FASTIN Drug Patent Profile

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When do Fastin patents expire, and when can generic versions of Fastin launch?

Fastin is a drug marketed by Glaxosmithkline and is included in one NDA.

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

DrugPatentWatch^® Litigation and Generic Entry Outlook for Fastin

A generic version of FASTIN was approved as phentermine hydrochloride by ELITE LABS INC on May 30^th, 1997.

Summary for FASTIN

US Patents:	0
Applicants:	1
NDAs:	1
Raw Ingredient (Bulk) Api Vendors:	34
Clinical Trials:	2
Patent Applications:	1,097
DailyMed Link:	FASTIN at DailyMed

Recent Clinical Trials for FASTIN

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
Martin Blomberg Jensen	Phase 2
AstraZeneca	Phase 2

See all FASTIN clinical trials

US Patents and Regulatory Information for FASTIN

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Glaxosmithkline	FASTIN	phentermine hydrochloride	CAPSULE;ORAL	017352-001	Approved Prior to Jan 1, 1982		DISCN	No	No

FASTIN Market Dynamics and Financial Trajectory: Phentermine Brand Analysis

Last updated: August 13, 2026

FASTIN was a prescription brand of phentermine hydrochloride, an older sympathomimetic appetite suppressant used for short-term obesity management. Its commercial position deteriorated after generic phentermine became widely available, while FDA regulation limited long-term use and the brand was discontinued. FASTIN has no meaningful current branded revenue base, no active exclusivity moat, and limited patent relevance. Current commercial value lies in the underlying generic phentermine market, not the FASTIN trademark.

What drug was FASTIN and who marketed it?

FASTIN was a U.S. prescription product containing phentermine hydrochloride. Phentermine is a Schedule IV controlled substance indicated for short-term use as an adjunct to caloric restriction and behavioral modification in obesity treatment.[1]

The brand was associated with King Pharmaceuticals during its later commercial life. Historical prescribing information identified FASTIN as a 30 mg extended-release capsule formulation of phentermine hydrochloride.[2]

FASTIN product profile

Attribute	FASTIN
Active ingredient	Phentermine hydrochloride
Drug class	Sympathomimetic amine anorectic
Primary use	Short-term obesity management
Dosage form	Extended-release capsule
Common strength	30 mg
Regulatory pathway	FDA-approved prescription drug
Controlled-substance status	Schedule IV
Current branded status	Discontinued
Current generic market	Phentermine tablets and capsules remain available
Biologic or biosimilar exposure	None

The brand competed with Adipex-P and generic phentermine. It did not have the clinical or commercial profile of newer chronic obesity drugs such as Wegovy, Zepbound, Saxenda, or Qsymia.

When did FASTIN lose exclusivity and when was it discontinued?

FASTIN’s commercial exclusivity ended when generic phentermine products became broadly available. The product’s economic protection was based primarily on brand recognition, distribution, and formulation positioning rather than a durable patent estate.

FDA records identify FASTIN as discontinued. The discontinuation was not classified as a withdrawal for safety or effectiveness reasons in the manner applied to drugs removed from the market for those grounds.[3] Generic phentermine remains FDA-approved and commercially distributed.

FASTIN exclusivity timeline

Period	Event	Commercial effect
Pre-generic period	FASTIN marketed as a branded phentermine product	Brand pricing and physician familiarity supported sales
Generic-entry period	Generic phentermine tablets and capsules expanded	Price erosion and formulary substitution reduced brand value
Later commercial period	FASTIN ownership and marketing changed within the branded-phentermine market	Limited ability to sustain premium pricing
Discontinuation period	FASTIN withdrawn from commercial distribution	Brand revenue ceased; generic demand continued
Current period	Generic phentermine remains available	Value resides in the molecule, not FASTIN

No current FASTIN exclusivity period protects the product. Any historical regulatory exclusivity has expired, and there is no known live patent position capable of blocking generic phentermine.

What patents protected FASTIN?

FASTIN is not protected by a meaningful active patent estate today. The principal commercial barriers were historical formulation and brand rights, not currently enforceable composition-of-matter patents.

The active ingredient, phentermine hydrochloride, is an established small molecule with a long history of generic availability. Any original compound patent protection expired decades ago. Historical patents associated with specific formulations, manufacturing processes, or controlled-release technologies would also have expired or become commercially irrelevant.

Patent categories relevant to FASTIN

Patent category	Relevance to FASTIN	Current status
Composition-of-matter patent	Applied to the underlying phentermine molecule	Expired
Salt or polymorph patent	Limited relevance for an old molecule	No meaningful current barrier identified
Extended-release formulation patent	Could have supported the 30 mg capsule	Historical protection only
Manufacturing patent	Could affect production efficiency	Not a practical market barrier
Method-of-use patent	Short-term obesity treatment	Expired or commercially nonexclusive
Trademark rights	FASTIN brand name	Does not prevent generic phentermine entry

The absence of a live patent moat explains why generic manufacturers could compete on price and why a branded FASTIN relaunch would face substantial substitution risk.

What is the FDA regulatory status of FASTIN?

FASTIN is not an actively marketed FDA product. Generic phentermine remains approved for short-term obesity treatment. The FDA labeling framework limits phentermine to short-term use, generally interpreted as a few weeks, rather than chronic weight-management therapy.[1]

Phentermine’s controlled-substance classification creates additional compliance requirements. Manufacturers and distributors must meet Drug Enforcement Administration controls covering quotas, recordkeeping, ordering, storage, and distribution.

FDA and regulatory considerations

The principal regulatory constraints are:

• Short-term labeling rather than chronic obesity-treatment labeling.
• Schedule IV controlled-substance requirements.
• Stimulant-related safety monitoring.
• Contraindications involving cardiovascular disease, uncontrolled hypertension, hyperthyroidism, glaucoma, agitation, and certain drug interactions.
• Restrictions on use with monoamine oxidase inhibitors.
• Heightened scrutiny of prescribing, dispensing, and online distribution.

FASTIN has no current FDA commercial position comparable to an active branded NDA franchise. Generic phentermine products carry the continuing regulatory value.

How did generic competition affect FASTIN’s market dynamics?

Generic substitution was the central force in FASTIN’s decline. Phentermine has low manufacturing complexity relative to newer peptide-based obesity medicines. Oral tablets and capsules can be produced by multiple manufacturers, and the product does not require biologic manufacturing, cold-chain distribution, or device assembly.

The resulting market dynamics were unfavorable for a branded product:

1. Generic manufacturers competed on price.
2. Pharmacies substituted generic phentermine under state and payer rules.
3. Physicians had limited clinical reason to prefer FASTIN over generic equivalents.
4. The short-term label reduced the value of long-duration patient retention.
5. Newer obesity medicines shifted clinical attention toward chronic weight management.

FASTIN could have retained limited demand through brand familiarity or a differentiated extended-release profile, but those factors were insufficient to overcome generic substitution.

FASTIN compared with competing obesity drugs

Product	Active ingredient	Market position	Duration of therapy	Patent/commercial profile
FASTIN	Phentermine	Discontinued brand	Short-term	No current brand moat
Adipex-P	Phentermine	Branded phentermine	Short-term	Competes with generics
Generic phentermine	Phentermine	Low-cost standard	Short-term	Multiple suppliers
Qsymia	Phentermine/topiramate	Chronic obesity therapy	Long-term	Combination and formulation rights
Wegovy	Semaglutide	Chronic obesity therapy	Long-term	Strong biologic and device estate
Zepbound	Tirzepatide	Chronic obesity therapy	Long-term	Strong biologic and formulation estate
Contrave	Naltrexone/bupropion	Chronic obesity therapy	Long-term	Combination-product protection

FASTIN’s main competitive disadvantage was not only price. Its label and pharmacology were optimized for short-term use, while the commercial obesity market shifted toward chronic therapies with larger clinical-trial programs and higher reimbursement potential.

What was FASTIN’s financial trajectory?

FASTIN’s standalone financial trajectory cannot be reliably reconstructed from current public-company reporting. King Pharmaceuticals and other historical owners reported product portfolios at varying levels of aggregation, and FASTIN was not consistently disclosed as a separate material reporting segment.

The financial trajectory is nevertheless clear:

• Early brand sales benefited from prescription demand for phentermine.
• Generic entry compressed price and volume.
• Marketing economics weakened as payers and pharmacies favored generic substitution.
• The brand’s value declined as obesity treatment moved toward chronic therapies.
• Discontinuation eliminated branded FASTIN revenue.
• Generic phentermine sales continued but were distributed across multiple manufacturers.

Revenue exposure by business model

Revenue source	Historical FASTIN relevance	Current relevance
Branded prescription sales	High before discontinuation	None or negligible
Generic phentermine sales	None for FASTIN brand	Active for generic manufacturers
Licensing income	No material continuing stream identified	None identified
Manufacturing royalties	No meaningful current stream identified	None identified
OTC FASTIN-branded supplements	Separate commercial category	Must not be attributed to prescription FASTIN

The distinction between prescription FASTIN and products sold under the FASTIN name in the supplement market is material. An OTC product using the FASTIN name may contain different ingredients and does not establish revenue for the discontinued phentermine drug.

Does FASTIN have Orange Book listings or Paragraph IV litigation?

FASTIN has no meaningful current Orange Book position that creates a generic-entry barrier. Its branded discontinuation means that Orange Book status, even where historical listings exist, does not support a live commercial exclusivity strategy.

Paragraph IV litigation is also not a current market issue for FASTIN. Paragraph IV challenges generally arise when an ANDA applicant seeks approval before expiration of listed patents for an active branded product. Because FASTIN is discontinued and its relevant patent period has elapsed, there is no active FASTIN litigation pathway comparable to the disputes surrounding newer obesity medicines.

Litigation and settlement status

No current high-value settlement agreement, active Paragraph IV dispute, or material patent litigation is associated with the discontinued FASTIN brand. Historical disputes involving phentermine products would not create present protection for FASTIN unless tied to a live, enforceable patent, which is not evident from the product’s current regulatory status.

What generic entry risks would affect a FASTIN relaunch?

A relaunch would face immediate and substantial generic-entry risk. Phentermine is widely recognized, inexpensive to manufacture, and available in established generic forms.

The main risks would include:

• Automatic or pharmacist-driven substitution.
• Low reimbursement for a branded short-term product.
• Limited payer incentive to cover the brand.
• Controlled-substance distribution restrictions.
• Competition from Adipex-P and generic phentermine.
• Clinical displacement by GLP-1 and dual incretin therapies.
• Regulatory difficulty in obtaining a differentiated chronic-use label.
• Limited patent protection for the active ingredient.

A relaunch could require a new formulation, delivery system, or combination product. That strategy would create development and regulatory costs, while also exposing the product to formulation-patent challenges and the clinical burden of demonstrating meaningful differentiation.

How strong is the FASTIN patent estate compared with modern obesity drugs?

FASTIN’s patent estate is weak because the underlying molecule is old, genericized, and commercially undifferentiated. Modern obesity drugs have stronger protection because they rely on newer active ingredients, long-acting formulations, injection devices, manufacturing processes, and method-of-use claims.

Patent strength factor	FASTIN	Modern obesity medicines
New active ingredient	No	Often yes
Long remaining patent life	No	Common
Device protection	No meaningful device estate	Often material
Formulation protection	Historical only	Often active
Manufacturing complexity	Low	High for peptide products
Generic substitution risk	Very high	Lower before loss of exclusivity
Biosimilar risk	Not applicable	Relevant to biologic products
Licensing value	Low	Can be significant

Biosimilar risk does not apply directly to FASTIN because phentermine is a small molecule, not a biologic. Generic risk is the relevant threat.

What is the commercial outlook for FASTIN?

The commercial outlook for prescription FASTIN is effectively inactive. The brand does not have a credible standalone growth trajectory, current patent protection, or regulatory exclusivity base.

The underlying phentermine market can remain commercially viable as a low-cost, short-term obesity-treatment segment. Its growth is constrained by the limited label, controlled-substance status, safety considerations, and competition from chronic therapies. Generic manufacturers can earn recurring volume, but the market supports commodity economics rather than branded-pharmaceutical margins.

Key Takeaways

• FASTIN was a discontinued prescription brand of phentermine hydrochloride.
• Generic phentermine, not FASTIN, remains the commercially active product category.
• The relevant FASTIN patent estate is expired or commercially ineffective.
• No current Paragraph IV dispute or settlement creates FASTIN exclusivity.
• FASTIN has no meaningful current branded revenue base.
• The product’s short-term label limited lifetime patient value.
• Generic substitution and newer chronic obesity drugs drove the brand’s decline.
• OTC products using the FASTIN name should not be treated as prescription-phentermine revenue.
• A relaunch would face high generic-entry, reimbursement, and clinical-displacement risk.
• Biosimilar exposure is irrelevant; conventional generic competition is the principal market risk.

FAQs

Is FASTIN the same as Adipex-P?

Both products contain phentermine, but they are separate brands. Generic phentermine competes with both products.

Can patients still obtain FASTIN from pharmacies?

The discontinued prescription FASTIN brand is generally not an active pharmacy product. Pharmacies may dispense generic phentermine or another currently marketed brand when clinically appropriate.

Did FASTIN have a patent on phentermine?

Any original patent protection for phentermine expired long ago. Historical formulation rights do not create current protection for the discontinued brand.

Are FASTIN supplements the same as prescription FASTIN?

No. Products sold as FASTIN supplements may contain different ingredients and are not equivalent to prescription phentermine hydrochloride.

Could a company relaunch FASTIN?

A company could pursue trademark, formulation, or regulatory strategies, but a relaunch would face substantial substitution from generic phentermine and competition from chronic obesity therapies. The historical brand alone would not provide market exclusivity.

References

1. U.S. Food and Drug Administration. (2023). Phentermine hydrochloride prescribing information. FDA.

2. King Pharmaceuticals, Inc. (Historical). FASTIN (phentermine hydrochloride) extended-release capsules prescribing information. U.S. Food and Drug Administration labeling archive.

3. U.S. Food and Drug Administration. (n.d.). Orange Book: Approved drug products with therapeutic equivalence evaluations and discontinued drug product list. FDA.