Last updated: August 27, 2026

Pentothal is the former U.S. brand name for thiopental sodium, an ultra-short-acting barbiturate anesthetic. Its commercial trajectory is defined by patent expiry, substitution by propofol and other induction agents, manufacturing disruption, and the withdrawal of major U.S. supply. Pentothal has no meaningful remaining U.S. patent moat, no active biosimilar issue, and limited disclosed financial value. Its residual market is concentrated in selected international, hospital, veterinary, emergency, and specialized procedural settings.

What is Pentothal and how is thiopental sodium used?

Pentothal is an injectable formulation of thiopental sodium used primarily for the induction of general anesthesia. It has also been used for short procedures, control of refractory seizures, and reduction of intracranial pressure in selected critical-care settings. The drug is administered intravenously and has a rapid onset because of its high lipid solubility.

The active ingredient is thiopental sodium, a barbiturate. The drug is supplied as a sterile powder that must be reconstituted before injection. The formulation is materially different from ready-to-use injectable anesthetics such as propofol.

Attribute	Pentothal
Active ingredient	Thiopental sodium
Drug class	Ultra-short-acting barbiturate
Dosage form	Sterile powder for injection
Primary use	Induction of general anesthesia
U.S. brand status	Legacy brand; no meaningful current U.S. commercial presence
Patent position	Core composition and use patents expired
Main substitutes	Propofol, etomidate, ketamine, methohexital
Biosimilar exposure	None; Pentothal is a small-molecule drug
Current commercial profile	Niche and geographically limited

FDA labeling identifies thiopental as an intravenous anesthetic with rapid onset and short initial duration of action. The label also identifies important risks, including respiratory depression, cardiovascular depression, laryngospasm, and contraindications in acute porphyria and certain hypersensitivity settings.[1]

When did Pentothal lose exclusivity?

Pentothal lost meaningful market exclusivity decades ago. Thiopental was introduced before the modern Hatch-Waxman framework, and any relevant composition, formulation, or use patents associated with the original product have long expired.

Exclusivity category	Pentothal status
Original compound exclusivity	Expired
U.S. composition patents	Expired
Formulation patents	Expired or commercially irrelevant
Method-of-use patents	Expired or commercially irrelevant
FDA new chemical entity exclusivity	Not applicable to current market
Orphan exclusivity	None identified
Pediatric exclusivity	None identified
Biosimilar exclusivity	Not applicable
Current patent cliff	No material future cliff

The present commercial constraint is supply economics, not intellectual-property protection. Any qualified manufacturer able to satisfy FDA or local regulatory requirements can compete through generic or legacy-product pathways, subject to market-specific registration requirements.

What patents protect Pentothal and thiopental sodium today?

No active U.S. patent estate appears to protect the basic thiopental sodium molecule or the conventional Pentothal injectable powder. The product is a mature small molecule, and the original protection period has expired.

Are there formulation patents for Pentothal?

Conventional thiopental sodium is a reconstituted injectable powder. Its formulation technology is established and relatively simple compared with modern lipid emulsions, liposomal products, depot injections, or device-enabled delivery systems.

Potentially protectable subject matter could include:

Modified reconstitution systems
Stabilized injectable formulations
Novel packaging
Ready-to-use presentations
Alternative salts or prodrugs
Drug-delivery devices
Manufacturing improvements

No such modern formulation platform has produced a recognized U.S. commercial franchise comparable with propofol emulsions or proprietary drug-delivery systems. A new formulation would require independent patent analysis and FDA approval, but it would compete against inexpensive generic anesthetics in a price-sensitive hospital market.

How strong is the Pentothal patent estate?

The patent estate is commercially weak. Its principal characteristics are:

No active core-molecule protection.
No meaningful Orange Book patent barrier.
No regulatory exclusivity that prevents generic competition.
No differentiated delivery technology supporting premium pricing.
Limited incentive for patent-supported reformulation because substitute products are widely available.

What is the FDA regulatory status of Pentothal?

Pentothal’s U.S. regulatory status is best characterized as legacy and commercially inactive rather than as a protected branded product. Thiopental products have historically been approved for injection, but major branded supply in the United States was discontinued.

FDA’s Drugs@FDA and Orange Book systems distinguish between discontinued products and products withdrawn for safety or effectiveness reasons. Discontinuation alone does not establish a safety withdrawal. Pentothal’s market exit was associated primarily with commercial and manufacturing factors, including supply interruption and the loss of a reliable U.S. supplier.[2][3]

What is the Orange Book status of Pentothal?

The Orange Book does not create a current patent barrier for Pentothal. Any discontinued listing does not restore exclusivity or prevent approval of another thiopental sodium product.

The practical Orange Book analysis is:

Orange Book issue	Assessment
Active listed patent blocking generic entry	No material barrier identified
Paragraph IV exposure	Low for the legacy brand because core patents are expired
Reference listed drug relevance	Limited by product discontinuation and market availability
30-month stay risk	Not a central current risk
Brand-generic litigation posture	Minimal
Current regulatory value	Historical rather than defensive

Why did Pentothal lose the U.S. market?

Pentothal’s U.S. decline resulted from a combination of clinical substitution and supply-side deterioration.

Clinical substitution

Propofol became the dominant induction agent in many operating-room settings because of rapid recovery, broad familiarity, and widespread availability. Etomidate gained use where cardiovascular stability is a priority. Ketamine retained a role in trauma, emergency medicine, and patients requiring analgesia or sympathetic stimulation. Methohexital remained relevant in certain procedural and electroconvulsive therapy settings.

Thiopental continued to offer advantages in selected cases, including low cost and established use in neuroanesthesia. Those advantages did not offset the broader operational convenience and purchasing availability of substitute products.

Manufacturing and supply interruption

Hospira, a major supplier of injectable hospital drugs, stopped producing thiopental in the United States after manufacturing and supply problems. The resulting shortage exposed the weakness of a low-volume product with limited manufacturing redundancy. FDA and professional pharmacy organizations documented the shortage and its effect on anesthesia practice.[2][4]

The economics are difficult for manufacturers:

Low unit price limits gross-margin potential.
Sterile injectable production has high quality and compliance costs.
Hospitals can substitute other induction agents.
Demand is fragmented across countries and specialties.
Manufacturing interruptions can make the product commercially unattractive.
Regulatory maintenance costs continue even when annual volume is low.

How does Pentothal compare with propofol, etomidate, and ketamine?

Pentothal competes in a mature intravenous induction market where clinical preference and supply reliability matter more than patent differentiation.

Drug	Main commercial advantage	Main limitation versus Pentothal	Market position
Propofol	Rapid recovery and broad availability	Cardiovascular and respiratory depression; emulsion handling	Primary substitute in many operating rooms
Etomidate	Relative cardiovascular stability	Adrenal suppression concerns; myoclonus	Emergency and high-risk induction
Ketamine	Analgesia, airway reflex preservation, hemodynamic support	Psychotomimetic effects and variable recovery	Emergency, trauma, and procedural use
Methohexital	Established procedural and ECT use	Barbiturate class limitations	Niche procedural anesthetic
Thiopental	Rapid onset, low acquisition cost, established neuroanesthesia use	Supply scarcity, barbiturate risks, limited commercial availability	Residual and regional niche

Pentothal’s competitive weakness is not primarily clinical inferiority in every use case. It is the combination of substitution, procurement risk, and unreliable availability.

What market dynamics affect Pentothal revenue?

Pentothal revenue has followed a long-term contraction curve rather than a conventional patent-cliff pattern.

Historical financial trajectory

The likely trajectory is:

Period	Commercial condition	Financial effect
Early commercialization	Broad use in surgical anesthesia	Strong product demand
Generic expansion	More suppliers and lower prices	Volume retained; price erosion begins
Propofol adoption	Progressive clinical substitution	Volume and hospital share decline
U.S. manufacturing disruption	Shortage and withdrawal of major supply	Revenue collapses in the U.S.
Current niche phase	Limited international and institutional use	Low, fragmented revenue

Public company filings generally do not report Pentothal revenue as a standalone line item. Where thiopental is included in a broader hospital injectable portfolio, the financial contribution is not separately quantified. The product should therefore be treated as a low-value legacy asset rather than as a material driver of pharmaceutical revenue.

Revenue exposure for manufacturers

Pentothal can have strategic value without producing significant revenue. A manufacturer may retain or acquire the product for:

Portfolio completeness in hospital injectables
Government or public-health procurement
Regional anesthesia supply contracts
Institutional continuity requirements
Manufacturing utilization
Cross-selling with other injectable products

The product is unlikely to justify substantial standalone commercial investment in the United States unless a supplier can secure stable procurement contracts or capture a shortage-driven premium.

Which companies have supplied or challenged Pentothal?

Pentothal and thiopental sodium have been associated with several manufacturers and distributors over time, including Abbott Laboratories and Hospira in the United States, with other regional suppliers active outside the United States.

The competitive structure has generally been fragmented:

Original branded supply was associated with Abbott.
Hospira became a significant U.S. injectable supplier.
International manufacturers have continued to supply thiopental in selected markets.
Generic competition is possible because core patents have expired.
No current challenger needs to overcome a meaningful patent estate.

There is no major active Paragraph IV campaign comparable with patent disputes involving high-revenue branded medicines. The commercial contest is based on manufacturing capability, regulatory registration, procurement access, and dependable supply.

What patent litigation and settlement agreements affect Pentothal?

No major active U.S. patent litigation or settlement agreement is central to Pentothal’s current market position. The product’s primary patents are too old to support a current exclusionary strategy.

The absence of litigation is itself commercially relevant. A generic entrant would more likely face:

FDA application and manufacturing requirements
Sterile injectable inspection risk
Drug-shortage procurement dynamics
Hospital formulary substitution
Supply-chain and raw-material constraints

It would be less likely to face:

A branded patent lawsuit
A Paragraph IV 30-month stay
A patent settlement delaying launch
A royalty-bearing license to the original brand owner

What generic launch risks exist for thiopental sodium?

Generic entry is legally straightforward but commercially difficult. The key risks are operational.

Regulatory and manufacturing barriers

Thiopental sodium requires sterile injectable manufacturing, validated aseptic processes, reliable active pharmaceutical ingredient supply, and compliance with current good manufacturing practice. FDA action against a manufacturing site could eliminate supply from a small market quickly.

Market and pricing barriers

A new entrant would face low expected pricing and uncertain volume. Propofol, etomidate, and ketamine are established substitutes, limiting the ability to raise prices even when thiopental is in shortage.

Launch scenarios

Scenario	Likely result
U.S. re-entry by a generic manufacturer	Low-volume institutional product with limited brand value
Shortage-driven launch	Temporary pricing improvement, followed by normalization
Government-backed supply contract	More durable market access
Reformulated premium product	Possible differentiation, but substantial clinical and regulatory burden
International niche expansion	More viable than broad U.S. relaunch if local demand persists

Does Pentothal face biosimilar or biologic competition?

No. Pentothal is a chemically synthesized small-molecule drug, not a biologic. Biosimilar pathways under the Public Health Service Act do not apply. Competition occurs through generic-drug and local pharmaceutical registration frameworks.

This distinction reduces regulatory complexity relative to biologics but also removes the possibility of biologic-style interchangeability barriers, extended exclusivity, or complex manufacturing differentiation.

What geographic markets still use thiopental?

Thiopental remains more commercially relevant outside the United States, although availability varies by country and institution. It may be retained for:

General anesthesia induction
Neuroanesthesia
Pediatric anesthesia in selected settings
Refractory status epilepticus
Intracranial pressure management
Veterinary anesthesia
Government or military medical supply

Geographic value depends on local anesthesiology practice, procurement policy, competing products, regulatory registration, and whether a manufacturer maintains an approved sterile injectable facility.

The product’s international opportunity is therefore regional rather than global. A country may retain demand while neighboring markets have fully transitioned to propofol or other agents.

What manufacturing and intellectual-property barriers remain?

The principal barrier is sterile manufacturing, not intellectual property.

Barrier	Current importance
Core patent protection	Low
Formulation patent protection	Low
API sourcing	Moderate
Sterile injectable capacity	High
FDA or local inspection compliance	High
Hospital contracting	Moderate to high
Clinical substitution	High
Product shortage exposure	High
Brand loyalty	Low
Reimbursement leverage	Low

A potential manufacturer would need to solve supply reliability and market access before relying on patent strategy. A novel formulation could create intellectual-property value, but it would require clear clinical or operational advantages over propofol and other available induction agents.

What is the outlook for Pentothal’s financial trajectory?

Pentothal’s base-case outlook is stable at a low level, with limited prospects for material revenue growth. The product may generate episodic value during shortages or through specialized contracts, but a broad return to its historic U.S. market is unlikely.

The investment case is strongest for a manufacturer that already has:

Approved sterile injectable capacity
Thiopental API access
Existing hospital distribution
International registrations
Government procurement relationships
A broader anesthetic portfolio

The investment case is weak for a company that would need to build manufacturing capacity or create a new commercial organization for thiopental alone.

Key Takeaways

Pentothal is the legacy brand for thiopental sodium, an ultra-short-acting intravenous barbiturate anesthetic.
Core patents and any meaningful exclusivity have expired.
No active U.S. patent estate materially blocks generic entry.
Pentothal has no biosimilar exposure because it is a small-molecule drug.
U.S. commercial decline resulted from propofol substitution, supply disruption, and weak sterile-injectable economics.
Public filings do not generally disclose Pentothal revenue separately.
Current value is concentrated in niche international, institutional, veterinary, and specialized clinical markets.
Manufacturing reliability, regulatory compliance, and procurement access are more important than patent protection.
A new U.S. entrant would face low prices, substitute products, and uncertain volume.
The product is a legacy portfolio asset, not a high-growth pharmaceutical franchise.

FAQs about Pentothal market and patent status

Is Pentothal still sold in the United States?

Pentothal is not a meaningful current U.S. commercial brand. Thiopental sodium availability has been affected by discontinuation and supply shortages, while other induction agents remain widely used.

Can a company launch generic thiopental without a Pentothal license?

Because the core intellectual-property protection has expired, a company generally would not need a license from the original brand owner. It would still need to satisfy applicable FDA approval, manufacturing, labeling, and supply requirements.

Why did hospitals replace Pentothal with propofol?

Propofol became more widely available and is associated with rapid induction and recovery. Hospital purchasing and anesthesia protocols also favored a dependable supply of established alternatives.

Could a new thiopental formulation obtain patents?

Yes. A genuinely novel formulation, delivery system, packaging configuration, or manufacturing process could potentially receive patent protection if it satisfies patentability requirements. The commercial value would depend on proving a meaningful clinical or operational advantage.

Is thiopental used in veterinary medicine?

Thiopental has historical and continuing use in selected veterinary settings, but availability varies by jurisdiction. Veterinary demand is unlikely to support the historical scale of the human anesthesia market on its own.

References

U.S. Food and Drug Administration. (n.d.). Pentothal sodium injection prescribing information. FDA labeling database.
U.S. Food and Drug Administration. (n.d.). Drug shortages: Thiopental sodium injection. FDA Drug Shortages Database.
U.S. Food and Drug Administration. (n.d.). Drugs@FDA and Orange Book: Approved drug products with therapeutic equivalence evaluations. U.S. Department of Health and Human Services.
American Society of Health-System Pharmacists. (n.d.). Drug shortages: Thiopental sodium. ASHP Drug Shortage Resource Center.
U.S. Food and Drug Administration. (n.d.). Generic drugs and abbreviated new drug applications. U.S. Department of Health and Human Services.

US Patents:	0
Applicants:	1
NDAs:	1
Raw Ingredient (Bulk) Api Vendors:	11
Clinical Trials:	3
Patent Applications:	1,744
DailyMed Link:	PENTOTHAL at DailyMed

Sponsor	Phase
Saint Vincent's Hospital, Korea	N/A
TC Erciyes University	Phase 4
Oslo University Hospital	Phase 4

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Abbott	PENTOTHAL	thiopental sodium	SUSPENSION;RECTAL	011679-001	Approved Prior to Jan 1, 1982		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Exclusivity Expiration

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