetic differences between immediate-release and sustained-release products. Substitution between formulations requires attention to strength, release mechanism, dosing frequency, and clinical indication (U.S. Food and Drug Administration [FDA], n.d.-a).

The drug is primarily a mature cardiovascular therapy. It competes with beta blockers, dihydropyridine calcium-channel blockers, non-dihydropyridine calcium-channel blockers such as diltiazem, and newer antiarrhythmic or rate-control strategies.

When does Calan lose exclusivity?

Calan lost meaningful market exclusivity decades ago. Verapamil is an established small-molecule active ingredient, and generic versions have been marketed for many years.

The relevant commercial conclusion is:

• No current brand exclusivity materially protects Calan.
• No meaningful regulatory exclusivity remains for the legacy product.
• Generic competition is legally and commercially established.
• The principal competitive barrier is manufacturing and distribution, not patent ownership.

FDA’s Orange Book is the primary public source for approved drug products, therapeutic-equivalence information, and listed patents or exclusivity. A historical product’s absence of current listed patents does not prove that no patent ever existed, but it indicates that listed patent protection is not a current barrier to generic substitution (FDA, n.d.-b).

What patents protect Calan and generic verapamil?

The current patent estate for Calan is weak from a commercial perspective.

Composition-of-matter protection

Verapamil hydrochloride was discovered and commercialized before the modern patent life structure that applies to newer pharmaceutical products. Any original compound patent rights have expired. Generic manufacturers therefore do not face a remaining composition-of-matter barrier.

Formulation patents

The most relevant historical intellectual property involved sustained-release delivery, tablet design, manufacturing processes, and dosing schedules. Any surviving formulation patent would need to be listed in the Orange Book or enforced against a specific product to create a meaningful commercial constraint.

There is no widely recognized active patent position that preserves market exclusivity for Calan SR as a brand. Extended-release verapamil remains commercially exposed to generic competition, subject to product-specific FDA approval and therapeutic-equivalence requirements.

Method-of-use patents

Verapamil has multiple clinical uses, but its core indications are longstanding. Method-of-use claims would have limited commercial leverage because:

1. The underlying molecule is generic.
2. Physicians prescribe verapamil across several established indications.
3. Generic manufacturers can pursue labels that omit protected indications where applicable.
4. Enforcement would require a current, enforceable claim and evidence of induced infringement.

No major active method-of-use patent dispute is publicly associated with Calan’s current commercial position.

What is the Orange Book status of Calan?

Calan’s Orange Book relevance is historical and regulatory rather than exclusivity-driven.

FDA’s Orange Book typically distinguishes among:

• Reference-listed drugs.
• Generic products approved through abbreviated new drug applications.
• Therapeutic-equivalence codes.
• Listed patents and regulatory exclusivity.

For an established product such as verapamil, the key commercial question is whether a generic product is therapeutically equivalent and available from multiple suppliers. That condition has existed for years for immediate-release and extended-release verapamil products.

The Orange Book does not establish market demand, supply reliability, or current brand availability. It also does not guarantee that a product listed in FDA databases is actively marketed at every strength or in every channel.

How many patents cover Calan?

No current, material Calan patent estate is apparent from the public regulatory profile of verapamil.

IP category	Current commercial relevance
Original verapamil compound patent	Expired
Original Calan product protection	Expired or no longer commercially material
Sustained-release formulation patents	No known blocking estate for the legacy brand
Method-of-use patents	No known material barrier to generic prescribing
Manufacturing patents	Potentially relevant to individual processes, but not a broad market barrier
Regulatory exclusivity	None of commercial significance
Biosimilar exclusivity	Not applicable

A precise historical patent schedule cannot be reconstructed reliably from the current Orange Book alone because older products may have changed sponsors, formulations, and listing practices over time.

Which companies are challenging Calan through Paragraph IV filings?

Calan is not a current high-value Paragraph IV battleground.

Paragraph IV litigation is most commercially important when:

• The reference drug has significant remaining sales.
• A patent expiry date is near.
• A generic launch could capture substantial value.
• The challenger can obtain first-filer or settlement leverage.

Those conditions do not describe legacy Calan. Generic verapamil entered the market long ago, and current public attention is not centered on a pending first generic challenge to the brand.

A historical Paragraph IV filing may have existed for a particular extended-release formulation, strength, or sponsor, but such activity would not change the present market conclusion: Calan has already passed the principal generic-entry event.

What is the FDA regulatory status of Calan?

FDA regulates Calan as an approved prescription drug product containing verapamil hydrochloride. Regulatory status varies by strength, dosage form, applicant, and marketing activity.

The relevant FDA pathways are:

• Original new drug application approval for the branded product.
• Abbreviated new drug application approval for generic immediate-release and extended-release products.
• Therapeutic-equivalence determinations recorded in the Orange Book.
• Labeling updates addressing contraindications, drug interactions, and dosing.

Verapamil labeling includes clinically important warnings involving hypotension, bradycardia, atrioventricular block, heart failure, hepatic impairment, and drug interactions. These safety issues affect prescribing and formulary positioning but do not create brand differentiation that can support premium pricing (FDA, n.d.-a; DailyMed, n.d.).

What is the market size and financial trajectory for Calan?

Public financial disclosures do not provide a reliable standalone revenue series for Calan. Pfizer and other large pharmaceutical companies generally aggregate mature products into broader portfolios, and generic manufacturers do not report product-level revenue for verapamil in public filings.

The financial trajectory is therefore best characterized qualitatively:

Period	Commercial condition	Financial implication
Brand launch and early adoption	Branded cardiovascular therapy with limited competition	Higher pricing and brand economics
Generic entry	Multiple abbreviated-approval products enter	Rapid price and share erosion
Mature generic phase	Several suppliers compete on price and supply	Low unit economics and fragmented revenue
Current market	Legacy brand with generic substitution	Limited brand revenue; value shifts to manufacturing scale

Calan is unlikely to represent a material revenue contributor for Pfizer relative to the company’s major patented and specialty products. For generic manufacturers, verapamil may provide recurring low-to-moderate revenue, but public filings do not isolate the product sufficiently to calculate market share or total market sales.

The key financial variables are:

• Generic prescription volume.
• Reimbursement rates.
• Wholesale acquisition price.
• Medicaid and Medicare reimbursement.
• Number of approved suppliers.
• Shortage risk.
• Active marketing status by strength.
• Hospital purchasing contracts.
• Production cost for extended-release products.

Price erosion is structurally stronger for immediate-release verapamil because production is relatively established and substitution options are broad. Extended-release products may retain somewhat better economics when fewer suppliers manufacture particular strengths or delivery systems.

How does Calan compare with competing cardiovascular drugs?

Calan competes in two distinct markets: chronic cardiovascular therapy and acute or chronic rate control.

Drug class	Representative products	Competitive effect on verapamil
Dihydropyridine calcium-channel blockers	Amlodipine	Strong competition in hypertension
Beta blockers	Metoprolol, atenolol	Strong competition in hypertension and rate control
Non-dihydropyridine calcium-channel blockers	Diltiazem	Direct clinical substitute
Antiarrhythmics	Flecainide, amiodarone, sotalol	Indication-specific competition
Generic verapamil	Multiple manufacturers	Direct price and availability competition

Amlodipine and metoprolol generally have broader prescribing familiarity in hypertension. Diltiazem is the most direct pharmacologic competitor in rate control and certain arrhythmia settings. Verapamil maintains clinical utility in selected patients, but its commercial position is constrained by generic substitution and prescribing alternatives.

What generic entry risks exist for Calan?

The generic-entry risk is already realized rather than prospective. The remaining risks relate to supply and product-level competition.

Immediate-release products

Immediate-release verapamil faces high generic substitution pressure. Multiple manufacturers can compete where approved products remain actively marketed. A brand relaunch would face limited ability to command a premium without a differentiated delivery system, adherence benefit, or distribution advantage.

Extended-release products

Extended-release verapamil has somewhat greater technical complexity. Risk factors include:

• Release-rate matching.
• Dose proportionality.
• Dissolution testing.
• Food-effect considerations.
• Manufacturing consistency.
• Product-specific therapeutic-equivalence requirements.

These factors can reduce the number of active suppliers at a particular strength, but they do not create durable brand exclusivity by themselves.

What patent litigation affects Calan?

No major active litigation is publicly associated with Calan’s current commercial position. The product is not commonly identified as a current high-value patent litigation target.

Any litigation involving verapamil would more likely concern:

• A specific generic manufacturer.
• Product liability.
• Manufacturing quality.
• Contract or supply disputes.
• A formulation or process patent unrelated to the core Calan brand.

The absence of high-profile patent litigation is consistent with the drug’s mature generic status.

Are there licensing deals for Calan or verapamil?

No current licensing transaction is publicly recognized as a material driver of Calan’s market value. Historical commercialization involved corporate ownership and product transfers among pharmaceutical companies, but those arrangements do not preserve present-day exclusivity.

Generic verapamil supply may involve contract manufacturing, authorized-generic arrangements, or distributor agreements. These arrangements are typically not disclosed at product level and are unlikely to alter the overall competitive structure.

Is there biosimilar risk for Calan?

No. Biosimilars apply to biological products, while verapamil is a chemically synthesized small molecule. The relevant competitive category is generic substitution, not biosimilar interchangeability.

This distinction matters commercially:

• Generic approval generally relies on pharmaceutical equivalence and bioequivalence.
• Biosimilar approval relies on comparative analytical and clinical evidence for a biologic.
• Calan does not require a biosimilar development program.
• Generic competition has a lower development and regulatory burden than biosimilar competition.

How strong is the Calan patent estate?

The Calan patent estate is weak.

Factor	Assessment
Composition-of-matter protection	None of current commercial significance
Brand exclusivity	None of current commercial significance
Formulation protection	Limited and not visibly blocking
Method-of-use protection	Limited commercial relevance
Generic substitution barrier	Low
Biosimilar barrier	Not applicable
Manufacturing complexity	Moderate for extended release, low to moderate for immediate release
Litigation leverage	Low
Pricing power	Low

The strongest remaining commercial defense is operational execution: reliable supply, regulatory compliance, hospital contracting, and low-cost production.

What is the outlook for Calan revenue and market share?

The base-case outlook is flat to declining brand revenue, with stable but low-value generic demand.

A realistic market trajectory is:

1. Brand sales remain limited because generic substitution is entrenched.
2. Generic volume remains supported by chronic cardiovascular use.
3. Unit prices remain under pressure.
4. Extended-release supply disruptions can temporarily improve pricing for active suppliers.
5. No patent event is likely to create a new exclusivity window.
6. Revenue growth would require a differentiated formulation, new delivery system, or specialty indication.

For an investor or licensing group, Calan is primarily a low-risk, low-growth generic asset. Its value depends on manufacturing economics and supply continuity rather than patent duration or commercial expansion.

Key Takeaways

• Calan is the legacy brand for verapamil hydrochloride.
• Core patent and regulatory exclusivity periods expired decades ago.
• Generic verapamil is the principal commercial product.
• No significant current Paragraph IV or patent-litigation event drives the market.
• Calan has no biosimilar risk because verapamil is a small molecule.
• Immediate-release products face intense generic competition.
• Extended-release products have greater manufacturing complexity but no visible blocking brand estate.
• Public filings do not disclose standalone Calan revenue.
• The financial outlook is mature, low-growth, and dependent on supply reliability and generic manufacturing costs.
• A commercial relaunch would require formulation, delivery, or clinical differentiation to overcome entrenched substitution.

FAQs About Calan Patent Expiry, Revenue, and Generic Competition

Is Calan still sold as a brand-name drug?

Calan may remain referenced in FDA labeling and pharmaceutical databases, but actual commercial availability varies by strength, formulation, supplier, and distribution channel. Generic verapamil is the dominant market option.

Is verapamil a generic drug?

Yes. Verapamil hydrochloride is widely available as a generic immediate-release and extended-release product, subject to product-specific FDA approvals.

Does Pfizer still make Calan?

Pfizer has historical association with Calan, but public filings do not establish current, material standalone commercial activity for the brand. Product availability should be evaluated through current FDA and wholesaler records.

Can generic verapamil be substituted for Calan SR?

Substitution depends on the approved product, dosage form, strength, and applicable therapeutic-equivalence designation. Calan SR should not be treated as interchangeable with every verapamil product solely because the active ingredient is the same.

Could Calan regain market value through a new patent?

A new patent could protect a genuinely novel formulation, delivery system, manufacturing process, or approved use. It would not restore exclusivity to conventional verapamil tablets by itself, and any new product would need separate FDA approval and commercial differentiation.

References

1. DailyMed. (n.d.). Verapamil hydrochloride and sustained-release verapamil hydrochloride labeling. National Library of Medicine. https://dailymed.nlm.nih.gov/

2. Pfizer Inc. (2024). Annual report on Form 10-K. https://www.pfizer.com/investors/financial-reports

3. U.S. Food and Drug Administration. (n.d.-a). Calan and verapamil hydrochloride prescribing information. Drugs@FDA. https://www.accessdata.fda.gov/scripts/cder/daf/

4. U.S. Food and Drug Administration. (n.d.-b). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

5. U.S. Food and Drug Administration. (n.d.-c). Generic drugs and abbreviated new drug applications. https://www.fda.gov/drugs/generic-drugs.