KANTREX Drug Patent Profile

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

Kantrex is a drug marketed by Apothecon and is included in six NDAs.

The generic ingredient in KANTREX is kanamycin sulfate. There are five drug master file entries for this compound. Additional details are available on the kanamycin sulfate profile page.

Summary for KANTREX

US Patents:	0
Applicants:	1
NDAs:	6

US Patents and Regulatory Information for KANTREX

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Apothecon	KANTREX	kanamycin sulfate	CAPSULE;ORAL	060516-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Apothecon	KANTREX	kanamycin sulfate	INJECTABLE;INJECTION	061655-003	Approved Prior to Jan 1, 1982		DISCN	No	No
Apothecon	KANTREX	kanamycin sulfate	INJECTABLE;INJECTION	061655-002	Approved Prior to Jan 1, 1982		DISCN	No	No
Apothecon	KANTREX	kanamycin sulfate	INJECTABLE;INJECTION	062564-002	Sep 21, 1984		DISCN	No	No

KANTREX (Drug fundamentals, exclusivity, patent landscape, and investment risk by FDA pathway)

Last updated: July 30, 2026

KANTREX is an established brand-name prescription drug with a defined U.S. regulatory history and an enforceable intellectual-property perimeter that shapes generic and challenger entry timing. From an investment standpoint, fundamentals hinge on: (1) remaining patent and regulatory exclusivity, (2) whether any Paragraph IV challenges are active or likely, (3) product lifecycle status (newness versus post-launch erosion), and (4) payer positioning and market concentration. Without the specific active ingredient(s), dosage form(s), and marketing authorization identifiers (NDC/ANDA/BLA) for KANTREX, a complete and accurate patent-to-exclusivity-to-entry investment model cannot be produced.

What is KANTREX’s active ingredient and what market does it target?

Featured snippet answer: A correct investment thesis for KANTREX requires the active ingredient and the therapeutic indication, because patent estates, exclusivity blocks, and generic risk differ materially across indications and dosage forms.

What therapeutic class does KANTREX belong to?

• Therapeutic class determines:
  • typical payer structures and pricing pressure
  • likelihood of formulary tier placement and step edits
  • sensitivity to safety-driven labeling changes
  • dependence on REMS or special distribution channels

Which dosage form(s) and strength(s) drive revenue risk?

• Patent protection often varies by:
  • solid oral versus injectable versus topical
  • immediate-release versus extended-release
  • combination formulations (API set or fixed-dose combinations)
• Generic entry risk is usually highest for:
  • single-API, off-patent oral dosage forms with established bioequivalence
  • products without tightly protected formulation or manufacturing steps

Which company markets KANTREX in the U.S.?

• Brand holder identity affects:
  • likelihood of active enforcement against generics
  • willingness to license or settle challenges
  • probability of platform expansion using the same API

What patents protect KANTREX and how strong is the patent estate?

Featured snippet answer: Patent strength is measured by the number of enforceable Orange Book-listed patents by category (composition, method of use, formulation, and manufacturing), plus whether key claims have survived challenges and remain unexpired.

How many KANTREX patents are typically listed for protection?

A full count requires the drug’s Orange Book listing(s). In the absence of the active ingredient and FDA application identifier for KANTREX, an accurate enumerated patent table cannot be produced.

What patent categories usually block generic substitution?

For small-molecule branded drugs, generic entry is blocked by at least one unexpired claim in one of these groups:

• composition of matter (active ingredient or salts)
• formulation patents (excipients, particle size, coatings, gelling systems)
• method of use (indication, dosing regimen)
• manufacturing/process claims (steps with critical parameters)

Are there known patents that expired already, leaving “thin” protection?

Investment-grade analysis requires:

• earliest composition patent expiration
• whether later-expiring formulation or method-of-use patents exist
• whether pediatric exclusivity or other regulatory extensions apply

When does KANTREX lose exclusivity in the U.S.?

Featured snippet answer: Loss of exclusivity depends on both patent expiry and FDA exclusivity (NCE, 3-year/5-year/7-year exclusivity, patent term adjustments, and pediatric exclusivity), plus Orange Book-listed patent status.

What exclusivity buckets typically govern entry?

• 5-year exclusivity: when an NDA has a new chemical entity or new active ingredient (varies by application facts)
• 7-year exclusivity: new indication with substantial clinical investigations supporting an NDA supplement (varies by facts)
• 3-year exclusivity: changes not qualifying for longer statutory benefits
• exclusivity extensions: patent term adjustment and pediatric exclusivity

How do patent term adjustments change the timeline?

• Patent term adjustment (PTA) can push the effective expiration out by months to years.
• Litigation and delays can create additional real-world entry windows beyond headline expiration dates.

What does “ready-to-market” generic timing look like?

A practical entry model ties:

• paragraph IV filing window (when ANDA can be submitted)
• 30-month stay (if applicable)
• settlement scenario versus adjudicated non-infringement/invalidity

What generic entry risks exist for KANTREX?

Featured snippet answer: Generic risk is driven by (1) whether any Orange Book patents remain unexpired at the time of FDA approval, and (2) whether challengers file Paragraph IV and win on invalidity/non-infringement.

Which generic companies are likely to challenge KANTREX?

• Company-level risk depends on:
  • challenger track record in similar APIs
  • whether proposed labels could carve out protected indications
  • manufacturing feasibility and stability data

What are the usual Paragraph IV pathways and outcomes?

• If Paragraph IV is filed and the NDA is sued within statutory time:
  • a 30-month stay typically applies
  • settlement can narrow entry date
• If the court rules for the generic:
  • entry can occur immediately after the legal decision and FDA readiness

What label carve-out strategies could avoid method-of-use patents?

• If KANTREX has method-of-use patents by indication:
  • generics may attempt to omit protected uses
  • label limitation can preserve exclusivity for the protected regimen
• Investment impact is high because carve-outs can reduce addressable market for generics, sustaining brand pricing longer.

How does KANTREX compare with other drugs in the same therapeutic class?

Featured snippet answer: Competitive durability depends on switching friction, dosing convenience, safety profile, and payer coverage, not only patent life.

What differentiators matter for payer coverage?

• formulary preference drivers:
  • lower total cost of care
  • lower monitoring burden
  • fewer adverse events
  • demonstrable comparative effectiveness claims in label

How does KANTREX’ pricing pressure evolve post-generic?

• In mature branded products:
  • the biggest risk is not first generic entry
  • it is the pace of subsequent “at-risk” generics and line-extension cannibalization

What is the risk of therapeutic class displacement?

• If new drugs with superior efficacy enter:
  • utilization can shift even while KANTREX remains on patent
• If safety signals emerge:
  • labeling restriction can reduce market access.

What is the Orange Book status of KANTREX?

Featured snippet answer: Orange Book status determines which patents must be carved around or invalidated for an ANDA to be approved.

What does Orange Book listing tell investors?

For each Orange Book patent, key decision inputs are:

• patent number
• expiration date
• patent type (e.g., “P” for composition of matter, “A” for method of use, “B” for formulation)
• listed NDA/strength/dosage form

Are there multiple NDAs or dosage forms for KANTREX?

• Multi-NDA portfolios can create staggered generic risk.
• Investors should model:
  • which SKU carries the majority of revenue
  • whether “high-revenue SKU” protection is thicker than others.

What KANTREX patent litigation affects generic approval timing?

Featured snippet answer: Litigation drives whether challengers face a 30-month stay, negotiate a design-around, or launch “at risk.”

What lawsuits typically determine entry dates?

• infringement suits filed by brand holder
• counterclaims for invalidity and non-infringement
• settlements with stated entry dates and payment terms

What settlement terms change financial outcomes?

• settlement entry dates can:
  • delay generic launches beyond statutory timing
  • allow partial launches with label carve-outs
• settlement scope matters:
  • number of patents resolved
  • number of strengths and dosage forms covered
  • geographic territory (U.S. only for Hatch-Waxman, but parallel actions can exist in other jurisdictions)

What is the current litigation posture?

A litigation timeline requires docket-linked data and Orange Book patent mapping. Without the active ingredient and FDA identifier for KANTREX, litigation details cannot be verified.

What is the FDA regulatory status of KANTREX (NDA, ANDA, labeling updates)?

Featured snippet answer: Regulatory status indicates whether the product is mature, has pending supplements, or faces safety or labeling constraints that change demand.

What is the approval pathway for KANTREX?

• If an NDA:
  • label breadth and exclusivity structure are key
• If a change is via an sNDA:
  • it can add or remove exclusivity depending on supplement status

Are there REMS or special risk controls?

• If REMS exists:
  • it increases barriers to distribution
  • it can influence generic adoption velocity

Are there recent label changes?

• Safety or efficacy changes can:
  • reduce TAM
  • increase monitoring cost
  • raise prescribing friction.

How would an investment-grade generic launch scenario model KANTREX revenue?

Featured snippet answer: Revenue risk is best modeled as a staged erosion curve linked to (1) first generic entry date, (2) number of authorized generics or entrants, and (3) payor switching and rebate changes.

Scenario A: No generic entry for the next exclusivity window

• Brand maintains:
  • higher net price and lower rebate pressure
• Primary risks:
  • class competition
  • payer formulary revisions
  • safety-driven declines

Scenario B: Single generic entry after 30-month stay or settlement

• Typical pattern:
  • market share begins shifting, then stabilizes depending on contracting
• Primary risks:
  • faster-than-expected subsequent entrants
  • increased pharmacy substitution

Scenario C: Multiple generics launch rapidly post-expiration

• Net pricing pressure escalates:
  • margins compress
  • marketing support may be reduced
• Primary risks:
  • loss of premium formulary positioning
  • inventory channel stocking and rebate renegotiations

Key takeaways for investors in KANTREX

1. A defensible investment thesis must map KANTREX’s active ingredient, indication, and dosage form to Orange Book-listed patents and FDA exclusivity.
2. Generic risk is determined by which patent categories remain unexpired (composition, formulation, method-of-use) at the time challengers could file and at the time courts or settlements resolve.
3. Patent litigation posture, including Paragraph IV filings and settlement scope, usually dominates near-to-mid-term entry timing more than headline patent expiration dates alone.
4. Revenue durability depends on payer contracting dynamics and competitive displacement in the same therapeutic class, not only on patent life.
5. A high-quality model is SKU-based: protect the high-revenue strength and dosage form first, because generic erosion spreads fastest from the largest revenue center.

FAQs

1) What is KANTREX’s exclusivity expiration date in the U.S.?
Exclusivity expiration must be computed from Orange Book patent expirations plus any statutory FDA exclusivity and extensions, mapped to KANTREX’s specific NDA and dosage form.

2) How many Paragraph IV ANDA challenges exist for KANTREX?
This depends on active Orange Book patent listings and public litigation records tied to the specific KANTREX application and strengths.

3) What patent types most often block generic approval for KANTREX?
For typical branded small molecules, the most blocking are composition-of-matter, formulation, and method-of-use patents that are listed against the relevant strength and dosage form.

4) Does KANTREX have formulation patents that prevent simple bioequivalence substitution?
If KANTREX has “formulation” or manufacturing-process patents listed, generics may face design-around requirements even when bioequivalence can be demonstrated.

5) Will biosimilars matter for KANTREX competitive risk?
Biosimilar risk only applies if KANTREX is a biologic; for standard small-molecule KANTREX products, the risk is from chemical generics and authorized generics rather than biosimilars.

References (APA)

1. U.S. Food and Drug Administration. Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations. FDA.
2. FDA Hatch-Waxman framework. U.S. Food and Drug Administration.
3. U.S. Code Title 21 (Hatch-Waxman provisions). U.S. Government Publishing Office.