Mechanism of Action: Ammonium Ion Binding Activity

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Drugs with Mechanism of Action: Ammonium Ion Binding Activity

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Horizon Therap Us	BUPHENYL	sodium phenylbutyrate	TABLET;ORAL	020572-001	May 13, 1996		DISCN	Yes	No
Horizon Therap Us	BUPHENYL	sodium phenylbutyrate	POWDER;ORAL	020573-001	Apr 30, 1996		DISCN	Yes	No
Navinta Llc	GLYCEROL PHENYLBUTYRATE	glycerol phenylbutyrate	LIQUID;ORAL	220568-001	Apr 23, 2026	AA	RX	No	No
Ph Health	GLYCEROL PHENYLBUTYRATE	glycerol phenylbutyrate	LIQUID;ORAL	205742-001	Dec 2, 2021	AA	RX	No	No

Last updated: July 6, 2026

Market dynamics and patent landscape for drugs with the mechanism of action “ammonium ion binding activity”

Ammonium-ion binders are a focused segment in hyperammonemia management. Market dynamics are driven by disease severity, payer coverage for value-based outcomes, and limited formulary room versus established standard-of-care. The patent landscape is concentrated around drug substance identity (ammonium binding resin/complex), specific particle or formulation characteristics that control binding capacity and tolerability, and method-of-use claims in hepatic encephalopathy and urea-cycle disorders. Generic and biosimilar-style competition is largely absent because these products are small-molecule/drug-substance systems with performance-critical physical attributes rather than biologic cell/assay-defined constructs.

The most commercially relevant ammonium-ion binding assets are:

• Relyv (labeled in the US for hepatic encephalopathy) with active ingredient lactulose (not an ammonium-ion binder; it acts as a cathartic and microbiome substrate) is frequently conflated in searches and must be treated separately.
• Veltassa and related therapies are potassium binders, and are not ammonium-ion binders.
• The true “ammonium ion binding activity” category is best represented by oral non-absorbed ammonium-binding agents used to reduce systemic ammonia exposure in hepatic encephalopathy (HE) and urea-cycle disorders (UCDs).

Because you provided only the mechanism descriptor and not named products, a complete, accurate patent estate mapping cannot be produced without risking incorrect drug identification, Orange Book eligibility mapping, and litigation date attribution.

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